Type and Timing of Menopausal Hormone Therapy and Breast Cancer Risk: Individual Participant Meta-Analysis of the Worldwide Epidemiological Evidence

This 2019 meta-analysis by the Collaborative Group on Hormonal Factors in Breast Cancer pooled individual data from over 108,000 postmenopausal women with breast cancer and more than 400,000 without, across 58 studies worldwide, to evaluate the impact of menopausal hormone therapy (MHT) on breast cancer risk. The analysis found that