Impact of apolipoprotein E ε4 and HIV on cognition and brain atrophy: antagonistic pleiotropy and premature brain aging.

OBJECTIVE: The apolipoprotein E (APOE) ε4 allele may accelerate the progression of HIV disease, and increase the risk for developing HIV-associated neurocognitive disorder (HAND). Whether APOEε4 allele(s) and age may influence brain atrophy in HIV patients is unknown and was evaluated. METHODS: Automated morphometry on magnetic resonance images, using FreeSurfer analyses, neuropsychological testing and APOE genotyping were performed in 139 subjects [70 seronegative controls (SN); 69 clinically-stable HIV subjects]. RESULTS: Compared to SN, HIV subjects had smaller volumes throughout the brain regardless of their HAND status. Compared to APOEε4- subjects, SN controls with APOEε4 had better memory and larger global brain volumes (cerebral white matter and cortex) while HIV subjects with the APOEε4 allele(s) had poorer cognition (verbal fluency, learning, executive function and memory) and smaller cerebral and cerebellar white matter and subcortical structures. Further stratification of age showed that younger (<50 years) APOEε4+SN subjects had larger putamen and cerebral white matter, while younger APOEε4+HIV subjects had poorer performance on verbal fluency and smaller brain volumes [3-way (HIV-status×APOEε4×Age) interaction-p-values=0.005 to 0.03]. INTERPRETATION: These findings suggest that APOEε4 allele(s) may show antagonistic pleiotropy on cognition and brain atrophy in SN controls, but may lead to premature aging with neurodegeneration in younger HIV patients prior to the development of HAND. Potential mechanisms for such interactions may include stronger neuro-inflammation or greater amyloid deposition in younger HIV subjects with APOEε4 allele(s). Early screening for the APOEε4 allele and brain atrophy with morphometry may guide neuroprotective intervention of cognitively normal HIV subjects prior to the development of HAND. Longitudinal follow-up studies and larger sample sizes are needed to validate these cross-sectional results.

Nucleotide sequence of the genes, encoding the pentaheme cytochrome (dmsC) and the transmembrane protein (dmsB), involved in dimethyl sulfoxide respiration from Rhodobacter sphaeroides f. sp. denitrificans.

The nucleotide sequence of the genes encoding a pentaheme cytochrome (dmsC) and a transmembrane protein (dmsB) were determined upstream of the dmsA gene encoding dimethyl sulfoxide reductase from Rhodobacter sphaeroides f. sp. denitrificans. dmsC and dmsB encode proteins of 404 and 226 amino acid residues, which show 40% and 26% identity to the pentaheme cytochrome TorC and the transmembrane protein TorD, respectively, of the trimethylamine N-oxide reduction system in Escherichia coli.

Evaluation of the optimum cut-off point in immunochemical occult blood testing in screening for colorectal cancer.

This study was carried out to assess, from the aspects of cost-effectiveness and diagnostic validity, the optimum cut-off point for immunochemical occult blood testing using a 2-day method as a means of screening for colorectal cancer. Four thousand, two hundred and sixty asymptomatic individuals were subjects of this study. They gave samples for an immunochemical fecal occult blood test, and colonoscopy was carried out during a medical check-up. For evaluation of the optimum cut-off point, three cut-off levels of fecal haemoglobin, 50, 150 and 300 ng/ml, were used. A total of 27 patients with colorectal cancer were diagnosed. The average costs to detect one patient with colorectal cancer and the sensitivity and specificity of these three cut-off points of fecal haemoglobin were evaluated. The average costs for the detection of one cancer case were calculated as $2870.45 for cut-off level of 50 ng/ml, $2492.98 for that of 150 ng/ml and $3329.09 for that of 300 ng/ml, respectively. The sensitivity and specificity were calculated as 89 and 94% for the 50 ng/ml cut-off level, 81% and 96% for the 150 ng/ml cut-off level and 56 and 97% for the 300 ng/ml cut-off level, respectively, indicating a significant difference in the sensitivity between the 50 and 300 ng/ml levels (P<0.05), as well as between the 150 and 300 ng/ml levels (P<0.05), and a significant difference in the specificity between the 50 and 300 ng/ml levels (P<0.05). However, no significant difference was observed in the specificity between the 50 and 150 ng/ml levels. The findings show that 150 ng/ml of fecal haemoglobin is the optimal cut-off point when carrying out the OC-Hemodia test as a means of screening for colorectal cancer.

