26/10/2015 9:14 AM AEDT | Updated 15/07/2016 12:50 PM AEST

Why A Young Or Male Family Member With Breast Cancer Denotes A Higher Hereditary Risk

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Younger women have a harder battle to beat breast cancer, according to new research, with experts encouraging people to find out if they have a hereditary marker in a bid to better combat the disease.

A new report shows breast cancer causes one death a week in women aged 20 to 39 but survival rates had improved in the last decade.

The study, by the Australian Institute of Health and Welfare, found that 795 women aged between 20 and 39 years would be diagnosed with breast cancer this year and 65 women would die from the disease.

The five-year survival rate of women in this age group was 72 percent in 1982-1986, and 88 percent today.

This is compared to 90 percent survival for women over the age of 40.

The study also showed the effect actress Angelina Jolie had on women of all ages who have a genetic predisposition to breast cancer.

Jolie had a preventative double mastectomy in 2013 after a genetic test found she had a mutation in her BRCA1 gene -- which increased chances of developing breast or ovarian cancer.

Since telling her story, the number of women who had a mastectomy to prevent breast cancer doubled, from 597 in 2012-2013 to 1256 in 2013-14.

National Breast Cancer Foundation director of research Alessandra Muntoni told The Huffington Post Australia that when it came to discovering your genetic risk of developing breast cancer, having a young relative with the disease, or a male relative, denoted a higher hereditary risk.

"They are both red flags for us, especially if the cancers are quite large or aggressive," Muntoni said.

"That type of breast cancer is due to a mutation in two common genes, BRCA1 and BRCA2, but it's very complicated."

Muntoni said that because everyone carried two genes, someone with breast cancer may carry one faulty gene, and one normal gene, so the chances of passing it on were 50 percent.

For those who did not know their family history, Muntoni said they could be be tested to see if they carry the mutated gene, but it was more complicated than a simple yes or no test.

"There are many different ways the genes can mutate and some mutations are associated with a higher risk of developing breast cancer, but others are of an uncertain clinical significance.

"In other words, the mutation may not significantly increase the chances of developing breast cancer.

"This means that problems arise when you don't know anything about your family history or if anyone has had cancer because it is a little bit difficult to look for a mutation randomly."

Experts agreed the best thing to do was to talk about genetic risk factors in families, and for all women of all ages to check their breasts regularly.

Find out how to check your breasts here, or if you feel pretty confident, test your breast IQ here.