Breast cancer survival rates among Chinese women born in East Asia and the United States

Background Few studies have been done to compare the breast cancer survival rates of the U.S.-born ethnically Chinese women and Chinese immigrants. The main purpose of this study was to explore the difference of breast cancer survival rates between the two populations. Methods 3858 ethnically Chinese women who had been diagnosed with primary breast cancer were recorded in the surveillance, Epidemiology and End Results (SEER) registries between 1973 and 2000. Kaplan-Meier estimates with the log-rank test, the proportional hazard model and their 95% confidence intervals (CIs) were used to compare the survival rates between the two birthplace groups. Results Among 2047 valid data, 780 (38.1%) ethnically Chinese patients with primary breast cancer died with a mean survival time of 178.17 months. The risk of death for an ethnically Chinese patient who was born in East Asia was found to be 1.18 (95% CI = 1.02–1.36), which was higher than the one who was born in the U.S. As for the subgroup whose age at diagnosis were greater than 55, the risk for patients born in East Asia was 1.42 (95% CI = 1.20–1.69), which was higher than those born in the US. Conclusion Among the ethnically Chinese women living in the United States and suffering from invasive breast cancer, those who were born in East Asia had lower survival rates than those who were born in the United States. A further analysis revealed that, for the patients whose age at diagnosis were over 55, the survival rate for patients who were born in East Asia was significantly worse than those who were born in the U.S., especially in localized stage group. Cultural differences might account for this increased risk.