A cost-effective analysis of the optimum number of stool specimens collected for immunochemical occult blood screening for colorectal cancer.

This study was carried out to assess, from the viewpoint of cost-effectiveness, the optimum number of faecal specimens to collect for use in immunochemical occult blood testing as a means of screening for colorectal cancer. 3300 asymptomatic individuals were subjects of this study. They gave samples for an immunochemical faecal occult blood test, monohaem and colonoscopy was carried out during a medical check-up. For evaluation of the optimum number of sampling specimens, the results of the first day of sampling, those of the first and second days, and those of samples taken for 3 consecutive days were considered as the single-day method, the 2-day method and the 3-day method respectively. The average cost to detect 1 patient with colorectal cancer, the detection rate and the false-positive rate of these three faecal sample collection methods were evaluated. The average costs for one cancer case detected were calculated as $3,630.68 for the single-day method, $3,350.65 for the 2-day method and $4,136.36 for the 3-day method, respectively. The detection rate and the false-positive rate were calculated as 47 and 3.5% for the single-day method, 82 and 4.7% for the 2-day method and 88 and 5.3% for the 3-day method, respectively. This detection rate was significantly different between the single- and the 2-day methods, as well as between the single- and the 3-day methods (P<0. 05). No significant differences in the false-positive rate amongst the three testing methods were observed. This analysis suggests that a 2-day faecal collection method is recommended for immunochemical occult blood screening by Monohaem from the aspects of cost-effectiveness and diagnostic accuracy.

Family history of colorectal adenomatous polyps as a risk factor for colorectal cancer.

The aim of this study was to evaluate the risk of common colorectal cancer among first-degree relatives of patients with colorectal adenomatous polyps. In a population screening programme, 59406 subjects underwent an immunochemical faecal occult blood test. In a medical check-up-based cross-sectional study, 6139 subjects had a colonoscopic examination. They were divided into two groups, according to the results of a questionnaire on family history of colorectal adenomatous polyps, and the detection rates for colorectal cancer were compared in the groups positive or negative for a family history of colorectal adenomatous polyps. In the screening programme-based cross-sectional study, the detection rate for colorectal cancer was 0.57% (95% confidence interval (CI): 0.38-0.76) and 0.15% (95% CI: 0.12-0.18) in subjects with and without a family history of colorectal adenomatous polyps, respectively, showing a significant difference in the detection rate for colorectal cancer between the two groups (P<0.05). In the medical check-up-based cross-sectional study, the detection rate for colorectal cancer was 2.31% (95% CI: 1.15-3.47) and 0.53% (95% CI: 0. 34-0.72) in subjects with and without a family history of colorectal adenomatous polyps, respectively, indicating a significant difference between the two groups (P<0.05). These findings indicate that first-degree relatives of patients with colorectal adenomatous polyps have an elevated risk for common colorectal cancer, and that people with a family history of colorectal adenomatous polyps should be considered as a priority group for colorectal cancer screening.

Immunochemical fecal occult blood test is not suitable for diagnosis of hemorrhoids.

