TUESDAY, Oct. 13, 2015 (HealthDay News) -- No matter the type or stage of breast cancer, minority women are more likely to be diagnosed later in the disease than white women, and they are also less likely to receive recommended treatments, a new study shows.
While prior studies have found such disparities before, the new research finds that it exists "across all breast cancer subtypes," study lead author Lu Chen, a researcher in the public health sciences division at Fred Hutchinson Cancer Research Center in Seattle, said in a news release from the American Association for Cancer Research (AACR).
The study received funding from the U.S. National Cancer Institute and was published Oct. 13 in the journal Cancer Epidemiology, Biomarkers & Prevention.
Chen's team looked at data from 18 U.S. population-based cancer registries. Specifically, the researchers analyzed the demographics, stage of disease, tumor grade and size, treatment, and health insurance status for more than 100,000 American women.
The researchers also recorded the women's tumor subtypes, which can factor into prognosis and care.
For example, the investigators looked at the tumor's hormone receptor (HR) status, which means the tumor is more or less sensitive to hormonal therapies. They also looked at whether or not the tumor tested positive for human epidermal growth factor 2-neu (HER2), which can point to more aggressive tumors.
According to the researchers, compared to black women, white women were more likely to have smaller tumors, and they were also more likely have less-aggressive forms of breast cancer.
In addition, women of other racial and ethnic groups were more likely than white women to be diagnosed with more advanced stages of breast cancer.
Black women were more likely to have large tumors and an aggressive form of the disease known as "triple-negative" breast cancer. They were also 40 to 70 percent more likely to be diagnosed with advanced disease, in all subtypes of breast cancer.
Across all types of breast cancer, Hispanic women were also 30 to 40 percent more likely to be diagnosed with stage 2 or 3 disease, the study found.
Racial and ethnic disparities also appeared to affect women's treatment. For nearly all types of breast cancer, black women were 30 to 60 percent more likely to receive inappropriate treatment, the study showed.
Meanwhile, Hispanic women were 20 to 40 percent more likely to receive substandard care.
The researchers said there was no difference in treatments between white women and Asian-American women.
All of these health disparities remained even after Chen's team took the women's health care insurance status into account.
Two experts in breast cancer care weren't surprised by the findings.
"It is well known that disparities in breast cancer affect women from minority groups, and in particular African Americans," said Dr. Paolo Boffetta, a professor of medical oncology at the Icahn School of Medicine at Mount Sinai, in New York City. However, the new study looks deeper, quantifying "the disparities at each stage of the natural and clinical history of the disease," he said.
"Addressing such disparities, and the resulting higher death rate in minority women, should be given the highest priority in the global effort to combat breast cancer," Boffeta said.
Dr. Stephanie Bernik is chief of surgical oncology at Lenox Hill Hospital, also in New York City. She said that the reasons behind the racial and ethnic gap in breast cancer diagnosis and care remain unclear.
"Socioeconomic factors probably play a role, as women with less resources are less likely to seek care and follow through with recommended treatments," Bernik said. "There needs to be more study as to how to optimize treatment for these women, as current strategies are not effective enough."
The U.S. National Cancer Institute has more on cancer health disparities.