"My mother fought cancer for almost a decade and died at 56," Jolie writes. "She held out long enough to meet the first of her grandchildren and to hold them in her arms. But my other children will never have the chance to know her and experience how loving and gracious she was."
She writes that, "They have asked if the same could happen to me."
Jolie said that after genetic testing she learned she carries the "faulty" BRCA1 gene and had an 87 percent chance of getting the disease herself.
She said she has kept the process private so far, but wrote about it with hopes of helping other women.
"I wanted to write this to tell other women that the decision to have a mastectomy was not easy. But it is one I am very happy that I made," Jolie writes. "My chances of developing breast cancer have dropped from 87 percent to under 5 percent. I can tell my children that they don't need to fear they will lose me to breast cancer."
Phone and email messages left by The Associated Press late Monday night seeking comment from Jolie representatives were not immediately returned.
She is anything but private in the details she provides, giving a description of the procedures.
"My own process began on Feb. 2 with a procedure known as a 'nipple delay,'" she writes, "which rules out disease in the breast ducts behind the nipple and draws extra blood flow to the area."
She then describes the major surgery two weeks later where breast tissue was removed, saying it felt "like a scene out of a science-fiction film," then writes that nine weeks later she had a third surgery to reconstruct the breasts and receive implants."
Many women have chosen preventive mastectomy since genetic screening for breast cancer was developed, but the move and public announcement is unprecedented from a star so young and widely known as Jolie.
She briefly addresses the effects of the surgery on the idealized sexuality and iconic womanhood that have fueled her fame.
"I do not feel any less of a woman," Jolie writes. "I feel empowered that I made a strong choice that in no way diminishes my femininity."
She also wrote that Brad Pitt, her partner of eight years, was at the Pink Lotus Breast Center in Southern California for "every minute of the surgeries."
Bertrand, Jolie's mother, died in January 2007. She had small roles in the movies "Lookin' to Get Out" in 1982 and "The Man Who Loved Women" in 1983. She raised Jolie and her brother after divorcing their father, Oscar-winning actor Jon Voight, when Jolie was a toddler.
Jolie has appeared in dozens of films including 2010's "The Tourist" and "Salt," the "Tomb Raider" films and 1999's "Girl, Interrupted," for which she won an Oscar.
But she has appeared more often in the news in recent years for her relationship with Pitt and her charitable work with refugees as a United Nations ambassador.
Meanwhile, CNN anchor Zoraida Sambolin announced Tuesday that she has breast cancer and is getting a double mastectomy.
Sambolin, who anchors CNN's "Early Start" morning show, talked about her condition on the show Tuesday while discussing Jolie's decision.
Celebrities react to Jolie's mastectomy revelation
Celebrities react to Angelina Jolie's revelation Tuesday in a New York Times editorial that she underwent a preventive double mastectomy:
"Huge prayers for Angelina Jolie & her family as she convalesces & bravo for raising awareness! #GetWellSoonAngie" Actress Octavia Spencer on Twitter.
"Angelina Jolie reveals double mastectomy. Proud of her for using her incredible platform to educate women." TV personality and breast cancer survivor Giuliana Rancic on Twitter.
"There is no difference between the star Angelina Jolie and the woman Angelina Jolie. The choices she made even as a director are still strong, when you read what she wrote about her own situation, and we all know that she didn't do that for herself but as giving an example to all the women on this planet earth who are suffering from the same disease." Cannes Film Festival director Thierry Fremaux in a statement.
"This absolutely blew my mind. Angelina Jolie speaking out about a difficult decision that will inform + empower others." Actress Nina Dobrev, on her website.
"#angelinajolie thank you for sharing your story and helping women around the world #inspirational" singer and breast cancer survivor Kylie Minogue on Twitter. Angelina Jolie's double mastectomy: Q&A
Oscar-winning actress Angelina Jolie disclosed Tuesday that she had a preventive mastectomy after learning she had a gene mutation that significantly raised her risk of breast cancer. A look at the procedure:
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 operation?
A: Jolie says that she inherited a faulty version of the BRCA1 gene. Doctors told her she had an 87 percent chance of getting breast cancer and a 50 percent risk of ovarian cancer. She said the surgery reduced her risk of breast cancer to below 5 percent.
Q: What did the procedure involve?
A: In double mastectomies, surgeons typically remove as much breast tissue as possible. In Jolie's case, the doctors preserved the skin covering her breasts, inserting "fillers" for the breast tissue to keep the skin elastic for reconstruction. 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 inherit this same faulty gene, or a similar mutated version of a related gene, BRCA2. (The name stands for breast cancer susceptibility gene). These mutations are most commonly found in women of Eastern European Jewish descent; one study found 2.3 percent of women in that group had the mutations about five times higher than in the general population. Other groups, including the Norwegian, Dutch and Icelandic, also have slightly higher rates of these mutations.
Q: How do these genes increase a woman's risk of breast or ovarian cancer?
A: The average woman has a 12 percent risk of developing breast cancer sometime during her life. In comparison, women who have inherited a faulty BRCA gene are about five times more likely to get breast cancer. In the U.S., about 5 to 10 percent of breast cancers are thought to be linked to harmful BRCA genes. Women with these faulty genes may also have a 15 to 40 percent risk of developing ovarian cancer, compared to about a 1.4 lifetime risk for women without such mutations.
Q: How can women find out if they have these gene mutations?
A: A genetic test using a blood test can detect these genes. Those at higher risk are those with 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. Genetic counseling is usually recommended to discuss the test and the results. "This does not mean every woman needs a blood test," Otis W. Brawley, chief medical officer of the American Cancer Society, said in a statement. "What it does mean is women should know their cancer family history" and discuss it with their doctor.
Q. What does the test cost?
A. The test can cost several thousand dollars. According to Myriad Genetics, the sole provider of such tests in the U.S., 95 percent of patients have insurance that covers the test and the average out-of-pocket cost is $100. Myriad has a patient assistance program for those who aren't covered by insurance.
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 tests of long-term use are still ongoing. Not everyone opts for surgery. "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 will prompt more procedures. "It's a very empowering message that women are not helpless when faced with a genetic cancer risk," Johnson said.
The Associated Press