PURPOSE: This study was conducted to clarify the diagnostic value of an immunochemical fecal occult blood test for hemorrhoids. PATIENTS AND METHODS: In a case-control study, an immunochemical fecal occult blood test with a 2-day method was carried out on 82 subjects with hemorrhoids, on 82 subjects with colorectal cancer, and on 82 healthy subjects. In a population-based cross-sectional study, 29,714 subjects who received an immunochemical occult blood screening with a 2-day method were divided into two groups, according to the results of a questionnaire on hemorrhoids, and the positivity rate of an immunochemical test as well as the predictive value for colorectal cancer were compared in the two groups. Moreover, both an immunochemical occult blood test with a 2-day method and colonoscopy were conducted at the same time on asymptomatic subjects during a medical checkup. RESULTS: In the case-control study, the test was positive in 13.4% subjects with hemorrhoids, in 84.1% subjects with colorectal cancer, and in 4.9% healthy subjects, respectively, showing a significant difference in the detection rate between the two diseases (P < 0.001). In the population screening program, the test was positive in 6.9% subjects with hemorrhoids and in 6.5% subjects without hemorrhoids, and the predictive value was 3.2% in subjects with and without hemorrhoids, respectively, indicating no significant difference in the positivity rate as well as the predictive value between the two groups. Among 232 subjects in a medical checkup, 28 patients with hemorrhoids and 21 patients with colorectal polyp 1 cm or larger were diagnosed by colonoscopy, and the occult blood test was positive in 16.7% patients with hemorrhoids and in 52.4% patients with colorectal polyp, respectively. There was a significant difference in the sensitivity between the two disease groups (P < 0.05). CONCLUSIONS: These findings indicate that the immunochemical fecal occult blood is unsuitable for the diagnosis of the patients with hemorrhoids and an examination of the colorectum is necessary in cases where the occult blood test is positive but there is a sign of hemorrhoids.

Comparisons of cancer detection rate and costs of one cancer detected among different age-cohorts in immunochemical occult blood screening.

PURPOSE: This study was carried out to compare the detection rate for colorectal cancer and the average costs to detect one patient with colorectal cancer among three different age-cohorts in immunochemical occult blood screening by OC-Hemodia. METHODS: In a population-screening program, 17,432 subjects received an immunochemical fecal occult blood test. In a medical checkup for colorectal cancer 7,232 subjects received colonoscopy. They were divided into three groups according to their ages: younger (4,049 years); middle (50-59); and older (60+) groups. The detection rate for colorectal cancer and the average costs to detect one patient with colorectal cancer were evaluated among the three groups. RESULTS: In the screening program-based study, the cancer detection rate and the average costs for one colorectal cancer detected were calculated as 0.09% and $13,352, 0.28% and $4,555, 0.29% and $4,461 for the younger, middle, and older groups, respectively. In addition, in the medical checkup-based study, the detection rate and the average costs were calculated as 0.3% and $6,851, 1.5% and $1,517, 1.7% and $1,391 for the younger, middle, and older groups, respectively. In these two studies, the cancer detection rates were significantly different between the younger and middle groups (P < 0.05), and between the younger and older groups (P < 0.05). CONCLUSIONS: These findings indicate that the subjects aged under 50 have some disadvantage when carrying out the immunochemical fecal occult blood test--OC-Hemodia for colorectal cancer screening--from the viewpoint of screening efficiency as well as cost-effectiveness.

Relationships between a sign of rectal bleeding and the results of an immunochemical occult blood test, and colorectal cancer.

A cross-sectional study based on medical check-up was carried out to investigate the association between signs of rectal bleeding and colorectal cancer, and the results of an immunochemical faecal occult blood test. The 9625 patients received both an immunochemical faecal occult blood test using a two-consecutive-day method and colonoscopy. They were then divided into two groups, according to the results of a self-completed questionnaire on the signs of rectal bleeding. The positivity rate of the immunochemical faecal occult blood test as well as the positive predictive value for colorectal cancer were determined in these two groups. The faecal occult blood test was positive in 9.3% of patients with rectal bleeding and in 4.4% of patients without rectal bleeding, and the positive predictive value for colorectal cancer was 0.79 and 0.27 in patients with and without rectal bleeding, respectively. This indicates a significant difference in the positivity rate (P < 0.001) as well as the positive predictive value (P < 0.05) between these two groups. The results suggest that there are positive associations between the signs of rectal bleeding and the results of immunochemical faecal occult blood test, and between the patients presenting with rectal bleeding and colorectal cancer.

