Predictive Value Of Rectal Aberrant Crypt Foci For Colorectal Advanced Neoplasms And Its Risk Factors

ObjectiveColorectal cancer (CRC) is one of the major causes of cancer related death in many countries including China. Among the multiple strategies for reducing the associated mortality, early detection and treatment under endoscope is currently considered most effective.Aberrant crypt foci (ACF) were described in 1987 by Bird and Good as putative preneoplastic lesions in the colon of carcinogen- treated rodents. ACF are defined by their characteristic morphology:the crypts are enlarged, they have thickened layer of epithelial cells, they have increased pericryptal space, they have irregular lumens, and they are microscopically elevated. ACF are identified in histological sections and under endoscopy after stain with methylene blue or indigo carmine. ACF have been used as a short-term bioassay to evaluate the role of nutritional components and,chemopreventive agents at an early stage of colon carcinogenesis. However, although they are thought to be the earliest identifiable neoplastic lesions in the colon carcinogenetic model, the development of these lesions is not clearly related to the early development of tumors. Therefore, there is a strong need to clarify the role of ACF in colon carcinogenesis and to validate their predictive value of rectal aberrant crypt foci (ACF) for colorectal cancer (CRC) and adenomas.Recently, many factors that may related to CRC had been studied, including family history of CRC, smoking, drinking, diet, using aspirin, cholecystitis or removal of gallbladder, appendectomy, diabetes, hypertension, hyperlipemia, coronary artery disease, physical activity, et al.If the number of ACF has strong predictive value for CRC or advanced adenoma, then their epidemiology should be similar, and risk factors for CRC should also predict the number of ACF.If some factors influence tumorigenesis at an early stage, then they should also be associated with the formation of ACF. Although recently ACF has been more and more concerned, due to the limit of magnifying endoscopy and dye technology and the complex of investigation to a large population,there were only few studies related to the risk factors of ACF. A better description of the distribution and prevalence of ACF, and the relationship of ACF with demographic and personal habits will be necessary to advance our understanding of the biological meaning of these lesions in early stage.Now, by observing the number of rectal ACF, collecting the results of colonoscopy and histology of patients, investigating the information of possible related factors for CRC, we descript the distribution and prevalence of ACF, evaluated the relationship between ACF and CRC or advanced adenoma, and screened the significant risk factors of ACF in the rectum.Methods1. PatientsFrom July 2008 to July 2009 in Nanfang Hospital, native patients who underwent colonoscopy for the first time and agreed to accept a rectal ACF quantification in vivo using high-magnification-chromoscopic-colonoscopy were recruited in our study and asked to complete a questionnaire. Those patients with severe rectitis or multiple ulcers in rectum, familial adenomatous polyposis and rectectomy were excluded.2. Data collectionThe contents of questionnaire included demographic information, sex, age, body height, weight, main clinical manifestations, smoking and drinking habits, using of aspirin, patient history of cancer or other diseases (including colorectal disease, gallstone history, appendectomy, diabetes mellitus, hypertension, coronary artery disease), family history of CRC for first degree relative and second degree relative, physical activity. Most of them agreed and then data input was performed by one of the researchers. Subjects with missing responses were telephoned by a researcher and the missing data were collected over the telephone. Information on the size, location, and macroscopic appearance of all polypoid lesions and CRC observed during colonoscopy was also recorded. When biopsy or polypectomy was performed, pathological findings were also recorded.3. Colonoscopy, Mucosal Staining and EvaluationBowel preparation included ingesting 2L of polyethylene glycol(PEG) solution in the morning 4 hours before examination. During colonoscopy, the rectal mucosa was washed with 20-50 ml of distilled water.After that,0.4% indigo carmine solution was applied to the mucosa with a spray catheter. After excess pools of indigo carmine were suctioned away, the number of ACF in the rectum was counted. This counting was conducted in the lower rectal region, extending from the middle Houston valve to the dentate line, approximately 13-15cm from the anal verge. The colonoscopic examination for detection of ACF was done using magnifying colonoscope. ACF were defined as lesions in which two or more crypts had dilated, often with oval or slit-like openings, and which were raised above the surrounding mucosa. When an ACF was identified, it was photo-documented, and several maximum diameter of the rectal ACF (≥3mm) were obtained with a cold biopsy forceps from