Endocrine Abstracts

JOINT3576

Introduction: Transsphenoidal surgery is the first-line treatment for non-functioning pituitary adenomas (NFPAs) in case of visual impairment or progressive tumor growth, for GH-secreting and ACTH-secreting adenomas, as well as for prolactinomas when medical treatment is not possible. Radiotherapy is generally proposed as second- or third-line treatment and is rarely performed before surgery. The objective of our study was to evaluate the efficacy on tumor volume control of pituitary radiotherapy as first-line treatment for patients with pituitary adenomas.

Methods: We retrospectively reviewed files from 10 patients with pituitary adenoma, who had radiotherapy as first-line treatment in a tertiary center between 2011 and 2019. We documented patient and tumor characteristics, time and reason for radiotherapy, duration of follow-up and calculated tumor volume change after radiotherapy.

Results: A total of 10 patients with pituitary adenomas (60% male) treated with first-line radiotherapy were included. Mean age upon diagnosis was 63.5 years (SD: 20.3). Five patients (50%) had NFPA, 2 had acromegaly and 3 had macroprolatinomas. Seven patients received conventional fractionated radiotherapy (VMAT) with median radiation dose of 54 Gy (Range: 45-54), while 3 patients received stereotaxic radiosurgery with median dose of 18 Gy (R: 18-24). Radiotherapy was performed after a mean follow-up of 70.9 months from diagnosis (SD: 91.6), and median maximal diameter before radiotherapy was 24.8 mm (R: 10-40). Among 5 patients with NFPAs, 3 had visual field defects upon diagnosis, 3 had panhypopituitarism and the choice of radiotherapy as first-line treatment was based on age (median age at diagnosis: 78 years, R: 61-83), in addition to comorbidities or patient preference. Among 5 patients with macroprolactinomas and acromegaly, the choice of radiotherapy was based on resistance to medical treatment and refusal of surgery. During a mean follow-up of 61.8 months after radiotherapy (SD: 46.3), tumor size decreased in 8 patients (80%), and was stable in 1 patient. Only 1 patient with a macroprolactinoma had a 6.5% increase in tumor size, 69 months after radiotherapy. Pituitary function was difficult to evaluate at last follow-up as data were missing, which was related to patients’ age. Still, most had hypopituitarism at baseline and no improvement is expected with radiotherapy as with pituitary surgery. No patient had salvage pituitary surgery during follow-up.

Conclusions: Radiotherapy can be performed as first-line treatment in patients with pituitary adenomas when surgery is not an option because of patient preferences or comorbidities and achieves tumor volume stabilization or decrease.