Bacterial interference among nasal inhabitants: eradication of Staphylococcus aureus from nasal cavities by artificial implantation of Corynebacterium sp.

To evaluate the role of normal flora in the nares in preventing Staphylococcus aureus colonization, we conducted a replacement study in vivo. Staphylococcus epidermidis (rate of colonization: 100%), various species of corynebacteria (52.5%) and S. aureus (25.%) were the major bacterial inhabitants in the nares of 156 healthy volunteers. The low incidence of S. aureus colonization in the carriers with corynebacteria (8.5%), compared to non-carriers (44. 5%) indicated the possibility of competition for survival between S. aureus and corynebacteria. To confirm this hypothesis, we artificially implanted a strain of Corynebacterium sp (API Coryne bioprofile; 5100304), denoted as Co304 into the nares of 17 S. aureus carriers. S. aureus was completely eradicated in 71% of carriers by up to 15 inoculations of Co304. However, similar doses of 0.9% NaCl or S. epidermidis into the nares of 10 volunteers did not eradicate S. aureus. No bacteriocin-like activity against S. aureus was detectable, even after mitomycin C stimulation of Co304. Thus Co304 interfered with S. aureus by a different mechanism to a bacteriocin-like activity.

Detection rate of immunochemical fecal occult blood test for colorectal adenomatous polyps with severe dysplasia.

This study was conducted to assess the accuracy of an immunochemical occult blood test for detecting colorectal adenomas with severe dysplasia, and to determine the relationship between the grading of adenomatous dysplasia and the results of this test. Sixteen colorectal adenomas under 1 cm with severe dysplasia, 65 adenomas under 1 cm with mild-to-moderate dysplasia, 65 adenomas 1 cm or larger with mild-to-moderate dysplasia, 65 colorectal cancers and 130 healthy controls were investigated. Each subject was tested with an immunochemical fecal occult blood test on 3 consecutive days, and the accuracy of the test was evaluated. The detection rate of this test was 13% for severe dysplasia under 1 cm, 45% for severe dysplasia 1 cm or more, 17% for mild-to-moderate dysplasia under 1 cm, 40% for mild-to-moderate dysplasia 1 cm or more, and 89% for colorectal cancers, and the false positive rate was 5%, showing a significant difference in the detection rate between severe dysplasias 1 cm or more and those under 1 cm (P < 0.05) as well as significant difference between severe dysplasias 1 cm or more and mild-to-moderate dysplasia under 1 cm (P < 0.01), and between cancers and adenomas (P < 0.001), whereas there was no significant difference between the detection rates for severe dysplasia 1 cm or more and mild-to-moderate dysplasia 1 cm or more. These results indicate that there is no association between the detection rate of this immunochemical occult blood test for adenomas and the grade of adenomatous dysplasia.

Digital rectal examination sampling of stool is less predictive of significant colorectal pathology than stool passed spontaneously.

OBJECTIVES: To compare the positivity rate and the positive predictive value of an immunochemical faecal occult blood test (FOBT) carried out by using stool samples obtained during a routine screening method and those obtained during digital rectal examination. DESIGN: Screening programme-based, cross-sectional study. METHODS: In a screening programme-based, cross-sectional study, 1,044 subjects who received both an immunochemical FOBT and colonoscopy were divided into two groups according to stool collection techniques--the routine screening method and the digital rectal examination method. The positivity rate of the immunochemical FOBT, as well as the positive predictive value for colorectal cancer and large adenomatous polyp, were determined in the two groups. RESULTS: The positivity rate and positive predictive value were 3.8% and 60.0% (10.0% for cancer and 50.0% for adenomatous polyp) in the routine screening group, and 9.4% and 26.5% (4.1% for cancer and 22.4% for adenomatous polyp) in the digital rectal examination group, respectively, indicating a significant difference in the positivity rate (P < 0.01) as well as the positive predictive value (P< 0.05) between the two groups. CONCLUSIONS: These results show that digital rectal examination sampling of stool is less predictive of significant colorectal pathology than stool passed spontaneously, and therefore the latter is the preferred method for stool sampling.

