Forecast of a future leveling of the incidence trends of female breast cancer in Taiwan: an age-period-cohort analysis

Breast cancer is the most common cancer among women in Taiwan. The age-standardized incidence rate has doubled in just 20 years, causing considerable concern to health professionals and the general public. This study used an ensemble of age-period-cohort models to estimate breast cancer incidence trends in Taiwan from 1997 to 2016 and project trends up to 2035. The (truncated) world standard population (World Health Organization 2000) proportions (age groups: 25-29, 30-34, …, 80-84, and older than 85 years) were used to calculate age-standardized incidence rates. The age-standardized incidence rate from 1997 (60.33/100,000 population) to 2016 (128.20/100,000 population) increased rapidly. The projection is that the increase in the age-standardized incidence will subsequently slow and exhibit a plateau in 2031 (151.32/100,000 population). From 2026 to 2035, the age-specific incidence rates for women older than 55 years old (postmenopausal breast cancer) are projected to increase with larger percentage increments for older women. A future leveling of female breast cancer incidence trends in Taiwan is anticipated. The majority of the patients with breast cancer in the future will be women aged 55 years and older. Education on lifestyle recommendations and mammography screening is required to reduce the burden of breast cancer. The results should have implications for other countries which are also confronted with the same public health problem of rapidly increasing breast cancer incidences.