Oral Contraceptive Used More than 5 Years is Associated with Increased Risk of Breast Cancer: A Meta-Analysis of 28,776 South East Asian Women

Abstract Background: Breast cancer associated with variety of hormonal inter-ethnic and reproductive factors. Duration of oral contraceptives use with breast cancer risk is not well understood in Southeast Asian women. Methods: A comprehensive literature search of published articles from January 2001 to June 2019 (PubMed, ProQuest, and EBSCO online article databases) and meta-analysis were performed to link the duration of oral contraceptive application with risk of breast cancer among women in Southeast Asia. We identified the reference category, being ≤5 years' duration and >5 years' duration of oral contraceptive application. We use the Fixed and random-effect models to rely pooled odds ratios (OR). Egger's and Begg's test used for publication bias was presented with funnel plots. All analyzed data in Review Manager 5.3 (RevMan 5.3) and Stata version 14.2. Results: A total of 385 studies were reviewed and 10 studies involving a total of 28,776 women were included in a meta-analysis. This study found a slight increase in breast cancer risk in Southeast Asian women with oral contraceptives application ≤5 years with OR = 1.21 (95% CI 0.96-1.52, p>0.05). A higher risk of breast cancer was found in women with oral contraceptive application >5 years with OR = 2.66 (95% CI 1.79-3.94, p<0.00001). Publication bias and heterogeneity were not found particularly in a group of Southeast Asian women with oral contraceptive application for more than 5 years. Conclusion: Oral contraceptives use more than 5 years are at a higher risk in breast cancer among women in Southeast Asia. Although other reproductive factors including age at first childbirth, menarche, menopause, and lactation might influence the risk of breast cancer. Keywords: breast cancer, five years, oral contraceptive, Southeast Asia