Women fighting cancer in one breast do not benefit from having both removed, according to new research that found long-term survival was equivalent after targeted surgery plus radiation.
A growing number of women have begun choosing the most radical surgical option - the double mastectomy, to remove all breast tissue - after a diagnosis, even when cancerous tissue was found only in one breast.
But the researchers aimed to determine whether evidence showed double mastectomies led to longer lives.
It was the first study to directly compare survival rates between the three main surgical interventions used in breast cancer: a single or a double mastectomy, or a lumpectomy to remove cancerous tissue, followed by radiation therapy.
The study found that in 2011, just over 12 per cent of patients diagnosed with a breast tumour opted for a double mastectomy, compared to 2 per cent in 1998.
However, "we can now say that the average breast cancer patient who has bilateral mastectomy will have no better survival than the average patient who has lumpectomy plus radiation", said the lead author, Stanford medical professor Allison Kurian.
Of the nearly 190,000 study subjects diagnosed between 1998 and 2011, 55 per cent had a lumpectomy followed by radiation therapy, 38.8 per cent had a single mastectomy, and 6.2 per cent had a double mastectomy.
Black or ethnic minority women, and those from poorer backgrounds, were more likely to have undergone a single mastectomy. In contrast, women who had both breasts removed were more likely to be middle class or wealthy, white, under the age of 50, or some combination.
The long-term survival rate for women who underwent lumpectomies with radiation was not statistically different from women who underwent double mastectomies, Kurian and co-author Scarlett Gomez found.
The long-term survival rate after single mastectomies was slightly lower, but the study published in the Journal of the American Medical Association said it was unclear if that was due to socio-economic differences.
Hollywood star Angelina Jolie had a double mastectomy to reduce her risk of developing breast cancer because she has a specific genetic mutation, but the study was not designed to look into the benefits of radical surgery in cases such as hers.