HIGH-PRECISION CONFORMAL FRACTIONATED RADIOTHERAPY IS EFFECTIVE IN ACHIEVING REMISSION IN PATIENTS WITH ACROMEGALY AFTER FAILED TRANSSPHENOIDAL SURGERY

Objective: Variable efficacy of pituitary radiotherapy in acromegaly is reported. Here we sought to assess the efficacy of high-precision conformal fractionated radiotherapy (CRT) in patients with acromegaly after failed TSS. Methods: A retrospective analysis was conducted a in tertiary care referral center between 1999 to 2013 on 36 acromegaly patients (M: 16, F: 20; median age: 36.0 years) with macroadenoma and mean growth hormone (GH) and insulin-like growth factor-1 (IGF1) upper limits of normal (ULN) of 15.9 +/- 14.3 ng/mL and 1.74 +/- 0.43, respectively. The cohort was divided into 2 groups: 30 patients (M: 13, F: 17) who were medical treatment naive, and 6 patients (M: 3, F: 3) who received medical treatment after CRT. Results: Normalization of GH (fasting GH <1 ng/mL), normalization of IGF1 (ULN <1), and remission (normalization of GH and IGF1) were achieved in 20 (55%), 23 (63%) and 20 (55%) patients, respectively. The mean time required to achieve remission was 63 +/- 33.4 months. Follow-up duration was the only predictor of achieving remission. GH level declined exponentially by 65% and 89% at 2 and 5 years, respectively. New onset hypopituitarism was noted in 33% of patients. Tumor control was achieved in 100% of patients. In groups 1 and 2, 18 (60%) and 2 (33.3%) achieved remission post-CRT, and the mean times required to achieve remission were 58.6 +/- 30.7 months and 102 +/- 42.4 months, respectively. Conclusion: High-precision CRT is an effective modality to achieve remission in patients with acromegaly after failed TSS.