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. Last Updated: 07/27/2016

Cancer-Gene Testing: Is It Worth It?

Janet didn't need a doctor to tell her something was wrong.


For more than a decade, she had watched as breast cancer stalked her family. Her mother was diagnosed in 1978, at the age of 47. Her aunt was struck a year later. The aunt's 29-year-old daughter was next, then another daughter, then one of Janet's sisters.


The two cousins and the sister died, and in 1992, the shadow fell on Janet. At the age of 40, she, too, had breast cancer.


By then, Janet's sister Susan -- four years younger and free of any sign of disease -- could not stand waiting for what she viewed as the inevitable. She decided to do the only thing she could to avoid the tragedy that had befallen her mother, aunt, cousins and sisters: She scheduled surgery to remove both healthy breasts.


Janet and Susan -- who used assumed names -- told their story last fall to several hundred geneticists and researchers gathered in Montreal, Canada, for the annual meeting of the American Society of Human Genetics.


As Janet began, the audience fell silent. The sorrow in her voice filled the hall, where doctors and researchers were beginning to grapple with a problem unlike any they had faced before.


Last year, the mystery in Janet's family was solved. Researchers identified the gene causing the breast cancer in families like hers.


But the discovery did little to lift the shadow. Instead, it introduced a fearsome power. Doctors could now predict, decades in advance, which members of those families would get cancer.


Within weeks of the discovery, Susan became one of the first women to undergo testing. Only days before the scheduled surgery to remove her breasts, doctors notified her of the results: She did not carry the breast cancer mutation.


That meant her risk of developing breast cancer was normal -- not astronomical, as it would be if she carried the gene. She canceled the surgery.


"I couldn't believe it,'' Susan said. "It was the first reason we had for hope.''


For many others, however, including other women in Janet's family, doctors have only bad news. Many of those women are carrying "genetic markers'' indicating they have the mutation. And doctors can do nothing to help them.


Some day, it may be possible to pluck out harmful genetic mutations, to "cure'' bad genes. Until then, doctors who have identified patients at risk can only watch helplessly as their fates unfold.


"There's that quote from Sophocles -- 'It is but sorrow to be wise, when wisdom profits nothing,''' said Dr. Francis Collins, the director of genetics research at the National Institutes of Health.


Collins directs the National Center for Human Genome Research, an ambitious effort to identify all the estimated 100,000 genes in humans -- including an unknown number of cancer genes.


Last year, researchers discovered genes that make it possible to identify the individuals at risk in families ravaged by colon cancer. More such genes are sure to follow, Collins said.


"These genes for cancer are getting cloned willy-nilly. Testing would have potential benefits if we knew what to recommend. But we don't.''


A few years ago, doctors found the gene for Huntington's disease, a crippling and ultimately fatal nerve disorder that killed folk singer Woody Guthrie. They are close to finding a genetic indicator of Alzheimer's disease.


Collins is among many geneticists who see a crisis building. Pressure to make testing available is coming not only from patients like Janet, but also from biotechnology companies, which stand to make a fortune selling test kits.


But this new ability to predict cancer raises a host of vexing scientific and ethical questions. How should the tests be interpreted outside the research lab? Should testing be offered to anyone? What kind of psychological support should be provided?


Cancer testing also is likely to have a disastrous impact on patients' health insurance. Insurance companies may drop coverage for people carrying cancer genes. And as the ability to test for such genes grows, the pool of people excluded from coverage could grow.


"We are all carrying around preexisting conditions, and we're learning more about how to find them,'' Collins said. "Pretty soon, we're all going to be uninsurable.''


At the same time, the case of Janet's family is an exception: Genetic testing in general does not produce clear-cut answers. The results are expressed in terms of probabilities.


In Janet's family, the probability for any individual woman is either very high or very low, making the results relatively simple to understand. But what happens when a woman has a slightly elevated probability, or double the usual risk? How should she respond to such information? Or what if a young man is told he is at high risk of getting Alzheimer's disease in his 60s? Is this knowledge he would be better off without?


There will be an urgent need for genetic counselors, professionals who can interpret test results and provide guidance. But add up the number of Americans at risk of breast cancer, colon cancer and Alzheimer's disease, and the numbers reach into the tens of millions. And there are now only 1,200 genetic counselors in the United States.