Risk of Second Primary Malignancies in Patients With Follicular Lymphoma: A United States Population-based Study

Abstract Background With the improving outcomes of patients with follicular lymphoma (FL), it is imperative to focus on survivorship issues, including the development of second primary malignancies (SPMs). We used a large US database to measure the risk of SPMs among FL survivors. Materials and Methods We used the Surveillance, Epidemiology, and End Results-13 registry to identify FL patients from 1992 to 2011. We calculated the risk of SPMs, developing ≥ 6 months after diagnosis, using the standardized incidence ratio (SIR) and absolute excess risk. We calculated the cumulative incidence of SPMs using the competing risk method and risk factors for SPMs using univariate and multivariate methods. Results Of a total of 15,517 patients with FL followed up for a median of 71 months, 1540 (9.9%) developed SPMs, with a SIR of 1.08 and absolute excess risk of 11.3 per 10,000 person-years. A significantly increased risk was noted for Hodgkin lymphoma (SIR, 5.85), acute myeloid leukemia (SIR, 4.88), and the following sites: oral cavity and pharynx (SIR, 1.43), stomach (SIR, 1.43), lung and bronchus (SIR, 1.35), melanoma of skin (SIR, 1.38), other nonepithelial cancers of the skin (SIR, 2.88), urinary bladder (SIR, 1.24), and kidney/renal pelvis (SIR, 1.43). The cumulative incidence of SPMs was 11.06% at 10 years. Multivariate regression showed that age > 65 years (SIR, 1.57; P P P  = .001) predicted a higher rate of SPMs. Conclusion Patients with FL have increased risk of both hematologic and solid malignancies. Risk factors for SPMs include advanced age, male gender, and receipt of radiation therapy.