ESTRO 2024 - Abstract Book

S2588

Clinical - Urology

ESTRO 2024

Bladder preservation therapy with transurethral resection of bladder tumour, neoadjuvant cisplatin-based chemotherapy followed by radiotherapy with a radiosensitiser is an established alternative to radical cystectomy for muscle-invasive bladder cancer. Despite its efficacy, a sub-set of patients may develop genitourinary (GU) and gastrointestinal (GI) toxicity, which can significantly impact the patient's quality of life. Recent studies in men having prostate cancer radiotherapy have suggested that patients taking angiotensin-converting enzyme inhibitors (ACEi) may have less GU toxicity, and ACEi are radioprotective in preclinical animal models, but no studies have looked at patients treated for bladder cancer. We hypothesised that concomitant ACEi may reduce the risk of GU toxicity in patients undergoing curative radiotherapy for bladder cancer.

Material/Methods:

A total of 300 patients treated with bladder preservation after diagnosis of muscle invasive bladder cancer at a large volume single cancer centre between 2016 and 2022 were identified. A comprehensive dataset was collected, recording baseline demographics, drug history, treatment details and acute toxicity data. Acute clinician-reported toxicity was assessed using RTOG grading weekly during treatment and at 6 weeks after completion of treatment. The statistical analysis was performed using Stata 18.0 SE with student t-tests for continuous variables and Chi Square test for categorical variables to compare the outcomes

Results:

A total of 295 patients were included in the analysis of this retrospective study. Among these 295 patients, 77 received ACEi, while 218 did not receive ACEi treatment. Patient characteristics are presented in Table 1, revealing no statistically significant differences in baseline characteristics, including age, Eastern Cooperative Oncology Group (ECOG) performance status (PS), tumour stage, and smoking status, between the two groups. On evaluating acute GU toxicity of Grade ≥2 during treatment and at 6 weeks, there was no statistically significant difference between ACEi and no ACEi groups, 48.9 vs 39% p =0.48 and 60 % vs 45.9% p = 0.27) (Table 1). For patients who received BCON as a radiosensitizer (n = 148), ACEi administration is often temporarily stopped during radiotherapy to prevent potential drug interactions with nicotinamide. Subgroup analysis excluding patients who received BCON as radiosensitizer found no significant difference in acute GU toxicity of Grade ≥2 up to 6 weeks post- treatment in ACEi vs no ACEi group, 68.4% vs 52.9%, p = 0.22 (table 1).

Table 1