Ethnic differences and factors related to breast cancer survival in Hawaii

Background. Previous studies have described differences in breast cancer survival among women from various ethnic backgrounds even after adjustment for stage at diagnosis. The aim of this study is to identify factors that could explain this disparity in prognosis and to update breast cancer survival patterns in Hawaii. Methods. The Hawaii Tumor Registry identified 3345 breast cancer cases diagnosed between 1980 and 1988. The following covariates were studied: ethnicity, stage at diagnosis, geographical residence, and menopausal, marital and socioeconomic statuses. The Kaplan-Meier method and proportional hazards regression were used to estimate survival by group. Results. Native Hawaiian and Filipino women had a higher risk of dying within 5 years than women of other ethnic groups. Japanese had the highest survival probability, followed by Chinese and Caucasians. Stage was the most important prognostic factor. Married women had better survival than widowed and divorced women. Filipinos had a much greater chance of dying from localized cancer than other women with localized disease. Geographical residence, menopausal and socioeconomic statuses were not associated with survival. Conclusions. Despite an overall improvement in breast cancer survival, ethnic disparity in prognosis still exists. Other possible explanations for the differential prognosis, such as treatment, diet, genetics, obesity, oestrogen receptor and hormonal statuses need to be explored in future studies.