Photo/Illutration Doctors perform a surgery to remove uterine tubes and an ovary to reduce the patient’s risk of developing cancer at Keio University Hospital in Tokyo's Shinjuku Ward. (Ryo Ikeda)

At least 260 women born with mutated genes that increase the risk of cancer underwent mastectomies or had their uterine tubes and ovaries removed to prevent the disease from developing, a yearlong survey showed.

The survey by the Japanese Organization of Hereditary Breast and Ovarian Cancer（JOHBOC） showed an increasing awareness that cancer can be caused by genetic factors and the removal of breasts, ovaries or uterine tubes can save lives.

The organization said women with mutations of their BRCA1 and BRCA2 genes who have been diagnosed with hereditary breast and ovarian cancer (HBOC) syndrome are far more vulnerable.

Three to 5 percent of breast cancer patients developed the disease through the mutated genes.

Forty to 90 percent of women with the mutated genes develop breast cancer in their lifetimes, compared with the overall average of 9 percent.

Around 1 percent of all women develop ovarian cancer, but the percentage shoots up to 20 to 60 percent among those with HBOC syndrome, according to the JOHBOC.

The organization surveyed 3,517 women who received genetic testing at 62 medical institutions certified by the organization, including St. Luke’s International Hospital and Showa University Hospital, between September 2018 and August 2019.

According to the preliminary results released on Jan. 26, 691, or about 20 percent, of those analyzed had mutations in their BRCA1 and BRCA2 genes.

The survey found that 85 HBOC syndrome patients, or roughly 12 percent, underwent preventative mastectomies, while 175, or about 25 percent, had their non-cancer-affected uterine tubes and ovaries removed.

The figure for the mastectomies included those who had both breasts removed even if they were cancer-free.

The JOHBOC conducted an earlier survey on women who received genetic testing at seven medical institutions over a one-year period from September 2015 through August 2016.

Although the number of institutions in the surveys was different, the previous survey found that 297 of the women tested had the genetic mutations, and 49, or nearly 20 percent, underwent preventative mastectomies.

The latest survey revealed that more women learned that their cancer was hereditary after undergoing tests to determine a suitable treatment.

“We must provide more counseling to patients and their families” in dealing with such cases, Seigo Nakamura, the director of the JOHBOC and a professor of breast surgical oncology at Showa University, said.

The public health insurance program in April will start covering the surgeries of HBOC cancer patients to remove noncancerous breasts, ovaries or uterine tubes.

If the patients opt out of such operations, the insurance program is expected to cover MRI and other tests conducted to check if they have cancer.