Single Institution Radiosurgical Experience of Treating Secretory and Non-Secretory Pituitary Adenomas
Faculty and Abstracts
Purpose: Multiple studies have demonstrated the efficacy and safety of radiosurgery in the management of secretory and non-secretory pituitary adenomas1,2. However, treatment with high dose radiotherapy can lead to toxicity including hypopituitarism and optic neuropathy3. Prior studies have suggested lower doses of radiosurgery may be adequate in achieving tumor control in non-secretory adenomas.4 Here, we describe our experience in treatment of pituitary tumors at a large academic center with lower than typical doses of radiosurgery.
Methodology: Utilizing a departmental treatment database, 53 patients who underwent Gamma Knife (Elekta) radiosurgery for pituitary tumors from January 1, 2011 through May 1, 2023 were identified. Clinical data was available for 52 patients. Dosimetric information was obtained from plan review within the GammaPlan (Elekta) workstation. Average patient age was 59. Median follow up was 34 months. Of the 52 patients identified, 11 had secretory tumors and 41 had non-secretory tumors.
Results: Median volume of treated lesions was 3.66 cm^3. In patients with secretory tumors, the median dose was 15.1 Gy prescribed to the 50% isodose line. Follow up imaging was available in 9/11 of patients, and significant tumor growth was noted in 1 patient requiring a salvage tumor resection. Biochemical control was achieved in 7/11 patients. In 41 patients with non-secretory tumors, median dose was 13.48 Gy. Treatment was prescribed to the 50% isodose line in all but 2 patients. Follow up imaging was available in 36/41 patients. Of these 36 patients, only 3 patients experienced significant tumor growth requiring additional intervention. In the overall cohort, 26/52 patients noted visual symptoms at baseline. At time of last follow up, 44/52 patients reported stable to improved visual symptoms. 18/52 patients required at least one replacement therapy for hypopituitarism at time of last follow up.
Conclusions: Despite prescribing relatively low doses of radiation therapy, our series demonstrates comparable local and biochemical control to historical data. Utilization of lower doses could allow a broader range of patients the opportunity for radiosurgery as treatment for pituitary adenoma through better sparing of optic structures. Further work is warranted to optimally define radiosurgical dose in this patient population.
References: 1. Mathieu D, Kotecha R, Sahgal A, et al. Stereotactic radiosurgery for secretory pituitary adenomas: systematic review and International Stereotactic Radiosurgery Society practice recommendations. J Neurosurg. 2021;136(3):801-812. doi:10.3171/2021.2.JNS204440
2. Kotecha R, Sahgal A, Rubens M, et al. Stereotactic radiosurgery for non-functioning pituitary adenomas: meta-analysis and International Stereotactic Radiosurgery Society practice opinion. Neuro-Oncol. 2020;22(3):318-332. doi:10.1093/neuonc/noz225
3. Kobayashi T. Long-term results of stereotactic gamma knife radiosurgery for pituitary adenomas. Specific strategies for different types of adenoma. Prog Neurol Surg. 2009;22:77–95
4. El-Shehaby AM, Reda WA, Tawadros SR, Abdel Karim KM. Low-dose Gamma Knife surgery for nonfunctioning pituitary adenomas. J Neurosurg. 2012 Dec;117 Suppl:84-8. doi: 10.3171/2012.6.GKS12986.