Risk Of Death From Early Stage Breast Cancer Highest In Black Women: Study

Black women have a higher risk of death seven years after being diagnosed with stage one breast cancer compared to non-Hispanic white women and other major ethnicities, according to a new study led by Steven Narod, a Professor in the Department of Medicine’s Division of Oncology and post-doctoral fellow Dr. Javaid Iqbal.

The study, published today in the Journal of the American Medical Association, found black women were less likely to be diagnosed with early stage breast cancer next to non-Hispanic white women, but more likely to die of breast cancer with small-sized tumours.

“For women with breast cancers of the same size, black women are more likely to experience spread of the cancer to the lymph nodes or other organs than white women,” said Narod, who is also the director of the Familial Breast Cancer Research Unit at Women's College Research Institute and Canada Research Chair in Breast Cancer. “On the other hand, our study found Japanese women experienced much better survival than white women.”

Researchers analyzed the medical records of 373,563 women diagnosed with invasive breast cancer between 2004 and 2011. When comparing non-Hispanic white women with Hispanic, black, Chinese, Japanese, South Asian women and other Asian women, along with other ethnicities, they found:

• Japanese women were more likely to be diagnosed with stage 1 breast cancer.
• Black women were less likely to be diagnosed with the early stage cancer.
• The risk of death from stage 1 breast cancer seven years after diagnosis was lower among South Asian women and highest among Black women.
• Black women were more likely to have small sized breast cancer that spread throughout the body.
• Black women were more likely to die of breast cancer with small sized tumours.

While differences in tumour characteristics may explain some of these findings, the researchers note factors including socioeconomic status, lifestyle and diet, access to and use of healthcare and adherence to treatment, may all play a role in the disparities among the ethnic groups.

“We are interested in all the factors which predict whether a breast cancer will or will not spread,” said Narod. “Traditionally, as researchers, we have focused on the cancer itself and the treatment, but there are other important factors that may play a role, including lifestyle. This study is so important because it shows that ethnic background is one of those factors.”