colon adenocarcinoma
Introduction
Introduction to colon adenocarcinoma Colon adenocarcinoma is a common malignant tumor of the colon glandular epithelium. It belongs to one of the various pathological types of colon cancer. It is the most common type of colon cancer. The rest are classified with mucinous adenocarcinoma and undifferentiated carcinoma. The form may be polypoid, ulcer type or the like. basic knowledge The proportion of illness: 0.002% Susceptible people: no special people Mode of infection: non-infectious Complications: intestinal obstruction
Cause
Colon adenocarcinoma
The cause of this disease is not clear, but the occurrence of this disease is related to the diet of poly-least and less fiber, adenoma-like polyps, schistosomiasis, non-specific ulcerative colitis, bacterial dysentery of colon adenocarcinoma, amoebic disease, etc. The incidence of the disease is closely related. About 40% of colon cancer is distributed in the rectum and rectum sigmoid colon, and the rest are distributed in the sigmoid colon, cecum, ascending colon, descending colon, transverse colon, liver and spleen.
Prevention
Colon adenocarcinoma prevention
Colon cancer is the third leading cause of death in the world. Although the treatment of colon cancer has made great progress, the 5-year survival rate of advanced colon cancer has not changed much. Therefore, the significance of colon cancer prevention is becoming more and more important.
According to the multi-stage theory of the cancer process. The occurrence of colon cancer also undergoes three stages of initiation, promotion, and progression. In morphology, it is characterized by normal mucosa hyperplasia adenoma formation adenoma carcinogenesis infiltration and metastasis. If the cancer of familial adenomatous polyposis becomes a model, the natural history of colon cancer can be as long as 10 to 35 years. This provides a very favorable opportunity for the prevention of colon cancer. According to different interventions at different stages of the natural history of colon cancer, China has developed the following prevention strategies.
1, primary prevention
Eliminate or reduce the exposure of the large intestinal mucosa to carcinogens before tumor formation, inhibit or block the carcinogenesis of epithelial cells, thereby preventing tumorigenesis. These include dietary interventions, chemoprevention, and treatment of precancerous lesions.
(1) Dietary intervention
British scholar Burkitt has long pointed out that colon cancer is a "modern disease" associated with modern lifestyles and diet types. A large number of epidemiological studies, especially immigration epidemiological studies, show that colon cancer has excessive onset and energy intake, obesity, excessive intake of saturated fatty acids, decreased physical activity, dietary fiber and micronutrients (vitamins A, E, C, trace element selenium and calcium) are associated with insufficient intake.
Dietary fiber is the most studied in terms of dietary intervention. As early as the 1960s and 1970s, Burkitt found that colon cancer was very rare among African blacks, and the African aborigines' diet contained a lot of dietary fiber, so he proposed that the high-fiber diet is a hypothesis for colon cancer protection factor. Subsequent studies have shown that dietary fiber can dilute or absorb carcinogens in the feces, speeding up the passage of food residues in the intestines, thereby reducing the exposure of intestinal mucosa to carcinogens in food. At the same time, dietary fiber can also protect colon cancer by changing the metabolism of bile acid, lowering the pH of the colon and increasing the production of short-chain fatty acids.
Early observational epidemiological studies and case-control studies have shown that dietary fiber has a protective effect on colon cancer with increasing intake. For example, Howe collected data from 13 case-control studies with a total of 5,287 patients and 10,470 controls, and found that 12 of these studies supported a negative correlation between dietary fiber intake and colon cancer incidence; The intake of C and beta carotene has only a small negative correlation with the onset of colon cancer.
In the prospective clinical intervention trials, such as the occurrence of colon cancer as an "end-point", long-term follow-up is required to reach a definitive conclusion, so some people advocate the use of precancerous lesions - adenoma (or recurrence) As an indicator of the risk of colon cancer, in recent years, some "intermediate markers" have been advocated to evaluate the effects of interventions, in order to greatly shorten the time required for intervention trials.
The most commonly used meta-term index is the rectal mucosal crypt sputum-labeled thymidine (HTdR) incorporation index (LI), which reflects the proliferation of cells. Studies have confirmed that LI is associated with colon cancer risk and has been widely used in diets. Evaluation of the intervention trial. In recent years, immunohistochemical assays have been established to detect the incorporation of brominated deoxyuridine (Br-UdR) and proliferating cell nuclear antigen (PCNA). These assays do not require radionuclides to reflect cell proliferation. Other intermediate indicators for evaluation included microscopic examination of abnormal crypts and microadenomas, as well as protein kinase C (PKC) and ornithine decarboxylase (ODC) activities.
