Stereotactic Radiation Therapy for the Treatment of Glandular Metastases From Renal Cell Carcinoma

The optimal management strategies for glandular metastases in patients with metastatic renal cell carcinoma (mRCC) are currently unknown. While local therapy may be effective, there is a paucity of data on Stereotactic Ablative Body Radiation (SABR) particularly considering the risks of duodenal injury and adrenal insufficiency with high-dose radiation in these locations.

We conducted an institutional review board-approved, single-institution, retrospective study of patients with RCC metastases to the adrenal and pancreas treated with SABR. Data on patient characteristics, therapies, toxicities, and outcomes were collected and analyzed. Outcome of patient with SABR-treated mRCC was compared between those with and without glandular metastasis.

A total of 46 patients with a median follow-up of 20 months with mRCC were included with 36 adrenal and 19 pancreatic metastases treated with SABR with a median dose of 40 Gray (Gy) delivered in 5 treatments. One-year overall survival was 82.2%, progression-free survival was 48.2%, and local control was 95.9%. Acute grade 2 and 3 toxicity related to SABR was 7.4%. One patient experienced a grade 3 duodenal bleed as a result of pancreatic SABR, whereas 6.1% of patients experienced adrenal insufficiency with a median time to onset of 4 months following adrenal SABR.

SABR for RCC metastases to the pancreas and adrenal gland is feasible, safe, and effective at achieving high rates of local control with a small risk of duodenal injury and adrenal insufficiency, respectively. Oncological outcomes of patients with SABR-treated mRCC with glandular metastasis were comparable to those without glandular metastasis.