The Risk of Thromboembolism in Patients with Muscle Invasive Bladder Cancer before and after Cystectomy Depending on Blood Group and Neoadjuvant Chemotherapy—A Multicentre Retrospective Cohort Study

Purpose: Previous studies have indicated that patients with muscle-invasive bladder cancer with non-O blood types have an increased risk of experiencing thromboembolic events (TEEs). This is finding is in relation to neoadjuvant-chemotherapy (NAC)-naïve patients. Aim: to establish the risk of TEEs and any association with blood types among NAC patients as well as NAC-naïve patients. Methods: Cystectomized patients at four centres treated from 2009 to 2018 (n = 244) were analysed. The quantities of patients corresponding to each blood group were as follows: A—108 (44%); O—99 (41%); B—30 (12%); and AB—7 (3%). NAC patients (n = 167) and NAC-naïve NAC-eligible patients (n = 77) were assessed. In total, 54 women (22%) and 190 men (78%), with a median age of 69 years, were included in the study. The occurrence of any type of TEE from six months pre-cystectomy to 12–24 months after was analysed using logistic regression adjusted for NAC and confounders. Results: Sixty-six TEEs were detected in 21% of the patients (n = 52). Pulmonary embolus (n = 33) and deep venous thrombosis (n = 11) were the most common forms. No significant differences between blood types were found in the analysis, although B blood type had a nearly significant increased crude risk compared with O blood type, for which there was an OR of 2.48 (95% CI 0.98–6.36). Adjustment for NAC and covariates weakened the OR, which plummeted to 1.98 (95% CI 0.71–5.51). Conclusions: No significant associations were found between blood types and TEE occurrences in this cohort including both NAC and NAC-naïve NAC-eligible patients.