Risk of radiation-related salivary gland carcinomas among survivors of Hodgkin lymphoma: a population-based analysis.

Abstract

Radiotherapy for Hodgkin lymphoma (HL) increases the risk of salivary gland carcinomas (SGC). To the authors' knowledge, however, the magnitude of the risk has not been assessed to date. The risks of SGC among 20,928 1-year survivors of HL who were diagnosed between 1973 and 2003 were evaluated in 11 population-based cancer registry areas of the Surveillance, Epidemiology, and End Results (SEER) program. Observed-to-expected ratios (O/E) were assessed by radiation treatment, sex, age at the time of HL diagnosis, calendar year of diagnosis, attained age, time since HL diagnosis, histologic type of SGC, and site of occurrence in the major salivary glands. Among 11,047 HL patients who received radiotherapy as part of their initial treatment for HL, 21 developed subsequent invasive SGC (O/E = 16.9; 95% confidence interval [95% CI], 10.4-25.8). The risk of radiation-related SGC was highest for younger HL patients (age <20 years) (O/E = 45.5; 95% CI, 12.4-116.5) and among 10-year survivors (O/E = 23.9; 95% CI, 13.1-40.1), with risks remaining elevated for at least 2 decades after irradiation. Significant differences in risk by histologic type were observed, with a particularly high risk of developing mucoepidermoid carcinomas (O = 14; O/E = 44.2 [95% CI, 24.2-74.2]) and adenocarcinomas (O = 4; O/E = 30.6 [95% CI, 8.3-78.2]) noted. HL patients treated with radiotherapy experienced a significantly increased risk of SGC, particularly when exposed at young ages or for at least 2 decades after exposure. Although the results of the current study reflect the late effects of former HL treatment approaches, they point to the importance of long-term follow-up and a heightened awareness of SGC risk in this population.