Radiotherapy regimens and concurrent Cabergoline use for non-functioning pituitary neuroendocrine tumors: a large, single-center cohort.

BACKGROUND: The standard treatment for non-functioning pituitary neuroendocrine tumors (PitNET) consists in transsphenoidal surgical resection, however when progression or recurrence happens, additional treatments like stereotactic radiotherapy (SRT) and dopaminergic agonists can be used. In this article we aim to describe and quantify the impact of SRT regimen and dose, as well as the use of concurrent cabergoline, on local tumor control and toxicities. METHODS: This is a retrospective cohort of patients with non-functioning PitNET treated between 2008 and 2023 with LINAC-based SRT on different dose regimens with or without cabergoline, in a single university hospital. RESULTS: One-hundred twenty-six (126) patients were assessed. Median follow-up was 62.6 months (7.1 – 135.8 months). Most patients already had a visual deficit (65.1%) or hormonal dysfunction (52.4%) before SRT. Lesion size (median larger diameter is 2.5cm) and younger age were correlated with the use of fractionated SRT (FRT) (respectively, p>0.001 and p=0.006). 5 year control rate was 96.8%. For single-dose radiosurgery (SRS), they were 90.5% and 57.2 months, respectively. For FRT, 66.7% and 44.9 months, respectively. Cabergoline use did not influence results. There were no differences in new hormonal deficits among groups. Symptomatic radionecrosis was reported in only one patient. Strokes and CNS bleeding were reported in three patients. There were no secondary malignancies reported. CONCLUSION: No difference was found between SRS and FRT, the usage of cabergoline did not affect response. SRT brings good control with low toxicity in non-functional PitNET. However further prospective research is needed.