Cyberknife fractionated radiotherapy for adrenal metastases: Preliminary report from a multispecialty Indian cancer care center

Abstract

Purpose: Metastasis to adrenal gland from lung, breast, and kidney malignancies are quite common. Historically radiotherapy was intended for pain palliation. Recent studies with stereotactic body radiotherapy (SBRT) including Cyberknife robotic radiosurgery aiming at disease control brings about encouraging results. Here we represent the early clinical experience with Cyberknife stereotactic system from an Indian cancer care center. The main purpose of this retrospective review is to serve as a stepping stone for future prospective studies with non- invasive yet effective technique compared to surgery.

Methods: We retrospectively reviewed four cases of adrenal metastases (three: lung and one: renal cell carcinoma) treated with Cyberknife SBRT. X sight spine tracking was employed for planning and treatment delivery. Patients were evaluated for local response clinically as well as with PETCT based response criteria.

Results: With a median gross tumor volume of 20.5 cc and median dose per fraction of 10 Gy, two patients had complete response (CR) and two had partial response (PR) when assessed 8-12 weeks post treatment as per RECIST. There was no RTOG grade 2 or more acute adverse events and organs at risk dosage were acceptable. Till last follow up all the patients were locally controlled and alive.

Conclusion: Cyberknife SBRT with its unique advantages like non- invasive, short duration outpatient treatment technique culminating in similar local control rates in comparison to surgery is an attractive option. World literature of linear accelerator based SBRT and our data with Cyberknife SBRT with small sample size and early follow up are similar in terms of local control in adrenal metastases. Future prospective data would reveal more information on the management of adrenal metastases.