Every woman who contracts ovarian cancer should be tested for the genes that cause it, regardless of family history, says the head of a cancer study from McGill University in Montreal.

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Dr. Patricia Tonin says her testing shows that women with no known family history of ovarian cancer can still carry a hereditary cancer gene mutation. (CBC)

Ovarian cancer is not always hereditary. However, the study has concluded it would be better if women who get the disease be tested for the BRCA1 and BRCA2 genetic mutations in order to protect future generations of their family.

The BRCA1 and BRCA2 genetic mutations are shown to increase the risk of breast and ovarian cancers.

"Currently, only women with a family history of breast and ovarian cancer are offered genetic testing, and if they happen to carry BRCA1 or BRCA2 mutations they are given cancer prevention strategies to reduce their risk for these cancers," said lead study researcher and author Dr. Patricia Tonin in a statement.

Actor Angelina Jolie recently made headlines for having preventative surgery because she has tested positive for BRCA1. In an effort to prevent hereditary cancer, she had a double mastectomy and also had her ovaries and fallopian tubes removed.

Ovarian cancer is the fifth most common women's cancer and is the most fatal of women's cancers, according to Ovarian Cancer Canada.

The organization says 17,000 Canadian women have the disease. It estimates that 2,600 women will be diagnosed with ovarian cancer this year.

Study shows all women should be tested

Tonin and fellow researchers tested more than 400 tissue samples from a group of French-Canadian women with ovarian cancer. Their family history of the disease did not play a role in the selection process.

It continues to be my biggest regret, that I did not do genetic testing. My mother died of breast cancer at age 49. - Esther Hockenstein, ovarian cancer patient .

The results showed that nearly a fifth of women who get the most common and aggressive form of ovarian cancer carry the genetic mutations. The conclusion has Tonin calling for more genetic testing.

People who know they are carriers, could — like Angelina Jolie — opt for preventative surgery.

Tonin, who works for the cancer research program at the Centre for Translational Biology at the McGill University Health Centre, told CBC News that it's possible to be a carrier, even with no apparent family history. She said it's possible the genes are passed undetected by men.

"There could be a lot of men in the family, and if you were the first person to inherit the gene — female — you are at increased risk. But it would not be recognizable, based on family history," Tonin said.

While men can also be carriers, Tonin is at the moment only calling for women with ovarian cancer to be tested. 

"It might help their family members. They might be — I hate to use the term — ground zero, but if they are it's possible that their family members could benefit from this. Not only their children, but also their siblings and other members of their family," Tonin told CBC News.

'My biggest regret'

Esther Hockenstein

Esther Hockenstein says she regrets not getting tested for the genetic mutation. (CBC)

Esther Hockenstein, 70, said she learned too late about her own risk of ovarian cancer.

"It continues to be my biggest regret, that I did not do genetic testing. My mother died of breast cancer at age 49," she said.

She said one of her sons who chose to get tested turned up positive as a carrier of the gene.

"He does have a daughter who is under 10. At some point, obviously, in her early 20s, the family will have to face discussing it and make some decisions," Hockenstein said.