Endocrine Abstracts

Purpose: To determine the risk of developing hypopituitarism after cranial irradiation for skull base meningiomas. Cranial irradiation is often chosen as first treatment in skull base meningiomas to avoid risk to proximally-located critical structures. While cranial irradiation has been associated with high risk of inducing hypopituitarism, few studies concern meningiomas.

Methods and materials: Fifty-two adult patients receiving photon-beam therapyfor skull base meningiomas between 1978 and 2014 were included. All five anterior pituitary axes were screenedusing baseline blood measurementsbefore radiotherapy, then each year until March 2019. The pituitary gland (PG) was delineated on CT and the mean dose to it was estimated.

Results: Mean age at diagnosis was 56 years ± 14 and 80% were women. Median follow-up was 7 years. Sixty percent of patients developed hypopituitarism (all 5 axes involved) 10 years after the radiotherapy. The frequency of gonadotropic, TSH, ACTH and GH deficiencies as well as hyperprolactinemia10 years after the radiotherapy was 37%, 28%, 18%, 15% and 13% respectively. Twenty-one percent developed deficiencies of two axes only, however noone-axis deficiency was observed. In the multivariate analysis, an estimated dose to the PG ≥ 50 Gy or a meningioma ≥40 mm significantly increased the risk of developing hypopituitarism.

Conclusion: Cranial radiation therapy in the treatment of skull base meningioma is correlated with a high risk of developing hypopituitarism (60% prevalence after 10 years), particularly when associated with tumor size of ≥ 40 mm and an estimated radiation dose to the PG ≥ 50 Gy. The gonadotropic axis was the most frequently affected.

Annual follow-up appears therefore necessary to identify patients requiring treatment for such deficiencies.