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Objective: To study whether delivering definitive radiotherapy (RT) to sites of oligoprogression in metastatic renal cell carcinoma (mRCC) enabled deferral of systemic therapy (ST) changes without compromising disease control or survival. Patients and Methods: We identified patients with mRCC who received RT to three or fewer sites of extracranial progressive disease between 2014 and 2019 at a large tertiary cancer centre. Inclusion criteria were: (1) controlled disease for ≥3 months before oligoprogression, (2) all oligoprogression sites treated with a biologically effective dose of ≥100 Gy, and (3) availability of follow‐up imaging. Time‐to‐event end‐points were calculated from the start of RT. Results: A total of 72 patients were identified (median follow‐up 22 months, 95% confidence interval [CI] 19–32 months), with oligoprogressive lesions in lung/mediastinum (n = 35), spine (n = 30), and non‐spine bone (n = 5). The most common systemic therapies before oligoprogression were none (n = 33), tyrosine kinase inhibitor (n = 23), and immunotherapy (n = 13). At 1 year, the local control rate was 96% (95% CI 87–99%); progression‐free survival (PFS), 52% (95% CI 40–63%); and overall survival, 91% (95% CI 82–96%). At oligoprogression, ST was escalated (n = 16), maintained (n = 49), or discontinued (n = 7), with corresponding median (95% CI) PFS intervals of 19.7 (8.2–27.2) months, 10.1 (6.9–13.2) months, and 9.8 (2.4–28.9) months, respectively. Of the 49 patients maintained on the same ST at oligoprogression, 21 did not subsequently have ST escalation. Conclusion: Patients with oligoprogressive mRCC treated with RT had comparable PFS regardless of ST strategy, suggesting that RT may be a viable approach for delaying ST escalation. Randomised controlled trials comparing treatment of oligoprogression with RT vs ST alone are needed. [ABSTRACT FROM AUTHOR]

Objectives: To determine conditional survival for patients with small renal masses (SRMs) undergoing active surveillance (AS). Materials and Methods: Patients were enrolled in a prospective AS protocol at our institution between May 2005 and January 2016. Patients with SRMs ≤4 cm with serial cross‐sectional imaging available in‐house for review were included. Overall survival (OS) was estimated using the Kaplan–Meier method and modelled via Cox proportional hazards models. The primary endpoints analysed were the conditional probability of survival and tumour growth over time. Landmark analysis was used to evaluate survival outcomes beyond the 2‐year mark after the initial scan. The relative conditional survival of patients on AS was compared to those undergoing partial nephrectomy (PN) using inverse probability of treatment weighting. Results: A total of 272 patients were included in this analysis. The mean initial SRM size was 1.74 ± 0.77 cm, and the mean mass size closest to the 2‐year mark was 1.97 ± 0.83 cm. The likelihood of continued survival to 5 years improved after the 2‐year landmark. Patients with masses <3 cm who survived the first 2 years on AS had a 0.84–0.85 chance of surviving to 5 years, and if they survived 3 years, the probability of surviving to 5 years improved to 0.91. A slow tumour growth (β: 0.12; P < 0.001) with parallel growth rates was found for tumours <3 cm. Patients on AS and those who underwent PN had similar OS for ~7 years, beyond which PN demonstrated a trend of lower risk of death compared with AS (hazard ratio 0.57; P = 0.07). Conclusions: The conditional survival probability of patients with SRMs <3 cm on AS increased after 2 years. This information may prove useful to urologists and patients who are considering continuing AS vs intervention after the first 2 years on AS. [ABSTRACT FROM AUTHOR]