A new study finds that women who carry BRCA gene mutations have the same mortality rates for malignancies those women who do not have this variant DNA.

These findings were published in the July 12 edition of New England Journal of Medicine, and contradict much of the current medical belief.

“Our main finding that female carriers have similar survival rates, or even better, partly undermined, though not all, previous publications on the subject,” noted study author Dr. Gad Rennert, National Center Clalit for cancer control and Caramel Medical Center in Haifa, Israel. “However, we use a design ‘clean’ it was not possible for other research groups and therefore the results of our study is closer to ‘truth’ than any other study on the issue.”

Practically speaking, the findings may impact treatment decisions for women who have one of two genetic mutations, called BRCA1 or BRCA2.

Many previous studies on the subject have suggested that the cancer that resulted from these mutations had a worse prognosis than other types of breast tumors.

BRCA mutations are more common among Ashkenazi Jewish women, which could help determine why breast cancer is the leading cause of all deaths from cancer among Israeli women. About 60 percent of Israeli Jews are Ashkenazi. About 2 percent of all women of Ashkenazi origin and 12 percent of Ashkenazi women with breast cancer carry one of these two mutations.

Breast cancers associated with BRCA1, in particular, tend to occur in younger women, are high grade and are not estrogen receptor-positive and all these factors are associated with a worse outcome.

However, the information about how BRCA status would affect a woman’s prognosis had been “inconsistent,” wrote the authors.

To clarify the picture, the authors analyzed all cases of invasive breast cancer diagnosed between 1 January 1987 and 31 December 1988 and registered in the Israeli National Center for registration. This accounted for the majority of women who had been diagnosed with breast cancer in Israel during that time period. The researchers examined tumor samples from patients and analyzed DNA, and also categorized the deaths over 10 years from diagnosis.

The authors were able to analyze the tumor samples of 1.794 and 2.514 participants obtained the medical records of 1,545 women. Ten percent of participants who were Ashkenazi Jewish had a BRCA1 or BRCA2.

The risk of dying from breast cancer was not significantly different among carriers and non-carriers, the researchers found. Moreover, both groups responded similarly well to chemotherapy.

“The importance of the study is that it demonstrates that despite the profile of prognostic factors, the carriers of [BRCA] get good results, something that is important for female carriers and doctors,” said Rennert. “It also demonstrates that chemotherapy is very effective in the carriers and that oncologists should not deny to the carriers, even with small tumors, the potential benefits of treatment.”

The next step is to customize treatments, “as it is likely that some treatments work best for carriers, while others may be resistant,” said Rennert.