Hypothyroidism secondary to radiation and chemotherapy in pediatric Hodgkin's Disease

Abstract

8532 Background: Hypothyroidism in pediatric Hodgkin's disease (HD) survivors is reported due to neck irradiation (RT). An effect of chemotherapy remains controversial. Methods: Records of 467 newly diagnosed HD patients treated on different regimens between 1979 and 2002 were reviewed. Radiation dose to the neck and clinical features were recorded. Hypothyroidism was defined as a TSH > 4.7 or need for thyroxine therapy. The cumulative incidence of hypothyroidism was calculated using SAS version 8.2 and treating relapse, death, or second cancer as competing risks. Results: Of 457 evaluable patients, 261 (57%) were male, 378 (83%) white; median age was 15.2 years (range 3 –21.7) and median time of thyroid follow up was 4.5 years (range 0.1 to 22.3). Treatment regimens used during this period were COPP, COPP/ABVD, VAMP, VEPA, VAMP/COP or Stanford V combined with RT or RT alone in selected patients with localized disease. The Table shows the cumulative incidence of hypothyroidism at 5 and 10 years according to the RT dose given. Patients in Group1 had no RT, a 7% incidence of hypothyroidism, and served as the reference group. Comparison of Group3 and Group4 shows a significant difference in cumulative incidence of hypothyroidism (p=0.004). Age at treatment was not a risk factor for developing hypothyroidism. The relative risk for females compared to males of developing hypothyroidism was 1.6 (p=0.0002) while the relative risk for blacks of developing hypothyroidism was 0.36 (p=0.0015) compared to non-blacks.Conclusions: Chemotherapy added to moderate (21–26.9Gy) dose RT, resulted in a higher incidence of hypothyroidism than high dose RT (>27Gy) alone. Table: Hypothyroidism Cumulative Incidence according to Radiation Dose / Chemotherapy No significant financial relationships to disclose.