For example, Alberts et al. added a 13.5 g/d wheat bran fiber to a group of 17 patients with colon cancer after surgery. The rectal crypt LI was used as an indicator, and 6 of the 8 patients with high LI were observed to have a significant decrease in LI. The total decline rate of the whole group was 22% (P<0 001="" reddy="" 10g="" d="" decosse="" 58="" fap="" 1="" 4="">11g /d wheat bran can reduce the recurrence of adenoma, while vitamin C (4g / d) and vitamin E (400mg / d) have no such effect.
However, large-scale prospective trials completed in recent years have failed to confirm the protective effects of dietary fiber. Schatzkin et al reported that 2079 patients with a history of colon cancer were randomly divided into two groups, one group was given dietary advice and received a low-fat, high-fiber diet, and the other group was kept on a regular diet and was not consulted. Colonoscopy was found 1 to 4 years later. There was no difference in the recurrence rate of colon adenocarcinoma between the two groups. A randomized controlled study by Albert et al. in Arizona recently showed that 1429 patients with a history of colorectal adenoma were given low fiber (adding 2.0 g of wheat bran/d) and high fiber (adding 13.5 g of wheat bran/d) diet. The recurrence rate of colorectal adenomas was the same in both groups. The results were also supported by a large sample prospective cohort study by Fuchs and Giovannucci et al. This is a health survey of 121,700 registered nurses (all women) in the United States since 1976. From 1980 onwards, the diet of each woman was investigated in a questionnaire form, and 88,777 subjects (34 to 59 years old) who met the study criteria were followed up until 1996. In the 16-year study group, 787 cases of colon cancer occurred, and 27,530 people underwent colonoscopy, and 1012 cases of colorectal adenoma were found. After analyzing the above data, after adjusting for age, total energy intake and other known risk factors, it was found that dietary fiber intake was not associated with the risk of colon cancer, and the highest fiber intake was compared with the lowest 20%. The relative risk of colon cancer was 0.95 (95% CI: 0.73 to 1.25), and no dietary fiber intake was found to be associated with colon cancer.
The Cochrane Center in Oxford, England, collected a randomized controlled trial of dietary fiber interventions until October 2001. Systemic reviews and meta-analysis were used to evaluate dietary fiber for the reduction and recurrence of colorectal adenomas. And the protective effect on colon cancer. There were 5 clinical trials that met the analytical criteria, including 4349 subjects. The analysis found that the relative risk of colorectal adenomas in the intervention group and the control group was observed by dietary supplementation with wheat bran or high-fiber diet for 2 to 4 years. ) is 1.04 (95% CI: 0.95 to 1.13), and the risk difference (RD) is 0.01 (95% CI: 0.02 to 0.04). The authors conclude that "the randomized controlled clinical trial to date does not have sufficient evidence to support increased dietary fiber intake and may reduce the occurrence or recurrence of colorectal adenomas in 2 to 4 years.
Because the interactions between the various nutrients in the diet are complex, the type of diet is more important than the specific ingredients, and dietary interventions are often not effective because of the addition of a single factor. In addition, the development of tumors is a long process. Dietary intervention is also a behavioral intervention. The protection of dietary fiber and other dietary components needs to be verified by more scientific and strict design and long-term prospective research.
(2) Chemoprevention
Chemoprevention is a new concept of tumor control proposed in recent years. It refers to the prevention of tumorigenesis by one or more natural or synthetic chemical agents, chemopreventive agents (CPA). In a broad sense, dietary intervention is also a kind of chemoprevention, which can be seen as a behavioral intervention because it is achieved by changing eating habits. Chemopreventive agents prevent the onset of tumors and inhibit their development by inhibiting and blocking the formation, absorption and action of carcinogens.
According to Vogelstein's colon cancer model, colon cancer is completed from a normal mucosa, through a series of molecular biological events, with an adenoma as an intermediate stage, and finally malignant, and chemopreventive agents can repress or reverse the occurrence of adenoma at different stages. Or inhibit its progression to malignant lesions (Figure 13).
1 Aspirin and other non-steroidal anti-inflammatory drugs: Aspirin and other nonsteroidal ant inflammatory drugs (NSAIDs) are the most widely studied colon cancer chemopreventive agents, the main mechanism is through irreversible acetylation and competitive inhibition ring Oxidase-1 and cyclooxygenase-2 (COX-1 and COX-2) block the synthesis of prostaglandins, promote tumor cell apoptosis, and inhibit tumor angiogenesis. Thun et al. reported in 1991 that 662,424 people were taking aspirin between 1982 and 1989. Infrequent use of those who died of colon cancer was 0.77 for men and 0.73 for women. The risk of male and female dying from colon cancer was further reduced to 0.60 and 0.58, respectively. In a 2-year follow-up survey of 47,900 medical staff, the relative risk of colon cancer was 0.68, as determined by a single survey, and the regular use determined by more than 3 surveys. The relative risk is further reduced to 0.35. In the nurses' health survey of Giovannucci et al., the risk of colon cancer in 89,46 female nurses who regularly took aspirin was 0.62, and the risk of taking 20 years or more was further reduced to 0.56.
