A health ministry panel has recently compiled a set of guidelines allowing women to undergo mastectomies to prevent breast cancer if they are genetically at risk.

Preventive mastectomy entered the spotlight after American actress Angelina Jolie announced in 2013 that she had undergone the procedure to reduce her chances of getting breast cancer after she was found to carry a genetic mutation putting her at high risk.

In Japan, there are an estimated 90,000 women with breast cancer, of which 5 to 10 percent is caused by genetic factors. Many cases are attributed to genetic mutations of BRCA1 or BRCA2, which raise the risk of breast or ovarian cancer.

Under the guidelines the research panel, led by Masami Arai, head of the gene oncology department of the Cancer Institute Hospital of the Japanese Foundation for Cancer Research, says that while a double mastectomy is "certain to lower the risks of breast cancer, there is no data (on it) improving the mortality rate."

The Health, Labor and Welfare Ministry panel then recommended that women "consider (mastectomy) under extreme care." In principle, surgery will not be recommended, with the decision left to the patients.

Even if a patient opts to have a mastectomy, the procedure does not give any guarantee that breast cancer will not occur, and the cost of the operation will not be covered by health insurance.