Women with breast cancer make no difference to their survival chances by deciding to have a double mastectomy, new research has shown.
A study in California found that women who had lumps removed followed by radiotherapy lived as long as those taking the drastic step of discarding both breasts.
Yet there is evidence of increasing numbers of women seeking double mastectomies after having cancer diagnosed in just one breast.
The same team of researchers who analysed data on 189,734 patients found that rates of the procedure soared from 2% in 1998 to 12.3% in 2011 - an annual increase of 14.3%.
Lead scientist Dr Allison Kurian, from Stanford University, said: "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.
"Furthermore, a mastectomy is a major procedure that can require significant recovery time and may entail breast reconstruction, whereas a lumpectomy is much less invasive with a shorter recovery period."
Of the women recruited, just over half (55%) had surgery to remove lumps followed by radiation treatment. Almost 40% had one breast removed and 6.2% on average underwent a double mastectomy over the 13-year study period.
Women electing to have complete breast removal were more likely to be white, younger than 50, and from the middle or upper social classes.
Long term survival rates did not differ significantly between women who underwent a double mastectomy and those who received a lumpectomy plus radiotherapy. After 10 years, just under 19% of the patients had died.
Survival rates were slightly worse for women who had one breast removed compared with breast-preserving treatment, possibly for socio-economic or ethnic reasons, said scientists.
The authors, whose research appears in the Journal of the American Medical Association, wrote: "In a time of increasing concern about over-treatment, the risk-benefit ratio of bilateral mastectomy warrants careful consideration and raises the larger question of how physicians and society should respond to a patient's preference for a morbid, costly intervention of dubious effectiveness.
"These results may inform decision-making about the surgical treatment of breast cancer."
They stressed that for some women with a genetic risk of breast cancer, a double mastectomy remained an effective treatment option.
It was also true that removal of both breasts might help alleviate a woman's fear of a second cancer occurring in the remaining breast.
In addition, some of the latest breast-reconstruction techniques achieved better results when both breasts were rebuilt together.
Co-author Dr Scarlett Gomez, from the Cancer Prevention Institute of California (CPIC), said: "We're hopeful that this study will open a dialogue between a patient and her physician to discuss these kinds of questions. It's an important piece of evidence that can guide their decision-making process."
A number of celebrities have had double mastectomy operations
Hollywood star Angelina Jolie is the latest and most high-profile star to highlight the dilemma facing women at high risk of developing breast cancer.
The star of Tomb Raider, Mr & Mrs Smith and Salt revealed last month that she had undergone a preventative double mastectomy to reduce her risk of developing the disease.
Her mother Marcheline Bertrand died of cancer in 2007 and days after Jolie revealed her surgery, her aunt, Debbie Martin, 61, died of breast cancer.
Jolie, a mother of six and wife of Brad Pitt, said she took the decision to have the procedure because she found she carries the "faulty" gene BRCA1, which sharply increases her risk of developing breast cancer and ovarian cancer.
Writing for the New York Times, she said her doctors had estimated she had an 87% risk of developing breast cancer and a 50% risk of ovarian cancer.
Former X Factor judge Sharon Osbourne revealed in November that she had undergone a double mastectomy.
The 60-year-old beat colon cancer a decade ago but opted for surgery after finding she carried a gene which increased the risk of developing breast cancer.
In an interview at the time with Hello! magazine, she said: "As soon as I found out I had the breast cancer gene, I thought 'The odds are not in my favour'.
"I've had cancer before and I didn't want to live under that cloud. I decided to just take everything off, and had a double mastectomy.''
Former Liberty X singer Michelle Heaton was another who took the decision to have drastic surgery.
She had a double mastectomy late last year after she was diagnosed with a mutated BRCA2 gene, which meant she had an 80% chance of developing breast cancer and a 30% chance of ovarian cancer.
Anastacia has undergone a double mastectomy after being diagnosed with breast cancer for the second time, the US singer has announced.
The I'm Outta Love star, 45, announced the second diagnosis in February, cancelling her planned European tour.
Now she has updated fans on her recovery as part of Breast Cancer Awareness Month.
She said in a statement: "In light of Breast Cancer Awareness Month l wanted to take the opportunity to support a cause particularly close to my heart.
"l was diagnosed with breast cancer for the second time earlier this year and am currently in the final stages of recovery after undergoing a double mastectomy."
She added: "It has been an intense journey but l am feeling great and ready to start the next chapter.
"Breast Cancer Awareness Month gives all who are facing this disease a chance to gain strength and support from each other.
"Early detection has saved my life twice. I will continue to battle and lend my voice in anyway I can."
Anastacia, who said she underwent a double mastectomy with Latissimus Dorsi flap surgical procedure, was first diagnosed with the disease in 2003.
Eluned Hughes, head of public health at the charity Breakthrough Breast Cancer, said: "Double mastectomies are not routinely offered to women with breast cancer in the UK unless they have a family history of the disease or a high risk of recurrence, as outside of these groups there is no evidence to suggest that this would be of benefit.
"Having a double mastectomy is a difficult decision - there may be many reasons why women from California are opting for this procedure, so it's important that every woman has all the information about the risks and benefits of the surgery for them.
"Our dedicated team of scientists are working to make personalised medicine the standard for breast cancer treatment. By gaining a full understanding of every type of breast cancer, what causes them to begin and by mapping how they grow and spread, we will be able to match up each and every patient with a precise treatment plan based on the most effective ways of beating their particular breast cancer - with the fewest side effects possible."