Abstract
The aim of this study was to evaluate the screening immunological fecal-occult-blood tests (IFOBT) for colorectal lesions, that it will veil early colorectal cancer in false negative group.
We had 4,819 people examined by IFOBT at Cancer Institute Health Center from November in 1997 to January in 2003. There were IFOBT positive in 545 cases, and negative in 4,274 cases. Total colonoscopy was performed among them, for 212 cases with positive test and for 259 cases with negative.
The sensibility and the specificity of IFOBT for invasive carcinoma and advanced cancer were 85% and 56%, the mucosal carcinoma and adenoma with severe atypia, 74% and 56%, adenoma polyps more than 10mm, 64% and 56% respectively.
According to macroscopic type and size of the lesion, there were much Ip types with more than 10mm and IIa types with more than 15mm in IFOBT positive group. However, small polyps (5-10mm in size) were commonly recognized in negative group. In spite of malignant lesions, 2 cases of advanced cancer, 7 cases of adenoma with severe atypia and mucosal carcinoma (8～10mm in size) were recognized in IFOBT negative group. Following polypectomy and mucosal resection, 45 cases with IFOBT positive became negative in 44cases (98%) .
In conclusion, IFOBT has been a useful test to detect advanced colorectal cancer, but it was not enough to detect the early stage of colorectal cancer. We have to consider an endoscopic screening test in addition to IFOBT for the lesions suited to endoscopic treatment.
