WEST PALM BEACH, Fla., July 12 (UPI) -- Women who have a genetic disposition for breast cancer appear to have outcomes that are similar to other women who develop the disease, researchers said Thursday.
Doctors in Israel reviewed the outcomes of women diagnosed and treated for breast cancer who have the BRCA1 and BRCA2 genetic mutations that make them highly likely to develop breast cancer in their lifetimes and compared them with women diagnosed with breast cancer but who do not carry the mutations.
"Breast cancer-specific rates of death among Israeli women are similar to carriers of a BRCA founder mutation and non-carriers," said Gad Rennert, chairman of the department of community medicine and epidemiology at Carmel Medical Center and Technion Faculty of Medicine in Haifa, Israel.
Reporting in the New England Journal of Medicine, Rennert and colleagues identified women with breast cancer in 1987 and 1988 in Israel and determined through analyses of stored tissues which patients carried the mutations and which ones developed breast cancer from other causes -- so-called sporadic cases.
The mutations are common among Ashkenazi Jewish ancestry, mainly people of Eastern Europe origin. About 60 percent of the Israeli population is Ashkenazi Jews. "A BRCA1 or a BRCA2 mutation was identified in 10 percent of the women who were of Ashkenazi Jewish ancestry," Rennert said.
While carrying the gene or developing breast cancer and having the genetic mutation are considered poor prognosis features, Rennert said that the evidence on outcomes is inconsistent.
In the study, the researchers found pathological tissue samples for 1,794 women and were able to retrieve the medical records for 1,545 of those women. Of those women, 1,317 were of Ashkenazi descent.
Rennert found that the overall 10-year survival for Ashkenazi women diagnosed with breast cancer who were non-carriers of the genes was 51 percent; the overall survival rate for BRCA1 gene carriers was 49 percent, and the overall survival rate for BRCA2 carriers was 48 percent. The differences were not statistically significant.
When the analyses were adjusted to look just at breast cancer rates, again there were no statistical differences in survival, he said.
Rennert said that further analyses indicated there might be differences in outcomes based on genetics if one looked at the size of the tumors at the time of diagnosis and whether the women elected to undergo chemotherapy following diagnosis. In those cases it suggested that having a mutation resulted in a worse outcome.
"These estimates are important to women with a BRCA mutation who face a decision between preventive surgery and intensive surveillance," Rennert said.
Some women diagnosed with breast cancer who carry the BRCA mutation opt to have bilateral mastectomy in order to heighten their chances of preventing recurrence. Other women choose to undergo regular, frequent testing to watch for recurrence and to take action then.
In an editorial that accompanies Rennert's study in the journal, Patricia Hartge, deputy director of the Epidemiology and Biostatistics Program in the Division of Cancer Epidemiology and Genetics of the National Cancer Institute in Bethesda, Md., said, "Investigations like the one reported by Rennert offer a glimpse into a research approach that will probably be used in other studies in the future. It may soon become routine to re-evaluate clinical-trial results according to genetic variants.
"Differing clinical outcomes associated with genes that increase the risk of cancer may fundamentally influence screening practices and the care of patients," she said.
