Association of ampullary and colorectal malignancies

BACKGROUND. Because of the similarities in terms of carcinogenesis and natural history between cancer of the ampulla of Vater and colorectal cancer, the authors examined whether ampullary and colorectal malignancies occur in the same individuals at increased rates. METHODS. We used data from the Surveillance, Epidemiology, and End,Results (SEER) Program of the National Cancer Institute for the period from January 1973 through December 1999. Person-years of follow-up for patients with ampullary (or colorectal) cancer were used to calculate the expected number of cases of colorectal (or ampullary) cancer as a second primary malignancy. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were calculated using Byar limits and assuming a Poisson distribution. RESULTS. The authors identified 2043 white patients with ampullary cancer who were included in the SEER registry between 1973 and 1999. Over an aggregate 5674 person-years of follow-up, 30 patients, compared with an expected 14, developed colorectal cancer, yielding an overall SIR of 2.14 (95% Cl, 1.45-3.06). Similarly, 57 of 262,066 white patients with colorectal cancer developed ampullary cancer over an aggregate, 1,270,255 person-years of follow-up, yielding an SIR of 2.18 (95% Cl, 1.69-2.85). CONCLUSIONS. Patients with ampullary cancer are at increased risk for a second primary colorectal malignancy, and patients with colorectal cancer are at increased risk for a second primary ampullary malignancy. These findings suggest that ampullary and colorectal. malignancies share common environmental and/or genetic risk factors.