Long-term safety of growth hormone replacement after CNS irradiation

Context: Radiotherapy is a central component in the treatment of many brain tumors, but longterm sequelae include GH deficiency and increased risk of secondary neoplasms. It is unclear whether replacement therapy with GH (GHRT) further increases this risk. Objective: The objective of the study was to assess the effect ofGHRTon the incidence of secondary tumors and tumor recurrence after cranial irradiation. Design and Setting: We conducted a retrospective matched-pairs analysis of previously irradiated patients, with and without GHRT, attending a tertiary center between 1994 and 2009. Patients: We reviewed the records for all patients undergoing GHRT at our institution over the study period. Patients were included if they had received cranial irradiation, GHRT for at least 12 months, and records of serial magnetic resonance imaging data and data for dose and fractionation of irradiation were available. GH-naïve control patients were selected from a radiotherapy database of patients attending the same hospital. Patients were matched for date of radiotherapy, age, site of primary diagnosis, radiation dose, and fractionation. Main Outcome Measure: The primary outcome measure was risk of tumor recurrence or secondary tumor. Results: Matched controls were identified for 110 GH-treated patients. Median follow-up was 14.5 yr.Nosignificant differences were apparent in thenumberof tumor recurrences (six vs. eight,GHRT vs. control group) or secondary tumors (five vs. three, respectively) between groups. Conclusions: Our study demonstrates no increased risk for recurrent or secondary neoplasms in patients receiving GHRT, thus supporting a high safety profile ofGHRTafter central nervous system irradiation.