Abstract
OBJECTIVE: This study examined long term radiological and biochemical control of functioning pituitary neuroendocrine tumors (PitNETs) treated with fractionated stereotactic radiotherapy. METHODS: A retrospective case series was conducted on patients treated with FSRT at the BC Cancer Agency between January 1, 1998, and December 31, 2021. Inclusion criteria comprised of patients with functioning PitNETs who had either inoperable condition or residual disease post-surgery, and who had failed maximal medical management. Baseline evaluations included Computed Tomography (CT) or Magnetic Resonance Imaging (MRI) scans, and pituitary hormone levels. Outcomes included local control (LC) defined as absence of growth on CT or MRI, progression-free survival (PFS), defined as time of FSRT to radiological or biochemical progression, objective hormonal response (OHR) in which hormone levels normalized or declined by more than 50% of baseline levels without medications, and biochemical control, that included OHR with or without medications. RESULTS: Out of a total of 202 patients treated with FSRT and followed for a median of 11.9 years, 51 (25%) had functioning PitNETs. Of 51 patients, 48 (94%) had uncontrolled hormonal levels despite medications. At 10 years post FSRT, LC was 91%, and PFS was 97%. OHR was 27% and biochemical control was 58%, CONCLUSION: FSRT is effective in controlling growth and hypersecretion of functioning PitNETs for 10 or more years post treatment.