Immunochemical faecal occult blood tests are superior to guaiac-based tests for the detection of colorectal neoplasms.

The aim of this study was to compare the performance of a guaiac-based faecal occult blood test (G-FOBT) with that of an immunochemical faecal occult blood test (I-FOBT). A total of 17,215 average risk individuals aged 50 to 74 enrolled in a population-based organised screening programme and performed a 3-day G-FOBT and a 2-day I-FOBT simultaneously. Among participants, 3.1% were found positive for the G-FOBT and 6.9% for the I-FOBT (p<10(-4)). Among the 1205 participants who tested positive and underwent a colonoscopy, the number of detected cancers and advanced adenomas was respectively 2.6 times higher and 3.5 times higher with the I-FOBT than with the G-FOBT. The positive predictive value of I-FOBT was similar to that of the G-FOBT for cancers (5.9% versus 5.2%) and was higher for advanced adenomas (27.2% versus 17.5%). The I-FOBT was superior to the G-FOBT for the detection of both cancers and advanced adenomas. However, the screen positive rate that staff and financial resources can accommodate has yet to be determined.