A new study has reported that relatively young (Asian) and Pacific Islander women have higher risk of breast cancer than white women in Californa. To conduct the study, the authors used previously-collected data from a study in which women with invasive breast cancer were linked to their California birth records. The women, all of whom were born in California during the 1960s, were identified from the population-based California Cancer Registry. The study included 3,799 women under age 45 who were diagnosed during the period 1988 to 2044. At total of 17,461 cancer-free women who served as controls were randomly selected from California birth records. Controls were matched to cases by birth year.

Asian-American and Pacific Islander women under 45 were found to have a 62% higher risk of breast cancer than white women in California. The risk was highest for women of Filipina and Japanese ancestry. The authors conclude that the study findings highlight the need for further evaluations of breast cancer risk among young Asian and Pacific Islander women and underscores the need to consider both ancestry and migration status in such evaluations.

Lifestyle differences influence breast cancer risk in Asian-Americans

The study highlights the impact on breast cancer risk of lifestyle differences between immigrants from Asia and their children. Rates of breast cancer are also increasing in urban Chinese women compared to rural women and in other groups that migrate to areas where they become more "Westernized." The lifestyle differences include diet primarily, but also incorporate level of physical actvity, and exposure to pollutants (including air pollution and light at night)). However, this does not explain why daughters of Asian immigrants should have substantially higher rates than the white population in California.