Purpose: Survivors of childhood Hodgkin's lymphoma (HL) are at risk for second malignant neoplasms (SMNs). It is theorized that this risk may be attenuated in patients treated with lower doses of radiation. We report the first long-term outcomes of a cohort of pediatric survivors of HL treated with chemotherapy and low-dose radiation.
Patients and methods: Pediatric patients with HL (n = 112) treated at Stanford from 1970 to 1990 on two combined modality treatment protocols were identified. Treatment included six cycles of chemotherapy with 15 to 25.5 Gy involved-field radiation with optional 10 Gy boosts to bulky sites. Follow-up through September 1, 2007, was obtained from retrospective chart review and patient questionnaires.
Results: One hundred ten children completed HL therapy; median follow-up was 20.6 years. Eighteen patients developed one or more SMNs, including four leukemias, five thyroid carcinomas, six breast carcinomas, and four sarcomas. Cumulative incidence of first SMN was 17% (95% CI, 10.5 to 26.7) at 20 years after HL diagnosis. The standard incidence ratio for any SMN was 22.9 (95% CI, 14.2 to 35) with an absolute excess risk of 93.7 cases per 10,000 person-years. All four secondary leukemias were fatal. For those with second solid tumors, the mean (+/- SE) 5-year disease-free and overall survival were 76% +/- 12% and 85% +/- 10% with median follow-up 5 years from SMN diagnosis.
Conclusion: Despite treatment with low-dose radiation, children treated for HL remain at significant risk for SMN. Sarcomas, breast and thyroid carcinomas occurred with similar frequency and latency as found in studies of children with HL who received high-dose radiation.