Long term toxicity and prognostic factors of radiation therapy for secreting and non-secreting pituitary adenomas

BACKGROUND: Radiotherapy is controversially discussed in the management of benign disorders for fear of late sequelae such as tumor induction. This study was initiated to investigate long-term toxicity, treatment outcome and prognostic factors after radiotherapy (RT) in patients with pituitary adenomas. METHODS: 92 patients with pituitary adenomas were included in this analysis. RT was conducted using either 3D conformal (16%) or fractionated stereotactic techniques (83%) in a postoperative adjuvant setting (16%), as second-line treatment for recurring tumors (78%) or as primary treatment (6%). Postoperatively, RT was offered to patients with residual tumor tissue or in case of locally extensive adenomas, in whom early recurrence was deemed likely. Patients were followed for a median time of 152.5 months, and analysed for overall and local progression-free survival (OS and LPFS). Multiple factors were analysed for prognostic impact. Patients were contacted with an institutional questionnaire about qualiy of life (QOL). Statistical analysis was performed using the log-rank test and the Kaplan-Meier method using a software tool (SPSS 19.0). RESULTS: Median follow-up was 152.5 months. Before treatment, 2% of all patients were diagnosed with adenoma-related hypopituitarism. Following surgery, 68% suffered from new pituitary deficits. RT was associated with mild toxicity, including visual deficits (5.4%) and hypopituitarism (10.9%). In particular, no radiation-induced brain necrosis or malignancy was observed. QOL was reported to be stable or improved in 92% of all patients, and RT was perceived to not compromise but increase QOL in the vast majority of patients (95%). OS after RT was 93.3% and 61.0% at 120 and 240 months. LPFS following RT was 90.4 and 75.5% at 120 and 240 months. Early initiation of RT after surgery instead of reserving it for recurring adenomas predisposed for improved outcome. CONCLUSIONS: RT for pituitary adenomas is safe and and self-reported QOL is stable or improved by almost all patients. Hypopituitarism rates are low. Local control appears improved in patients irradiated postoperatively over those undergoing RT for previously resected recurrent tumors.