IROCK gathering moss.

Top Line: Ablative stereotactic body radiation (SBRT) for primary renal cell carcinoma (RCC) tumor is gaining traction.

The Study: The IROCK consortium is back with a report describing outcomes for 95 patients from 9 centers with large RCC (T1b+ or 4+ cm) treated with primary SBRT. Of note, on average there was a delay of several months between diagnosis and SBRT treatment, potentially indicating that these tumors had faster growth kinetics on active surveillance. The majority of patients had both kidneys intact and 90% had clear cell histology. At 2 and 4 years, the rate of progression-free survival was 81% and 65%. Only 3% of patients had local failure, which is comparable to the local failure rate with partial nephrectomy. Nearly 50% had pre-existing chronic kidney disease (CKD). Among those who didn’t, roughly one-third developed CKD after SBRT at a median of 20 months, and the average reduction in eGFR after treatment was -7.4 mL/min. There were no grade 3+ complications. Per usual, SBRT wasn’t standardized. Nevertheless, half received a single fraction, the median total dose was 26 Gy, and the median BED10 was 87.5 Gy.

TBL: SBRT to larger RCC has a low rate of local failure at the expense of potential moderate decline in long-term renal function. | Siva, Int J Radiat Oncol Biol Phys 2020