Breast cancer is the most diagnosed cancer in U.S. women.  Findings from the CPIC study, under the direction of CPIC Research Scientist Scarlett Lin Gomez, Ph.D., were recently published online in the American Journal of Public Health. They revealed that rates vary by specific ethnicity and also by country of origin “ with nearly a three-fold difference between some ethnic populations.  The highest breast cancer rates in Asian women are in Japanese women, regardless of place of birth, and the lowest rates are in foreign-born Laotian women.  For U.S.-born Asians, Chinese and Filipino women carry the highest risk, which has been rapidly increasing over time.  Rates among U.S.-born Chinese and Filipino women under age 55 were even higher than those among whites, which was particularly unexpected.

CPIC scientists' discovery that there is a higher breast cancer rate in Asian women living in the U.S. than in their home countries raises questions regarding environmental and non-genetic factors in breast cancer causation.  

"Health disparities and inequities experienced by Asian Americans largely have been under-described because of stereotypes about supposed positive health profiles and a lack of detailed data about the many different populations within the group typically classified as 'Asian'," said Dr. Gomez. "Examining data enhanced to enable the study of cancer incidence in U.S. immigrant groups, as we did in this study, is an important step toward building a base of evidence that can inform health policies for U.S. Asian populations."

According to Dr. Gomez, further research is needed to better understand underlying factors.  Changes in reproductive factors (e.g., higher age at first live birth, lower breast feeding rates, earlier onset of menstruation), lifestyle factors (e.g., diet) and other environmental exposures may be affecting the rates.

SOURCE Cancer Prevention Institute of California