Purpose: The aim of this retrospective analysis was to find out whether low-dose radiation, which is used in the treatment of Graves' ophthalmopathy, could cause radiation-induced cancer, which would in turn adversely affect the survival of the irradiated population and cause an increase in the cancer-specific death rate.
Methods and materials: From 1963 to 1978, 250 patients received bilateral orbital irradiation for a progressive Graves' ophthalmopathy. Median age was 49 years. Overall survival and causes of death were evaluated with the help of patients still living, registration offices, medical records, referring physicians, and relatives. Survival curves were calculated with the Kaplan-Meier method. The outcome for each patient was compared with data from life tables regarding gender, age, and calendar period-specific person-years at risk. In addition, treatment outcome for living patients was evaluated with a questionnaire.
Results: After a median follow-up of 31 years, 102 patients are still alive, 123 patients have died, and 25 patients have been lost to follow-up. The 10-year, 20-year, and 30-year survival rates were 89%, 68%, and 49%, compared with the age-adapted survival rate of the normal population of 92%, 76%, and 52%. Evaluation of cancer-specific survival was possible in 166 cases. The 10-year, 20-year, and 30-year cancer-specific survival rates were 98%, 92%, and 88%, compared with 97%, 93%, and 87% in the normal population. Treatment response was evaluable in 94 cases. A complete response was reported in 41 patients, a partial response in 39 patients, and no change in 14 patients.
Conclusions: No significant evidence of radiation-induced cancer death was seen in this small cohort of patients treated with radiotherapy for Graves' ophthalmopathy. The long-term treatment results seem to be satisfactory. Studies with greater numbers of patients are necessary to examine the risks and benefits more precisely.