However, the role of aspirin in preventing colon cancer has not been demonstrated in randomized controlled clinical trials. In a trial of 22071 male medical staff using aspirin to prevent coronary heart disease, the relationship between aspirin and colon cancer was also analyzed. The data showed that the experimental group and the control group had no evidence of colon cancer, colon polyps or carcinoma in situ. Significant differences, according to analysis, may be related to low doses of aspirin, short duration of administration or insufficient follow-up time.
There are few reports on the protective effect of non-aspirin NSAIDs on colon cancer. A recent large-scale retrospective found that 104,217 elderly people over the age of 65 were taking prescriptions for non-aspirin NSAIDs from Medicaid. The relative risk of colon cancer is 0.61, and of course, its role should be confirmed by well-designed prospective studies.
2 folic acid: folic acid is a micronutrient in the diet, rich in vegetables and fruits, epidemiological studies found that people with high folic acid intake have a low incidence of colon cancer, while decreased folic acid intake (often seen in large drinkers) increases Risk of colon cancer and colorectal adenoma. Studies have shown that diets containing large amounts of folic acid have a protective effect on colon cancer (male RR = 0.78, female RR = 0.91), while the effect of adding folic acid to the diet is more pronounced (male RR = 0.63, female RR = 0.66). ). In Giovannucci's nurse health survey, women's daily intake of more than 400g of folic acid has a significant protective effect on colon cancer (RR=0.25), but the protective effect will not appear until 15 years later, suggesting that folic acid is in the early stage of colon cancer. Play a role.
3 Calcium: Case-control and cohort studies in the human body Most showed that the application of high-calcium diet and calcium additive was negatively correlated with the occurrence of colon cancer and colorectal adenoma, but only some of the results were statistically significant. The main reason may be that the calcium intake is not accurately estimated or is related to other dietary factors. In recent years, Baron et al reported that 930 patients with a history of colorectal adenoma were randomized to receive calcium supplements (3 g/d calcium carbonate, 1.2 g calcium) or placebo. Colonoscopy was performed at 1 and 4 years after the start of the study. The incidence of adenoma in the calcium group was decreased, which was significantly different from the placebo group (RR=0.85). Moreover, the protective effect of calcium additive was 1 after taking the drug. It can be observed in years.
4 Estrogen: In the past 20 years, the mortality rate of colon cancer in males in the United States has been decreasing, while women are more obvious. One explanation is that women use hormone replacement therapy extensively after menopause. The mechanism by which estrogen prevents colon cancer may be related to reducing secondary bile acid production, decreasing insulin growth factor-1, or directly acting on intestinal mucosal epithelium.
Calle et al reported that colon cancer mortality was significantly lower in women who received hormone replacement therapy (RR = 0.71), and more significant in patients who continued to use for more than 11 years (RR = 0.54). Similar results were found in the nurses' health study (RR = 0.65), but the protective effects of hormones disappeared 5 years after discontinuation. The results of two meta-analyses published in recent years have also shown that hormone replacement therapy can reduce the overall risk of colon cancer by 20%. The above observations suggest that the protective effect of estrogen may occur in the late stage of colon cancer.
5 Vitamins and Antioxidants: Vitamins and antioxidants in vegetables and fruits have been thought to reduce the incidence of colon cancer for many years, but many prospective studies do not support this hypothesis. For example, nurse health research, doctor health research, etc. have not found the addition of beta carotene to the diet, vitamin A, B, D or E for colon cancer.
In a randomized controlled trial, 864 patients with a history of colorectal adenoma were given a placebo, beta carotene, vitamin C and vitamin E, and beta carotene and vitamins C and E. Colonoscopy was performed 1 year and 4 years later, and no difference was found in the 4 groups of adenomas.
(3) Treatment of precancerous lesions
Precancerous lesions of colon cancer are generally considered to include adenomatous polyps, ulcerative colitis, and Crohn's disease, and adenomas are particularly closely related to colon cancer. Epidemiology, animal experiments, and clinical and pathological studies have confirmed that the vast majority of colon cancers are cancerous from adenomas, especially large, villous, and adenomas with severe atypical hyperplasia. According to Morson's study, if the colorectal adenoma is not removed, colon cancer can occur in 4% of patients within 5 years, and 14% can be cancerous within 10 years. Stryker et al also demonstrated that untreated colorectal adenoma patients can have a colon cancer rate of up to 24% within 20 years. Therefore, early detection and timely treatment of colorectal adenoma is an ideal way to prevent and reduce the occurrence of colon cancer. Gilbertsen began to perform sigmoidoscopy (hard-slice) examinations every year for asymptomatic people over 45 years old in the 1950s. He found that polyps were removed. A total of 18,158 people were examined in 25 years, and only 13 cases of low colon cancer occurred in the tested population. And both are early, which is 85% lower than the expected 75-80 cases. In 1976, Lee analyzed the trend of colorectal cancer in the United States for 25 years. The incidence of colon cancer increased significantly while rectal cancer decreased by 23%. In the 1950s, rectal cancer accounted for 55% of colon cancer, but in the 1970s it was only 30.7%. It is believed that the cause of the reduction in rectal cancer is likely to be the result of extensive sigmoidoscopy and active treatment of low adenomas found.
