San Antonio Breast Cancer Symposium, Dec. 7-10

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The annual San Antonio Breast Cancer Symposium was held from Dec. 7 to 10 in San Antonio and attracted 8,000 participants from around the world, including medical oncologists, radiation oncologists, researchers, and other health care professionals. The conference highlighted recent advances in the risk, diagnosis, treatment, and prevention of breast cancer, with presentations focusing on emerging treatments in hard-to-treat patient populations, including patients with metastatic breast cancer.

In a phase 3 study of postmenopausal patients with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+/HER2−) metastatic breast cancer that progressed on prior endocrine and targeted therapies, Aditya Bardia, M.D., of the Massachusetts General Cancer Center and Harvard Medical School in Boston, and colleagues found that elacestrant, a developmental oral selective estrogen receptor degrader, offers improved progression-free survival (PFS) and a decreased risk for death compared with standard care.

The authors randomly assigned 477 patients in the second/third-line setting to receive either elacestrant or standard of care (fulvestrant or an aromatase inhibitor). Stratification factors included ESR1 mutation status, prior fulvestrant, and presence of visceral disease. The study had two primary end points of PFS; the secondary end points included overall survival, safety, tolerability, and quality of life. The study met both PFS primary end points. Compared with standard care, the reduction in the risk for disease progression or death in the elacestrant arm was 30 percent overall and 45 percent in patients with mutated ESR1. At 12 months, the rate of progression-free survival was higher in patients receiving elacestrant (22.32 percent) versus standard care (9.42 percent). For both end points, results in key prespecified subgroups, including visceral metastases, number of prior lines of therapy, pretreatment with fulvestrant, and geographical region, were consistent with the overall outcome.

"The prespecified interim analysis on overall survival planned at the time of the final PFS analysis demonstrated a trend in favor of elacestrant in all patients. The drug was well tolerated and the side effects in line with other hormonal therapies -- manageable and reversible," Bardia said. "Elacestrant has the potential to become the new therapeutic option for patients with ER+/HER2− metastatic breast cancer. The last endocrine therapy approved by the U.S. Food and Drug Administration was fulvestrant in 2002."

The study was supported by Radius Health, the developer of elacestrant.

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In an analysis of data from the I-SPY 2 clinical trial, Laura Esserman, M.D., of the University of California San Francisco Breast Cancer Center, and colleagues found that race does not significantly affect pathologic complete response and event-free survival associated with breast cancer treatment.

The authors analyzed data from 974 patients, which included follow-up data for 907 patients and a median follow-up time of 4.4 years. The researchers found that Black women who received appropriate therapies based on their tumor profiles saw the same treatment benefits as White women.

"The study highlights the need to broaden access to molecular diagnostic tests by expanding access in low-resource settings. Oncologists need to adopt risk stratifications using the modern tools of precision oncology," Esserman said. "It is critical for African American women to be able to get optimal care and seek out the centers that are engaged in cutting-edge trials and following the most up-to-date guidelines."

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Kirsten Kubler, M.D., Ph.D., of the Broad Institute in Cambridge, Massachusetts, and colleagues found that tamoxifen may increase the risk for uterine cancer through the phosphoinositol-3-kinase (PI3K) signaling pathway in patients with breast cancer.

The authors used whole-exome sequencing of tamoxifen-associated uterine cancers to characterize and better understand the molecular pathology and compared the results to de novo uterine cancers. The researchers found a decrease in the mutational frequency of two key genes in the PI3K signaling pathway in tamoxifen-associated uterine cancers, noting that this finding was surprising because these mutations are prevalent in de novo uterine cancer. Results were validated using droplet digital polymerase chain reaction in an independent set of tamoxifen-associated uterine cancers. In addition, preclinical studies were performed in mice to analyze the effect of tamoxifen on healthy endometria. These studies showed that tamoxifen alone can activate the PI3K pathway.

"Our findings introduce a new concept that drugs can sometimes take on the role of driver mutations, as we showed to be the case with tamoxifen," Kubler said. "This is in contrast to other drugs, such as chemotherapy, in which cells may acquire driver mutations that are caused or selected by drugs. In short, tamoxifen can activate PI3K cross-talk in the uterus, so that tamoxifen-associated uterine cancers do not need PIK3CA or PIK3R1 mutations."

A study coauthor disclosed financial ties to the pharmaceutical and biotechnology industries.

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SABCS: Black Race Predicts Breast Cancer-Related Lymphedema

MONDAY, Dec. 13, 2021 (HealthDay News) -- Black race is the strongest predictor of breast cancer-related lymphedema after axillary lymph node dissection, according to a study presented at the annual San Antonio Breast Cancer Symposium, held from Dec. 7 to 10 in San Antonio.

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