Outcome after pathologic complete eradication of cytologically proven breast cancer axillary node metastases following primary chemotherapy

Purpose Pathologic complete remission (pCR) of primary breast tumors after primary chemotherapy (PCT) is associated with higher relapse-free survival (RFS) and overall survival (OS) rates. The purpose of this study was to determine long-term outcome in patients achieving pCR of cytologically proven axillary lymph node (ALN) metastases. Methods Patients with cytologically documented ALN metastases were treated in five prospective PCT trials. After surgery, patients were subdivided into those with and without residual ALN carcinoma. Survival was calculated by the Kaplan-Meier method. Results Of 925 patients treated, 403 patients had cytologically confirmed ALN metastases. Eighty-nine patients (22%) achieved ALN pCR after PCT. Compared with the group without ALN pCR, 5-year CIS and RFS were improved in patients achieving ALN pCR (93% [95% Cl, 87.5 to 98.51 and 87% [95% Cl, 79.7 to 94.31 v 72% [95% Cl, 66.5 to 77.5] and 60% [95% Cl, 54.1 to 65.9], respectively; P < .0001). Residual primary tumor did not affect outcome of those with ALN pCR. Combination anthracycline/taxane-based PCT resulted in significantly more ALN pCRs, although outcome after ALN pCR was not improved by taxanes. We constructed a nomogram demonstrating that patients who do not benefit from neoadjuvant anthracyclines are unlikely to benefit from subsequent taxanes. Conclusion ALN pCR is associated with an excellent prognosis, even with a residual primary tumor, pointing to biologic differences between primary and metastatic cells. ALN pCR represents an early surrogate marker of long-term outcome. Response to initial PCT has important potential as a guide to subsequent therapy.