Predictors of Pathologic Complete Response Following Neoadjuvant Chemotherapy in Invasive Breast Cancer With Microcalcifications

Background/Aim: Microcalcifications associated with breast cancer often persist after neoadjuvant chemotherapy (NAC), complicating surgical decision-making even when pathologic complete response (pCR) is achieved. This study aimed to identify clinical and imaging factors associated with pCR in invasive breast cancer with microcalcifications following NAC. Patients and Methods: This retrospective study included 106 female patients with invasive ductal carcinoma and mammographic microcalcifications who underwent NAC followed by surgery at a single institution between January 2021 and January 2023. Clinicopathological characteristics, breast magnetic resonance imaging (MRI) response, and changes in microcalcifications on mammography were analyzed. Univariate and multivariable logistic regression analyses were performed to identify independent predictors of pCR. Results: The overall pCR rate was 45.3% (48/106). pCR rates by molecular subtype were: HER2-enriched 81.5%, HR+/HER2+ 52.8%, triple-negative 25.0%, and Luminal A 11.1% (p<0.001). Radiologic complete response (rCR) on breast MRI was achieved in 46 patients, of whom 37 (80.4%) achieved pCR (p<0.001). Decreased or disappeared microcalcifications after NAC were associated with a higher, though non-significant, pCR rate (60.9% vs. 41.0%; p=0.266). On multivariable analysis, rCR [odds ratio (OR)=14.29; 95% confidence interval (CI)=5.00-50.00; p<0.001), HER2-enriched subtype (OR=25.00; 95%CI=4.55-100.00; p<0.001), and HR+/HER2+ subtype (OR=5.26; 95%CI=1.15-33.33; p=0.043) were independent predictors of pCR. A predictive model incorporating rCR, molecular subtype, and microcalcification response yielded an area under the ROC curve (AUC) of 0.904. Conclusion: In patients with invasive breast cancer and microcalcifications undergoing NAC, HER2-enriched molecular subtype and radiologic complete response on breast MRI are strong independent predictors of pCR. These findings may help surgeons consider less extensive resection of calcified areas in selected patients.