Women who have survived breast cancer should find out if theirs was an inherited form of the disease. If so, breast cancer gene mutations increase their chance of developing ovarian cancer by 10 times.
That's the finding of a study published in the July issue of the Journal of Clinical Oncology, based on work by a Salt Lake genomic company, Myriad Genetic Laboratories, in collaboration with 12 of the nation's top hereditary cancer centers. Genomics is the use of genes to understand disease.In 1994 and 1995, Myriad researchers isolated the two genes linked to breast cancer - hence the name given them, BRCA1 and BRCA2 (BReast CAncer1 and 2).
The multi-center study examined 238 women who had breast cancer before age 50 or ovarian cancer at any age and who also had at least one relative with either disease. By doing the first full sequence analysis of both BRCA1 and BRCA2, responsible for most hereditary forms of the two cancers, the study found that nearly 40 percent of the participants had mutations in one of the two genes, causing the disease.
Everyone - male and female - has the two genes. To look for an abnormality in the genes, 17,000 individual chemical letters have to be examined in each patient, said Dr. Tom Frank of Myriad, lead researcher in the study.
A BRCA1 or BRCA2 mutation doesn't mean someone will inevitably get breast cancer or ovarian cancer, but the majority will. And one-third to one-half will get breast cancer before the age of 50.
"The significance of the finding is that any women under 50 with other relatives who had the diseases are at very high risk for having an abnormality that can affect their children," said Frank.
It can be a lethal abnormality. The findings documenting increased risk of ovarian cancer are particularly important, he said, because "ovarian cancer is a bad one." It is usually symptomless until it is advanced; it's not commonly checked for. And two-thirds of women diagnosed with ovarian cancer die within five years.
The genetic testing lets women know if they have the mutated BRCA1 and BRCA2 genes so that doctors can take appropriate steps to screen for ovarian cancer.
Unfortunately, Frank said, tests for ovarian cancer are not often used because they "do not work very well."
Women who are found to have the hereditary form of breast cancer "should think seriously about having their ovaries removed after they have had their children or are 35."
Because some tissue is left behind, it's not foolproof. But it greatly reduces the risk of developing ovarian cancer.
The BRCA1 and BRCA12 gene test isn't complicated from the patient's point of view. It's a matter of having blood drawn. The hard part takes place at Myriad, where it takes three weeks to check out those 17,000 chemical letters. The test isn't used routinely, partly because of cost and partly because doctors have had a hard time deciding who should be screened for the disease. More than that, doctors have been used to looking at cancer as something with "vague causes. The idea it can be very straightforward takes a different mind-set.
"Look how long it took us to realize that the stomach ulcer is not caused by stress but is an infection," said Frank. "It took 10 years to learn we needed to give antibiotics, not milk."
And while people think of these as breast cancer genes, the ovarian cancer is the part people really need to pay attention to, said Frank. "It can kill someone who survives breast cancer, which is really a tragedy. But it's hard to get doctors and patients to realize this is a two-cancer syndrome.
"What this study does is help doctors identify which women have a hereditary form of breast cancer, which can be very important information."