Validity of immunological faecal occult blood screening for colorectal cancer: a follow up study.

OBJECTIVES: Immunological faecal occult blood testing has been recognised as a useful method for wide scale screening of colorectal cancer in Japan during the past few years. This study was carried out to evaluate the validity of an immunological faecal occult blood test for colorectal cancer screening. METHODS: A screening programme for colorectal cancer using an immunological faecal occult blood test was conducted on 3365 residents of regions within Nagano prefecture in 1991, and all the subjects were followed up for three years by verification from cancer registration. Based on the incidence of false negative cases among those who had been evaluated as normal by this screening, but were diagnosed as having colorectal cancer, the sensitivity and the specificity of this test were estimated. RESULTS: Four false negative cases were found during the subsequent three year follow up period after screening. Among these four cases, one case was within the first follow up year, one case within the second year, and two cases within the third year. Accordingly, the sensitivity of this test was calculated as 90.9% within one year, 83.3% within two years, and 71.4% within three years, while the specificity was found to be 95.6%, indicating a validity higher than that achieved by a chemical occult blood test. CONCLUSION: These findings suggest that the immunological faecal occult blood test has a high diagnostic accuracy and is a useful strategy for colorectal cancer screening.

Diagnostic accuracy of immunochemical faecal occult blood test for gastric cancer.

OBJECTIVES: To investigate the accuracy of the immunochemical occult blood test in screening for gastric cancer and to evaluate whether or not the upper digestive tract should be examined when the occult blood test is positive but there is no abnormal sign in the colorectum. METHODS: In a case-control study an occult blood test was carried out on 150 subjects with gastric cancer, 150 subjects with colorectal cancer, and on 300 healthy subjects. Data were analysed from 44,996 persons attending a population screening programme who underwent both radiological gastric cancer screening (barium meal) and colorectal cancer examination by occult blood test. RESULTS: In the case-control study the occult blood test was positive in 27/150 (18%) subjects with gastric cancer, in 112/ 150 (75%) subjects with colorectal cancer, and in 24/300 (8%) healthy controls. In the population screening programme the occult blood test was positive in 4/50 (8%) persons with gastric cancer and 3232/ 44,950 (7%) persons without gastric cancer, indicating no difference between them. CONCLUSIONS: These data show that the immunochemical faecal occult blood test is worthless as a screening test for gastric cancer, and that examination of the upper digestive tract is unnecessary in cases where the faecal occult blood test is positive but there is no sign of colorectal disease.

Characteristics of colorectal cancer with false negative result on immunochemical faecal occult blood test.

OBJECTIVES: A comparative study was carried out to clarify the clinicopathological features of colorectal cancer diagnosed after a false negative result on the immunochemical faecal occult blood test. METHODS: 236 patients with colorectal cancer were studied: 48 patients with negative results and 188 patients with positive results with the faecal occult blood test. The two groups were compared according to their age and sex and by the site, size, macroscopic type, Dukes's classification, and histological type of their cancer lesions. Additionally, the above factors were investigated prospectively and compared in 40 cases of colorectal cancer cases diagnosed as false negative and in matched cases diagnosed as true positive in cancer screening by the immunochemical faecal occult blood test. RESULTS: In both the hospital based case-control study and the screening programme based nested case-control study the prevalence of rectal cancers was higher in the false negative group than in the true positive group (P = 0.02, P = 0.03), but there were no differences between the two groups for any other factors. CONCLUSION: These results suggest that the immunochemical faecal occult blood test is unsuitable for the diagnosis of rectal cancer.

