Adjuvant Chemotherapy Plus Radiotherapy versus Chemotherapy Alone for Locally Advanced Bladder Cancer after Radical Cystectomy.

ABSTRACT

BACKGROUND: Survival with locally advanced bladder cancer (LABC) following radical cystectomy (RC) remains poor. Although adjuvant chemotherapy (AC) is standard of care, one small, randomized trial has suggested a potential survival benefit when combined with post-operative radiotherapy (PORT). OBJECTIVE: We examined the association of AC + PORT with overall survival (OS) in patients with LABC after RC. METHODS: Using a prior phase 2 trial to inform design, we conducted observational analyses to emulate a hypothetical target trial of patients aged 18-79 years with pT3-4 Nany M0 or pTany N1-3 M0 urothelial bladder carcinoma following RC who were treated with AC (multiagent chemotherapy within 3 months of RC) with or without PORT (≥45 Gy to the pelvis) from 2006-2015 in the NCDB. Patients who received preoperative chemotherapy or radiotherapy were excluded. The associations of treatment with OS were evaluated using multivariable Cox regression. RESULTS: 1,684 patients were included, with 66 receiving AC + PORT and 1,618 AC alone. Compared to patients treated with AC alone, those treated with AC + PORT were more likely to have pT4 disease (52% vs 26%; p < 0.01), positive surgical margins (44% vs 17%; p < 0.01), and be treated at a non-academic facility (75% vs 53%; p < 0.01). Crude 5-year OS was 19% for AC + PORT versus 36% for AC alone (p = 0.01). Adjusted 5-year OS was 33% for AC + PORT versus 36% for AC alone (p = 0.49). After adjusting for baseline characteristics including pathologic features, AC + PORT was not associated with improved OS compared to AC alone (HR 1.11; 95% CI 0.82-1.51). CONCLUSIONS: Although infrequently utilized, the addition of radiotherapy to AC is not associated with improved OS in LABC. These results highlight the need for prospective trials to better define the potential benefits from PORT with regard to symptomatic progression and oncologic outcomes.