Breast Cancer Epidemiology and Risk Factors: A Comprehensive Review

Abstract

Breast cancer remains the most commonly diagnosed malignancy among women worldwide and a leading cause of cancer-related mortality. Despite advances in screening and therapy, its global burden continues to rise, particularly in low- and middle-income countries, highlighting rising incidence in Asia and persistently high mortality in sub-Saharan Africa. The disease’s incidence reflects a complex interplay between genetic, hormonal, environmental, and lifestyle determinants. Established risk factors include age, family history, reproductive behavior, hormonal exposure, obesity, alcohol consumption, and radiation exposure. Strong evidence supports associations between breast cancer risk and high mammographic breast density, hormonal exposures (hormone replacement therapy and oral contraceptives), early menarche, late menopause, delayed first childbirth, and limited breastfeeding duration. Genetic factors, notably BRCA1 and BRCA2 mutations, contribute to 5–10% of cases, predominantly in younger women and those with family history. Emerging evidence implicates atrial fibrillation, metabolic syndrome, and microbiome alterations in modulating breast cancer susceptibility. Meanwhile, protective factors such as physical activity, breastfeeding, and healthy dietary patterns have shown potential to mitigate risk. This review synthesizes current epidemiological trends and evidence-based risk factors contributing to breast cancer development, highlighting regional disparities, modifiable exposures, and emerging genetic insights. Understanding these determinants is essential to guide preventive strategies, early detection, and tailored public health interventions.