Global burden and trends in premenopausal and postmenopausal breast cancer: a population-based study

Background Breast cancer has distinct causes, prognoses, and outcomes and effects in patients at premenopausal and postmenopausal ages. We sought to assess the global burden and trends in breast cancer by menopausal status. Methods We did a population-based analysis of global breast cancer incidence and mortality among premenopausal and postmenopausal women. Menopausal status was defined using age as a proxy, whereby breast cancer cases or deaths at age 50 years or older were regarded as postmenopausal. Age-standardised breast cancer incidence and mortality in 2018 were calculated using GLOBOCAN data. Incidence trends for 1998-2012 were assessed in 44 populations from 41 countries using the Cancer in Five Continents plus database, by calculating the annual average percent change. Findings Approximately 645 000 premenopausal and 1 center dot 4 million postmenopausal breast cancer cases were diagnosed worldwide in 2018, with more than 130 000 and 490 000 deaths occurring in each menopausal group, respectively. Proportionally, countries with a low UNDP human development index (HDI) faced a greater burden of premenopausal breast cancer for both new cases and deaths compared with higher income countries. Countries with a very high HDI had the highest premenopausal and postmenopausal breast cancer incidence (30 center dot 6 and 253 center dot 6 cases per 100 000, respectively), whereas countries with low and medium HDI had the highest premenopausal and postmenopausal mortality, respectively (8 center dot 5 and 53 center dot 3 deaths per 100 000, respectively). When examining breast cancer trends, we noted significantly increasing age-standardised incidence rates (ASIRs) for premenopausal breast cancer in 20 of 44 populations and significantly increasing ASIRs for postmenopausal breast cancer in 24 of 44 populations. The growth exclusively at premenopausal ages largely occurred in high-income countries, whereas the increasing postmenopausal breast cancer burden was most notable in countries under transition. Interpretation We provide evidence of a rising burden of both premenopausal and postmenopausal breast cancer worldwide. Although early diagnosis and access to treatment remain crucial in low-income and middle-income countries, primary prevention efforts seeking to decrease exposure to known breast cancer risk factors are warranted in all world regions to curb the future breast cancer burden. Copyright (c) 2020 World Health Organization. Published by Elsevier Ltd. This is an Open Access article published under the CC BY-NC-ND 3.0 IGO license, which permits users to download and share the article for non-commercial purposes, so long as the article is reproduced in the whole without changes, and provided the original source is properly cited. This article shall not be used or reproduced in association with the promotion of commercial products, services or any entity. There should be no suggestion that WHO endorses any specific organisation, products or services. The use of the WHO logo is not permitted. This notice should be preserved along with the article's original URL.