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.

Does stool collection method affect outcomes in immunochemical fecal occult blood testing?

PURPOSE: This paper compares the positive predictive value of an immunochemical fecal occult blood test for colorectal neoplasms between the stool specimens obtained during the digital rectal examination and those obtained during the routine screening. METHODS: In a medical check-up, 1,688 subjects received both an immunochemical fecal occult blood test and a colonoscopy. Fecal occult blood was tested by two methods: digital rectal examination and routine screening. The positivity rate of an immunochemical fecal occult blood test and the positive predictive value for colorectal cancer and large adenomatous polyp were determined by these two methods. RESULTS: The positivity rate and the positive predictive value were 5.4 percent and 19.8 percent (4.4 percent for cancer and 15.4 percent for adenomatous polyp) in the digital rectal examination method and 3.5 percent and 27.1 percent (6.8 percent for cancer and 20.3 percent for adenomatous polyp) in the routine screening method, respectively. These figures indicate a significant difference in the positivity rate (P < 0.01) and the positive predictive value (P < 0.05) between these two methods. CONCLUSIONS: These findings indicate that the stool obtained by routine screening has a better positive predictive value than stool collected during the digital rectal examination.

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.

Association of diverticulosis coli and vascular ectasias and the results of fecal occult blood test.

BACKGROUND/AIMS: This study was conducted to clarify the diagnostic value of an immunochemical fecal occult blood test for diverticulosis coli and vascular ectasias of the colon, and to assess the association of these diseases to the results of fecal occult blood test. METHODOLOGY: An immunochemical fecal occult blood test over 2 consecutive days was carried out on 72 patients with diverticulosis coli, on 36 patients with vascular ectasias of the colon, on 36 patients with colon cancer, and on 144 healthy subjects. RESULTS: The test was positive in 13.8% patients with diverticulosis coli, in 11.1% patients with vascular ectasias, in 83.3% patients with colon cancer, and in 6.2% healthy subjects, respectively, showing a significant difference in the detection rate between colonic diverticulosis and colon cancer, between vascular ectasias and colon cancer (P < 0.001). However, there was no significant difference in the detection rate between diverticulosis coli and healthy subjects, and between vascular ectasias and healthy subjects. In addition, there was no significant association between the degrees of diverticulosis coli and vascular ectasias to the results of immunochemical fecal occult blood test. CONCLUSIONS: These findings indicate that the immunochemical fecal occult blood is unsuitable for the diagnosis of the patients with colonic diverticulosis and patients with vascular ectasias, and these disorders have little influence on the results of fecal occult blood test.

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.

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.

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.

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.

Colorectal cancer in iron deficiency anemia with a positive result on immunochemical fecal occult blood.

We examined the relationships between iron deficiency anemia, immunochemical fecal occult blood test results, and colorectal cancer. Samples were collected from 17,664 asymptomatic individuals for an immunochemical occult blood test, and colonoscopy was carried out during medical check-up. The positivity rate on the occult blood test and detection rate for colorectal cancer were compared in those with and those without iron deficiency anemia. In addition, the detection rate for colorectal cancer was determined in four groups stratified by occult blood test results and the presence of iron deficiency anemia. The occult blood test was positive in 18.4% of those with and in 3.8% of those without iron deficiency anemia (P < 0.001), and colorectal cancer was detected in 2.7% of those with and in 0.4% of those without iron deficiency anemia (P < 0.05). The highest rate of colorectal cancer was found in subjects with both iron deficiency anemia and positive occult blood test result. These findings indicate positive associations between iron deficiency anemia and immunochemical occult blood test results, and between iron deficiency anemia and colorectal cancer. Colonoscopy is thus necessary particularly in cases of positive immunochemical occult blood test result and iron deficiency anemia.

Colonoscopic evaluation of immunochemical fecal occult blood test for detection of colorectal neoplasia.

BACKGROUND/AIMS: This study was carried out to assess the validity of three testing methods of immunochemical occult blood according to the number of collection times as a means for colorectal cancer screening. METHODOLOGY: Four thousand six hundred and eleven asymptomatic individuals, who received both an immunochemical occult blood test with a three-day method and colonoscopy during a medical checkup, served as subjects for this study. For evaluation of the desirable number of sampling times, we used the results of the first day for the 1-day method, the results of the first and second days for the 2-day method, and the results of three-consecutive days for the 3-day method. Sensitivities and specificities of these three testing methods were evaluated. RESULTS: Sensitivities and specificities for colorectal cancer were calculated to be 56% and 97% for the 1-day method, 83% and 96% for the 2-day method, and 89% and 94% for the 3-day method, respectively, showing a significant difference in sensitivity between the 1-day and the 2-day methods, as well as the 3-day method (p < 0.01), and in specificity between the 1-day as well as the 2-day and 3-day methods (p < 0.05). CONCLUSIONS: These findings indicate that the immunochemical fecal occult blood test is useful for the diagnosis of colorectal cancer, and that 2-day testing is recommended as a means of screening for colorectal cancer.