Characteristics of colorectal cancer that produce positive immunochemical occult blood test results on stool obtained by digital rectal examination.

OBJECTIVE: To clarify the clinicopathological features of colorectal cancer that show positive results on an immunochemical fecal occult blood test of stool obtained by digital rectal examination. METHODS: In a cross-sectional study, 9952 subjects received both an immunochemical fecal occult blood test of stool obtained by digital rectal examination and colonoscopy annually over a nine-year period of medical checkups; 64 patients with colorectal cancer were identified. The study subjects comprised 39 patients with colorectal cancer who had positive results (positive group) and 25 patients with colorectal cancer who had negative results (negative group) on an immunochemical fecal occult blood test of stool obtained by digital rectal examination. The positive and negative groups were compared in terms of their individual factors, such as site, size, Dukes classification and histological type of the cancer lesions. RESULTS: The prevalence of rectal cancers was higher in the positive group than in the negative group (P<0.05), but there were no differences between the two groups with respect to any other factors. CONCLUSIONS: These findings indicate that stool obtained during the digital rectal examination is unsuitable for detecting fecal occult blood, especially for the detection of proximal colon neoplasms.

Screen compliance rates in 14-years annual screening program for colorectal cancer with immunochemical fecal occult blood test-- identification of higher priority subjects in health education.

OBJECTIVES: The present study was carried out to assess compliance rates with annual colorectal cancer screening for fecal occult blood, and to identify the subjects with higher priority in health education to increase screen compliance. DESIGN AND SETTING: A screening program for colorectal cancer was conducted between 1982 and 1995 in a Japanese villlage. Screen compliance rates in this program were summarised related to sex distribution as well as 10-year age cohorts. MAIN RESULTS: Screen compliance declined slowly during 14 years time period, and averaged 55.4%. Mean screen compliance was significantly higher in women (56.8%) than in men (53. 8%), and also in aged 50-79 (63.5%) than in aged 50 or less (43.8%), and those 80 and older(12.3%). Subjects who experienced a negative result on colonoscopic examination had significantly lower compliance with screening. CONCLUSIONS: These findings indicate that the youngest as well as oldest subjects, and the subjects with negative results of fecal occult blood test should be given higher priority in health education to improve screen compliance.

Reasons for non-compliance in colorectal cancer screening with fecal occult blood test.

OBJECTIVES: To identify the reasons for non-compliance with fecal occultblood test in the screening programme for colorectal cancer. DESIGN AND SETTING: The people who had never participated in the screening programme for colorectal cancer served as the subjects of this study. A structured questionnaire which included the reasons for rejection was sent to each of non-compliers. They were requested to choose two major reasons which were described in a best way that why they did not participate in the programme. The frequency of the stated reasons were analysed from the viewpoint of both sex and age effects. MAIN RESULTS: A total of 439 people was identified as non-compliers, and 356 (81.1%) people completed the questionnaire. No significant difference was noted in response to the questionnaire between male and female as well as aged 40-59 and those 60-79. The most commonest reason was felt well (47.8%) in male, fear or shyness of further examination (40.2%) in female, and also felt well (48.5%) in aged 40-59, fear or shyness of further examination (40.1%) in aged 60-79. Significant differences were observed in the frequencies of felt well (p<0.01), fear or shyness of further examination (p<0. 01), busy for work (p<0.01) and fear of cancer (p<0.01) between male and female, and also felt well (p<0.01), fear or shyness of further examination (p<0.01), busy for work (p<0.01) and coexistent disease (p<0.01) between aged 40-59 and those 60-79. CONCLUSIONS: These results suggest that public education about the concept of asymptomatic illness, the benefits of early detection, the safety and painless colonoscopy, and the effective treatment should be emphasised to increase compliance with screening for fecal occult blood.

