Abstract
The present study expanded on our previous study (Morikawa et al. Gastroenterology 2005; 129: 422) by adding data obtained after that study ended or by repeated colonoscopies. Screening total colonoscopies and simultaneous one-time immunochemical fecal occult blood tests (IFOBTs) were performed for 115,275 cases overall. We calculated IFOBT's sensitivity for colorectal cancer and investigated the factors affecting sensitivity.
Invasive cancer was identified in 100 patients. The sensitivity of one-time IFOBT for detecting invasive cancer was 64.0% (64/100). Its sensitivity for invasive cancer at the proximal colon was significantly lower than that for cancer detected in the distal colon (48.5% [16/33] vs. 71.6% [48/67], P = 0.02). Factors (sex, age, size, location, form, and progression) affecting sensitivity were investigated with logistic regression analysis. The presence of cancer in the proximal colon was an independent factor for obtaining a false-negative result with the IFOBT. We conclude that IFOBT's sensitivity is reduced in the right colon.
