Treatment of secretory pituitary adenoma with radiation therapy.

A retrospective review of 44 patients with secretory pituitary adenoma treated with radiation therapy (median total dose of 4,500 cGy with a median fraction size of 225 cGy) was performed to analyze response rates and possible variables associated with failure to respond and with complications. The treatment technique used for 75% of the patients was a combination field; an opposed-lateral fields technique was used for the remainder. Median follow-up was 78.5 months, with 59% followed up for more than 60 months and 34% for more than 120 months. Overall survival was 90%, and disease-free survival was 62%. Response rates were 86% for the group with prolactinoma, 67% for the group with acromegaly, and 50% for the group with Cushing disease; the overall response rate was 71%. Findings of suprasellar extension and those from treatment with opposed-lateral fields correlated significantly with failure to respond. A higher percentage of patients with invasive macroadenomas also failed to respond. More complications were found in patients treated with opposed-lateral fields, but the numbers were too small to reach significance. Radiation therapy remains an important adjunct for the treatment of many patients with secretory pituitary adenoma.