Risk of non-Hodgkin lymphoma after radiotherapy for solid cancers.

Abstract

Abstract Ionizing radiation increases risk for acute leukemia, but less is known about radiation and risk of other hematologic malignancies such as non-Hodgkin lymphoma (NHL). We compared second primary NHL incidence among patients who did and did not receive initial radiotherapy for first primary solid malignancy during 1981-2007 reported in nine Surveillance, Epidemiology, and End Results (SEER) Program population-based cancer registries. We identified 5590 second NHL cases among 1 450 962 1-year cancer survivors. NHL risk was increased after initial radiotherapy for all solid cancers combined (multivariate Poisson regression relative risk [RR]: 1.13, 95% confidence interval [CI]: 1.06-1.20), non-small cell lung cancer (RR: 1.53, 95% CI: 1.08-2.17) and prostate cancer (RR: 1.19, 95% CI: 1.09-1.32). NHL risk increased with longer latency after radiotherapy for non-small cell lung cancer (ptrend = 0.003) but decreased for prostate cancer (ptrend = 0.017). There was no clear NHL risk pattern by NHL subtype or age. Our study provides limited evidence that radiotherapy for solid malignancy is associated with increased risk of subsequent NHL.