Long-term efficacy of hyperthermic intravesical chemotherapy for BCG-unresponsive non-muscle invasive bladder cancer

•This study described that HIVEC resulted in durable long-term responses.•The 2-year recurrence free survival was 35%.•With only one severe adverse event in 56 patients, HIVEC is a safe treatment option.•HIVEC seems to be a valuable alternative bladder-sparing treatment option. The recommended treatment for patients with Bacillus Calmette-Guérin (BCG) unresponsive non-muscle invasive bladder cancer (NMIBC) is radical cystectomy (RC). However, many patients refuse, or are unfit for RC. Therefore, alternative bladder-sparing treatment modalities are needed for BCG-unresponsive NMIBC. In this study we sought to assess the long-term efficacy of hyperthermic intravesical chemotherapy (HIVEC) as alternative to radical cystectomy in BCG-unresponsive non-muscle invasive bladder cancer patients. Retrospectively collected data from 56 patients with BCG-unresponsive NMIBC who received ≥5 HIVEC instillations between October 2014 and March 2020 was analyzed. All patients met the BCG-unresponsive criteria according to the current EAU guideline on NMIBC 2020. Patients were followed-up with cystoscopy and/or bladder biopsies, urine cytology and annually CT-urography. The Primary outcome was the high grade (HG) recurrence-free survival (RFS), defined as the time from the first HIVEC instillation until histologically confirmed intravesical recurrence or last follow-up. The Kaplan Meier method was used to estimate survival outcomes. Secondary outcomes were: complete response rate (CR), adverse events (AE), assessed by the Common Terminology Criteria for Adverse Events v5.0 (CTCAE) and tumor progression to muscle invasive disease or distant metastases. The median follow-up was 32.2 months (IQR 13.7–44.8). The 1- and 2-year HG-RFS was 53% (SE:6.8) and 35% (SE:6.9), respectively. The CR for patients with CIS was 70% (21/30) at 6 months. Overall, 80% of the population developed an AE, only 1 was classified as CTCAE ≥3. Limitation of this study was the small sample size. HIVEC resulted in a 2-year HG-RFS of 35% for BCG-unresponsive NMIBC patients without severe side-effects and therefore HIVEC seems to be an alternative treatment option for patients who refuse or are unfit for RC.