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Colorectal cancers are the most frequent cancer in Norway for men and women combined. Several theories have been suggested as etiological explanations. In this review the influence of dietary factors on the cell proliferation rate has been evaluated. A higher cell proliferation rate is statistically associated with increased risk of colorectal cancer. Foods associated with a lower cell proliferation rate match the staple foods in parts of the world were the incidence of colorectal cancer is low. Vegetarians show a low rate of cell proliferation, and low incidence of colorectal cancer. The low incidence of colorectal cancer among vegetarians may be due not only to the lack of animal foods, but also to several other healthy lifestyle habits. We conclude that a well planned lacto-vegetarian diet or a mixed diet with abundant amounts of vegetables and fruits is beneficial as regards the rate of cell proliferation, and most likely also reduces the risk of developing colorectal cancer.

One hundred and sixteen patients were included, during 18 months, in a double-blind placebo-controlled intervention study, with calcium, vitamins A, C, E and selenium (in a cocktail) or placebo against growth of colonic polyps. Patients were randomized within three arms, according to diameter of the largest polyp, < 5 mm, 5-9 mm or > 9 mm. Polyps > 9 mm were resected, the others were left to be measured annually before resection after 3 years. The protocol (performed in all of the patients) included registration of demographic data, family and personal history, measurement of polyps, collection of blood specimens, stools and biopsy samples. Registration of nutritional status, diet history and 5-day prospective food consumption, was performed in 108 patients. The patient compliance was registered every third month by the hospital pharmacist, with concomitant delivery of new boxes of capsules. Additionally, stool collections were performed from all of the patients for the measurement of faecal calcium, bile salts and fat. Inclusion rate of 37, 41 and 38 patients in each of the three 6-month periods was uniform. The group with the largest polyps measuring 5-9 mm comprised 44% of the material. The sex ratio corresponded to that in overall referrals for colonoscopy. The age relationship of size and multiplicity of polyps and the distribution of polyps in the large bowel corresponded to previous experience in polyp-bearing individuals of the same age.(ABSTRACT TRUNCATED AT 250 WORDS)

A reliable and sensitive in situ method for measuring polyp size is fundamental for growth studies of colonic polyps. A measuring probe inserted through a colonoscope can give a visual assessment of polyp diameter, and from a picture of the polyp the area of the polyp on the picture can be calculated by computerized analysis. To test the reliability and sensitivity of these two in situ measurements, 43 colonic polyps (mean diameter, 8.5 mm; range, 4-20 mm) removed by snare diathermy resection were examined. The maximal diameter was measured, and two Polaroid pictures taken of each polyp. After polypectomy each polyp was subjected to extracorporeal reassessment of diameter and measurement of weight and volume. By computerized analysis of the pictures the following variables were estimated: 1) area of the polyp on the picture; 2) largest diameter; 3) maximum width 90 degrees on the largest diameter; 4) maximum distance from centre of gravity; and 5) minimum distance from centre of gravity. Results showed good correlation between diameter measured in situ and after removal (r = 0.93), diameter raised to the 3rd power and weight (r = 0.93), and also to volume (r = 0.77). Area analysis compared with weight was less good (r = 0.72). A very high correlation was demonstrated between weight and volume (r = 0.99). We conclude that the measurement of diameter in situ with a measuring probe is sensitive and somewhat more reliable than computerized analysis of size. The present 3-year follow-up and intervention study will show which of the two methods is preferable for evaluation of polyp growth.

The reproducibility of polyp localization and size measurements was tested to evaluate the reliability of observations during follow-up examinations of sigmoidoscopically diagnosed polyps. Our findings suggest that 25% of polyps less than 5 mm in diameter but only 5% of those larger than 5 mm are likely to be missed by a single endoscopic examination. Localization measurements made during insertion and withdrawal of the endoscope on different days of examination diverged proximal to 30 cm from the anal ring during repeat colonoscopy. Otherwise, reproducibility was good, demonstrating that sigmoidoscopy may be a fairly accurate procedure for evaluation of site and size of polyps during follow-up studies.

Epidemiological studies have suggested an association between diet and colorectal cancer. Case/control studies, however, have been scarce, and studies based on interview with cancer patients who have symptoms from their cancer are inevitably prone to bias. An endoscopic population screening study for detection of colorectal adenomas enabled a double-blind registration of diet during 5 consecutive weekdays. Neither the participant nor the dietitian was informed of the findings at endoscopy. The estimation of 23 nutritional components was based on analysis of local commercial food and on the composition of foods in Norway. Results showed increasing consumption of fat and decreasing consumption of fiber and cruciferous vegetables in the presence of increasing neoplastic changes. The present material will form the basis for dietary-related follow-up studies.

The design of a population screening study, including endoscopic screening for polyps in the rectum and sigmoid colon, was tested in a defined population sample of 200 women and 200 men aged 50-59 years. The attendance rate was 81%. A simple bowel cleansing procedure performed immediately before the examination gave satisfactory conditions for endoscopic examination in 94% of attendants. Polyp prevalence was 35%. The present material and results represent the basis for further follow-up studies of risk factors for the development of cancer in the same group of individuals.