BRCA testing guidelines for women with breast cancer

Abnormalities in BRCA1 and BRCA2 in women with breast cancer associated with 10-fold increased risk of ovarian cancer

July 1998

A study published in the July issue of the Journal of Clinical Oncology provides new guidelines to help physicians recognize which women should be assessed for hereditary breast and ovarian cancer. Scientists at 12 of the country's leading hereditary cancer centers collaborated with Myriad Genetic Laboratories to examine 238 women diagnosed with breast cancer before age 50, or with ovarian cancer at any age, who had at least one relative with either disease.

Nearly 40 percent of the participants were found to have abnormalities in either of two genes responsible for most hereditary breast and ovarian cancer, BRCA1 and BRCA2, which led to their cancer.

"This study tells us that all women with breast cancer diagnosed under age 50, and with a history of breast or ovarian cancer in a close relative, should consider testing," suggests coauthor Funmi Olopade, MD, associate professor of medicine and director of the Cancer Risk Clinic at the University of Chicago Medical Center.

"This is important because women and their doctors have struggled with the issue of who should be advised to be tested for hereditary breast and ovarian cancer," said Dr. Olopade.

"The data in this study enabled us to create a simple table that indicates a woman's likelihood of having inherited an abnormality in either of the two major breast-ovarian cancer genes, based on her personal and family history of breast and ovarian cancer."

In contrast to previous studies, the study did not find that women of Ashkenazi Jewish ancestry were more likely to carry a mutation in BRCA1 or BRCA2 compared to women of other ethnic backgrounds. This is probably because "this was the first study to test for BRCA1 and BRCA2 in a large number of women from diverse ethnic backgrounds," explained Dr. Olopade.

"Most studies up to now have looked only at BRCA1, and so we've only had half the story," said co-author Tom Frank, MD, of Myriad Genetic Laboratories. "By looking at the entire sequences of both genes in all of the participants and comparing the results to their family history, we were able to develop clear guidelines to help physicians identify patients who should be evaluated for hereditary breast and ovarian cancer."

Another of the study's findings suggests that breast cancer survivors should try to find out if they have the hereditary form of the disease; abnormalities in BRCA1 and BRCA2 in women with breast cancer were found to be associated with a 10-fold increase in the risk of developing ovarian cancer.

One of the most important findings of the study, note the authors, was the observation that women with breast cancer who have mutations in either gene have this sharply elevated risk, which was previously associated only with BRCA1.

Most women with breast cancer are not at a significantly increased risk of ovarian cancer, and so the possibility of this disease does not factor into their healthcare. This study suggests that their doctors should know if a patient has the hereditary form of breast cancer so that her risk of ovarian cancer can be assessed and managed appropriately, with increased surveillance or consideration of prophylactic ovary removal (oopherectomy).

Summary:
Researchers argue that all women with breast cancer who were diagnosed before age 50 and have family histories of breast or ovarian cancer should consider testing for BRCA1 and BRCA2 mutations, which increase their risk of ovarian cancer 10-fold; nearly 40 percent of the 238 women studied had mutations.