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Genes, Families and Breast Cancer
Dr. Stephen Edge
Dr. Edge spoke for an hour about genetics and breast cancer, he emphasized that genetic risk factors- indeed all of the risk factors together- account for only a small percentage of breast cancers:
"It is critically important for the general public to recognize one fact -- and this is probably the most important fact I will give you tonight: The majority of women with breast cancer have no identifiable risk factor. Because most women who get breast cancer have no known risk factors, it is critical for all women in our society, regardless of whether they have a risk factor, to undergo regular breast cancer screening."
In the absence of known breast cancer prevention strategies, early detection still remains the best chance for survival and cure, according to Dr. Edge. He cited recent advances in the war on breast cancer, including improved screening for early cancer, the development of less aggressive and disfiguring surgery, and improvements in hormonal therapies and chemotherapy.
Despite the advancements, Dr. Edge said the medical and research communities "need to do better" in screening for and determining who will get breast cancer. Known risk factors for breast cancer include advancing age, a personal history of breast cancer, early menarche or late menopause, and being childless or having a first child after age 30. Given the rising incidence of breast cancer and different breast cancer rates among different cultures, Edge maintained that there must be environmental and dietary factors, although these have yet to be identified.
Obviously, he said, family history is a risk factor. He stressed, however, that having breast cancer somewhere in the family does not by itself indicate high risk for breast cancer.
"When we talk about family history, we can break it down into those who have a low risk and a high risk. Low risk might be someone who had a single relative in her postmenopausal years and she may have some minor risk factor, first child after 30 or early menarche and so on. Those women have an increased risk for sure, but it’s only mildly increased breast cancer risk."
Of most concern, according to Dr. Edge, are the very high risk families in which breast or ovarian cancer may afflict over half the women in the family. In high risk families, the cancer tends to have an early onset and tends to be bilateral (affecting both breasts or ovaries). This kind of highly hereditary cancer has been attributed to mutations in certain genes and accounts for about 10 percent of all breast cancers. Most of the hereditary forms of breast cancer have been linked to mutations in two specific genes, dubbed BRCA1 and BRCA2.
Although anyone can carry the breast cancer gene mutations, recent research has identified Ashkenazi Jews as a population that carries an abnormally high percentage of these genes. Studies show that one percent of all Ashkenazi Jews carry mutations in BRCA1 that greatly increase the risk of breast cancer.
When talking about cancer and heredity, the question naturally arises about genetic testing. Dr. Edge pointed out that genetic testing for breast cancer is not a simple blood test and there are both risks and benefits to any kind of genetic testing. In terms of benefits, testing can indicate whether a woman’s lifetime risk of breast cancer is high or low and that may relieve some of the burden of concern for an individual. It may also allow medical personnel to intensify screening efforts in very high risk women, while allowing other women to undergo normal screening. He said, however, that it is not yet known whether additional or more frequent screenings have an impact on the risk of dying of breast cancer.
Dr. Edge emphasized that there are risks inherent in genetic testing for breast cancer. For one thing, he said, regardless of statistical risk, the actual risk to any individual woman cannot be known. Knowing that someone does not have the gene may provide some emotional relief, but that doesn’t protect her from getting breast cancer.
In addition, he pointed out, there is a real danger of discrimination. "It is real and it has happened. People have lost their jobs and been denied insurance simply because they carry a genetic trait." Real family issues and ethical concerns have also developed around the family’s right to know versus the patient’s right to know, and even around questions of paternity.
And the fact remains, Dr. Edge said, "We don’t have any effective intervention or treatment or prevention to offer the individual who is affected by the gene. The outcome of breast cancer appears to be no different for carriers of mutations in this gene, than for people who are not."
BRCA1 testing right now must be considered investigational, and the error rate is still unknown, he said. But if a client chooses such testing, Dr. Edge recommended that it be done in the setting of a comprehensive risk evaluation program that includes assessment of the individual, careful cancer screening, and counseling on an individual basis. "It is absolutely mandatory that genetic counseling must precede testing. I don’t think at this point in time that this is something that should be done in an individual doctor’s office."
Dr. Edge’s comments ended with the continued admonition that with or without genetic risk, all women must consider themselves at risk and thus must make every effort to participate in regular breast screenings, Breast Self-Exam, Mammography, and regular gynecological checkups.
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First Created: September 18,1997
Last Updated: September 18,1997