Sensitivity and specificity of several immunochemical tests for colorectal cancer.

BACKGROUND/AIM: The purpose of this study was to evaluate the diagnostic accuracy of new different immunochemical fecal occult blood tests for colorectal cancer, including Iatro Hemcheck, Immudia-Hem Sp, LA Hemochaser, Monohaem and OC-Hemodia. METHODOLOGY: Ninety-six patients with colorectal cancer and the same number of healthy controls served as subjects for the study. In this study, each subject received a set of five immunochemical tests over three consecutive days; and sensitivities and specificity of these tests were evaluated. RESULTS: Mean sensitivity and specificity in a set of five immunochemical tests were 91.0% and 95.2%, respectively. Sensitivities and specificity of five different immunochemical tests were calculated as 92.7% and 92.7% for Iatro-Hemcheck, 90.6% and 96.9% for Immudia-Hem Sp, 88.5% and 96.9% for LA Hemochaser, 91.7% and 95.8% for Monohaem, and 91.7% and 93.8% for OC-Hemodia, respectively, showing no significant difference in sensitivity and specificity among five tests. CONCLUSIONS: These results suggest that immunochemical tests for fecal occult blood tests has high diagnostic validity for colorectal cancer. In addition, there is no significant difference in the degree of accuracy among the several types of immunochemical tests.

Colorectal adenomatous polyps detected by immunochemical occult blood screening.

BACKGROUND/AIMS: This study aimed to evaluate the validity of immuno-chemical occult blood screening for colorectal adenomas and to clarify the characteristics of this disease which are detected. METHODOLOGY: We studied 140 colorectal adenomas and 140 healthy controls in a hospital based case control study, in which three-day testing was conducted to assess the accuracy of the immuno-chemical occult blood screening test (total 280 patients). A further 80 colorectal adenomas 1 cm or larger, which were detected by a screening program, were compared with matched cases detected by the outpatient clinics (total 160 patients). A comparison of characteristics including tumor location, shape and histology was made between the two groups. RESULTS: Sensitivity and specificity were calculated to be 46% (61% for tumors larger than 1 cm, 30% for those less than 1 cm), and 96% respectively, showing a significant difference in sensitivity between large and small adenomas (p < 0.01). The proportion of rectal adenomas was significantly higher in the outpatient clinics (41%) than in the screening program (21%) (p < 0.05), whereas no differences were noted in the other measures. CONCLUSIONS: These results suggest that immuno-chemical occult blood is inadequate as a screening test for detecting small adenomas, as t can not differentiate between the detection of rectal adenomas from large adenomatous polyps.

Immunologic detection of fecal occult blood from upper digestive tract diseases.

BACKGROUND/AIMS: This study was conducted to evaluate the accuracy of the immunochemical occult blood test for upper digestive tract diseases. METHODOLOGY: The test was performed on 226 subjects, including 124 upper digestive tract diseases (12 ulcerative esophagitis cases, 10 esophageal cancer cases, 33 gastric ulcer cases, 33 gastric cancer cases, and 36 duodenal ulcer cases), 34 colorectal cancer cases, and 68 healthy subjects, after which, the accuracy of this test was evaluated. RESULTS: The test was positive 23 in upper digestive tract diseases (2 in ulcerative esophagitis, 2 in esophageal cancer, 5 in gastric ulcer, 8 in gastric cancer, 6 in duodenal ulcer), 31 in colorectal cancer, and 3 in healthy subjects, respectively. Thus, the sensitivity was 19% for upper digestive tract diseases (16.7% for ulcerative esophagitis, 20% for esophageal cancer, 15% for gastric ulcer, 24% for gastric cancer, 20% for duodenal ulcer) and 91% for colorectal cancer, and the specificity was 96%. Significant difference was noted in the sensitivity between upper digestive tract diseases and colorectal cancers (p0.001), whereas there was no difference among 5 upper digestive tract diseases. CONCLUSIONS: These results indicate that the immunochemical occult blood is inadequate as means for detection of upper digestive tract diseases, and that an examination of upper digestive tract is unnecessary in cases where the immunochemical occult blood test is positive, but there is no evidence of diseases in colon and rectum.

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.

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.