Long-Term Data Confirm CRT Benefit in Muscle-Invasive Bladder Cancer

Long-term data from a phase III trial confirmed that adding chemotherapy to radiation therapy (RT) improves locoregional control and reduces the rate of salvage cystectomy in patients with muscle-invasive bladder cancer, according to results of the BC2001 study (abstract 280) presented at the 2017 Genitourinary Cancers Symposium, held February 16–18 in Orlando, Florida.

“We wanted to look at the impact of adding synchronous chemotherapy to RT to see whether that could improve locoregional recurrence control,” said Emma Hall, PhD, of the Institute of Cancer Research in London, lead statistician of the trial. The researchers also sought to examine whether an 80% RT dose to the uninvolved bladder could reduce toxicity without compromising local control.

The trial included 458 patients with T2–T4a bladder cancer. Patients were treated with 3D conformal RT. Centers could opt to administer 55 Gy in 20 fractions over 4 weeks or 64 Gy in 32 fractions over 6.5 weeks. The chemoradiotherapy (CRT) regimen added 12-mg/m² intravesical mitomycin C on day 1 of RT, and fluorouracil (5-FU) as a continuous infusion at 500 mg/m² over 24 hours on days 1–5 and 16–20, corresponding to RT fractions.

At nearly 10 years of median follow-up, the study found improvements with CRT in locoregional control (hazard ratio [HR], 0.59; 95% CI, 0.41–0.83; P = .003) and invasive locoregional control (HR, 0.52; 95% CI, 0.33–0.81; P = .004).

After adjusting for prognostic factors such as age, disease stage and grade, RT dose, neoadjuvant chemotherapy, and others, the results also showed that CRT improved bladder cancer–specific survival (HR, 0.73; 95% CI, 0.54–0.99; P = .043) and metastasis-free survival (HR, 0.74; 95% CI, 0.54–1.00; P = .051).

The rate of salvage cystectomy in patients who received CRT was also lower at 2 years (11% vs 17% in patients who received RT alone) and 5 years (14% vs 22%; P = .03).

No statistically significant differences were found in overall survival.

Earlier data from the trial found that reduced high-dose volume RT did not significantly reduce late side effects compared with standard RT. There were also no differences in overall survival, disease-specific survival, or locoregional control in patients who received the reduced high-dose volume RT, suggesting that it is safe to pursue clinical trials of volume-sparing RT.

“With 10 years follow-up we see an improvement in locoregional control and a reduced salvage cystectomy rate confirmed with CRT, and if you take that together with the good quality of life that we’ve seen, we think this is important in this patient group,” said Hall. “We believe that these updated results are robust and support the use of CRT with 5-FU and mitomycin C, and they confirm that this should be a standard of care in muscle-invasive bladder cancer.”