Trends in breast cancer mortality in Asturias, Spain

Age-Period-Cohort Analysis of Female Breast Cancer Mortality in Korea

Purpose

Despite the low mortality rate of breast cancer among women in Korea, the breast cancer mortality rate has increased. The aim of this study was to examine trends in breast cancer mortality from 1983 to 2012 in Korea, assessing the importance of age, period, and birth cohort as risk factors.

Materials and Methods

Data on the annual number of deaths due to female breast cancer and on female population statistics from 1983 to 2012 were obtained from Statistics Korea. A log-linear Poisson age-period-cohort model was used to estimate age, period, and cohort effects.

Results

The increasing breast cancer mortality can be explained predominantly by a birth cohort effect: the risk of breast cancer death showed a steady increase until the 1968 birth cohort, and decreased thereafter. There was a sharp increase in the magnitude of the age effect up to 60 years old, then a moderate increase in the effect during the sixties, followed by another sharp increase from 70 years old. The period effect on breast cancer mortality seems negligible based on its adjusted relative risk, even though it was statistically significant after adjusting for age and cohort effects.

Conclusion

In this study, the mortality pattern of breast cancer in Korea can be explained predominantly by a birth cohort effect. Hence, the overall mortality rate of breast cancer may increase for a while, and show a gradual decrease in the future, which will start from the younger age group.

Age-period-cohort analysis of female breast cancer mortality in Korea

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.