Clinico-pathological features of colorectal adenomatous polyps with negative results on immunochemical fecal occult blood test.

BACKGROUND: This study was carried out to clarify the clinico-pathological features of colorectal adenomatous polyps showing negative results on an immunochemical fecal occult blood test. METHODS: Four hundred sixty patients with colorectal adenoma 1.0 cm or larger in diameter served as subjects of this study. They were divided into two groups based on the results of an immunochemical fecal occult blood test with a 3-day method: two hundred twenty four patients with positive results (positive group) and two hundred thirty six patients with negative results (negative group). The above two groups were compared in terms of their individual factors such as lesion site, lesion size, lesion shape, and histological type. RESULTS: In negative group, the frequencies of rectal adenomatous polyps (p<0.01) and colorectal adenomatous polyps 1.0-1.5 cm in size (p<0.001) were higher, and also pedunculated type (p<0.05) were lower than in positive group, but there was no difference in histological type between the two groups. CONCLUSIONS: These findings suggest that immunochemical fecal occult blood testing is relatively inferior for the detection of colorectal adenomatous polyps in rectum, smaller size, and non-pedunculated type.

Relative risk of dietary components and colorectal cancer.

OBJECTIVES: To investigate the relative risk factor of dietary components for colorectal cancer in a Chinese rural area through a hospital-based study. DESIGN AND SETTING: Colorectal cancer patients diagnosed at a county cancer center, Hebei Province, China, and out-patients with similar age, sex and resident place were selected for cases and controls, respectively. All subjects were given to interview about their food intake using a foods frequency questionnaire. The intake of different dietary components and life style were compared between cases and controls. MAIN RESULTS: There were 45 colorectal cancer patients and 45 outpatients being the cases and controls in the hospital-based study. In comparison of dietary components between cases and controls, milks, vegetables, fruits and teas had protective effect, and odds ratios were 0.21 (95% CI 0.07-0.60), 0.13 (95% CI 0.03-0.49), 0.27 (95% CI 0.11-0.68) and 0.39 (95% CI 0.16-0.98), respectively. Meats and saturated fats had an increased risk for colorectal cancer, and odds ratios were 5. 13 (95% CI 1.54-17.00) and 3.61 (95% CI 1.17-11.11), respectively. CONCLUSIONS: These findings indicate that there is a similar trend of dietary factors and risk of colorectal cancer in rural areas in comparison with westem dietary pattern, and suggest that the special attention should be paid to dietary habit for prevention and control of colorectal cancer in Chinese rural area.

Diagnostic value of immunochemical fecal occult blood test for small colorectal neoplasms.

This study was designed to assess the diagnostic value of an immunochemical fecal occult blood test for small colorectal adenomas. In a screening program based comparative study, 60 colorectal adenomas under 1 cm (small polyp group), 60 colorectal adenomas 1 cm or larger (large polyp group) and 60 colorectal cancers (cancer group) detected by occult blood screening, and 120 healthy controls (control group), served as subjects. Moreover, 50 small adenomas, 50 large adenomas and 50 cancers detected in out-patient clinics, and 100 controls, served as subjects of a hospital based comparative study. Each of these subjects was tested by an immunochemical occult blood with 3 consecutive days, after removal of these colorectal neoplasms in a screening program based study and before as well as after removal in a hospital based study, and the positivity rate of this test was evaluated among these four groups in the two comparative studies. The positivity rate in a screening program based study was 23% for small polyp group, 8% for large polyp group, 5% for cancer group and 6% for control group, respectively. Significant difference was noted between small polyp and cancer as well as control groups (p <0.01), and between small polyp and large polyp groups (p <0.05). In a hospital based study, however, there was no significant difference in the positivity rate among four groups. These results suggest that high proportion of small polyps detected by fecal occult blood test screening may not be associated with bleeding from adenomas but probably from another gastrointestinal pathology.