Risk of second malignancy after non-Hodgkin's lymphoma: A British cohort study

Purpose To assess long-term site-specific risks of second malignancy following non-Hodgkin's lymphoma (NHL) in relation to treatment and demographic factors. Patients and Methods A cohort of 2,456 patients with NHL who were first treated from 1973 to 2000 and were younger than 60 years from centers in the British National Lymphoma Investigation were observed, and occurrences of second malignancy was compared with expectations based on general population cancer rates in England and Wales. Results In total, 123 second malignancies occurred. Relative risks (RRs) were significantly elevated for all malignancies combined (RR = 1.3-1 95% Cl, 1.1 to 1.6) and for leukemia (RR = 8.8 95% Cl, 5.1 to 14.1) and lung cancer (RR = 1.6; 95% Cl, 1.1 to 2.3). RRs of malignancy overall diminished significantly with increasing age at first treatment. Leukemia risk was significantly increased after chemotherapy (RR = 10.5 95% Cl, 5.0 to 19.3) and mixed-modality treatment (RR = 13.0; 95% Cl, 5.2 to 26.7). Relative risks of lung (RR = 1.9; 95% Cl, 1.1 to 3.1) and colorectal (RR = 2.1; 95% Cl, 1.1 to 3.6) cancers were significantly raised following chemotherapy. Conclusion NHL patients are at elevated risk of developing second malignancy, particularly leukemia and lung cancer. The relative risk is greater with patients who are younger at first treatment. Chemotherapy predisposes patients to an increased risk of leukemia, and possibly lung and colorectal cancers. The role of specific drug treatments in the etiology of solid cancers after NHL deserves further investigation.