Hollywood actress Angelina Jolie's decision to undergo a double mastectomy has prompted other women to have the procedure, an NHS clinic has said.
Researchers at Genesis Prevention Centre Family History clinic in Manchester said they have seen a rise in the number of women having preventative double mastectomies over the last few years.
Jolie announced in May 2013 that she had undergone a double mastectomy to reduce her chances of getting breast cancer.
The mother-of-six wrote in the New York Times that doctors had estimated she had an 87% risk of breast cancer and a 50% risk of ovarian cancer due to a faulty hereditary gene.
"I decided to be proactive and to minimise the risk as much I could," she wrote.
In a letter to the editor, published in the open access journal Breast Cancer Research, researchers from the Genesis Prevention Centre said preventative double mastectomies at the clinic more than doubled from January 2014 to June 2015.
There were 83 procedures performed during this period, up from 29 between January 2011 and June 2012.
Women who carry the BRCA1 or BRCA2 genetic faults have a higher risk of breast and ovarian cancer.
The experts said they have also seen the "Angelina effect" in a higher number of referrals to the clinic, which covers a population of five million.
They said: "Although the main impact of the Angelina effect was from June to November 2013, this trend continued through 2014 with increased referrals from 201 in January-June 2012 to 388 in January to June 2014, and rising by 366 for the last six months, to give a total of 754 for 2014.
"Women attending for risk assessment and discussions concerning bilateral risk-reducing mastectomy, unprompted, still mention the effects of Angelina Jolie on their attendance anecdotally to clinic physicians and still reflect on the impact of her speaking publicly in their pre-surgery consultations with the clinical psychologist in 2015."
Lester Barr, chairman of Genesis Breast Cancer Prevention, said: "These observations are particularly interesting as they demonstrate that women who were referred for gene testing in the months after Angelina's story broke went on to have a preventative mastectomy.
"It means that Angelina's announcement did not simply lead to a knee-jerk reaction in those at risk from breast cancer, but encouraged them to find out more about the procedure and what steps they would need to take to reduce their risk."
Mr Barr said the "Angelina effect" was more profound than that caused by the death from cervical cancer of reality TV star Jade Goody in 2009.
"We know that the Angelina effect has been long-lasting, especially in comparison to other celebrity-led awareness trends, such as the Jade Goody effect.
"However, we're now confident that Angelina's story will continue to raise awareness of the BRCA gene mutations and that this increased knowledge, particularly among medium and high-risk women, will be passed on to the next generation."
Gareth Evans, professor of clinical genetics at Genesis Breast Cancer Prevention and lead author of the letter, said the rise in mastectomies started around nine months after Jolie's announcement.
"While we haven't analysed women's motivations for undergoing this type of surgery, the correlation suggests that if the increased uptake of double mastectomies can be attributed to 'the Angelina effect', the effect has been prolonged and has resulted in both increased referrals to our clinic, and increased rates of preventative surgery."
Yinka Ebo, health information manager at the Breast Cancer Now charity, said: "This research suggests not only that the 'Angelina Jolie effect' has been long-lasting but also that women are being referred to family history clinics and genetic centres appropriately, which is really encouraging to see."
Samia al Qadhi, chief executive of Breast Cancer Care, said: "We know other regional genetic clinics across the country have also had more referrals.
"Angelina's courage in sharing her experiences has highlighted this incredibly important issue of family history and breast cancer.
"The percentage of women ringing our helpline to ask questions about family history and breast cancer increased five-fold after she made her announcement.
"This means that many more women with a strong family history have been encouraged to find support and are taking action."