— For prostate cancer, using all the known markers could identify 1 percent of men with nearly five times the average risk, the researchers computed. In developed countries, a man's average lifetime risk for the disease is about 14 to 16 percent, lower in developing nations.
—Markers can also make a difference in estimates of breast cancer risk for women with the BRCA1 or BRCA2 gene mutations. Such women are rare, but their lifetime risk can run as high as 85 percent. Researchers said that with the new biomarkers, it might be possible to identify the small group of these women with a risk of 28 percent or less.
For patients like Vicki Gilbert of England, who carries a variation of the BRCA1 gene, having such details about her cancer risk would have made decision-making easier.
Gilbert, 50, found out about her genetic risk after being diagnosed with the disease in 2009. Though doctors said the gene wouldn't change the kind of chemotherapy she got, they suggested removing her ovaries to avoid ovarian cancer, which is also made more likely by a mutated BRCA1.
"They didn't want to express a definite opinion on whether I should have my ovaries removed so I had to weigh up my options for myself," said Gilbert, a veterinary receptionist in Wiltshire. "...I decided to have my ovaries removed because that takes away the fear it could happen. It certainly would have been nice to have more information to know that was the right choice."
Gilbert said knowing more about the genetic risks of cancer should be reassuring for most patients. "There are so many decisions made for you when you go through cancer treatment that being able to decide something yourself is very important," she said.
Dr. Charis Eng, chair of the Genomic Medicine Institute at the Cleveland Clinic, who didn't participate in the new work, called the breast cancer research exciting but not ready for routine use.
Most women who carry a BRCA gene choose intensive surveillance with both mammograms and MRI and some choose to have their breasts removed to prevent the disease, she said. Even the lower risk described by the new research is worrisomely high, and might not persuade a woman to avoid such precautions completely, Eng said.
AP Medical Writer Maria Cheng contributed to this report from London.
Nature Genetics: http://www.nature.com/ng
PLOS Genetics: http://www.plosgenetics.org
Breakthrough Breast Cancer: http://www.breakthrough.org.uk/
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