Stereotactic Radiotherapy (Srt) For Oligometastatic (Om) Relapse And Metastatic Oligoprogression (Op) In Renal Cell Carcinoma (Rcc) Patients (Pts): A Study Of The Getug Group.

e16105 Background: RCC is considered as radioresistant and radiation therapy of metastases is usually reserved only to palliate symptoms. However, by delivering ablative doses, SRT may increase local disease control. This study aimed to assess the place of SRT in the management of OM and OP RCC pts. Methods: Data of RCC pts receiving SRT with curative intent were retrospectively collected in 6 French referral centers. Local progression free survival (LPFS) for each lesion, progression free survival (PFS), survival without change of systemic treatment (TTS), and overall survival (OS) from the end of SRT were assessed in all included patients. Results: A total of 194 pts (Men = 76%, median age, 64 yrs) receiving SRT for 259 metastases (brain [n = 122]; bones [n = 89]; liver, lung, lymph nodes, kidney, pancreas, adrenal gland and soft tissues, [n = 48]) were included: 104 pts received SRT for OP during systemic therapy, 83 received initial SRT for OM relapse and 7 pts after a partial response to systemic treatment. Delivered doses by target ranged from 8 to 60 Gy in 1 to 11 fractions (median biologically effective dose BED7 = 54.4 Gy, from 13.3 to 180). Acute and late severe toxicity was observed in 6 (3%) pts. After a median pts follow-up of 13 (range 0-59) months (mo), complete, partial and stable local responses were observed in 17%, 38% and 36% of the treated lesions with a median LPFS of 17 (95% CI 15-25) mo. Among 131 relapsing pts, 36 had local relapse. Median LPFS for brain, bone and other lesions was 14, 15, 42 mo, respectively. Higher planned target volume and higher BED7 independently improved LPFS (HR 0.98, P= 0.001; HR 0.98, P= 0.0003). PFS, TTS, and OS were, 8 (6-10), 13 (10-17), and 29 mo (23–42), respectively. The median PFS, TTS, and OS were 9, 11 and 23 mo in pts treated for OP and 8, 14 and 34 mo in pts treated for OM. In 76% of OM pts, SRT was delivered without systemic therapy. Three of 7 pts treated with SRT after partial response to systemic treatment did not relapse after 22-mo median follow-up. Conclusions: SRT is effective and safe for OM and OP RCC pts and may delay introduction or change of systemic therapy. Prospective studies are needed to confirm these results.