Global Burden and Attributable Risk Factors of Breast Cancer in Young Women: Historical Trends from 1990 to 2019 and Forecasts to 2030 by Sociodemographic Index Regions and Countries

Background: Breast cancer in young women (BCY) is much less common but has significant health sequelae and societal costs. We aimed to evaluate the global and regional burden of breast cancer in women aged 15-39 years from 1990 to 2019.

Methods: We collected detailed data on breast cancer from the Global Burden of Disease Study 2019 (GBD 2019) Data Resources. The age-standardised incidence rate (ASIR), age-standardised mortality rate (ASMR), age-standardised disability-adjusted life years rate (ASDR), and estimated annual percentage change (EAPC) were used to assess the disease burden of BCY. The Bayesian Age-Period-Cohort model was used to forecast disease burden from 2020 to 2030.

Results: From 1990 to 2019, significant increases in ASIR were found for BCY (EAPC = 0.59, 95% confidence interval (CI) = 0.5 to 0.68), whereas decreases in ASMR (EAPC = -0.41, 95% CI = -0.53 to -0.3) and ASDR (EAPC = -0.35, 95% CI = -0.46 to -0.24). Across countries with varying sociodemographic indexes (SDI), all regions showed an upward trend in BCY morbidity, except for countries with a high SDI. While mortality and DALYs rates have decreased in countries with high, high-middle, and middle SDI, they have increased in countries with low-middle and low SDI. Countries with lower SDIs are projected to bear the greatest burden of BCY over the next decade, including both low and low-middle categories. Alcohol use was the main risk factor attributed to BCY deaths in most countries, while exposure to second hand smoke was the predominant risk factor for BCY deaths in middle and low-middle SDI countries.

Conclusions: The burden of breast cancer in young women is on the rise worldwide, and there are significant regional differences. Countries with a low-middle or low SDI face even more challenges, as they experienced a more significant and increasing BCY burden than countries with higher SDIs.