This means that breast cancer patients can wait and see how they feel about things and how their health is before they decide whether to have more surgery - for instance, to remove the healthy breast to lower any risk that breast cancer might return in that one.
"Our study is the largest of its kind, and our findings suggest that younger women with breast cancer who have a BRCA mutation have similar survival to women who do not carry the mutation after receiving treatment", Eccles said in a press release.
The study, published in The Lancet Oncology journal, found no difference in overall survival regardless of whether the women had the faulty gene or not.
In addition, a subgroup analysis of 558 women with triple-negative breast cancer suggested that women with a BRCA mutation may initially have a survival advantage during the few years after diagnosis.
BRCA mutations are inherited and occur in either the BRCA1 or BRCA2 gene.
PALB2 - Works similarly to the BRCA genes. Jolie surgically removed and reconstructed her breasts as a preventive measure after learning her BRCA status. This action prevents DNA inside BRCA-mutated cancer cells from being repaired, which can stop tumor growth.
Actor and director Angelina Jolie attends The 23rd Annual Critics' Choice Awards at Barker Hangar on January 11, 2018 in Santa Monica, California.
"Decisions about timing of additional surgery to reduce future cancer risks should take into account patient prognosis after their first cancer, and their personal preferences", she added.
For this study, researchers followed more than 2,700 women recruited from more than a hundred British hospitals for almost a decade.
Katherine Woods of the Breast Cancer Now charity said: 'Coming somewhat as a surprise, this crucial new knowledge could enable many patients to make even more informed choices regarding their treatment.
Fiona MacNeill, of the Royal Marsden NHS Foundation Trust, who was not involved in the research, said: "This study can reassure young women with breast cancer, particularly those with triple negative cancer or who are BRCA carriers, that breast conservation with radiotherapy is a safe option in the first decade after diagnosis and double mastectomy is not essential or mandatory at initial treatment".
"Our data provides some reassurance that patients who are diagnosed with a BRCA gene fault as part of their cancer treatment journey can complete and recover from their breast cancer treatment, which is important", she said.