Genetics / Health / Medicine / Science

Taking the chance

Why did Angelina Jolie have a double mastectomy?

Another question from Jess, via Twitter. I’m sure most people heard about Angelina Jolie’s decision to have a double mastectomy after discovering she carries a faulty copy of a gene called BRCA1, at the time, and her piece about her decision seems to have caused a wave of other women to get the same testing done.

Angelina Jolie in one of her most recognisable film roles.

BRCA1 and 2 genes confer a risk of developing breast cancer, and in fact a number of other cancers too, including ovarian cancer. There are some widely varying estimates on how likely these mutations are to cause significant risk, and often these figures are quoted to encourage people to get testing and to undergo preventative procedures, like Jolie’s double mastectomy. For an individual, it typically increases risk of developing breast cancer less than 50% — in other ways, the chances are equally good that someone carrying a faulty BRCA1 or 2 gene will not actually develop breast cancer. BRCA mutations account for only 5-10% of breast cancers, and 10-15% of ovarian cancers.

So should everybody be tested for the faulty BRCA genes? Probably not. Angelina Jolie was tested for a specific reason: her mother died of breast cancer and died before the age of 60. That kind of family history can suggest a risk of carrying a harmful variant of the gene, and indeed, it proved to be true in Angelina Jolie’s case. She was quoted “an 87 percent risk of breast cancer and a 50 percent risk of ovarian cancer”. Given those statistics, it’s not surprising that she decided to take preventative measures.

It’s still important to remember that a percentage risk is not a promise that something will happen. Even when something has a 99% chance of happening, in one case in a hundred (on average), it will not happen. Any operation carries risks to do with anaesthesia and post-operative infections, as well. It’s worth asking whether that risk is worth it; an individual’s situation is always going to be unique.

What would I do if I found out I carried a faulty copy of BRCA1 or 2? I’d educate myself on symptoms and warning signs, make sure I got checkups whenever I found something concerning, and otherwise try and reduce my risk. I wouldn’t go for a double mastectomy unless the risks were judged to be significant within the next ten years. After all, you can always have the operation done later in life as your risk increases due to age. What you can’t do is take it back.

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