Disease-Free Survival of Patients with Muscle Invasive Bladder Cancer Treated by Radical Cystectomy vs. Bladder-Sparing Therapy at a Nationwide Level

Abstract

<h3>Purpose/Objective(s)</h3> Organ-sparing treatment has become the standard of curative cancer treatment for many tumor types. For patients with muscle invasive bladder cancer (MIBC), radical cystectomy (RC) is still the recommended treatment according to both the American Urological Association and the European Association of Urology guidelines. An attempted RCT between RC and bladder sparing therapy (BST) failed due to low accrual and noncompliance. A large prospective comparative study is the best alternative to compare outcomes between modalities. We hypothesized that the two-year disease-free survival (DFS) with BST is equal to the DFS with RC in selected patients with non-metastasized MIBC. <h3>Materials/Methods</h3> All patients diagnosed with MIBC between November 2017 and November 2019 were identified via the population-based Netherlands Cancer Registry. Detailed clinical data was retrieved by consulting medical files. Only patients treated with BST or RC were included. BST was defined as patients treated with concurrent chemoradiation (CRT) or external beam radiation followed by brachytherapy (BT). The primary endpoint was DFS, defined as free from muscle invasive locoregional recurrence, distant metastasis or death. Secondary endpoint was overall survival (OS). Two-year follow-up (FU) data were collected Survival was analyzed with a Cox proportional hazards model, we present the crude results in this abstract. Time was defined from treatment start to first event. Patients were censored at end of FU if alive or at last contact if lost to follow-up. <h3>Results</h3> A total of 1429 patients were included, 1100 underwent RC, 283 concurrent CRT and 44 BT. Median follow-up was 22 months (range: 1-43 months). Patients treated by RC and BST had similar DFS with a crude HR 0.96 (95%CI 0.78-1.16). The 2-year DFS for patients treated by RC, concurrent CRT or BT was 56% (95%CI 53-60%), 56% (95%CI 50-63%) and 67% (95%CI 52-82%) respectively. After a median time of 15.8 months, salvage cystectomy was performed in 21 patients (6,4%) of which 17 in the CRT and 4 in the BT group. The 2-year OS for patients treated with RC, concurrent CRT or BT was 63.8% (95%CI 61-67%), 68.3% (95%CI 62-74%) and 85.9% (95%CI 75-96%) respectively. The crude HR for OS was 0.84, 95%CI 0.66-1.05, (p=0.14) for RC vs CRT and 0.40 95%CI 0.17-0.77(p=0.015) for RC vs BT. Our study is limited by the inherent biases of observational data. <h3>Conclusion</h3> At two years, DFS did not significantly differ between patients treated with BST and RC. We conclude that after appropriate selection BST leads to similar DFS rates compared to RC. Nevertheless, these results should be interpreted with care, as the treatment groups were not yet matched for case-mix variables. The results of this study can be used to aid patients and physicians to choose the modality best tailored to their individual preferences.