Ethnicity and race as modifiers of the association between patient sex and stage at diagnosis of bladder cancer

Background: With over 80,000 projected new diagnoses in 2024, bladder cancer remains a significant public health concern. Given the absence of routine screening protocols, identifying high-risk populations becomes crucial for early detection and intervention. This study aimed to investigate whether race and ethnicity modify the association between sex and stage at diagnosis in adults with primary bladder cancer. Methods: An analytical cross-sectional study of 235,586 patients was completed using the NCI Surveillance, Epidemiology, and End Results database. Inclusion criteria consisted of patients 18 years and older diagnosed with a primary bladder malignancy from 2000 to 2019. The exposure variable was sex, and the primary outcome was the stage at diagnosis. An unadjusted and adjusted multinomial logistic regression analysis was performed to calculate the relative risk ratios (RRR) and 95 % confidence intervals (CI). Additionally, effect modification was explored by including the interaction term between the exposure variable and race and ethnicity. Results: Our data revealed that ethnicity and race were effect modifiers of the association between sex and stage at diagnosis of primary bladder cancer. Among non-Hispanic (NH) White, Hispanic, and NH-Black women, the RRR of Distant vs. In-Situ staging increased by 75 % (RRR 1.75; 95 % CI 1.65-1.86), 86 % (RRR 1.86; 95 % CI 1.56-2.22), and 96 % (RRR 1.96; 95 % CI 1.64-2.33) respectively. The RRR for Regional vs In-Situ staging in Hispanic and NH-Black women increased by 60 % (RRR 1.60; 95 % CI 1.38-1.87) and 78 % (RRR 1.78; 95 % CI 1.53-2.07) respectively. Conclusion: These findings emphasize the importance of tailoring prevention, screening, and treatment strategies to address disparities among high-risk groups. Future studies may investigate the influence of risk factors such as smoking status on this association between race and ethnicity and stage at diagnosis of bladder cancer.