COLORECTAL-CANCER - EVIDENCE FOR DISTINCT GENETIC CATEGORIES BASED ON PROXIMAL OR DISTAL TUMOR LOCATION

Developmental and biologic differences in proximal and distal colon may reflect differing susceptibilities to neoplastic transformation. Differences in proximal and distal colorectal cancer suggest that each may arise through different pathogenic mechanisms. Proximal tumors appear to represent a genetically more stable form of the disease and may arise through the same mechanisms that underlie inherited nonpolyposis colon cancer. Distal tumors show evidence of greater genetic instability and may develop through the same mechanisms that underlie polyposis colorectal cancer syndromes.