Women newly diagnosed with breast or ovarian cancer who are also carriers of cancer-associated mutations like BRCA1 or BRCA2 are no more likely to die of their tumors than those who don’t have the mutations, according to a new study as reported in a news release from Stanford University.
Increasingly, doctors recommend genetic testing for newly diagnosed breast or ovarian cancer patients to learn whether they carry any of several inherited cancer-associated mutations. Knowing a cancer’s genetic fingerprint can help doctors sift among treatment options, and it can help alert a patient’s blood relatives that they might also carry the risky mutation.
However, women who learn that they carry such a mutation may worry it means they face a worse outcome. Yet, a study of about 26,000 people with breast or ovarian cancer shows that, in fact, carriers of inherited mutations have equivalent or better outcomes than women without these mutations — perhaps due to a greater sensitivity to the chemotherapy often used to treat such cancers.
The researchers studied about 22,000 breast cancer and 4,000 ovarian cancer patients in California and Georgia who were diagnosed between 2013 and 2017 and whose genetic test results, treatment and disease course were known. About 17% of ovarian cancer patients carried mutations in any of several cancer-associated genes; between 10% and 17% of breast cancer patients had any of the mutations. (The percentage varied according to the type of breast cancer the women had.) Patients were followed for about 41 months after diagnosis.
The researchers found that none of the mutations increased the likelihood that the women died from their cancer during the study period. In fact, among patients with a type of cancer called triple-negative breast cancer, the presence of a BRCA1 or BRCA2 mutation decreased the likelihood that they would succumb to their disease within the study period, as did the presence of BRCA2 mutation in women with ovarian cancer.
“Prior studies have suggested that patients with inherited mutations in genes such as BRCA1 and BRCA2 may be more responsive to chemotherapy because of their cancer’s reduced ability to repair damaged DNA,” Kurian said, “so it makes sense that these patients might have better survival. This is not surprising, but it is important to have solid evidence from a large, diverse, contemporary sample that represents the U.S. population.”
