Background: Although breast cancer in women remains relatively rare in Korea, its incidence and mortality figures are increasing, consistent with the increasing risk observed in successive generations of Korean women. The aim of the current study was to examine time trends of breast-cancer mortality during the period 1984-2003 in Korea, assessing the importance of the effects of age, period and birth cohort as risk factors.
Methods: Data on the annual number of deaths due to female breast cancer and on female population statistics from 1984 to 2003 were obtained from the Korean National Statistical Office. A log-linear Poisson age-period-cohort model was used to estimate age, period and cohort effects.
Results: The trend of breast cancer mortality was explained by an age-cohort model based on goodness of fit, even though the significance of the cohort effect was marginal (p=0.08) after adjusting for age. The risk of breast cancer death was found to increase with age after adjusting for the cohort effect, and it was different from the cross-sectional age curve. Also, breast cancer mortality increased along with the birth cohort.
Conclusions: Even though the cohort effect was found to have a marginally significant effect on breast cancer mortality, it is expected to be more significant in the future given the recent on-going changes in diet and reproductive behavior shown by Korean women.