A study conducted by University of Toronto cancer specialist Dr. Steven Narod has recently revealed that women with a family history of breast cancer faced high risk of developing the disease themselves even if the they tested negative for gene mutations that can cause that type of cancer.

The breast cancer’s most common gene mutations are BRCA1 and BRCA2, but they are only responsible for 15 percent of the total number of the disease’s cases, with just one person in five tested from the same family developing cancer because of a BRCA gene.

For the research, Dr. Steven Narod monitored approximately 1,500 women from families with a history of breast cancer, all of whom had tested negative for the BRCA1 and BRCA2 mutations.

After having tracked the women over a period of five years, Narod found that they were exposed to a higher by four times risk of developing breast cancer than average women.

Consequently, the researcher, who reported his findings on Monday at a meeting of the American Association for Cancer Research, deemed women’s family histories a much stronger predictor of breast cancer than the gene tests. Furthermore, he urged women who fell into the category of ones with a family history of the disease to take the anti-cancer drug tamoxifen, as well as to appeal to MRI cancer checkups instead of undergoing mammograms, which is currently the mainstay method to diagnose breast cancer.

Although the BRCA1 and BRCA2 gene mutations are also linked to high risk of developing ovarian cancer, Narod’s study did not show that women with a family history of breast cancer were more prone to developing ovarian cancer too.