Mediterranean Diet, Physical Activity, and Metabolic Syndrome in Breast Cancer Survivors on Adjuvant Endocrine Therapy: A Cross-Sectional Study From North Africa

Objective This study aimed to determine the prevalence of metabolic syndrome and to examine its association with Mediterranean diet adherence and physical activity among women receiving adjuvant endocrine therapy for hormone receptor-positive breast cancer, in North Africa.Methods This cross-sectional study recruited 150 women in Oran, Algeria (May 2022-December 2025), receiving either tamoxifen (n = 73) or aromatase inhibitors (n = 77). Metabolic syndrome was defined per International Diabetes Federation 2006 criteria. Mediterranean diet adherence was assessed using a culturally adapted 14-item Mediterranean Diet Adherence Screener (adapted MEDAS). Physical activity level (PAL) was estimated using GENI software and entered as a continuous variable in the primary analysis, with sedentary/non-sedentary categorization (PAL < 1.40) as a secondary analysis. Dietary intake was assessed using a 24-h recall and a three-day food record with photographic verification. Factors independently associated with metabolic syndrome were identified using multivariable logistic regression.Results Metabolic syndrome was highly prevalent, affecting 68.0% of participants. Although overall prevalence did not differ between treatment groups (aromatase inhibitors: 72.7% vs. tamoxifen: 63.0%; p = 0.202), the two regimens differed in individual metabolic abnormalities: aromatase inhibitor users had lower HDL-cholesterol, higher fasting glucose, and higher blood pressure, while tamoxifen users had higher triglycerides. In multivariable analysis, higher PAL (OR = 0.44 per 0.1-unit increase; 95% CI: 0.28–0.68; p < 0.001) and greater Mediterranean diet adherence (OR = 0.72; 95% CI: 0.60–0.87; p = 0.001) were independently associated with lower odds of metabolic syndrome. The model showed an apparent AUC of 0.832 (5-fold cross-validated AUC: 0.800) and satisfactory calibration (Hosmer–Lemeshow p = 0.400).Conclusion Metabolic syndrome affects more than two-thirds of breast cancer survivors receiving endocrine therapy, and was independently associated with lower Mediterranean diet adherence and lower physical activity. Given the cross-sectional design, these associations cannot establish causality; nonetheless, these findings support further prospective and interventional research to determine whether modifying these behaviors could reduce this risk.