WEDNESDAY, Feb. 15, 2006 (HealthDay News) -- Younger women with non-BRCA hereditary breast cancer are up to six times more likely to develop a new cancer in the other breast in the next 20 years, when compared with the general population, a new Swedish study finds.
"We did not expect this high rate of new tumors in the contralateral breast," said study co-author Dr. Henrik Gronberg, a professor of cancer epidemiology and biostatistics at Karolinska Institute in Stockholm.
His team reviewed data from 120 families and 204 women with breast cancer and a family history of breast cancer, but not of the type caused by mutations in the BRCA1 or BRCA2 genes, also known to boost breast cancer risk.
Overall, the probability of these women getting cancer in the other breast was 5.5 percent at five years and up to 27.3 percent at 20 years -- about six times the expected risk at 20 years. In comparison, the general population's risk of getting a primary breast cancer was figured at 1.9 percent at five years and 4.9 percent at 20 years, the researchers said.
When they analyzed risk by age group, the scientists found that the 15-year likelihood of developing cancer in the other breast was much higher for women under 50 than for those over 50. Forty percent of those under 50 had a probability of developing cancer in the other breast at 15 years after the original cancer diagnosis, compared to 10 percent in those over 50.
The risk is similar to the estimated risk among BRCA1 and BRCA2 mutation carriers, Gronberg said.
The study findings appear in the March 15 issue of Cancer.
In previous research, other investigators had found that breast-cancer survivors are 25 percent more likely to develop cancer in another part of their body than those without a cancer history.
And it's well known that women with mutations in BRCA1 and BRCA2 genes have a higher risk of breast cancer. In 2004, researchers reported that BRCA1 and 2 gene-mutation carriers are also more likely to get breast cancer in the opposite breast. The researchers found that more than 37 percent of the 87 women studied who were known to carry a BRCA gene mutation and who had a lumpectomy for breast cancer developed a new cancer in the untreated breast within 10 years of the original diagnosis. That report also appeared in Cancer.
The study findings suggest that several courses of action are wise, Gronberg said. "Young women, those under age 50, with hereditary breast cancer, regardless of BRCA1/2 mutation status, should consider a prophylactic operation in the opposite breast within two to three years after the treatment of the first cancer," he said. "This will reduce the risk of being diagnosed with a new breast cancer in the opposite breast."
For women over age 50, he said, "the need for prophylactic surgery is much less, and the use of adjuvant hormonal therapy is most appropriate among these women."
Genetic counseling is also important for women with hereditary breast cancer, Gronberg said.
The study results probably won't surprise those in the genetic-counseling field, said Scott Weissman, a certified genetics counselor and co-chairman of the familial cancer risk counseling special interest group for the National Society of Genetic Counselors.
Genetic counseling can help women decide what options to pursue, he said. "We try to identify the mutation in a gene causing a breast cancer in the family," he said. "If we are able to identify one, we can counsel these women about their chances of getting a cancer in the opposite breast."
"You can very much put numbers on it," Weissman said. Women can be told their chances of getting another cancer in specific percent terms, over a specific time period, he said.
"Genetics counseling can help guide you on how to manage the risk," he said. That might mean more frequent screening for breast cancer or adding a breast MRI to regular mammograms.
More information
To learn more about genetic counseling, visit the National Society of Genetic Counselors.
