Pancreas cancer as a second primary malignancy. A population-based study

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Abstract
Background. The study of second primary malignancies may give clues to the etiology of various cancers. Little is known about risk factors for pancreatic carcinoma; therefore, its occurrence as a second primary malignancy was investigated. Methods. Data from the Surveillance, Epidemiology, and End‐Results (SEER) program were used for the period from January 1, 1973 through December 31, 1990. Person‐years of follow‐up for various cancer sites were calculated, excluding the initial 6 months after diagnosis, and were multiplied times the age‐and sex‐specific incidence rates for pancreas cancer to calculate the expected number of second primary pancreas cancer cases. The observed number of cases was divided by the expected number to estimate the relative risk (RR) of pancreas cancer as a second primary cancer, and 95% confidence limits were calculated. Results. The risk of second primary cancer was elevated after lung cancer for men (RR 1.3, 95% CI 1.0‐1.6) and women (RR 2.5, 95% CI 1.9‐3.2). An elevation in risk also was found after head and neck cancer in women (RR 1.8, 95% CI 1.2‐2.5) and bladder cancer in women (RR 1.5, 95% CI 1.1‐2.0), but not in men. Other significant elevations were found after prostate cancer (RR 1.2, 95% CI 1.1‐1.3), and a decreased risk was found after lymphoma in men (RR 0.2, 95% CI 0.0‐0.8). Conclusions. Second primary pancreas cancer is increased after tobacco‐related malignancies, particularly in females, supporting the role of cigarette smoking as a risk factor for pancreas cancer and suggesting a stronger effect of cigarette smoking for women. The elevation in risk after prostate cancer and the decreased risk after lymphoma in males need to be confirmed in other data sets. Cancer 1995;76:589–92.