Sedentary work and breast cancer risk: A systematic review and meta‐analysis

OBJECTIVES: This systematic review and meta‐analysis aimed to assess sedentary work's contribution to breast cancer risk quantitatively using thorough research articles. METHODS: We performed a meta‐analysis using a registered protocol in PROSPERO (registration number: CRD42020204629). Literature from PubMed, Embase, and Cochrane involving sedentary work and breast cancer risk was reviewed. We calculated the overall pooled risk ratios (RRs) and 95% CI with a random‐effect model from the included studies. Furthermore, we performed stratified analyses by characteristics of studies. RESULTS: Thirty‐one studies (13 cohort studies and 18 case‐control studies) were included in the analysis. The overall effect of the pooled analysis was an RR of 1.16 (95% CI 1.08‐1.23). The results were 1.20 (95% CI 1.10‐1.30) and 1.12 (95% CI 1.02‐1.23) for cohort and case‐control studies. The effect of sedentary work did not seem to be consistently attenuated by controlling body mass index, menopausal status, or experience of hormone replacement therapy. CONCLUSION: The results from this meta‐analysis suggest that sedentary behavior within the occupational domain was associated with a 15.5% increased risk of breast cancer. It is essential to reduce the sedentary time spent at work and to secure time for leisure‐time physical activity among sedentary workers as a primary preventive measure.