A Canadian breast cancer specialist wants people to learn from actress Angelina Jolie's experience and seek genetic testing.

Jolie wrote an op-ed piece that appeared in the New York Times Tuesday called "My Medical Choice" about her decision to have a preventive double mastectomy after her mother died of cancer at age 56 and tests for the "faulty" BRCA 1 mutation revealed she had a high likelihood of developing breast and ovarian cancer.

Below we answer some questions about the procedure:

Is the testing covered in Canada?

Provincial health plans cover the cost of BRCA1 and BRCA2 mutation testing in patients that meet criteria, such as a diagnosis of breast or ovarian cancer in a family history.

"Only 10 per cent of the women with a mutation have been identified, so if we can use this to increase the number to 20 or 25 per cent I think that would be an opportunity," said Dr. Steven Narod, director of the Familial Breast Cancer Research Unit at Women's College Research Institute in Toronto.

The main factors that keep women from getting the blood test for the mutation are that they don't know that tests are available and doctors don't regularly ask about family medical history, Narod said.

"We know scientifically that you are just as likely to get a mutation from your dad as from your mom," Narod said.

"The fact is, we've missed all the women who inherited the mutation from their father, because they didn't come to the attention of the geneticist because they didn't have the extended family history of breast cancer."

What does the procedure involve?

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.

"Basically, you have to go through a full mastectomy, get tissue expanders put in, go through a full year of expansion to create a pocket in between your rib cage and your pectoral muscles so they have somewhere to put the implant," said Theresa Quick of Toronto, who underwent a preventive double mastectomy last year.

Both of Quick's grandmothers died of breast cancer. Her mother also had breast cancer, carried BRCA 1 and died at 52 of ovarian cancer.

For those who test positive and choose to have a preventive mastectomy, the procedure and reconstructive surgery are paid for by provincial plans.

Dr. William Foulkes, a cancer geneticist at McGill University and Montreal's Jewish General Hospital, said Jolie's announcement goes a long way to demystifying the surgical experience. Foulkes is concerned about people rushing out for genetic testing.

"If your risk of having a mutation is, say, one per cent and the test costs $1,600, is that a good use of health-care dollars?" said Foulkes. "I think our job is to make the test cheaper."

How many women have this faulty gene?

Only a small percentage of women have this same faulty gene, or a similar mutated version of a related gene, BRCA2.

While breast cancer is the most common cancer in women over 20, five to 10 per cent  of all cases are hereditary.

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.

In Jolie's case, Narod speculated she may have inherited a mutation specific to French-Canadians that represents 80 per cent of the BRCA1 mutations in Quebec.

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

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.

"Age of diagnosis of cancer is a really important predictor of whether the cancer is hereditary," said Rochelle Demsky, a genetic counsellor at Princess Margaret Cancer Centre in Toronto.

What other preventive options exist?

Narod said women at high risk from mutations are offered screening tests such as MRIs to detect cancer earlier.

Drugs such as tamoxifen and raloxifene can also be given preventatively for women without breast cancer who carry the mutations although clinical trials into their long-term use are ongoing.

Another preventive surgery, bilateral prophylactic oophorectomy — removing both ovaries and Fallopian tubes — is also an  option.

Among BRCA1 carriers, the number of deaths from ovarian cancer is about the same as the number of deaths from breast cancer, Narod said, noting there is no screening or early detection available for ovarian cancer.

At the B.C. Cancer Agency, part of the hereditary cancer program involves a high-risk clinic in Vancouver for women who don't have cancer but are found to have one of the genetic mutations.

In the last year, among the 300 women in the program who didn't have cancer, 27 per cent chose to have mastectomies, said Dr. Barb McGillivray, the medical director. Fifty-five per cent chose to have their tubes and ovaries removed.

How relevant is Jolie's decision to other women?

For most women, genetics will not play a big part in whether 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.

With files from CBC's Kelly Crowe, The Associated Press and The Canadian Press