Can axillary surgery be omitted in patients with breast pathologic complete response after neoadjuvant systemic therapy for breast cancer? A real-world retrospective study in China

Purpose Studies show that axillary surgery can be potentially omitted in certain breast cancer patients who achieve breast pathologic complete response (pCR) after neoadjuvant systemic therapy (NST). However, potential differences between the ypT0 and ypTis subgroups remain to be explored. Furthermore, whether axillary surgery can be omitted in patients with clinically assessed positive axillary lymph nodes (cN+) remains unknown. This study was to evaluate the status of axillary lymph nodes for patients who achieved breast pCR after NST in the real-world study. Methods This retrospective cohort study included 258 patients with early or locally advanced breast cancer who underwent breast and axillary surgery after NST. Clinical and pathologic data were compared between patients with breast pCR (ypT0/is) and those without breast pCR. Results The rate of breast pCR after NST was 27.1% (70/258). Among the patients with initial cN0, the rate of axillary pCR was similar between the breast pCR and breast non-pCR groups (100% vs. 85.7%, P = 0.1543). Among those with breast pCR, the rate of axillary pCR was 100% in both the ypT0 and ypTis subgroups. Furthermore, among those with initial cN+, the rate of axillary pCR was higher in the breast pCR group than in the breast non-pCR group (82.7% vs. 22.9%, P < 0.0001). Among the patients with breast pCR, the rate of axillary pCR was higher in the ypT0 subgroup than in the ypTis subgroup (94.3% vs. 58.8%, P = 0.0034). Conclusion Axillary surgery may potentially be omitted in patients with initial cN0 who achieve breast pCR (ypT0/is), and may also be considered for omission in patients with initial cN + who achieve ypT0 (not ypTis).