In Zhejiang Province Medical University from 1977 to 1980, colon cancer screening was conducted in Haining City over 30 years old. Two screenings completed 238 826 cases of 15cm colonoscopy, and 4076 cases of low colorectal polyps were found. 1410 cases of adenoma were surgically removed. By 1998, a total of 6 colonoscopy or 60cm fiber sigmoidoscopy (after 1988) were followed up. All the polyps detected were removed. According to Haining tumor registration data, the city's average rectal cancer from 1992 to 1996. Morbidity and mortality were 41% and 29% lower than those from 1977 to 1981, respectively.
However, the value of removing precancerous lesions for colon cancer prevention remains to be confirmed by more rigorous clinical trials. To this end, the US NCI funded a multi-center prospective clinical trial (National Polyp Study, NlPS) involving seven units including the Sloan-Kettering Memorial Cancer Center. In the NPS, 9112 patients who underwent total colonoscopy between 1980 and 1990, 2632 patients with adenomas who met the study conditions, and 1418 patients with adenoma were randomly divided into 2 groups and followed up according to different examination frequency. At the time of total colonoscopy and barium enema, the average follow-up time was 5.9 years, during which only 5 asymptomatic early colon cancers (polyposis) were found, but no invasive colon cancer. The incidence of colon cancer in this group was reduced by 90% and 88%, respectively, compared with the two reference groups in patients with polyp history without surgical removal. The incidence of colon cancer in this group also decreased by 76% compared with the general population. This study fully supports the idea that colorectal adenoma can develop into colorectal adenocarcinoma, and it proves that the treatment of precancerous lesions can prevent the occurrence of colon cancer.
2, secondary prevention
Screening for high-risk populations of colon cancer to identify asymptomatic preclinical tumor patients. Early diagnosis and early treatment can improve the survival rate of patients and reduce the mortality rate of the population. Because screening can not only find early colon cancer, but also the precancerous lesions of colon cancer - adenomatous polyps, so that it can be treated in time to prevent cancer. In this sense, screening is both a secondary prevention measure for colon cancer and an effective primary prevention measure.
The natural history of colon cancer is long. From the development of precancerous lesions to invasive tumors, it is necessary to undergo molecular biological events such as multiple gene deletions and mutations. It is estimated that it takes 10 to 15 years, which provides for early detection of lesions. opportunity. Early colon cancer has a good prognosis. According to the US NCI disease surveillance (SEER) data, the 5-year survival rate of carcinoma in situ was 94.1% and the local lesion (Dukes'A) was 84.6% in 59,537 colon cancers from 1978 to 1983. When there is a distant transfer, it drops to 5.7%.
The 5-year survival rates of Dukes A, B, C, and D in 1385 colon cancers in Shanghai Cancer Hospital were 93.9%, 74.0%, 48.3%, and 0.31%, respectively. However, the proportion of A+B in the general clinical cases is usually only about 40%, while the C+D period is as high as 60%. Armitage reports that Dukes' Phase A only accounts for 6% in most hospitals in the UK. Because early colon cancer is mostly asymptomatic or the symptoms are not obvious, it has been confirmed that screening can increase the detection rate of early cases, and can also find precancerous lesions and timely treatment, thereby reducing the incidence of colon cancer. It is concluded that screening for colon cancer may reduce the mortality rate of the population. In the United States, the mortality rate of colon cancer decreased by 20.5% from 1973 to 1995, and the incidence rate decreased by 7.4%, especially after 1986. It is generally believed that this may be related to the widespread development of colon cancer screening and polyps found by colonoscopy. It is unlikely to be the result of changes in diet and lifestyle.
Recently, the United States NCI, the United States Preventive Service Task Force (USPSTF) and the American Gastroenterological Association have commonly used screening methods for colon cancer, including: anal finger test, fecal occult blood test, sigmoidoscopy, The use of gastroenterology and colonoscopy has been evaluated, and this is the most authoritative and comprehensive review of the evidence for the effectiveness of colon cancer screening.
(1) Anal diagnosis
Anal examination is simple and easy, you can check the rectum within 8cm from the anus. About 30% of colorectal cancer in the country is within this range, but only 10% of colorectal cancer in Europe and America can be diagnosed by anal examination. The detection rate of polyps in the sigmoid colonoscopy (15-18 cm) of colon cancer in Haining City in China was 1.7%, while the anus was only 0.17%. In addition, when the large-scale examination, the examiner's swelling and sensation of the fingertips failed, resulting in a decrease in the detection rate. A case-control study in the United States showed that patients who died of distal rectal cancer between the ages of 45 and 1971 between 1971 and 1986 had no difference in the rate of anal examinations 1 year before diagnosis compared with the control group (OR= 0.96). Therefore, anal digital examination has a limited effect as a screening method, but it is an essential part of a full physical examination for symptomatic patients.
