Trends of breast cancer incidence and risk factor prevalence over 25 years.

INTRODUCTION

To examine the trends in the prevalence of breast cancer risk factors in relation to breast cancer incidence trends and to explore whether the changes in risk factors differed by ethnicity in Hawaii over a 25-year period.

METHODS

We pooled 17 population-based epidemiological studies conducted in Hawaii between 1975 and 2001. The study population of 82,295 women included subjects of Caucasian, Japanese, Native Hawaiian, Chinese, and Filipino ancestry. We computed age-adjusted prevalence estimates by ethnic group for 5-year time periods. Logistic regression was used to evaluate trends over time.

RESULTS

The prevalence of an early age at menarche, nulliparity, and parity of fewer than three children, but not that of a late age at first live birth, increased during the study period. Whereas current smoking decreased for all ethnicities over time, the age-adjusted prevalence of overweight, obesity, college education, and alcohol use increased. Trends differed by ethnicity. For Native Hawaiians, the prevalence of overweight, obesity, alcohol use and nulliparity rose over time. For Japanese, the prevalence of overweight, early age at menarche, and having fewer than three children increased. Caucasians showed an increasing prevalence of overweight, obesity, college education, and nulliparity. In Filipina women, we observed changes in reproductive behavior and increasing obesity.

CONCLUSIONS

Despite a slowing trend for some breast cancer risk factors, the overall risk profile in this population may lead to further increases in breast cancer incidence. Different ethnic groups may benefit from specific prevention strategies.