Your chances of surviving breast cancer may depend on whether you are black or white, Asian or Hispanic. A new study finds that survival is not entirely dependent on diagnosing the disease at an early stage or on access to quality care.
Dr. Steven Narod and his team at Women’s College Hospital in Toronto analyzed the medical records of 452,000 women in the U.S. who were diagnosed with breast cancer between 2004 and 2011. They found that black women have a higher risk of death seven years after being diagnosed with stage one breast cancer when the tumor is small and most likely to be successfully treated, compared to non-Hispanic white women and other racial and ethnic groups, including women from South Asia.
"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," Narod said, adding that the data showed "Japanese women experienced much better survival than white women."
"Cancers are not more common in young, black women," he said, "but those that do get breast cancer are more likely to have an aggressive course than white women and much more likely than a Chinese or Japanese woman."
The results also showed that black women were less likely to be diagnosed when the cancer is in an early stage, and that they are more likely to have small tumors that spread throughout the body. More than 90 percent of the women who were diagnosed with stage 1 breast cancer survived seven years, but Narod says the proportion who died was about nine percent higher for black women than for white women.
The researchers noted that other factors play a role in surviving breast cancer: wealth, lifestyle and diet, access to health care and following doctors' orders. These factors may also help explain the differences in survival, but Narod said this study proves race and ethnic background are also important.
Breast cancer - the most common cancer in women worldwide - killed an estimated half million women in 2011, according to the WHO.
While Narod's study tracked African American women in the U.S., he said it's likely that women in sub-Saharan Africa are also at risk for an aggressive type of breast cancer, although no study has been done that includes that group.
Narod said he would like to compare data from both those populations, along with black women elsewhere, such as in the Caribbean. He said such a study would help researchers learn what is influencing the outcome - genetics or different environments and lifestyles.
Narod holds a research chair in breast cancer and is also a professor of public health at the University of Toronto. The study was published in the Journal of the American Medical Association.