A recently published study by researchers from the Cancer Prevention Institute in California, however, reveals that Asian-American women have seen an increase in breast cancer diagnosis over the past 15 years — although Japanese women were exempt from this.
The study focused on the seven major Asian populations that migrated to America: Chinese, Japanese, Korean, Filipino, Vietnamese, South Asians (Asian Indians and Pakistanis), and Southeast Asians (Cambodians, Laotians, Hmong, Thai). While Filipino and Vietnamese belong to Southeast Asia, the ethnic groups seem to have been separated due mainly to the number of cancer incidences in their respective populations.
Scarlett Lin Gomez and her team of researchers examined the prevalence of cancer incidences by age and stage among Asian-American women in California from 1988 to 2013. They found that, in that time period, 45,721 invasive breast cancer cases were identified in their chosen population.
The research found that the largest increase of breast cancer incidences occurred in Korean, South Asian, and Southeast Asian women. As for the exemption of Japanese women, it seems the lack of increase has to do with the group having already experienced the spike earlier.
"[South Asian (Indian and Pakistani), Vietnamese, and Southeast Asian] also happen to be the most recently immigrated groups ... Their patterns are mirroring what we saw for Japanese Americans back in the 70s and 80s," Gomez says.
Breast Cancer Incidences
As mentioned earlier, the research was divided into two particular subgroups: age and stage.
According to the research, all Asian-American ethnic groups saw an increase in breast cancer occurrences for women over 50 years of age. For those under 50, however, women from Vietnam and other Southeast Asian groups were more affected.
Late stage diagnoses were observed in Filipino, Korean, and South Asian women but distant stage breast cancer incidences occurred most in Filipino women.
The most prevalent subtypes of breast cancer were defined by tumor expression of hormone receptors and human epidermal growth factor receptor 2 (HER2). Gomez reveals that more HER2 breast cancers were recorded for Chinese, Filipino, Korean, and Vietnamese women than white women in California.
"These patterns warrant additional attention to public health prioritization to target disparities in access to care, as well as further research in identifying relevant breast cancer risk factors for specific breast cancer subtypes," Gomez says.
She added that further study should be done to investigate risk factor and early life exposures, with attention to the genetic susceptibility of Filipino and Japanese women.