Can Some HER2-Positive Breast Cancer Patients Avoid Surgery?

Certain patients with HER2-positive breast cancer may eventually be eligible for non-surgical management of the malignancy, according to a new study. Patients with hormone receptor–positive tumors, radiologic evidence of residual disease following neoadjuvant chemotherapy, and ductal carcinoma in situ (DCIS) on initial biopsy were associated with incomplete pathologic response, suggesting that those without these characteristics could fare well without surgical management.

“Evidence is growing that certain patients are exceptional neoadjuvant chemotherapy responders, suggesting that when properly identified…[some] of these women may be candidates for non-operative treatment,” said Susie Sun, MD, of the University of Texas MD Anderson Cancer Center in Houston, according to a press release. She presented results of the new study at the American Society of Breast Surgeons Annual Meeting, held April 30–May 5 in Dallas.

The study included 280 women with clinical stage cT1-T2, cN0-N1 HER2-positive breast cancer, treated with neoadjuvant HER2-targeted regimens and who then underwent surgical resection and axillary surgery. Following neoadjuvant chemotherapy, 102 patients (36.4%) had a pathologic complete response (pCR) in the breast and lymph nodes, and 50 patients (17.9%) had residual DCIS in the breast only.

DCIS was a component on the initial biopsy in 46.1% of the cohort, and DCIS was eradicated after neoadjuvant chemotherapy in 35.7% of these patients. Sixty-nine percent of patients with DCIS on the initial biopsy had residual disease following therapy, compared with 57% of those without DCIS (P = .04). Hormone receptor–positive status was also a positive predictor of residual disease on a multivariate analysis, with an odds ratio of 2.7 (P < .0001). Incomplete radiologic response was also significantly associated with residual disease.

Combined imaging modalities including MRI, mammogram, and ultrasound had a sensitivity for pathologic response after neoadjuvant chemotherapy of 97.1%, and a specificity of 12.2%. The positive predictive value was 65.9%, and the negative predictive value was 70.6%.

“[The] findings are extremely important because of the inability of medical imaging to reliably confirm the absence of cancer following initial neoadjuvant chemotherapy,” said the study’s senior author Henry Kuerer, MD, PhD, also of MD Anderson Cancer Center.

The authors hope that these findings can help guide clinical trials testing whether surgery can be omitted from the therapy of HER2-positive breast cancer patients who respond particularly well to systemic therapy.

“As we look to the future of treatment for patients with breast cancer, it is clear that a better understanding of tumor biology will guide us in omitting unnecessary treatments for some tumor types while remaining appropriately aggressive for others,” said Carla Fisher, MD, of the Indiana University School of Medicine, according to a press release from the American Society of Breast Surgeons. “While still in the early stages of discovery, we look forward to additional research in this area to improve outcomes for our patients with breast cancer.”