CHICAGO – Patients with clinically node-negative HER2-positive or triple-negative breast cancer (TNBC) who achieve a pathological complete response in the breast after neoadjuvant chemotherapy could benefit from clinical trials to evaluate the option of omitting axillary node surgery in this population, according to a retrospective analysis of more than 22,000 cases in the National Cancer Database reported at the Society of Surgical Oncology Annual Cancer Symposium.
Alison U. Barron, MD, breast surgery oncology fellow at Mayo, presented the results. “In patients with HER2+ breast cancer and TNBC who are clinically node negative (cN0) and achieve a breast pathological complete response, this data supports omitting axillary surgery in clinical trials assessing no surgery after neoadjuvant chemotherapy (NAC),” she said. “In patients who present with clinically positive node [cN1] disease with a breast pathological complete response, surgical staging of the axilla is still recommended.”
“Response rates to NAC have increased,” Dr. Barron said. She cited previous reports that showed response rates ranging from 9%-13% for anthracyclines to 19%-26% with the addition of taxanes, and to 60%-70% with the addition of trastuzumab and pertuzumab in HER2+ disease. “Furthermore, we know that tumor biology affects response rates, with TNBC and HER2+ disease having the highest rates of pathologic complete response,” she said.
“In the current era when we frequently operate on patients, we find no residual cancer in the tissue at the time of surgery,” Dr. Barron said. “The question arises as to whether we can limit surgery in patients with a pathological complete response.” While imaging has limited ability to reliably detect pCR with 100% specificity, she noted that recent trials have shown the potential of tumor-bed biopsy to identify pCR in patients after NAC (Ann Surg. Published online Oct. 23, 2017.; ).
The National Cancer Database data the Mayo researchers analyzed yielded an overall breast pCR of 29%. “When broken down by tumor subtype, we saw significantly higher rates of breast pCR in patients with HER2+ disease (42%, n = 3,107) and TNBC (35%, n = 2,469), compared with patients with hormone-receptor positive (HR+)/HER2-negative disease (12%, n = 1,020),” she said.