Assessment of SAbR Safety and Efficacy for Renal Cell Carcinoma Glandular Metastases

Summary: 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 radiation (SAbR) particularly considering the risks of duodenal injury and adrenal insufficiency with high dose radiation in these locations. Here, we report local control (LC), progression-free survival (PFS), overall survival (OS) rates as well as toxicities related to SAbR for RCC metastases to the pancreatic and adrenal glands. This IRB-approved, single-institution, retrospective study included patients with RCC metastases to the adrenal glands and pancreas treated with SAbR. Data on patient demographics, functional status, tumor characteristics, International Metastatic RCC Database Consortium (IMDC) risk category, local and systemic treatments, toxicities, and outcomes were collected and analyzed. RECIST 1.1 principals were utilized to determine LC rates and PFS. PFS was determined from the initiation of SAbR to progression (at SAbR-treated or other sites), or death. OS was defined from the start of SAbR to death. Two independent reviewers assessed these measures and analyzed patient electronic health records for toxicities using CTCAE v5 and relatedness scores. 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. Sixteen patients (29.6%) were treatment naïve with oligometastatic disease, and thirty-eight (70.3%) were oligo-progressive on systemic therapy with 1-3 prior lines of systemic therapy. One year OS was 82.2%, PFS was 48.2%, and LC 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, while 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 LC with a small risk of leading to duodenal injury and adrenal insufficiency, respectively. Oncologic outcomes of SAbR treated mRCC patients with glandular metastasis was comparable to those without glandular metastasis. Mihailo Miljanic (he/him/his), MD, MBA (Presenting Author) - UT Southwestern Medical Center; Tidie Song, B.S. (Co-Author) - UT Southwestern Medical Center; Alana Christie, MS (Co-Author) - UT Southwestern Medical Center; Allen Yen, MD (Co-Author) - UT Southwestern Medical Center; Young Suk Kwon, MD, MPH (Co-Author) - UT Southwestern Medical Center; Aurelie Garant, MD (Co-Author) - UT Southwestern Medical Center; Todd Aguilera, MD, PhD (Co-Author) - UT Southwestern Medical Center; Zabihullah Wardak, MD (Co-Author) - UT Southwestern Medical Center; Hans Hammers, MD (Co-Author) - UT Southwestern Medical Center; Kevin Courtney, MD, PhD (Co-Author) - UT Southwestern Medical Center; Suzanne Cole, MD (Co-Author) - UT Southwestern Medical Center; James Brugarolas, MD, PhD (Co-Author) - UT Southwestern Medical Center; Robert Timmerman, MD (Co-Author) - UT Southwestern Medical Center; Raquibul Hannan, MD, PhD (Co-Author) - UT Southwestern Medical Center