Abstract
BACKGROUND: Patients with breast cancer planned for neoadjuvant chemotherapy (NAC) represent a diverse population including high-risk early breast cancer (EBC) and locally advanced breast cancer (LABC). Staging investigations are routinely performed, but the clinical utility is unclear. METHODS: Using a provincial cancer registry, we identified breast cancer patients referred for NAC between 2020 and 2022. Patients with staging investigations were stratified into EBC (anatomic clinical stage I-II) and LABC (stage III). Rates of metastatic (M1) disease and associated factors were assessed. RESULTS: Among 529 EBC patients, 515 (97.4%) underwent staging. The M1 disease rate was 5.4%. The M1 rate for cT1-2N0 was 1.1%, and for cT1-2N1 it was 7.9%. In multivariable analysis, cT1N1 (OR 5.31; 95% CI 1.05-27.0; p = 0.044) and cT2N1 (OR 4.59; 95% CI 1.02-20.67; p = 0.047) were associated with M1 disease in EBC. All 320 LABC patients underwent staging. The M1 disease rate was 22.8%, significantly higher than in EBC (p < 0.001). A higher cT/N stage correlated with M1 disease in LABC, although most subgroups demonstrated rates of ≥10%. CONCLUSIONS: These findings support a risk-adapted approach to pre-treatment staging in patients planned for NAC, omitting staging in asymptomatic cT1-2N0 disease, considering it for node-positive EBC, and performing it routinely in LABC.