Endocrine cancers and second primary tumors

Abstract

Purpose To explore etiologic clues for endocrine cancers by evaluating risk of multiple cancers in conjunction with thyroid and adrenal cancer. Methods We conducted cohort studies including all 2-month survivors of thyroid and adrenal cancer (excluding neuroblastoma) in the U.S. Surveillance, Epidemiology and End Results (SEER) cancer registries program (1973–2000). Relative risks are expressed as the ratio of observed (O) to expected (E) number of cases. Absolute excess risks (EAR) are expressed as the difference between O and E, divided by the person-years (PY) at risk, and then expressed per 10,000 PY. Results Among 29,456 thyroid cancer survivors, 2214 developed a second cancer (O/E = 1.11, 95% CI = 1.06–1.15, EAR = 7.47/10,000 PY), with the highest risk seen in the first year (26%). Patients less than 40 years at diagnosis of thyroid cancer had a 39% increased risk; older patients had a 6% increased risk. We observed a likely radiotherapy-related excess of leukemia. Consistently increased risks also were observed for cancers of the breast, prostate, and kidney; a decreased risk was observed for lung cancer. Based on small numbers of cases, cancers of the salivary glands, trachea, scrotum, adrenal glands, and brain or CNS occurred in excess. Among 811 survivors of adrenal cancer, a 1.76-fold (95% CI = 1.33–2.27) risk of second cancers was observed (O = 57, EAR = 71.36/10,000 PY). Following adrenal carcinoma excesses, were observed for lung, bladder, and prostate cancer; kidney cancer occurred in excess after pheochromocytoma. Young carcinoma patients ( Conclusion Thyroid cancer survivors are at moderately increased risk of second cancers of many different organs. Enhanced clinical surveillance, radiotherapy, and hormonal and genetic factors likely play a role. Survivors of adrenal carcinoma are at increased risk of cancers of the lung, bladder, and prostate. Second cancer risks among young patients suggest Li–Fraumeni syndrome.