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ASBrS 2019: Factors Associated With Nonoperative Management of Select Patients With HER2-Positive Breast Cancer

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Key Points

  • Patients with incomplete pathologic response were more likely to have hormone receptor–positive than hormone receptor–negative tumors.
  • Also correlating with residual disease in the breast and nodes was incomplete radiologic response.
  • Women with both invasive disease and DCIS on initial biopsy were less likely than those without DCIS to achieve pathologic complete response in the breast.

Tumor hormonal status, possible ductal carcinoma in situ (DCIS) on initial biopsy, and imaging results following neoadjuvant chemotherapy may help physicians predict whether surgery might be safely eliminated for HER2-positive breast cancer that is traditionally treated aggressively. These findings were presented by Sun et al at the Annual Meeting of the American Society of Breast Surgeons (ASBrS). The new study compared the clinicopathologic characteristics of patients with HER2-positive breast cancer who had no evidence of residual cancer on a pathology report following neoadjuvant chemotherapy with those who did.

“More than 56,000 cases of HER2-positive breast cancer, a comparatively aggressive tumor, are diagnosed in the United States annually,” said lead researcher Susie Sun, MD, of The University of Texas MD Anderson Cancer Center. “Evidence is growing that certain patients are exceptional neoadjuvant chemotherapy responders, suggesting that when properly identified, someday certain … women may be candidates for nonoperative treatment.”

Dr. Sun pointed out, however, that confirmation of neoadjuvant chemotherapy response using traditional medical imaging is often inconclusive, with a high rate of false-negatives, making identification of appropriate patients difficult. “Our study show[ed] that hormone receptor positive–disease, presence of DCIS at diagnosis, and inconclusive imaging results following neoadjuvant chemotherapy correlated with an incomplete response to neoadjuvant chemotherapy, suggesting these women must go on to surgical treatment,” she explained.

Study Methods, Findings

The study examined 280 patients with HER2-positive breast cancer treated with neoadjuvant chemotherapy followed by surgical resection. Multivariate analyses were performed to determine predictors of residual disease. 

Of the 280 patients, 102 (36.4%) had a pathologic complete response to neoadjuvant chemotherapy in both the breast and lymph nodes. Patients with incomplete pathologic response were more likely to have hormone receptor–positive than hormone receptor–negative tumors (73.4% vs 50.8%, respectively; P < .0001). Also correlating with residual disease in the breast and nodes was incomplete radiologic response (odds ratio [OR] = 5.62, P = .002), meaning that radiologists were unable to rule out residual disease.

DCIS was found in 129 (46.1%) patients on initial biopsy. In this group, 32 (24.8%) had residual DCIS only following neoadjuvant systemic therapy. The therapy failed to eradicate in situ disease in 64.3% of patients. Women with both invasive disease and DCIS on initial biopsy were less likely than those without DCIS to achieve pathologic complete response in the breast (31% vs 43%, P = .038). Post-neoadjuvant chemotherapy imaging had a sensitivity of 97.1% and negative predictive value of 70.6% for residual cancer.

“This study is particularly important right now because it may help identify optimal patients for ongoing clinical trials omitting surgery for carefully selected HER2-positive patients,” commented the study’s principal investigator Henry Kuerer, MD, PhD, FACS, also of The University of Texas MD Anderson Cancer Center. “Findings are extremely important because of the inability of medical imaging to reliably confirm the absence of cancer following initial neoadjuvant chemotherapy. They help delineate the types of HER2-positive tumors that should not be included in our trials.”

“No one wants to have surgery unnecessarily,” said Dr. Sun. “This study and the clinical trial may help us delineate in the future which patients may be effectively treated nonoperatively, while allowing us to provide more aggressive surgical intervention to the women with HER2-positive breast cancer who need it.”

Disclosure:  For full disclosures of the study authors, visit breastsurgeons.org.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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