Stereotactic body radiation therapy (SBRT) is a safe and effective treatment option for patients with oligometastatic renal cell carcinoma (RCC), according to investigators.
Patients with clear cell RCC who had previously received systemic therapy were more likely to achieve local control, reported Ciro Franzese, MD of Humanitas Clinical and Research Center in Milan, and his coauthors.
These findings contribute to a shifting landscape in RCC; modern techniques are opening doors once closed by disappointing historical results. Several recent SBRT studies have demonstrated local control rates of approximately 90%, compared with conventional RT rates of 20%.
“While the outcomes from conventional RT were quite poor, with SBRT, different biological mechanisms occur due to the use of higher doses per fraction,” the authors wrote in The Journal of Urology.
The present retrospective study involved 58 patients with oligometastatic RCC who were treated with SBRT between 2004 and 2006. Patients previously underwent primary tumor excision, had no greater than three distant extracranial metastases, and were not surgical candidates. Study endpoints included median overall survival (OS), progression-free survival (PFS), and in-field local control (LC). Stratified analysis was also performed in patients with clear cell RCC.
Just over 90% of patients achieved LC at 18 months. Slightly less than half (46.2%) were progression-free at 1 year, and this number dropped to one-third (35%) by 18 months. Median OS was just over 2 years (28 months). Although all patients (100%) were alive at 2 years, this rate dropped to 83% by the 5-year mark.
In patients with clear cell RCC, those treated with systemic therapy prior to SBRT were more likely to achieve LC compared with patients who did not receive systemic therapy (HR 0.15; P = .032).
Overall, SBRT was well tolerated. No grade 3 or higher adverse events occurred. The most common adverse events were pain, fatigue, nausea, and vomiting.
The authors concluded that SBRT is a safe and effective option for patients with oligometastatic RCC. They called for future research to address “the radiobiology of RCC” in order to “understand the role of SBRT and, particularly, its possible interaction with medical therapies.”
The authors reported no conflicts of interest.
SOURCE: Franzese et al. J Urol. 2018 Sep 1. doi: 10.1016/j.juro.2018.08.049.