Women who carry the BRCA1 or BRCA2 gene mutation have a 60-70% increased risk of developing breast cancer, so many opt for a mastectomy. Now a new study has found that women with these gene mutations who are diagnosed with early stage breast cancer reduce their risk of death if they have a double mastectomy, rather than a single.

According to US and Canadian researchers, women with BRCA gene mutations not only have an increased risk of developing breast cancer in the first place, they are also much more likely to develop the disease a second time.

There is not much information on the long-term survival experiences of women with these gene mutations who are treated for breast cancer, so the researchers decided to look into this further.

They looked at the experiences of 390 women who had survived for at least 20 years after being diagnosed with early-stage breast cancer. The women were known to be carriers of the gene mutations, or were likely to be carriers, and all underwent either a single or double mastectomy.

Over the 20-year period, 79 of the women died of breast cancer.

The study found that those who underwent a double mastectomy had a 48% reduced risk of dying from breast cancer compared to those who underwent a single mastectomy.

Based on this data, the researchers estimated that for every 100 women who undergo a double mastectomy, 87 will be alive 20 years later. For every 100 women who undergo a single mastectomy, this number falls to 66.

The benefits associated with a double mastectomy were most apparent in the second decade of follow-up. Over half of the deaths that occurred among the participants during the second decade involved those who had developed breast cancer for the second time.

The researchers said that it is ‘reasonable to propose bilateral (double) mastectomy as the initial treatment option for a woman with early-stage breast cancer who carries a BRCA1 or BRCA2 mutation'.

Details of these findings are published in the British Medical Journal.