2002 年 29 巻 4 号 p. 778-785
Background 30+ % of whole population are screened for but death rate yet keeps increasing of colorectal cancer (CRC) in Japan. Low specificity of fecal occult blood test (FOBT) is considered to be the reason. Detection rate of a CRC screening plan markedly improved following the switching of FOBT data interpretation.
Objective To prove a hypothesis that protrusion of colon mucosa is a major causative factor of colonic bleeding.
Setting Membership-based multiphasic health testing plan participants. Test protocol includes quantitative EIA FOBT, rectosig-moidoscopy and optional barium enema.
Participants 8, 966 health test plan participants who had 23, 188 health tests including 69, 558 FOBT during 2 years. 152 cases of CRC and /or colon adenoma detected were studied.
Methods FOBT data were compared concerning density, resemblance of 3 figures, chronological change between CRC and non-CRC cases, as well as before and after removal of protrusion.
Results FOBT densities, both of colon cancer and adenoma cases, were unexceptionally high and resembled in each case that markedly decreased to near zero after removal of protrusion. FOBT data of rectal cancer and adenoma cases were not necessarily high and dispersed widely.
Conclusion Unexceptionally noted marked decrease of FOBT after removal of masses in colon adenoma cases in exactly same manner as in colon cancer cases suggested that origins of bleeding was collisions between masses and colon contents rather than fragility of tissues.
When interpreted properly paying attention to the continuity of being positive and resemblance of FOBT, 30ng/ml should be optimal cut-off value for cancer detection.
