Breast cancer tumors are usually tested for different proteins, including hormone receptors and a tumor growth factor called HER2. Tumors that lack the three proteins are more common in African-American women and are harder to treat effectively. But this testing may not be enough to help doctors understand which cancers carry a high risk of returning.
A research team looked deeper, studying the genes and molecules in the breast cancer tumor cells of African-American women. These researchers found that the breast cancer in African-American women was more likely to contain genes and other molecules that put their tumors at a high risk of returning than non-African American women.
"Ask your oncologist about genetic testing for breast cancer."
This research was presented by co-author Raquel Nunes, MD, medical oncologist from the Washington Cancer Institute in Washington, DC, at the recent annual meeting of the American Society of Clinical Oncology.
The research team studied 100 African-American women with stage I to III breast cancer. Women aged 22 to 98, with an average age of 60, were included in the study.
The researchers used a test that looked at genes inside the breast cancer cells and other characteristics of the genes that enabled the researchers to group the women according to their risk of cancer recurrence (coming back).
Dr. Nunes and her team linked the tumor grade with the results of the genetic testing and determined a probability of risk for cancer recurrence. Tumor grade is the extent that tumor cells differ from normal cells; the higher the grade, the more abnormal/cancerous the cells.
A test for 70 genes, called the MammaPrint, was used to classify the risk of breast cancer recurrence. The BluePrint test identified different molecules in the breast cancer tumors and grouped them into three subtypes. The TargetPrint test looked for genetic information on production of the estrogen and progesterone hormone receptors and HER2 by the tumor cells.
The results showed that women identified as high risk on the MammaPrint had a high-grade breast cancer tumor type.
Based on the results of the gene analyses, the researchers found that 66 of the women had a high risk of breast cancer recurrence. All of the women with little or no estrogen receptors, 93% of the women with HER2 positive had high risk breast cancer.
Dr. Nunes and team concluded that genetic and molecular testing provided more information on breast cancer tumors than routine testing done to identify hormone receptors and HER2 only.
The authors remarked that subtyping tumors based on molecular findings meant that hormone receptor positive, hormone receptor negative and HER2 positive tumors could classified into different groups and that could allow for more specific treatments to be used.
This research was presented at a poster session at the annual meeting of the American Society of Clinical Oncology in Chicago, Illinois held May 30 through June 3.
Funding for the research was provided by a grant from the Safeway Foundation.