Genetic Testing Is Increasingly Important in Breast Cancer

The use and importance of genetic testing is growing in the breast cancer space, especially as more targeted and personalized therapies are moving through the pipeline and into the clinic.

For example, for patients with HER2-negative metastatic breast cancer with germline BRCA mutations, there have been 2 PARP inhibitors approved — olaparib (Lynparza) and talazoparib (Talzenna).

“Now that PARP inhibitors are FDA approved for metastatic breast cancer with germline BRCA mutations, physicians could use PARP inhibitors for their patients with metastatic BRCA-positive breast cancer,” Banu K. Arun, MD, said in an interview with OncLive, a sister publication of Oncology Nursing News.

Arun, the co-medical director of breast medical oncology in The Clinical Cancer Genetics Program at The University of Texas MD Anderson Cancer Center, recently sat down with OncLive to discuss genetic testing in breast cancer. She emphasized that for patients with BRCA1- and BRCA2-mutatnt metastatic breast cancer, response rate is almost doubled for the patients who are given a PARP inhibitor.

Also, women with a BRCA mutation should also discuss the risk of ovarian cancer with their healthcare providers, too, as risk for the disease is up to 45% in patients with a BRCA1 mutation, and 25% for those with a BRCA2 mutation, according to Arun.

“There are also family implications,” she said. “Once you find a mutation in the patient, each first-degree relative has a 50% risk of carrying the mutation; ideally, these family members should consider genetic testing. If they are positive, then they would do risk management interventions, such as adding MRI to their breast screening, considering double mastectomy, ovarian screening or oophorectomy.”

While genetic testing for family members could lead to greatly improved outcomes, many individuals express apprehension about getting it done, according to a genetic counselor, who said that the results could be emotionally overwhelming.

When patients with breast cancer and their family members do go for genetic testing, providers should be looking for more than just BRCA mutations. They should also be checking for abnormalities in PALB2, ATM, and CHEK2, which can be ordered on the same testing panel as BRCA1 and BRCA 2.

“If patients are positive, it might not have immediate therapeutic implications at this time, as we do not have sufficient data,” Arun said. “For example, we don’t have enough data to recommend bilateral mastectomy. However, for unaffected family members, it can have screening implications, such as adding MRIs to the screening or screening for other cancers.”

Additionally, having that extra genetic information may come into play down the line. Arun noted that there are multiple clinical trials looking at PARP inhibitors in combinations — including some examining other hereditary mutations, such as PALB2.

Ultimately, oncology nurses and other providers should always discuss family history with their patients when considering genetic testing and the possibility of genetic mutations.

“If they have a patient with, for example, breast and uterine cancer, and a family history of thyroid cancer, maybe the patient is a candidate for PTEN mutation testing,” Arun said. “Some patients with breast cancer have family members with colon cancer and ovarian cancer, therefore checking for Lynch syndrome might be helpful.”

“Taking into account personal history of cancer, age of onset is important, as well as considering any family history of different types of cancer.”

A version of this article originally appeared on OncLive as, “Significance of Genetic Testing Continues to Increase in Breast Cancer.”