(2) fecal occult blood test
Intestinal invasive bleeding is the most common early symptom of colon cancer and colorectal adenoma. Since Greegor first screened colon cancer with FOBT in 1967, FOBT has been the most widely used colon cancer screen because of its economy, simplicity and safety. The methods of detection, the existing methods of occult blood test are mainly chemical methods and immunological methods.
In the chemical method, Hemoccult II (Smith Kline Diagnostics) is the most widely used and most studied. It uses the peroxidase-like activity of heme to react with guaiac in the presence of H2O2 to produce blue color; therefore, animal blood, red meat and some vegetables such as carrots, turnips, broccoli and certain drugs such as iron Non-steroidal antipyretic and analgesic drugs can also produce false positive reactions. It is generally believed that the normal human intestinal gastrointestinal bleeding volume is less than 2ml per day, while the detection sensitivity of Hemoccult II is 4-6ml/100g stool, so FOBT positive indicates pathological bleeding. Ransohoff and Lang systematically evaluated FOBT: the sensitivity of a single unhydrated FOBT screening colon cancer was 40%, the specificity was 96% to 98%, and the sensitivity after hydration increased to 50% to 60%, but The specificity has dropped to 90%. Recently, Lieberman et al reported that hydration FOBT screening for colon cancer sensitivity is 50% (95% CI: 30% to 70%), for cancer and precancerous lesions (large villous with atypical hyperplasia) The adenocarcinoma has a sensitivity of 24% (95% CI, 19% to 29%) and a specificity of 94% (95% CI, 93% to 95%). In the western countries, the FOBT positive rate was 2% under controlled diet conditions, and among FOBT positive patients, about 10% were colon cancer and 30% were polyps. However, the false positive rate of the chemical method FOBT (benzidine method) in the normal population of China's census can be as high as 12.10% (23706/206125), which greatly limits its application value, which may be related to other gastrointestinal bleeding diseases such as gastritis. Gastric ulcer, gastric cancer and high prevalence of sputum are related.
The earliest clinical trial of FOBT screening for colon cancer was hosted by the Sloan-Kettering Memorial Cancer Center from 1975 to 1985. 21,756 asymptomatic individuals over 40 years of age were screened, randomized to the screening group and the control group, in the colon Among the cancers, 65% of the screening group were Dukes'A and B, while the control group was only 33%; the 10-year survival rate of the screening group was significantly higher than that of the control group (P<0.001), and the colon of the screening group was followed up for 10 years. The cancer mortality rate was 43% lower than that of the control group (P=0.053). The study showed an increase in the proportion of early cancer, prolonged survival and decreased colon cancer death. The effect of FOBT on screening for colon cancer can reduce colon cancer mortality, which has been demonstrated by at least three well-designed large-scale randomized controlled clinical trials (Table 6), which is Class I evidence, so the USPSTF prioritizes it as A. Class recommendations (ie strongly recommended) are used for crowd screening.
(3) Immunology
FOBT was developed in the late 1970s. By using the specific immune response of hemoglobin and corresponding antibodies, it avoids the disadvantages of chemical methods to limit diet and improves the specificity and sensitivity of screening. In 1987, Zhejiang Medical University successfully developed the reverse indirect hemagglutination (RPHA-FOBT) kit. In Haining City and Jiashan County, Zhejiang Province, a group of 3034 high-risk populations with a history of rectal polyps were screened for RPHA FOBT. 11 cases of colorectal malignant tumor, 465 cases of polyps (195 cases of adenoma), with 60cm fiber enteroscopy as the reference standard, proved that the sensitivity of RPHA-FOBT screening for colon cancer was 63.6%, specificity was 81.9%, Youden The index is 0.46, which is superior to the chemical method. The study also showed that the sensitivity of RPHA-FOBT screening polyps was only 22.1%, but it was about 40% positive for villous and tubular villous adenomas with a high malignant tendency. On this basis, Zheng Shu et al. used a sequential method for colon cancer screening in 75,813 people over the age of 30 in Jiashan County, a high incidence area for colon cancer. The total positive rate of RPHA-FOBT was 4.2%, and 21 cases of colon were screened. Dukes' A and B in cancer accounted for 71.4%.
