Cancer researchers find there are no easy answers
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May 14, 1997
Web posted at: 10:33 p.m. EDT (0233 GMT)
WASHINGTON (CNN) -- When scientists discovered a breast cancer gene in 1994, they hoped it would help women predict their chances of getting the disease. New studies have shed some light on the subject, but not as much as researchers would like.
"Basically, we really don't know what to tell women," said
Dr. Margaret Tucker, co-author of one new study. "We really don't know what the co-factors are that explain why some women have a very high risk of developing breast cancer early."
Tucker participated in the study at the National Cancer Institute of a group of more than 5,000 Jews of Eastern European ancestry living in Washington. The study found that a little more than 2 percent had a specific gene mutation that is associated with cancer.
Among those who had the gene, said co-author Dr. Jeffrey Struewing, "We found that there was a significantly increased risk of breast, prostate and ovarian cancer among carriers identified in the community."
Women with the defect, the study found, run a 56 percent chance of getting breast cancer. While high, the percentage is actually much lower than a previous study which estimated the risk at 76 percent to 87 percent.
5 women with mutation did not get cancer
Further confusing the picture is the fact that five women over 70 with the mutation did not get cancer. That is why researchers concluded there is no way of predicting which women with the mutation will get the disease.
Tucker stressed that mutations in the two genes known
to be associated with breast, ovarian and prostate cancer --
genes known as BRCA1 and BRCA2 -- account for only 7 percent of breast cancer in Jewish women.
Struewing said the researchers were leery about increasing anxiety among Ashkenazi Jews, those of Eastern and Central European ancestry who account for about 90 percent of the American Jewish population.
"It could increase alarm," he said, "but I think that our estimate of cancer is lower than the previous ones, so I would think that it might lower the anxiety."
Nor was it clear to what extent the study might predict cancer rates in other groups. It is known, however, that the average American woman has a 7 percent or 8 percent risk of getting breast cancer by age 70.
2nd study finds surgery enhances life expectancy
Another study reported in the New England Journal of Medicine claims that prophylactic breast and ovarian surgery "provides substantial gains in life expectancy."
Prophylactic surgery is the removal of healthy tissue.
The second study, at the Dana-Farber Cancer Institute, found that women strongly disposed to cancer could live an average of three to five years longer by having their breasts removed at age 30, and two years longer if they had ovarian surgery by age 40.
The researchers in the Dana-Farber study estimated that even without preventive surgery, women with the defective genes could expect to live an average of 65 years or more, as long as they got frequent checkups and mammograms.
"We're not advocating these surgeries," said Dr. Deborah
Schrag. "A woman facing these decisions will want to consider her self-image, her ability to have children, her ability to nurse her children, as well as relief of her anxiety about getting cancer."
"I think the issue is not whether a Jewish person should be
tested or not, but what information do we have to date, which is more than we had two weeks ago. Some people may decide for
themselves that they do not wish to know, because there's too
There are some who argue that the screening process is not always accurate, and that there are other options short of surgery. Bernadine Healy, former director of the National Institutes of Health, is one of them.
"The fortune tellers are reading a pretty cloudy crystal ball," she says. "This problem becomes especially worrisome when statistical prophecies lead to irreversible decisions."
Ultimately, researchers say, questions about gene testing can't be resolved until much more is known about the other factors that contribute to cancer.
Correspondent Jeff Levine and Reuters contributed to this report.
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