Fatty Acid Intake and Bladder Cancer Risk: A Multicenter Case-Control Study in Iran

Bladder cancer is a major public health concern worldwide. While smoking and occupational exposures are established risk factors, the role of dietary fatty acids (FAs) in bladder cancer risk remains unclear. Data were collected from 711 bladder cancer cases and 3,297 controls in the IROPICAN study (2017–2020) across ten Iranian provinces. Dietary intake was assessed using a validated food frequency questionnaire. Intakes of total fat, saturated FAs (SFAs), monounsaturated FAs (MUFAs), polyunsaturated FAs (PUFAs), and trans FAs (TFAs) were analyzed. Principal component analysis (PCA) identified fatty acid consumption patterns. Multivariable logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CIs), adjusting for confounders. PCA suggested that balancing FA intake, specifically increasing omega-3 FAs, moderating omega-6, and reducing saturated fats, was associated with a favorable profile for bladder cancer risk. OR for stearic acid intake was 0.28 (95% CI: 0.12–0.67). Conversely, OR for high intake of palmitoleic acid, alpha-linolenic acid (ALA), and docosapentaenoic acid (DPA) was elevated. Sex-specific effects were found stearic acid was protective in men, while PUFAs were protective in women. No associations were observed for total fat or cholesterol. These results highlight the importance of FA subtypes, rather than total fat intake, in dietary recommendations.