those patients who signed informed consent for biopsy. By numbers of ACF in the rectum, patients with no ACF were classified as ACF grade 0, and those with 1-5,6-10 and more than 10 were classified as ACF gradeⅠ,Ⅱ,Ⅲrespectively.4. Histologic ExaminationSpecimens of all lesions biopsied during colonoscopy were sent to the Pathology Laboratory of the Department of Gastroenterology in Nanfang Hospital, and all the specimens were reviewed by at least tow pathologists with special expertise in gastrointestinal pathology. Dysplasia was classified as low-grade dysplasia or high-grade dysplasia, on the basis of the degree of cytologic atypia and the presence of any architectural abnormality in the gland. Adenoma with low-grade dysplasia included adenoma cases with either mild or moderate dysplastic changes. Both adenoma with severe dysplasia and carcinoma in situ were categorized as adenoma with high-grade dysplasia. Cancer was diagnosed only if there was a clear histological demonstration of penetration of the carcinoma through the muscularis mucosa into the submucosa, which we confirmed from the histological result of resected bowel. Patients were classified by their most advanced histological lesion at the baseline colonoscopy. ACF specimens obtained were immediately fixed in 10% buffered formalin solution and were embedded in paraffin, step-sectioned perpendicular to the lumen in 4-μm sections, mounted onto slides, and stained with hematoxylin and eosin (H&E). ACF were classified as nondysplastic and dysplastic.5. Statistical AnalysisAll statistical analyses were performed with SPSS software version 13.0. Independent -Sample T test, One-Way ANOVA and Chi-square test were used to analyze the mean number and prevalence of ACF. Binary logistic regression analysis was used to assese the prediction value of rectal ACF for advanced adenomas or cancer, and to identify the independent risk factors of ACF.Results971 eligible subjects completed the counting of rectal ACF, including 499 polyp-free; 157 with hyperplastic polyps; 144 with nonadvanced adenoma nonadvanced adenoma,55 with advanced adenoma,81 with CRC; the other 35 (without pathological findings). Histological analysis showed that the prevalence of dysplastic ACF was 13.1%.1. Mean Number and prevalence of ACFOverall, the mean numbers of rectal ACF were significantly different in sex, age groups and different histological types. The mean number of rectal ACF was higher in man compared with women. By multiple comparisons, we found that the mean number of rectal ACF increased with the raise of age grade. The difference of mean number of ACF between those during 50-59 and not younger than 60 was not significant (P=0.130). But those between the other age groups were significant (P<0.05), and in those age groups, the mean number of ACF all increased with the raise of age grade. The mean numbers of rectal ACF were significantly different between polyp-free group with hyperplastic polyps group, nonadvanced adenoma group, advanced adenoma group and CRC group (P=0.000), but between the other 5groups except for polyp-free group, the differences were not significant (P=0.000). The prevalence of ACF in differente sex groups was not significant. But it was significant in age groups. The prevalence of rectal ACF increased with the raise of age grade. The prevalence of dysplastic ACF was 13.1%.2. Predictive Value of ACF for Advanced Adenomas and CRCThe prevalence of advanced adenoma was significantly different in groups with different number of ACF, and so was the prevalence of CRC. For advanced adenoma, after adjusted for sex and age, those with 6-10 ACF (P,0.037;OR,2.736;95%CI, 1.063-7.042) and more than 10 ACF (P,0.002;OR,4.357;95%CI,1.689-11.241) increased the risk of advanced adenoma;The effect of those with 1-5 ACF was not significant (P,0.720; OR,1.185; 95%CI,0.469-2.995). For cancer, those with 6-10 ACF(P,0.004;OR,3.115;95%CI,1.430-6.788)and more than 10 ACF (P,0.008; OR, 3.084; 95%CI,1.341-7.090) increased the risk of advanced adenoma;While the effect of those with 1-5 ACF was also not significant (P,0.948; OR,1.027; 95%CI, 0.466-2.261).3. Risk Factors of ACFFor those with ACF in the rectum, the risk factors were age (P,0.000; OR,1.087; 95%CI,1.062-1.113) and smoking (P,0.008;OR,1.900;95%CI,1.184-3.050), and using aspirin was a protective factor(P,0.045;OR,0.300;95%CI,0.093-0.973).Conclusions1. The mean number of rectal ACF presented a tendency of increasing with the raise of age group, and was higher in polyp and cancer group compareing with normal group. Man had higher mean number of rectal ACF than women. The prevalence of rectal ACF increased with the raise of age grade. The prevalence of dysplastic ACF was low even in bigger ACF. 2. After adjusted for sex and age, those with 6-10 ACF and more than 10 ACF significantly increased the risk of advanced adenomas and cancer; The effect of those with 1-5 ACF was not significant. We should pay more attention to those patients with more than 5 ACF in the rectum during colonoscopy.3. Age and smoking were risk factors for those with ACF in the rectum. Using aspirin was a protective factor.