Double mastectomy: What Angelina Jolie did, and why

Angelina Jolie says that she has had a preventive double mastectomy after learning she carried a gene that made it extremely likely she would get breast cancer. (AP / Amel Emric)

Oscar-winning actress Angelina Jolie announced on Tuesday that she had a preventive mastectomy after learning she had a gene that significantly raised her risk of breast cancer. Here's a crash course in the procedure Jolie had and why.

Q: What kind of surgery did Jolie have?

A: Jolie had a preventive double mastectomy, meaning she chose to have both her breasts removed even though she had not been diagnosed with cancer.

Q: Why did she have the mastectomies?

A: Jolie says that she has a "faulty" version of the BRCA1 gene that means she had an 87 per cent chance of getting breast cancer. By having both breasts removed preventatively, she said her breast cancer risk drops to below 5 per cent.

Q: What did the procedure involve?

A: In double mastectomies, surgeons typically remove as much breast tissue as possible. In Jolie's case, because she was having a reconstruction done shortly afterward, the doctors preserved the skin covering her breasts, inserting "fillers" where the breast tissue would have been, to keep the skin elastic. According to Jolie, she had implants put in nine weeks later.

Q: How many women have this faulty gene?

A: Only a small percentage of women have this same faulty gene, or a similar mutated version of a related gene, BRCA2. These mutations are most commonly found in women of Eastern European Jewish descent; one study found 2.3 per cent of women in that group had the mutations -- about five times higher than in the general population. Other ethnic groups, including the Norwegian, Dutch and Icelandic people, also have slightly higher rates of these mutations.

Q: How do these genes increase a woman's risk of breast cancer?

A: The average woman has a 12 per cent risk of developing breast cancer sometime during her life. In comparison, women who have inherited a faulty version of a breast cancer gene are about five times more likely to get breast cancer. In the U.S., about 5 to 10 per cent of breast cancers are thought to be linked to harmful versions of the BRCA1 and BRCA2 genes.

Q: How can women find out if they have these gene mutations?

A: A genetic test using a blood test can usually detect these genes. In the U.S., there are no standard guidelines recommending women for BRCA1 or BRCA2 genetic testing. The tests usually cost at least several hundred dollars. Women may be at higher risk for having a harmful mutation if they have close family members diagnosed with breast or ovarian cancer at an early age. Jolie says that her mother fought cancer for nearly a decade before dying at age 56.

Q: What other options might Jolie have had?

A: Doctors would likely have suggested earlier screening tests, including mammograms or MRIs, but those would only help them spot breast cancer earlier, not prevent it. They might also consider using breast cancer drugs preventively, though trials into their long-term use is still ongoing. "This is not a decision that people take lightly," said Dr. Emma Pennery, clinical director at the British charity, Breast Cancer Care. "You cannot decide to have a double mastectomy next week."

Q: How relevant is Jolie's decision to other women?

A: For most women, genetics will not play a big part in whether or not they get breast cancer. "The majority of women considering their breast cancer risk should focus on things like a healthy lifestyle, eating a balanced diet, keeping a healthy weight and not drinking too much alcohol," said Dr. Peter Johnson, chief clinician at Cancer Research U.K. About one third of breast cancer cases in Britain are largely tied to modifiable lifestyle risk factors.

But for women with a similar genetic risk to Jolie, it's possible her decision to go public about her double mastectomies will prompt more procedures. "It's a very empowering message that women are not helpless when faced with a genetic cancer risk," Johnson said.