The risks of breast and ovarian cancer for women with the BRCA1 or BRCA2 gene mutations have been identified on Wednesday in new research described as "the most accurate estimates ever provided".
The findings of a long-term study of almost 10,000 women from countries around the world, including Australia, over the past two decades show women with the BRCA1 mutation have a 72 percent risk of developing breast cancer by the age of 80, whereas people with the BRCA2 mutation are at a 69 percent risk.
Co-conducted by the Peter MacCallum Cancer Centre, University of Melbourne and Cancer Council Victoria, the research also shows people with the BRCA1 mutation have a 44 percent chance of developing ovarian cancer throughout their life, compared to just a 17 percent risk posed by a BRCA2 mutation.
The BRCA1 and BRCA2 genes help in the creation of proteins that act to suppress tumours, repair damaged DNA and maintain genetic stability. Any faults in either of those two genetic strands have been found to put people at a higher risk of developing breast and ovarian cancer.
Co-author of the study, Professor John Hopper from the University of Melbourne told HuffPost Australia the findings could spark "a rethink about how genetic risk for people is expressed" and highlight the importance of age when determining breast and ovarian cancer risk.
"It makes us realise how important age is in determining and knowing the relationship between risk and age, especially if we're going to work out how to prevent people getting cancer," he said.
"Those results could flow on to other causes of genetic risk and breast cancer in general."
The findings also extended on previous research in determining that the risk of breast cancer linked to the mutations increases rapidly throughout a woman's younger years before peaking and remaining consistently high throughout her life.
The risk associated with the BRCA1 mutation was found to peak for carriers during their 30s, whereas the BRCA2 mutation peaks during a person's 40s. Family history and the gene abnormality were also found to be indicators of a person's risk.
"We showed that these carriers are still at high risk even later on at life even if they haven't yet developed breast cancer," Hopper said.
"Previously, people thought the risk for carriers would go down the longer they don't have breast cancer but that isn't the case."
Head of the Cancer Epidemiology & Intelligence Division at Cancer Council Victoria, Associate Professor Roger Milne told HuffPost Australia the findings are a confirmation of the risks, which were already known.
"It's a solid confirmation of most of the things that we knew. This is the gold standard study that gives us the best information on what those risks are," he said.
"I think its really important that people who know they carry a mutation get a good handle on what those risks are... We know that [the BRCA mutations are] present, but rare in the general population, [and they can be] in women and men who don't have breast cancer."
Milne also said the research shouldn't act as something to scare people into immediately getting tested, but suggested people should take an interest in their family history of health, particularly when it comes to breast and ovarian cancer.
"It's a good idea to see what you might be able to do to have the best possible health outcomes. In terms of breast or ovarian cancer it doesn't hurt to get informed," he said.
"People don't need to panic and go out and get tested immediately. If people are concerned about their family history, start by talking to their GP and discuss whether they want to take it any further."
Awareness of the two gene mutations rose sharply in 2013 after Angelina Jolie underwent a preventive double mastectomy because of a mutated BRCA1 gene. In a post for the New York Times, Jolie said she made the decision after being told of her high chances of developing breast and ovarian cancer.
My doctors estimated that I had an 87 percent risk of breast cancer and a 50 percent risk of ovarian cancer, although the risk is different in the case of each woman.
"I wanted to write this to tell other women that the decision to have a mastectomy was not easy," she said in that post.
"But it is one I am very happy that I made. 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."
Since Jolie's mastectomy, it was revealed in 2016 that wait times for genetic counselling skyrocketed with efforts being made to lower the prices for testing.
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