| Abstrakt: |
Background: Given the widespread prevalence of breast cancer as a global malignancy, there is a compelling need to delve into its risk determinants. Objective: This study aims to investigate the potential relationship between indicators of left-handedness and breast cancer, employing systematic review, meta-analysis, and Mendelian randomization methods. Design: Systematic review and meta-analysis. Methods: The systematic review and meta-analysis, encompassing case-control and cohort designs, conducted a database search on June 17, 2022, utilizing Medline and Embase. For Mendelian randomization analysis, the exposure variable, left-handedness, was sourced from the UK Biobank. Data for breast cancer outcomes were obtained from two cohorts: the Breast Cancer Association Consortium and the Finnish Biobank (Finngen). Results: Eight studies were included in the meta-analysis to investigate the correlation between left-handedness and breast cancer in females. The analysis of cohort studies revealed a hazard ratio (HR) of 1.21 (95% confidence interval (CI): 1.01–1.45), whereas case-control studies showed an odds ratio of 0.81 (95% CI: 0.52–1.26). Subgroup analysis indicated an elevated HR in premenopausal left-handed women. However, Mendelian randomization did not confirm a significant association. Conclusion: Our findings suggest a potential correlation between left-handedness and breast cancer, particularly in premenopausal women. However, due to limited studies and unclear supporting theories, definitive conclusions are premature. Plain language summary: Investigating the link between handedness and breast cancer: a systematic review, meta-analysis, and mendelian randomization Breast cancer is a common disease worldwide, and it's important to understand what might increase the risk of developing it. This study looked at whether being left-handed could be linked to a higher chance of getting breast cancer. To investigate this, we reviewed multiple studies and combined their results. We also used a special method called Mendelian randomization to analyze genetic data. This study included eight studies, with some showing a slightly higher risk of breast cancer in left-handed women, especially before menopause. However, other studies did not find a significant link. The genetic analysis did not confirm a strong connection between left-handedness and breast cancer. In conclusion, there might be a connection between left-handedness and breast cancer, particularly in younger women, but more research is needed to be sure. [ABSTRACT FROM AUTHOR] |
