Genetic testing not only for the well

Genetic testing not only for the well

Predictive tests under-used in those who already have cancer

October 27, 1998

Although public debate, and corporate marketing efforts, has focused almost exclusively on the risks and benefits of genetic testing for the worried well, the group most likely to benefit from genetic information--cancer patients--is often omitted from the discussion. Now a cancer-risk specialist is reminding cancer surgeons that therapy doesn't end with removing the first cancer; it should also include preparing for the next.

There are more than 600,000 new cancer survivors in the United States every year. Five to 10 percent of them are genetically predisposed to develop second cancers. Many of their relatives, about a million more people, are also at increased risk. Yet too few of these patients or families are currently given the option, or helped to weigh the risks and benefits, of genetic testing.

"Genetic counseling and the option of testing should become an integral part of the management of nearly every patient affected by cancer," said Funmi Olopade, MD, associate professor of medicine and director of the cancer risk clinic at the University of Chicago, speaking at the American College of Surgeons annual meeting in Orlando, Florida. "The most effective approach to preventing, detecting and treating cancer begins with identifying individuals at high risk," she added. "If we miss the opportunity to start that process with people who have already come to us for help, we are not providing comprehensive care," said Olopade.

Genetic testing for several rare inherited cancer syndromes--such as Von-Hippel Lindau or multiple endocrine neoplasia syndromes--has become standard, especially at academic centers. But for far more common malignancies with a familial component--such as breast, ovarian, and colon cancer--it has remained controversial. Yet there is mounting evidence that many of these common cancers result from genetic flaws and that patients who have had a cancer already, and their families, can benefit from greater awareness of their risks.

For example, a study published last July found that nearly 40 percent of 238 women who were diagnosed with either ovarian cancer or breast cancer before age 50, and who had at least one relative with either disease, had abnormalities in one of the two genes responsible for most hereditary breast and ovarian cancer--BRCA1 or BRCA2. Breast cancer patients with a mutation had a 10-fold increase in the risk of developing ovarian cancer.

In addition, recent hospital-based studies have found unexpectedly high rates of genetic abnormalities in breast or ovarian cancer patients who do not have a family history of the disease.

Frustrated by the continued concern over the use of genetic testing in the general population and the under use among those most at risk, the American Society of Clinical Oncology is preparing and constantly updating genetic testing guidelines, said Olopade, and training physicians when to offer genetic tests and how to interpret the results.

"Genetic testing for cancer survivors can provide unique opportunities for secondary prevention so that many more patients can reduce their risks of dying from a second cancer, and relatives at risk can be identified and encouraged to participate in cancer-prevention programs."