Risk of second malignancies in patients with early-stage classical Hodgkin's lymphoma treated in a modern era.

Second malignancies remain an issue affecting morbidity and mortality in long-term survivors of early stage Hodgkin's lymphoma (HL). We undertook this study to determine if treatment in the modern era resulted in decreased second malignancies. Patients diagnosed with stage I-II cHL between 1988 and 2009 who received radiation therapy (RT) were selected from the Surveillance, Epidemiology, and End Results (SEER) database. Freedom from second malignancy (FFSM) was estimated using the Kaplan-Meier method. Univariate analysis (UVA) was performed using the Log-Rank test, and included age, gender, year of diagnosis, and stage. Multivariable analysis (MVA) was performed using Cox Proportional Hazards modeling. The study cohort included 8807 patients. The median age at diagnosis was 32 years (range: 2-85). The majority of patients had stage II disease (n = 6044, 69%), 597 (7%) had extranodal involvement (ENI), and 1925 (22%) had B symptoms. Median follow-up for the entire cohort was 7.2 years (range: 0-22). Five hundred twenty-three (6%) patients developed a second malignancy. Median latency to second malignancy was 5.8 years (range: 0.1-21.5). Of the 523 patients that developed a second malignancy, 228 (44%) occurred in the first 5 years, 139 (27%) were diagnosed between years 5-10, and 156 (30%) beyond 10 years. The 10 year FFSM for patients treated between 1988 and 1999 was 93.0% versus 95.1% for patients treated between 2000 and 2009 (P = 0.04), On MVA, treatment between 2000 and 2009 was associated with a HR for second malignancy of 0.77 (95% Confidence Interval: 0.62-0.96, P = 0.02) compared to the treatment between 1988 and 1999. Our analysis suggests that in patients treated with RT for stage I or II cHL, treatment prior to 2000 had a slightly higher risk of second malignancy compared to treatment in 2000 and later. Further studies, with longer follow-up of patients treated in the modern era are needed to confirm these findings.