BART
After radical cystectomy and chemotherapy in high-risk muscle-invasive bladder cancer, does adjuvant pelvic radiotherapy reduce locoregional relapse?
Absolute Effect
At 2 years, locoregional control was 91.2% with RT vs 76.4% with observation: an absolute improvement of 14.8 percentage points, NNT ≈ 7. The HR was 0.27 (95% CI 0.10–0.71; P=.004).
Two-year DFS was 59.9% vs 52.8%, while OS was 68.1% vs 57.0%; these time-to-event differences were not statistically significant in the primary analysis.
Toxicity
Late grade ≥3 toxicity was similar: 8.5% with RT vs 10.5% with observation. Acute grade 2 toxicity was higher with RT, mainly diarrhea/enteritis and proctitis.
Clinical interpretation
BART provides randomized phase III evidence that postoperative RT can substantially reduce pelvic relapse in high-risk MIBC after cystectomy and perioperative chemotherapy. The locoregional effect is larger than the observed DFS/OS differences, emphasizing the importance of distinguishing local control from survival.
Sources
BART clinical outcomes, IJROBP. BART toxicity report, PubMed.