Research at Yale is adding to increased national awareness that the development of breast cancer and its long-term outcomes may be split down racial lines.
A recent study, conducted by Yale radiology professor Meena Moran, found that black women are more likely to have a “local relapse” of breast cancer — a relapse in the breast itself or in nearby lymph nodes — than white women. But this does not mean they cannot receive successful treatment, said Moran, who presented her findings to the American Society for Therapeutic Radiology and Oncology in Los Angeles on Wednesday.
Moran tracked over 2,000 white women and 207 black women who underwent lumpectomies — surgery that removes the tumor but keeps the breast intact — over a period of 30 years. The study, the largest of its kind to date, aimed to determine whether lumpectomy is an appropriate therapeutic tool for black women, she said.
Results revealed a 4 percent higher rate of relapse for black women over the period than for white women, she said. Moran said the results showed no difference in the rate at which the cancers spread or the overall survival rate of the two groups.
Although the difference between the two recurrence rates was statistically significant, Moran said that she is actually encouraged by the relatively small magnitude of the disparity.
“The bottom line is that African-Americans do respond to treatment worse than Caucasians and their cancers are more aggressive, but if they can get adequate treatment, this recurrence rate is only slightly higher,” she said. “This shows that African-Americans can have breast cancer therapies and reasonably expect near-equivalent outcomes to Caucasian women.”
She said black women’s rates of relapse and long-term outcomes crucially depend on the quality of treatment they receive — whether the tumor is completely removed and whether follow-up radiation therapy is thorough and carefully searches the entire breast and lymph nodes.
Previous research about the differences in breast-cancer patterns between racial groups show that, while the rate of breast cancer is lower among black women, they typically have more aggressive forms, a higher mortality rate and a pattern of earlier diagnosis.
Associate professor of pharmacology and oncology Michael DiGiovanna said, given results from past studies, Moran’s findings do not surprise him. He said the finding complements research showing that black women are twice as likely to develop certain types of cancers that have been identified as aggressive and less sensitive to existing treatments.
“We believe these types of breast cancer are more likely to result in relapse and death, generally from distant metastases,” he said, explaining the higher rate of relapse and mortality among black women. “Dr. Moran’s study suggests that such aggressive types of cancer may also be relatively resistant to radiation therapy, which is given to the breast after a lumpectomy to prevent local relapses.”
Physicians at the medical school are currently researching underlying biological differences between the two groups that may explain observed differences in the way they develop breast cancer, but Moran said these cellular mechanisms need to be examined more thoroughly.
For instance, research shows that black women’s tumor cells contain fewer estrogen and progesterone receptors, which means the group is less responsive to existing therapies that target these receptors, she said.
In 2004, medical school associate professor of epidemiology Beth Jones found that black women are also more likely to develop mutations in the p53 gene, which acts to stop tumor growth, Moran said.
Jones said gathering information about these biological differences may reveal new ways to prevent breast cancer or reverse its effects.
“Our goal is to continue to illuminate the reasons for the differences, so we can ultimately develop prevention strategies and tailor treatments more effectively,” she said.
But these biological differences may reflect environmental and behavioral variations that can be curtailed through education, Moran said. Socioeconomic factors, including access to screening, treatment and nutrition, as well as health-care behavior such as compliance with treatment, play a key role in the equation, she said.
While researchers are responsible for spreading awareness of emerging research, Moran said affected women themselves should shoulder the responsibility of “being involved with their own care.”
“This information has to be brought into the community and African Americans can help themselves by going for their screening mammogram, and be detected earlier,” she said. “But I think that’s starting to happen slowly.”
Moran said researchers at the medical school are currently working on finding additional biological markers that distinguish tumor cells in black women from those in white women. She said this line of investigation may allow scientists to develop novel therapies that specifically target black women with breast cancer.