Studies on Relatives of Sporadic Colorectal Cancer Patients

Abstract

Epidemiologic studies demonstrate that first degree relatives of sporadic colorectal cancer patients are at increased risk for the same neoplasm. Based on this, a prospective screening study demonstrated a 3-fold risk for neoplasia in relatives aged 40 or more years. The risk rose from 3-fold if there was one affected relative to 5-fold if there were 2 or more such relatives. Calculations of costs demonstrated that it was 4-fold more cost-effective to use colonoscopy as the primary screening exam if there were more than one affected first degree relative, otherwise flexible sigmoidoscopy and fecal occult blood testing were the most economic method. Measuring the rectal epithelial proliferation in a sample of these first degree relatives demonstrated that the probability of it being increased was greatest in the young male relatives. This biomarker may help delineate a high risk subgroup for prospective primary and secondary prevention. Using proliferation as a measure of response we gave 1.25–1.5 g calcium ion/day for 3 months to such relatives and significantly suppressed their proliferation only while they took calcium.