Background: In Mexico, added sugar intake remains well above recommended levels. Excessive sugar consumption is a well-established risk factor for non-communicable diseases such as obesity, type 2 diabetes, and cardiovascular disease. In contrast, evidence linking sugar intake to cancer risk remains inconsistent. Experimental studies suggest that sugars may contribute to cancer etiology not only through obesity-related pathways but also via inflammatory and oxidative mechanisms and insulin resistance, even in the absence of weight gain.
Objective: To evaluate the association between total and added sugar intake and breast cancer immunophenotypes in Mexican women.
Methods: We conducted a secondary analysis including 1,045 incident breast cancer cases and 1,030 population-based controls from a case–control study carried out between 2007 and 2011 in Northern Mexico. Information on estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) expression was obtained from medical records to classify tumors into immunophenotypes, including luminal, HER2-positive, and triple-negative subtypes. Dietary intake was assessed using a previously validated semi-quantitative food frequency questionnaire. Total and added sugar intakes were estimated following the Pan American Health Organization (PAHO) nutrient profile model, which distinguishes intrinsic and added sugars across food categories. Unconditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for the association between sugar intake and breast cancer overall and by immunophenotype.
Results: Higher added sugar intake was associated with increased odds of breast cancer (OR for tertile 3 vs. tertile 1: 3.15; 95% CI: 2.40–4.10; P-trend <0.001). Added sugar intake was positively associated with breast cancer risk among both premenopausal women (OR = 2.60; 95% CI: 1.70–3.90; P-trend <0.001) and postmenopausal women (OR = 3.40; 95% CI: 2.50–4.70; P-trend <0.001). Associations for total and added sugars remained statistically significant for ER-positive and ER-negative tumors, as well as for luminal and HER2-positive immunophenotypes, but not for triple-negative tumors.
Conclusions: These findings suggest that sugar intake may represent a modifiable risk factor for breast cancer. Our results contribute to ongoing discussions regarding sugar-related public health policies, including taxation, regulation of food marketing, and reformulation of ultra-processed products.