URBANA The scientist who led the discovery of genes responsible for 15 percent of all breast cancers says every woman age 30 and over should be tested for those genetic mutations, regardless of family history.

And women with a family history of reproductive cancer not linked to the BRCA1 or BRCA2 genes should get more extensive genetic testing, says Mary-Claire King, professor of genome sciences and medicine at the University of Washington School of Medicine.

King spoke at the University of Illinois on Monday afternoon at a talk marking the 10th anniversary of the Institute of Genomic Biology.

King said genetic testing is important for cancer prevention and treatment and for families themselves, and should be part of every woman's complete medical care. More than 40,000 women die of breast cancer, and 14,000 from ovarian cancer, each year.

"It's technically easy to do. It's not expensive to do," King said. "The major cost is not the testing itself. The major cost is how to care for women who turn out to have mutations, because they have to be cared for."

But preventive surgery is much less expensive than caring for a cancer patient, she said.

King and her colleagues spent 17 years finding and mapping the BRCA1 gene, which can cause both breast and ovarian cancer. In 1994, the gene was successfully cloned, and the closely related BRCA2 gene was cloned the following year. The discovery revolutionized genetics and cancer treatment.

Mutations in the gene interfere with the repair of DNA, deoxyribonucleic acid, the hereditary material in every human cell.

Women, or men, who carry the mutation have a higher risk of developing cancer. One study showed 80 percent of women with the mutation developed breast or ovarian cancer by age 80. In some families, there's also an increased risk of pancreatic or prostate cancer with the genetic mutations, though not as large, she said.

The mutation can be inherited through a father, not just a mother. One big challenge is getting physicians to ask patients about a history of breast or ovarian cancer in their father's family, not just their mother's, King said.

Because families are smaller than in the past, a history of breast or ovarian cancer might not be as obvious as it was in the 19th or early 20th centuries, when multiple family members may have gotten the disease, she said.

"In about 50 percent of the women in whom we identify inherited mutations of these genes, there's no immediate family history of breast or ovarian cancer that would have triggered concern," she said.

Before the work of King and other geneticists, scientists had different theories about the causes of breast cancer, from diet and stress to the use of contraceptives to a possible genetic link.

King started by identifying hundreds of families with long histories of breast and ovarian cancer.

She was able to show linkages across multiple generations and eventually narrowed the gene to a specific chromosome, then went on to isolate the gene in the lab.

There are more than 1,000 different mutations within the BRCA1 and BRCA2 genes, and more left to discover, she said.

King and her colleagues have now studied more than 5,000 families, including some "mystery families" where no common genetic mutation has been found. Researchers are sequencing the entire genome for women in those families, she said.

The cost of genetic sequencing has dropped precipitously since the Supreme Court ruled in 2013 that human genes cannot be patented, she said. The cost, around $250, is well within the budget of middle-class women, but "DNA repair does not care if you are middle class or not," she said.

It should be considered a public health issue, similar to vaccinations for contagious diseases, so every women has access to screening, she said.

The disease is an important public health problem, the risk of disease due to genetic mutation is high, the mutations responsible for the disease can be accurately identified, and effective treatments exist for women identified at risk, she said.

"They are not pretty, but they exist, and they work," she said.

Preventive surgery, such as a mastectomy or the removal of the ovaries and fallopian tubes between the ages of 35 and 40, has proven to drastically reduce cancer risk, she said.

And the study of how the BRCA1 and BRCA2 genes work has led to chemotherapy treatments that effectively target the tumors, she said.

Studies of women with the genetic mutation show that those born more recently have a higher risk of developing breast cancer, even if it's the same mutation in the same family, King said.

"This difference cannot be genetics. The difference must be changes in lifestyle," she said.

Research has shown that the earlier a girl starts her period, and the later she has her first child, her cancer risk increases. At the start of the 20th century, the average girl started menstruating at age 16 and had her first child by age 21. Today, the average start is about age 11, and more women are postponing childbirth until after age 30, King said.

Other than the genetic mutations, much of the increase in breast cancer worldwide can be pinned on those factors, she said.

UI Professor Gene Robinson, director of the Institute for Genomic Biology, said King's work has "changed the way we think of the role of genes in diseases that have both genetic and environmental causes," and how genetic therapy can help cancer patients make decisions about their health.

King has also used genetic science for humanitarian causes, to identify victims of human rights abuses in Rwanda, Serbia, the Philippines and South America, he said.

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All women should get tested for cancer gene, says scientist who led discovery - Champaign/Urbana News-Gazette