Stereotactic Gamma Knife Radiosurgery is Effective for the Treatment of Acromegaly

Objective: To assess the effectiveness of Gamma Knife (Elekta, Stockholm, Sweden) radiosurgery for acromegaly. Study Design: Retrospective. Patients/material and Methods: Data was collected from 35 patients in eight regional centers, via the UK National Acromegaly Register. All patients had neurosurgery and a perfexion Gamma Knife was used for radiosurgery at one institution (Sheffield, United Kingdom). The mean peak dose was 53 Gy. Results Biochemical: Of 35 patients, 66% achieved a normal age and sex-adjusted IGF-1 at median follow-up of 65 months after Gamma Knife. Of 30 patients tested, 72% achieved controlled (<2.5 µg/L) nadir GH level, median follow-up of 60 months; of these patients 35% (n = 8) were also receiving medical therapy. The mean IGF-1 before and after Gamma Knife was 777 and 436 µg/L, respectively (p = 0.015). Mean GH level before Gamma Knife in 24 patients was 5.62 µg/L and after was 1.25 µg/L (p = 0.0051). The probability of control of IGF-1 and GH levels did not correlate with dose of radiation delivered. Radiological: Post Gamma Knife MRI demonstrated pituitary tumor size unchanged or reduced in 100% of 24 patients at median follow-up of 50.5 months. Endocrine Side Effects: A total of 17% (6/35) developed new endocrine disturbances. Of these three were being treated with medical therapy. Other Side Effects: No patient suffered visual disturbance on follow-up. Conclusions: Gamma Knife radiosurgery for acromegaly is a safe and effective long-term adjunctive treatment.