Jolie said she did after learning she had the BRCA-1 genetic mutation, which raises the risk for breast and ovarian cancer, and because her own mother died of ovarian cancer at the age of 56.
She wrote "we often speak of Mommy's mommy and I find myself trying to explain the illness that took her away. They have asked if the same can happen to me..."
She tells them not to worry but wrote "the truth is I carry a faulty gene."
Dr. Marisa Weiss of Lankenau Hospital and founder of breastcancer.org says that faulty gene - BRCA1 is rare but it greatly increase someone's risk for breast cancer.
"It can vary between 40 percent and 87 percent depending on what study you look at, there is also an elevated risk for ovarian cancer," Dr. Weiss says.
A preventative mastectomy lowers her risk of breast cancer from 87 % to 5 %.
Dr. Weiss applauds Jolie's bravery and strength.
Especially for sharing that her choice "in no way diminishes her femininity"
"That's important for women to hear because they fear if they lose their breasts they will become unattractive and that's not the case at all," she says.
But Dr. Weiss also cautions the test to look for the breast cancer genes is not for everyone.
"It is really only recommended for people who have a significant family history," she says.
Dr. Weiss says there are important things ANY woman can do to reduce the risk of breast cancer:
*Maintain healthy weight
*Limit alcohol to 5 drinks per week (3 is better)
*Exercise 5-7 hours per week
*Eat healthy- plant based foods are best
*Try to avoid unnecessary radiation (from CT scans) while at a young age
Dr. Weiss also recommends avoiding products with BPA, which mimics estrogen; also avoid other environmental chemical hazards for which may fuel cancer.
About 36% of American women who find out they have the BRCA mutations have preventive double mastectomies - the highest rate of any industrialized nations. The rate went up 150% between the 1990s and early 2000s.
Dr. Susan Domchek of the University of Pennsylvania's Basser Research Center for BRCA, says easy access to information, and a wider range of reconstruction options figure are factors in the rise.
Melanie Corbman, a genetic counselor at Cancer Treatment Centers of America's Philadelphia hospital says virtually all young, newly diagnosed women who are BRCA-positive decide to have a double mastectomy.
"Young women want to be around to watch their children grow up," Corbman says. She adds,"Women who have had the experience of losing a mother or sister to breast cancer want to prevent themselves from getting breast cancer."
When they are normal, BRCA 1 and 2 are genes that suppress tumors by preventing uncontrollable cell growth. But when those genes are defective, they can lead to a number of cancers - breast, ovarian, pancreatic, and prostate.
According to the National Cancer Insitute, both BRCA genes are similar, but mutations under BRCA 1 can lead to more aggrerssive cancers, because they don't respond to hormone therapies.
And the BRCA gene mutations can be passed along both the mother's and father's side of families.
The National Cancer Institute says about 12% of all women will develop breast cancer at some time in their lives. When the BRCA mutations are present, the risk goes to 60%. Myriad Genetics, which makes the only breast cancer gene test, says the risk can be as high as 87%.
The average risk of ovarian cancer is 1.4%. The genetic mutations raise that to 15% to 40%.
While a prophylactic double mastectomy dramatically reduces the chance of breast cancer, it doesn't eliminate it entirely.
Only about 5-10% of breast cancers are thought to have a hereditary tie, so testing isn't recommended for most women.
But there are factors which make some women high risk:
For women of Ashkenazi Jewish descent, 1.) a first-degree relative diagnosed with breast or ovarian cancer; 2.) two second-degree relatives on the same side of the family with breast or ovarian cancer.
For women not of Ashkenazi Jewish descent: two first-degree relatives diagnosed with breast cancer, one of whom was diagnosed at age 50 or younger; three or more first-degree or second-degree (grandmother or aunt) relatives diagnosed with breast cancer regardless of their age at diagnosis; and breast cancer diagnosed in a male relative.
Myriad Genetics makes the only FDA-approved genetic test for the BRCA genes, because it patended the genes. However, the U.S. Supreme Court has been asked to allow other tests.
The cost for BRCA1 and BRCA2 mutation testing can cost about $3000. Some insurance companies cover the cost, while others don't.
In her op-ed, Jolie said, "It has got to be a priority to ensure that more women can access gene testing and lifesaving preventive treatment, whatever their means and background, wherever they live."