Understanding female breast cancer risk in the Indian population: Evidence from a systematic review and meta-analysis.

[BACKGROUND] Breast cancer incidence in India is expected to rise by about 5.6 % annually, translating to an estimated increase of 0.05 million new cases per year. This systematic review and meta-analysis aim to investigate the influence of India's unique context on breast cancer risk by identifying and synthesising population-specific risk factors.

[METHODS] We conducted a systematic literature search across the PubMed, Scopus, and Embase databases up to December 22, 2024. Observational studies assessing breast cancer risk factors among Indian women were included, and quality was assessed using the Joanna Briggs Institute Checklist. A meta-analysis using a random-effects model estimated pooled associations between key risk factors and breast cancer.

[RESULTS] Among the 1871 articles identified, 31 studies met the inclusion criteria of which case-control studies were of moderate to high quality. The meta-analysis revealed significant positive associations with breast cancer risk for late menopause (age >50 years), delayed first pregnancy or childbirth (age >30 years), multiple abortions, higher age at marriage, increased waist-to-hip ratio (≥0.85), and family history of cancer, particularly breast cancer. Among lifestyle factors, poor sleep quality, irregular sleep patterns, sleeping in a lighted room, and elevated stress levels were also positively associated with risk in individual studies. In contrast, higher levels of physical activity showed an inverse association.

[CONCLUSIONS] Reproductive timing, hormonal exposure, central obesity, and family history influence breast cancer risk primarily among Indian women. In conclusion, the review highlights the critical need for large, extensive, population-based prospective cohort studies in India to define breast cancer prevention and early detection strategies with greater precision.