Colonic Polyps, Occult Blood, and Chance

Fecal occult blood testing (FOBT) is the simplest and cheapest way to screen the populace for colorectal tumors. Though primarily intended to uncover early malignant neoplasms, it also reveals benign neoplastic polyps.¹ This is a potentially important benefit of FOBT, because most colorectal cancers arise from malignant transformation of benign polyps—the so-called adenoma-carcinoma sequence.² Hence, widespread detection and removal of asymptomatic polyps could dramatically decrease the incidence of bowel cancer, at least in theory. The best studies of FOBT indicate a substantial yield of adenomas—about 20% of individuals with positive test results aged 50 through 59 years, rising to about one third of those over 70 years.³ These are impressive numbers and, on the surface, lend support to those who advocate general FOBT surveillance of middle-aged and elderly people.

In this issue of The Journal, however, Ransohoff and Lang⁴ argue that a major proportion of small (<1