A variety of immunological FOBT reagents are available in the United States, such as Hemeselect, InSure, and FlexsureOBT, which use monoclonal or polyclonal antibodies against human hemoglobin to detect fecal occult blood. One of the high-risk groups of 240 colon cancers with InSure TM reagent showed that InSureTM had a sensitivity of 87% (20/23) for screening for colon cancer and 47.4% for adenomas >10 mm. (9/19), the specificity of detection in a group of normal people over 40 years old was 97.9% (88/98), and the specificity of the normal population under 30 years old was 97.8% (92/94). Studies have shown that the immunological method FOBT including InSureTM does not react with myoglobin, animal hemoglobin, is not interfered by diet and drugs, and is negative for feces of upper gastrointestinal bleeding. Recently, the American Cancer Society (ACS) Colon Cancer Advisory Group evaluated the available evidence that immunological FOBT can increase the specificity of screening compared to chemical FOBT, adding the following in the 2003 ACS Colon Cancer Screening Guidelines. Note: "In the detection of fecal occult blood, the immunological occult blood test is easy for patients to accept, its sensitivity and specificity is better than or at least the same.
(4) sigmoidoscopy
Gilbertsen began to screen colon cancer and polyps with sigmoidoscopy in the early 1950s, and sigmoidoscopy (25cm hard) was performed on 18,158 people. After 25 years of follow-up, the screening group was compared with the national average. The incidence of sigmoid and rectal cancer is significantly reduced. Due to the difficulty in inserting the rigid colonoscopy, the patient acceptance rate is low. Since the invention of the optical fiber colonoscopy in 1969, the 60cm fiberoptic colonoscopy was introduced into the clinic in 1976. Now the 25cm hard lens has been replaced by the 60cm fiber enteroscopy. More than 80% of family physicians have equipped and used 60cm colonoscopy.
The Kaiser Permanence Multiphasic Health Checkup (MHC) in the United States randomly divided 10,713 people aged 35 to 54 into trials and controls. Among the 5156 people who were screened, 20 cases of colon cancer were detected, and Dukes' A stage accounted for 60%. After 16 years of follow-up, the 5-year survival rate was 90%, and the 10-year survival rate was 80%. The control group Dukes 'A phase is only 48%, and the 10-year survival rate is also 48%. The number of colon cancer deaths in the experimental group was significantly smaller than that in the control group (12 and 29, respectively). However, further analysis found that, if only the colon cancer mortality rate was within the range that can be achieved by colonoscopy, the difference between the experimental group and the control group was not statistically significant.
Lieberman et al found that 70% to 80% of patients with distal colonic polyps in the fiberoptic colonoscopy also had new organisms in the proximal colon. A randomized controlled trial found that in patients with polyps detected by colonoscopy, the incidence of colon cancer was reduced by 80% after a complete colonoscopy and removal of the adenomas found. Therefore, 60cm fiber enteroscopy for screening can not only remove precancerous lesions within the reach of the endoscope, and can be used as an indication for full colonoscopy, which can reduce the incidence of all colon cancer. Experts believe that if colonoscopy is found to have polyps, the indications for further colonoscopy should be as follows: patients over 65 years old; villi or 1 cm or multiple adenomas; family history of colon cancer.
According to the statistics of 3147 colon cancers in China, 82% occur below the splenic spleen, that is, the 60cm colonoscopy is accessible. Therefore, its application value seems to be larger than that of Western countries. The Cancer Research Institute of Zhejiang Medical University used 60cm fiber enteroscopy as a rescreening method for sequential screening of colon cancer. 60cm colonoscopy was performed on 36.2 high-risk groups, and 21 cases of colon cancer and 331 polyps were found. In another group of 3034 high-risk subjects, 11 cases of colorectal malignant tumors and 563 cases of polyps were detected by 60cm colonoscopy. Before the 60cm colonoscopy, mannitol powder and plenty of drinking water were used for intestinal preparation. The intestinal cleanliness was satisfactory or basically satisfactory in 95%, and all of the more than 6,000 colonoscopy examinations did not have a perforation. According to China's national conditions, 60cm fiber enteroscopy can not be used as a primary screening method, but as a simple, feasible and relatively reliable rescreening or diagnostic measures is still worth promoting.
At least two case-control studies have shown that sigmoidoscopy can reduce the mortality of colon cancer. In Selby's study, sigmoid colonoscopy is used, while Newcomb's study is mainly fiberoptic colonoscopy. Both studies showed that those who had had more than one colonoscopy had a 70% to 90% reduction in the risk of dying from distal colon and rectal cancer than those who had never had a microscopy.
