Stereotactic ablative radiotherapy for primary kidney cancer - An international patterns of practice survey

Purpose: To conduct an international survey of radiation oncologists treating primary renal cell carcinoma (RCC) with SABR to ascertain the general patterns of SABR use, common dose/treatment/follow-up details, and expected outcomes.

Materials and methods: A 51-question survey was created containing the following themes: prevalence and clinical scenarios in which RCC SABR is used, dose-fractionation schedules, treatment delivery details, follow-up/outcome assessments, and implementation barriers. The survey was distributed widely across multiple influential radiation oncology societies and social media, and ran from January to April 2023.

Results: A total of 255 respondents participated, mostly from academic centers within Europe/North America. Of these, 40 % (n = 102) currently offer SABR (50 % having begun within the last 3 years). Common barriers in non-users included lack of referrals by urologists and lack of supportive practice guidelines. Of respondents who do offer SABR, 77 % treat both small (4 cm or less) and large (>4 cm) renal masses. Dose-fractionation strategies varied from 27-52 Gy (3-5 fractions) for multifraction regimens, and 15-34 Gy for single fractions. Apart from treatment for medically inoperable disease, scenarios in which SABR was likely to be offered were for recurrence post surgery/thermal ablation and for oligometastatic kidney lesions. Uncommon scenarios included RCC with renal vein/inferior vena cava thrombosis, and as cytoreductive therapy in metastatic RCC. Expected local control outcomes were generally above 70 %, higher for small versus large renal masses.

Conclusions: SABR is a relatively newer indication for primary RCC, offered by less than 50% of respondents, with both consistent and variable practice patterns observed.