J-shaped association between uric acid and breast cancer risk: a prospective case–control study

BACKGROUND/AIM: In terms of breast cancer risk, there is no consensus on the effect of uric acid (UA) levels. The aim of our study was to clarify the link between UA and breast cancer risk in a prospective case–control study and to find the UA threshold point. METHODS: We designed a case–control study with 1050 females (525 newly diagnosed breast cancer patients and 525 controls). We measured the UA levels at baseline and confirmed the incidence of breast cancer through postoperative pathology. We used binary logistic regression to study the association between breast cancer and UA. In addition, we performed restricted cubic splines to evaluate the potential nonlinear links between UA and breast cancer risk. We used threshold effect analysis to identify the UA cut-off point. RESULTS: After adjusting for multiple confounding factors, we found that compared with the referential level (3.5–4.4 mg/dl), the odds ratio (OR) of breast cancer was 1.946 (95% CI 1.140–3.321) (P < 0.05) in the lowest UA level and 2.245 (95% CI 0.946–5.326) (P > 0.05) in the highest level. Using the restricted cubic bar diagram, we disclosed a J-shaped association between UA and breast cancer risk (P-nonlinear < 0.05) after adjusting for all confounders. In our study, 3.6 mg/dl was found to be the UA threshold which acted as the optimal turning point of the curve. The OR for breast cancer was 0.170 (95% CI 0.056–0.512) to the left and 1.283 (95% CI 1.074–1.532) to the right of 3.6 mg/dl UA (P for log likelihood ratio test < 0.05). CONCLUSION: We found a J-shaped association between UA and breast cancer risk. Controlling the UA level around the threshold point of 3.6 mg/dl provides a novel insight into breast cancer prevention.