Non-invasive and invasive breast cancers share the same genetic mutations

Women diagnosed with early stage, non–invasive breast cancer who carry the same mutations in two inherited breast/ovarian cancer genes as women diagnosed with invasive breast cancer, may benefit from high risk treatment, Yale researchers report in the February 23 issue of Journal of the American Medical Association.

The inherited breast/ovarian cancer genes are BRCA1 and BRCA2, which are associated with an increased risk of breast and/or ovarian cancer. The results are part of a five–year study of a common form of early stage breast cancer called ductal carcinoma in situ (DCIS). Led by Elizabeth B. Claus, M.D., associate professor in the Department of Epidemiology and Public Health (EPH) at Yale School of Medicine, the Yale team examined genetic and environmental risk factors for the development of DCIS. They genetically tested 369 women with DCIS for alterations in BRCA1 and BRCA2. “We found that 0.8 percent of these women had disease–associated mutations in BRCA1, while 2.4 percent had such mutations in BRCA2,” said Claus. “These numbers are similar to those reported for women with more advanced breast cancer.”

Claus said women with mutations were more likely to be diagnosed with DCIS at a young age, to have also been diagnosed with ovarian cancer and to have a first degree family member (mother, sister or daughter) diagnosed with breast cancer, particularly at a young age. “This study highlights the fact that although DCIS is generally associated with a favorable clinical prognosis, it is important to consider women diagnosed with DCIS and with an appropriate personal or family history of breast and ovarian cancer, as potential members of the inherited breast/ovarian cancer syndromes defined by BRCA1 and BRCA2,” said Claus. “As such, this subset of DCIS patients should be screened and followed according to high–risk protocols as are similar women diagnosed with invasive breast cancer.”