| Sumario: | Simple Summary: Radiological imaging is commonly used in patients with breast cancer to assess disease stage before starting chemotherapy, but its benefit varies by stage. Using population-wide data, we studied how often these tests detected cancer that had already spread in patients planned for chemotherapy before surgery. We found that cancer spread was very uncommon in patients with small tumors and no lymph node involvement, even when chemotherapy was planned, suggesting that routine staging scans can be safely avoided in this group. In contrast, patients with larger tumors or lymph node involvement had a higher likelihood of cancer spread. These results support more selective use of staging tests, which could reduce unnecessary scans, costs, patient anxiety, and treatment delays, while helping refine future guidelines and policy decisions. 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.
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