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Characteristics of colorectal cancer with false negative result on immunochemical faecal occult blood test
H Nakama1, N Kamijo, K Fujimori
1Department of Public Health, Shinshu University School of Medicine, Japan.
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.