Gamma-knife radiosurgery in acromegaly: the results from the Croatian acromegaly registry.

PURPOSE

The aim of our study was to evaluate the efficacy and safety of Leksell gamma-knife radiosurgery in the treatment of residual growth hormone-secreting pituitary adenomas after the surgery.

MATERIALS AND METHODS

We conducted a retrospective analysis of 23 acromegaly patients treated with gamma-knife radiosurgery between 1996 and 2019. The therapeutic success of radiosurgery was defined as IGF-1 normalization without suppressive medication (complete response) or as IGF-1 normalization with medication (partial response).

RESULTS

The median follow-up was 57 (10-198) months. Complete response was achieved in 11 patients (47.8%) with actuarial remission rates of 17.4%, 26.1%, 39.1% and 47.8% at 1, 2, 4, and 7 years, respectively. The median time to complete the response was 21 (6-85) months. Partial response was achieved in another nine patients (39.1%) after a median time of 48 (6-144) months from radiosurgery. Patients who achieved complete remission had significantly lower IGF-1 levels before radiosurgery ( = 0.016) as well as smaller tumour volume ( = 0.016) and radiologically less invasive tumours ( = 0.022) in comparison to patients who did not achieve IGF-1 normalization. Tumour growth control after radiosurgery was established in all patients. During the follow-up, new hormone deficiencies were found in seven patients (30.4%) which corresponds to the incidence of one new case of hypopituitarism per 7.1 patient years.

CONCLUSIONS

Gamma-knife radiosurgery offers endocrine remission and tumour growth control in a substantial proportion of patients with GH-secreting adenomas. Given the high cost of life-long medical treatment and a moderate risk of radiation-induced side effects, radiosurgery for growth hormone-secreting pituitary adenomas should be considered in all patients with residual tumours.