Natural history of hereditary cancer of the breast and colon.

The natural history of 106 patients from eighteen families manifesting hereditary breast cancer syndromes, and 117 affected patients from twenty families manifesting nonpolyposis hereditary colon cancer were evaluated. Findings were compared with the American College of Surgeons (ACS) long-term audits for breast and colon cancer respectively. The cardinal features of hereditary cancer were observed within the study group, including: (1) a significant younger age of onset (49 years, breast; 46 years, colon); (2) an excess of proximal lesions in the hereditary colon series (49%); and (3) an excess of bilaterality in the hereditary breast cancer patients. The clinical stage at presentation was similar for the hereditary and ACS audit patients. Five-year survival was significantly improved (P less than .05) for both hereditary cancer populations as compared to the ACS audits (67% hereditary breast cancer and 52% nonpolyposis hereditary colon cancer). Improved survival in hereditary colon and breast cancer patients may have a bearing on the design of future clinical protocols.