Women with the early stages of breast cancer are following Angelina Jolie's example and demanding double mastectomies.
The number choosing the operation to remove both breasts has doubled in 10 years ago despite evidence other less aggressive treatment are just as effective.
Hollywood star Angelina went public in 2013 about her double mastectomy after finding out she carried the BRCA1 mutation.
She had the operation because she lost her mother, grandmother and aunt to the disease and feared she was at risk too.
New research by the University of California, San Diego set out to explore why risk-reducing breast surgery or contralateral prophylactic mastectomy (CPM) has increased.
It found the procedure has increased among all stages of breast cancer, even in patients with ductal carcinoma in-situ - stage 0.
Recent data suggested that up to 25 per cent of newly-diagnosed breast cancer patients are undergoing CPM, representing up to half of women undergoing mastectomy.
Only about five per cent of women with breast cancer received CPM in 2006, representing about 10 to 15 per cent of mastectomies performed.
Lead author Dr Rebecca Marmor said until about the 1980s mastectomy was considered the standard of care
She added: "As large trials came out demonstrating the efficacy of breast conservation, I think a lot of surgeons assumed that breast conservation would be patient's preference.
"We want to understand what is motivating some women who are choosing CPM, and sometimes even demanding it in the face of resistance from their own surgeons and oncologists."
The team trawled breast cancer community websites for keywords, searching for the terms 'contralateral', 'prophylactic', and 'double mastectomy' to identify the reasons behind patient's choices.
Results found the fear that the cancer may come back was the most frequent reason, followed by the perception that CPM is the best treatment for breast cancer.
Some patients had already suffered a recurrence of breast cancer, so chose CPM to stop the cancer from returning for good.
Yet others said plastic surgeons recommended CPM to them to optimise their cosmetic reconstruction outcomes.
Previous studies have looked at the increase in CPM, but Dr Marmor says her team's study was 'unique' as they were able to see the actual communication between patients themselves.
She said: "Now we have a better understanding of what beliefs some patients hold, which is that CPM is the best treatment for breast cancer.
"We also were able to study what patients are saying to each other about CPM.
"Now that we have a sense of what they're saying to each other, we want to work to correct their misconceptions."
The team is currently analysing another health community to make sure the results are consistent
They hope to develop a tool to aggregate patient experiences, so women can learn about different treatment options from other patients similar to themselves.
The study was presented at the 2016 Clinical Congress of the American College of Surgeons.