Sensitivity of immunochemical fecal occult blood test for colorectal flat adenomas.

BACKGROUND/AIMS: To assess the sensitivity of an immunochemical fecal occult blood test for colorectal flat adenomas, and to determine the relation between the size of flat adenomas and the results of this test. METHODOLOGY: Eleven colorectal flat adenomas under 1cm, 18 flat adenomas 1cm or larger, 187 polypoid adenomas under 1cm, 42 polypoid adenomas 1cm or larger and 144 healthy controls were investigated. Each subject was tested with an immunochemical occult blood test on two consecutive days, and the accuracy of this test was evaluated. RESULTS: The sensitivity of this test was 18% for flat adenomas under 1cm, 67% for flat adenomas 1cm or more, 19% for polypoid adenomas under 1cm and 60% for polypoid adenomas 1cm or more. Specificity was 95%, showing a significant difference in the sensitivity between flat adenomas 1cm or more and those under 1cm (p<0.05) as well as a significant difference between flat adenomas 1cm or more and polypoid adenomas under 1cm (p<0.001), whereas no significant difference was seen in the sensitivity between flat adenomas 1cm or more and polypoid adenomas 1cm or more. CONCLUSIONS: These results indicate that the sensitivity of immunochemical occult test for flat adenomas was similar to the sensitivity for common polypoid adenomas. The size of adenomas is a more important morphological factor for determining the sensitivity of this fecal occult blood test.

A case-control study on risk of changing food consumption for colorectal cancer.

OBJECTIVES: To investigate the relative risk factor of food items for colorectal cancer in four time periods through a case-control study in a Chinese rural area. METHODS: Colorectal cancer patients diagnosed at a county cancer center, Hebei Province, China, and non-cancer outpatients with similar age, sex, and place of residence were selected for cases and controls, respectively. There were 102 (93.6%) colorectal cancer patients and 99 (90.8%) outpatients being the cases and controls, respectively in the present investigation, who agreed to be interviewed about their food intake, during a 20-year period, through a food frequency questionnaire. The risks of intake of different food items and lifestyle for colorectal cancer were compared between cases and controls. RESULTS: During the 20-year period, diets of both cases and controls changed with increase in intake of animal foods and fruits, and alcohol consumption tended to increase. In the food items, milk intake showed a protective effect in both males and females, and the odds ratios were 0.38 (95% CI 0.16-0.90) and 0.28 (95% CI 0.10-0.81) for males and females, respectively. A reduced risk of fruit intake could be seen in males, while a reduced risk of vegetables could be observed in females. Meat intake and saturated fats were the prominent risk factors for colorectal cancer in males and females, respectively. A comparison of life habits, showed that tea drinking had a consistent protective effect in females, and the odds ratios were 0.21 (0.08-0.58), 0.23 (0.08-0.67), 0.25 (0.10-0.64), and 0.11 (0.04-0.30) for periods of 20-, 10-, 5-years ago, and current time, respectively. CONCLUSIONS: These findings indicate that change in food consumption is strongly associated with a change in risk of colorectal cancer, and dietary meat has increased the risk of colorectal cancer. Increase in the consumption of milk and fruits may be a significant measure for colorectal cancer prevention in low-incidence areas.

Colorectal cancer risk in first-degree relatives of patients with colorectal adenomatous polyp.

BACKGROUND/AIMS: To evaluate any risk of colorectal cancer in first-degree relatives of patients with colorectal adenomatous polyp. METHODOLOGY: In a screening program-based cross-sectional study, 44821 subjects received an immunochemical fecal occult blood test using a 2-consecutive-day method. They were divided into two groups, according to the results of a self-completed questionnaire on family history of colorectal adenomatous polyps, and the positivity rate of an immunochemical fecal occult blood test as well as the positive predictive value for colorectal cancer were determined in these two groups. RESULTS: The fecal occult blood test was positive in 8.5% of subjects with family history and in 4.8% of subjects without family history, and the positive predictive value for colorectal cancer was 6.8% and 2.4% in subjects with and without family history of colorectal adenomatous polyps, respectively, indicating a significant difference in the positivity rate of the fecal occult blood test (P < 0.01) as well as the positive predictive value for colorectal cancer (P < 0.05) between these two groups. CONCLUSIONS: These results show that first-degree relatives of patients with colorectal adenomatous polyp have an increased risk for colorectal cancer, and that the subjects with family history of colorectal adenomatous polyps as well as cancers should be considered as a priority group for prevention of colorectal cancer.

Lower specificity of occult-blood test on stool collected by digital rectal examination.

BACKGROUND/AIMS: To compare the diagnostic accuracy of an immunochemical fecal occult-blood test for colorectal cancer between the stool specimens obtained during the routine screening and those during the digital rectal examination. METHODOLOGY: One hundred and fourteen patients with colorectal cancer and 228 healthy controls served as subjects of the study. Fecal occult-blood was tested by both of two methods; by the routine screening and by the digital rectal examination, and the sensitivity and specificity of an immunochemical fecal occult-blood test were determined in these two methods. RESULTS: The sensitivity and specificity were 79.8% and 96.5% in the routine screening method, and 86.0% and 79.8% in the digital rectal examination method, respectively, showing a significant difference in the specificity (P < 0.01) between these two stool collection methods. There was no significant difference in the sensitivity between these two stool collection methods. CONCLUSIONS: These findings indicate that the stool specimens collected at the time of the digital rectal examination is not suitable for testing of fecal occult-blood.