Risk of second malignant neoplasms among lymphoma patients with a family history of cancer.

Radiotherapy and chemotherapy are known risk factors for second cancers after lymphoma. The role of genetic influences, however, remains largely unknown. We assessed risk of second cancers associated with family history of any cancer in 41,181 patients with Hodgkin lymphoma (HL) (n = 7,476), non-Hodgkin lymphoma (NHL) (n = 25,941), or chronic lymphocytic leukemia (CLL) (n = 7,764), using a large population-based database. Family history of cancer was based on a diagnosis of any cancer in 110,862 first-degree relatives. We found increased relative risk (RR) (1.81, 95% confidence interval (CI): 1.04-3.16) of breast cancer among HL patient with positive (vs. negative) family history of cancer. Among CLL patients with positive (vs. negative) family history of cancer, we observed elevated risks of bladder (RR = 3.53, 95% CI: 1.31-9.55) and prostate cancer (RR = 2.15, 95% CI: 1.17-3.94). For NHL patients with positive (vs. negative) family history of cancer, we observed non-significantly increased risk of non-melanoma skin cancer (RR = 1.94, 95% CI: 0.86-4.38) and lung cancer (RR = 1.99, 95% CI: 0.73-5.39). Our observations suggest that genetic factors, as measured by positive family history of cancer, may be influential risk-factors for selected second tumors following lymphoproliferative disorders.