According to Thiis-Evensen et al., 799 subjects were randomly selected from the Norwegian general population in 1983 and randomly divided into the colonoscopy group and the control group. 81% of the screening group received a colonoscopy, such as polyps. mirror. 13 years later (1996), 451 (71%) of the 2 groups underwent total colonoscopy and found no difference in the incidence of polyps between the screening group and the control group, but the screening group had high-risk polyps (1 cm, with atypical The incidence of hyperplasia was lower than that of the control group (RR=0.6, 95% CI: 0.3-1.0, P=0.07), and another 2 cases of colon cancer occurred in the registered screening group and 10 cases in the control group (RR=0.2, 95% CI: 0.03 to 0.95). However, because the overall mortality rate of the screening group is greater than that of the control group (mainly due to cardiovascular disease death), it is difficult to conclude that the colonoscopy screening is conducive to reducing the mortality rate of colon cancer. Currently, there are two randomized controlled trials of sigmoidoscopy screening for colon cancer in the United Kingdom and the United States. Despite the lack of reliable evidence for the efficacy of sigmoidoscopy in the screening of colon cancer, ACS and USPSTF still recommend 60 cm fiberoscopy as one of the primary means of colon cancer screening.
(5) total colonoscopy
Colon cancer screening with a full colonoscopy alone has reduced the incidence and mortality of colon cancer. There are no clinical trials, but full colonoscopy is often combined with other screening methods, such as FOBT or sigmoidoscopy, to reduce the incidence of colon cancer. The effect of death is clear. Lieberman and Imperiale have shown that half of patients with progressive neoplasms (1 cm in diameter, villous adenomas and carcinomas with atypical hyperplasia) have no distal colon and rectal polyps. The need for a full colonoscopy as a screening tool. However, colonoscopy is expensive, preparation is complicated, patient acceptance is poor, and there is a certain complication rate (several complication rate is about 0.3% of perforation bleeding, and the mortality rate is about 1/20000). Therefore, it is reasonable to use colonoscopy alone for screening. Sex is subject to further verification.
(6) Gastric double contrast enema
Although the ACS recommendation has used a double contrast enema (DCBE) as a screening tool for colon cancer every 5 years, no studies have shown that DCBE is effective in reducing the incidence and mortality of colon cancer. Winawer et al. used national polyp study data to evaluate the results of total colonoscopy as a gold standard and found that <0 5cm="" dcbe="" 32="" 0="" 6="" 1cm ="" 53="">1cm of polyps (including 2 cases of cancerous polyps) is 48%, while the specificity of DCBE is 85%. Although the sensitivity of DCBE is low, it can be examined in the whole colon, and the complication rate is low. It is widely accepted by medical staff and patients, so it can still be used as one of the screening methods for colon cancer.
(7) Other technologies
In response to recent advances in new technologies for detecting colon and adenomatous polyps, the American Cancer Society's ACS Colorectal Cancer Advisory Group held a seminar in April 2002 on CT colorectal imaging and immunological feces. The effects of occult blood test, fecal molecular markers, and capsule video endoscopy in colon cancer screening were evaluated and agreed.
CT Colonography, also known as virtual colonoscopy, began in 1994. It is a rapid multi-scan of spiral CT, which is a two-dimensional or three-dimensional imaging of the internal structure of the colon, simulating the results of colonoscopy, but Invasive operation of the colonoscope is avoided. According to the results of several central studies in the United States, the sensitivity of CT colorectal imaging of >1 cm is close to 90%, while it is reduced to about 50% for <0.5cm, and 100% for colon cancer. No false positives.
The colon cancer process involves multiple gene mutations, and the mutated DNA in the tumor cells and their precursor cells is exfoliated and can be detected from the feces by PCR amplification. Detection of colon cancer using mutant DNA in feces as a molecular marker is a new technology developed in recent years. The mutant DNA detection kit developed by EXACT detects 15 common mutation sites of colon cancer including K-ras, APC, p53 gene and mutation points on the microsatellite instability marker bat-26. In a small sample double-blind trial, 61 subjects included 22 colon cancers, 11 large adenomas, and 128 normal subjects. The sensitivity of fecal mutant DNA to colon cancer was 91%, the sensitivity of adenoma was 82%, and the specificity was 93%. If K-ras mutation was not included, the sensitivity of intestinal cancer remained unchanged, and the adenoma decreased to 73. %, while the specificity increased to 100%.
The advisory team reviewed these new technologies and reached unanimous conclusions: CT colorectal imaging and fecal mutant DNA testing are promising new technologies, but there is currently no sufficient evidence to recommend screening as a means of screening. Its sensitivity and specificity are superior to or equal to the chemical method, and it is more convenient for patients. Capsule video endoscopy is not suitable for colon cancer and polyps because its design is limited to the upper digestive tract and small intestine.
(8) Screening program
In 1980, the American Cancer Society (ACS) proposed a guideline for colon cancer screening. Although it has been revised several times, the basic points have not changed. The American Gastroenterological Association, a high-risk group for colon cancer, proposes a stratified screening program for colon cancer risk.
1 In view of the relatively low incidence of colon cancer in China, the age of onset is advanced, and health resources are limited, the ACS program is difficult to implement in China. On the basis of previous work, Zheng Shu et al proposed a sequential screening method for colon cancer.
