A prospective phase I dose-escalation trial of stereotactic ablative radiotherapy (SABR) as an alternative to cytoreductive nephrectomy for inoperable patients with metastatic renal cell carcinoma

Abstract

Background

Cytoreductive nephrectomy is thought to improve survival in metastatic renal cell carcinoma (mRCC). As many patients are ineligible for major surgery, we hypothesized that SABR could be a safe alternative.

Methods

In this dose-escalation trial, inoperable mRCC patients underwent SABR targeting the entire affected kidney. Toxicity (CTCAE v3.0), quality of life (QoL), renal function, and tumour response (RECIST v1.0) were assessed.

Results

Twelve patients of mostly intermediate (67%) or poor (25%) International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) prognostic class, median KPS of 70%, and median tumour size of 8.7 cm (range: 4.8–13.8) were enrolled in successive dose cohorts of 25 (n = 3), 30 (n = 6), and 35 Gy (n = 3) in 5 fractions. SABR was well tolerated with 3 grade 3 events: fatigue (2) and bone pain (1). QoL decreased for physical well-being (p = 0.016), but remained unchanged in other domains. SABR achieved a median tumour size reduction of − 17.3% (range: + 5.3 to − 54.4) at 5.3 months. All patients progressed systemically and median OS was 6.7 months. Crude median follow-up was 5.8 months.

Conclusions

In non-operable mRCC patients, renal-ablative SABR to 35 Gy in 5 fractions yielded acceptable toxicity, renal function preservation, and stable QoL. SABR merits further prospective investigation as an alternative to cytoreductive nephrectomy.

Trial Registration

ClinicalTrials.gov NCT02264548. Registered July 22 2014 – Retrospectively registered: https://clinicaltrials.gov/ct2/show/NCT02264548

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