lundi 17 septembre 2007

DNA test for breast cancer: to test or not to test?

Breast cancer is the most common form of cancer among women today. Although the awareness has increased, it is still the second leading cause of cancer death in women.
According to figures from the World Health organisation, 1.2 million women were expected to be diagnosed with it in 2006. Some have decided to wage a war against the disease and opted for a possible cancer-free future with DNA testing.
For a few years, the DNA test has been able to reveal the percentage of risk for a woman of effectively developing a cancer. In the US, the number of women being tested grows every year. Those who have been tested call themselves "previvors".
Breast and ovarian cancers often run through several generations in a family. They originate in a defective copy of a gene known as BRCA1 - for British Cancer gene 1. Those bearing the mutant gene have 60 to 90% to develop breast cancer. Now, for women, the question is: does DNA testing ease or complicate life?
Some might say that having the chance of knowing the risk, how could one not do something about it? Indeed, DNA forecasts offer the first clues for how to deal with a serious disease that may never arise and gives an indication of the family turmoil that nearly always does.
However, the genetic testing on BRAC1 and BRCA2 is complex, as there are hundreds of possible mutations to look for.
Today, the NYT tells the story of 33 year-old Deborah Lindner, who discovers that she is more than likely to have breast cancer at some point in her lifetime. Her DNA having been tested in search of the BRCA gene, she decided to go for the most radical option: a mastectomy. The procedure is said to reduce risks by 90 per cent.
All in all, physicians and scientists do not recommend DNA testing for low-risk individuals for several reasons. First, only 5 to 10% of all breast and ovarian cancers originate in a mutation of those genes. Then, there is not a 100% reliable means of preventing the disease once the mutation is discovered. Various cases show evidence that the disease can always come back.
Yet for women being at a high hereditary risk on their family history, genetic testing can provide important information.
If they are tested positive, they face several options, plastic surgery being only one among others. They could either follow more agressive screenings, take preventive medications, or even alter their lifestyle to reduce risks. Ultimately, the decision remains highly personal.

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