A. Using the questionnaire as a quantitative assessment of the risk of colon cancer, calculate the AD value of the risk of colon cancer in each subject, with AD 0.3 as the positive threshold; and RPHA FOBT for the subject, 2 The project initially screened out high-risk groups.
B. Re-screening for high-risk groups with 60cm fiber enteroscopy.
C. 60cm colonoscopy patients with FOBT follow-up, FOBT continued positive is recommended for full colonoscopy and / or gas sputum double contrast.
2 Using this model, among the 75 813 people over 30 years old in Jiashan County, the high-risk population was screened out, 4299 people were screened for high-risk population, 3162 cases (73.6%) of 60cm colonoscopy were completed, and 21 cases of colon cancer were detected, of which colon cancer accounted for 62%. Dukes A+B accounted for 71.4%. On the basis of the promotion of the program, the inspectors proposed a further optimization plan:
A. Screening subjects 40 years old.
B. The following 1 should be used for 60cm fiberoscopy: RPHA FOBT positive; first-degree relatives have colon cancer history; I have a history of cancer in the past; 2 or more of the following symptoms, such as chronic constipation, mucus and blood, chronic Diarrhea, history of intestinal polyps, chronic appendicitis, history of mental stimulation.
C. If the 60cm colonoscopy is negative, the FOBT review is positive, and a full colonoscopy or gas sputum double contrast should be performed.
Calculate the AD value of the risk of colon cancer in each subject, with AD 0.3 as the positive threshold; and RPHA FOBT for the subjects, which are used to screen out high-risk groups.
D. Re-screening with high-risk groups with 60cm fiber enteroscopy.
E.60cm colonoscopy patients with FOBT follow-up, FOBT continued positive is recommended for full colonoscopy and / or gas sputum double contrast.
3, three levels of prevention
Active treatment of patients with clinical cancer to improve the quality of life of patients and prolong survival.
Complication
Colon adenocarcinoma complications Complications, intestinal obstruction
When a tumor develops to a certain stage, especially when it has already caused obstruction, it will trigger a series of symptoms. These include: weakness, fatigue, anemia, unexplained weight loss, persistent abdominal pain, melena or bloody stools, changes in bowel habits, etc. Rectal cancer can locally invade the bladder, vaginal wall, or peripheral nerves, causing pain in the perineum or tibia, but these symptoms occur late. Anemia, colonic fistula, partial or complete intestinal obstruction and intestinal perforation are common complications of colon cancer and are also the main cause of patient visits.
Symptom
Colon gland cancer symptoms Common symptoms Diarrhea and constipation alternate bloody abdominal pain feces pus and blood stasis like stool mucus
The onset of colon cancer is concealed. In the early stage, only faecal occult blood is positive. It is gradually bloody stool, dysentery-like pus and bloody stools. It is often urgency and heavy, sometimes intractable constipation, thin stool shape, or mushy stool, or alternating diarrhea and constipation. These changes become colon cancer. Outstanding performance. Patients often have varying degrees of abdominal pain, often with erosion, necrosis and secondary infections. If it occurs on the right side, it will produce dull pain in the right abdomen, sometimes with postprandial abdominal pain.
Left colon cancer often complicated with intestinal obstruction, abdominal cramps, accompanied by abdominal distension, bowel sounds hyperthyroidism and so on.
Examine
1(FOBT)
1967GreegorFOBTFOBT(SRID)(LA)(CIE)(ELISA)(RPHA)RPHARPHA63.6%72.7%RPHA81.9%61.7%RPHA
(dot-ELISA)
2
3
1
2
3)
4(CEA)
1965Goldr26CEACEA(49%60%)(52%77%)(30%50%)(64%)(60%)CEACEA20CEACEACEACEA2
1CEACEACEA50%CEA25%CEA>5µg/L(0.43)5µg/L
2CEA6141013CEACEA2Moertal(1993)417CEA59%60016ACEA115CEA47(40.1%)Martin60CEA93.3%95%CEA17%25% CEACEA2
5
(PCR)-(PCR-RFLP)DNA101DNA2
1Ki-rasrasras351211(31.4%)61l(2.9%)11213GlyAsD(4)
2Ki-rasDNAKi-ras1PCRRFLP12186Ki-ras(33.3%)4Volgelstein249ras8
6
30cm226X
7
6%11%10%20%33%50%
1
96%ThoeriMenuk11.7%45.2%;87%59%96%X8.4%
70%80%(654-2)
(4);;40
2CT
CTCTCTCTMossCT
1(5mm)
2
3;
4()
CTCTCT48%72%25%73%
3MRIMRICTMRI3
42
;;
5376%88.8%38%BCT
5
CEAAFPCA-50CA19-9
67Ga-25cm(74165mEq)2496h(ECT)67Ga131ICEA
Diagnosis
diagnosis
1();
2;
3;
4;
5
Differential diagnosis
1
X
2()
X10
3
X;X
