Influences of ethnicity, treatment, and comorbidity on breast cancer survival in Hawaii.

The purpose of this study was to examine factors contributing to the ethnic discrepancies in breast cancer survival described previously. Through the use of the Hawaii Tumor Registry and insurance claims data, 1,052 breast cancer patients' survival times were examined in relation to demographics, disease characteristics, comorbidity, and treatment patterns as compared to national guidelines for breast cancer treatment. In stepwise and hierarchical Cox regression models, TNM stage was the strongest predictor of survival and explained all of the ethnic survival differences. In addition, comorbidity and treatment patterns were significant in predicting survival. In this population of health plan members, ethnic differences in survival were not a result of differential treatment, but due to variations in early detection. These results support the hypothesis that pre-existing conditions and treatment patterns are related to breast cancer survival even after controlling for stage at diagnosis indicating the usefulness of insurance claims data in this research field.