According doctoral candidate, Alexandra van den Broek, “Our study is, as far as we know, the first study showing that within certain carriers of BRCA mutations, subgroups with an increased or decreased risk for contralateral breast cancer (CBC) can be made."
Researchers surveyed over 5,000 women diagnosed with unilateral, invasive breast cancer in 10 hospitals in the Netherlands. Two hundred and eleven women carried the BRCA1 or BRCA2 mutation. After a median follow-up of 8 years, nearly 9 percent of participants developed breast cancer in the other breast. The overall 10-year risk for developing contralateral breast cancer in gene noncarriers was 6 percent and the risk for carriers was nearly 18 percent.
For gene carriers diagnosed with their first breast cancer at below the age of 40, the 10-year risk for developing contralateral breast cancer rose to an alarming 26 percent. Between the ages of 40 and 50, the risk was only 11.6 percent.
Additionally, mutation carriers with a triple-negative first tumor had a 10-year cumulative risk of 18.9 percent for developing contralateral breast cancer compared with just 11.2 percent among carriers with a non-triple-negative first tumor.
van den Broek cautioned that although the figures can seem surprising to cancer survivors, she explained it is critical to know who faces the highest risk and by how much. She states, "Guidelines for prophylactic measures and screening in the follow-up of patients with breast cancer carrying the BRCA1 or BRCA2 mutation are important to provide patients with the best information and counseling ... If these results are confirmed, [it will be] possible to personalize the guidelines for these specific subgroups."
The next phase of van den Broek’s research will be to confirm her results among a study with a wider range of patients, and to explore the data more deeply to determine subgroups with increased or decreased risks.