Among studies discussed Tuesday at the 50th annual meeting of the American Society of Clinical Oncology were several that focused on treating women with triple-negative breast cancer, disease that tests negative for the hormone receptors estrogen and progesterone and for HER2; and women with early-stage breast cancer that is confined to the breast and lymph nodes.
Treatment for Hereditary TNBC
Several abstracts looked at treatments for triple-negative breast cancers among women with the gene mutations BRCA1 or BRCA2. These are hereditary gene mutations that greatly increase the chances of developing breast and ovarian cancer. Those with BRCA1 gene mutations are more likely to develop triple-negative than other types of breast cancer.
Findings from the phase II randomized GeparSixto study were presented Tuesday by Gunter Von Minckwitz, MD, PhD, chairman of the German Breast Group and professor at the University of Frankfurt. His team found that adding carboplatin to standard chemotherapy before surgery increased the chances of ridding the body of early triple-negative breast cancer among those with either a BRCA mutation or a family history of breast or ovarian cancer. Carboplatin is a platinum chemotherapy medicine used to treat ovarian, lung and other cancers.
The researchers looked at pathologic complete response, meaning cancer cannot be found after pre-surgery chemotherapy. Among women with no BRCA gene mutation, the study found a pCR rate of 40.2 percent. But that rate increased to 44.9 percent in women with a family history but no mutation, and to 57.9 percent in women with a BRCA mutation. Adding carboplatin increased the pCR rate by 14 percent, 20 percent, and 25 percent, respectively.
Knowing the BRCA status and family cancer history may help doctors weigh whether to recommend including carboplatin—and its known side effects—to pre-surgery treatment for TNBC, Dr. Minckwitz said. Common side effects include low blood cell counts, hair loss and nausea.
It is important to note that this analysis included 295 participants, of whom only 38 had a BRCA mutation and 78 a family history. The hereditary gene mutations were mostly BRCA1.
Melinda Telli, MD, of Stanford Cancer Institute in California, said after the presentation, “In my opinion [gene mutation status] has implications for all therapeutic studies in triple-negative breast cancer, and I would advocate this should be more uniformly assessed in triple-negative breast cancer trials moving forward.”
Predicting Return of Early-Stage Breast Cancer
A test recently approved by the FDA, called PAM50 or Prosigna, may be useful for predicting the chances of cancer returning to the breast and lymph nodes in postmenopausal women with hormone-sensitive early-stage disease. The test, which examines changes in 50 genes, could help prevent unnecessary surgery among this group, according to results presented Tuesday by Florian Fitzal, MD, of the Medical University of Vienna, Austria.
The researchers looked at tumor samples from 1,308 women who took part in the ABCSG 8 clinical trial. The participants had hormone-positive, HER2 negative disease in the breast and in up to three lymph nodes. For treatment, they received either mastectomy or lumpectomy followed by radiation therapy, and all took 5 years of hormonal therapy with either tamoxifen alone or tamoxifen followed by an aromatase inhibitor.
Using the PAM50, the researchers predicted the women’s risk of cancer returning to the breast and lymph nodes based on the cancer’s subtype of luminal A or luminal B. Both types are hormone-sensitive, but luminal B cancers tend to have genetic traits that make them more aggressive.
After an average of 11 years follow-up, the test successfully predicted which participants had local or regional recurrences based on the cancer subtype, no matter what the women’s age, the size of tumor or the number of lymph nodes with cancer. It also showed lumpectomy plus radiation did not impact participants’ chances of having cancer return, even when they had the more aggressive luminal B subtype. This suggests the surgery choice does not affect the chances of regional recurrence in these breast cancer subtypes.
During discussion after the presentation, Julia White, MD, of Ohio State University, said the test may help women with early-stage breast cancer confused by the multitude of surgery options.
“This is additional evidence that gene profiles can be used to stratify…risk of local recurrence,” Dr. White said. “This brings us one step closer to more personalized local therapy for early-stage breast cancer.”
Look for more updates from the meeting in the coming weeks, and learn more about our free webinar covering findings from ASCO, to be held noon to 1 p.m. ET on Tuesday, June 24.