Assessing who is at high risk for breast cancer

March 30, 2007|By Frank D. Roylance | Frank D. Roylance,Sun reporter

With breast cancer making headlines again, more women with a family history of the disease are asking their doctors whether their own risk level is high enough to warrant more aggressive screening.

"There has already been an increase. A lot of women have called and said, `Do I need an MRI?'" said Dr. Nagi Khouri, director of breast imaging at the Johns Hopkins Breast Center in Baltimore.

If their doctors agree they are at high risk, these women could soon have easier access to highly sensitive but expensive magnetic resonance imaging to detect early cancers.

The American Cancer Society this week reversed a 2003 policy weighted against MRIs amid increasing scientific data supporting the value of annual MRI screening for high-risk women. That move could push insurance companies to pay for more of the costly tests.

Although doctors still see traditional breast exams and mammography as the most cost-effective way to screen women at normal risk for cancer, the higher sensitivity of MRI scans to cancers missed by the standard tests makes them a worthwhile addition to regular X-rays for high-risk patients, the society said.

"Women at very high risk of breast cancer can be diagnosed much earlier when combining the two technologies rather than mammography alone," said Dr. Christy A. Russell, chairman of the ACS panel.

Public awareness of the importance of family medical history has been increasing, Khouri said. "The greater the number of family members [with breast cancer], the more worried they are, and they're asking, `What more can I do?'"

So who, exactly, is deemed to be at high risk for breast cancer?

The cancer society guidelines, published in CA, A Cancer Journal for Clinicians, outlined three approaches doctors can use - alone or in concert - to assess a woman's risk: family history, genetic testing and clinical indicators.

Surprisingly, having one close relative with breast cancer is not a major worry. Many Americans can name one, but scientists say most of those cancers are "sporadic," and don't confer significant added risk to relatives.

Some may be the result of environmental factors, or an inherited gene with a low risk of turning up in close relatives.

That said, researchers have identified several genetic mutations that do confer a major increase in lifetime risk. They say 1 percent to 2 percent of women have a family medical history suggesting such a gene is present.

If so, it imposes an 80 percent lifetime risk of developing breast cancer, and often ovarian cancer as well. Among the warning flags:

Two or more close relatives (parents, grandparents, children, grandchildren, half-siblings, aunts, uncles, nieces and nephews) with breast or ovarian cancers.

Close relatives with breast cancer occurring before age 50.

A family history of breast and ovarian cancers.

One or more relatives with two cancers (breast and ovarian or two independent breast cancers).

Male relatives with breast cancer. (The National Cancer Institute says more than 2,000 men are expected to be diagnosed this year with breast cancer. Four hundred will die.)

Studies of families with these kinds of medical histories have turned up two genes that appear to boost susceptibility to breast cancer. They are called BRCA1 and BRCA2.

While they are present in as many as one in 500 people in the general population, they are found in half the families with a high incidence of both breast and ovarian cancers. One in 50 women of Ashkenazi Jewish descent carries the gene.

Large-scale studies have found that 65 percent of women with the BRCA1 gene will develop breast cancer by the age of 70. Of those with the BRCA2 gene, the risk is 45 percent.

When a woman carries this gene, there is a 50 percent chance that a sister, mother or daughter will have it, too.

On the other hand, a genetic test showing the BRCA mutation is absent means the woman's risk is no higher than it would be without a family history of breast cancer.

Physicians have a variety of quick and inexpensive statistical tools, or models, available to assess a woman's individual risk. Enter the patient's family cancer history, and the models calculate her risk of developing breast cancer.

The results sometimes vary with the model used. But doctors generally offer a genetic test to women with a lifetime risk greater than 10 percent. A tally of 20 percent or 25 percent or more would be enough, under the new ACS guidelines, to warrant an MRI screening.

"One of the stumbling blocks will be what the insurers will do," Khouri said. An MRI breast screening costs $1,000 or more. And while some insurance companies are paying for them now, the demand has been low so far.

With the new ACS guidelines, that is likely to change, and insurers may decide to take a harder line. "We don't want to wake them up, really - but are they going to say, `Wait, we are going to be deluged with ... requests?'" Khouri asked.

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