Calcifications Affect Pathologic Complete Response and MRI Prediction after Neoadjuvant Chemotherapy in Human Epidermal Growth Factor Receptor 2-positive Breast Cancer

Background: The optimal surgical management of human epidermal growth factor receptor 2 (HER2)-positive breast cancer with calcifications remains controversial, particularly when pathologic complete response (pCR) is suspected. Purpose: To identify factors associated with pCR after neoadjuvant chemotherapy in patients with HER2-positive breast cancer and assess whether calcifications affect the performance of radiologic complete response (rCR) at MRI for predicting pCR. Materials and Methods: This retrospective study included patients with HER2-positive breast cancer who received neoadjuvant docetaxel, carboplatin, trastuzumab, and pertuzumab and underwent surgery between January 2021 and October 2023. The association of clinicopathologic factors and imaging features at mammography and MRI with pCR was analyzed using logistic regression. The diagnostic performance of rCR at MRI for predicting pCR was compared between patients with and without calcifications using the χ² test. Results: Among the 732 patients included (mean age, 51.9 years ± 10.3 [SD]), 64.8% (474 of 732) had calcifications, 47.0% (344 of 732) had rCR at MRI, and 41.1% (301 of 732) had pCR. The factors associated with pCR included the estrogen receptor-low subtype (odds ratio [OR], 3.07 [95% CI: 1.31, 7.21]; P = .006), the hormone receptor-negative subtype (OR, 3.28 [95% CI: 2.16, 4.98]; P < .001), absence of calcifications (OR, 1.65 [95% CI: 1.15, 2.37]; P = .006), and rCR at MRI (OR, 7.33 [95% CI: 5.18, 10.38]; P < .001). The pCR rate and positive predictive value (PPV) of rCR at MRI were lower in patients with calcifications than in patients without calcifications (pCR, 37.1% vs 48.4%, P = .003; PPV, 60.0% vs 73.1%, P = .01). When the pCR definition was broadened from ypT0 to ypT0/Tis, there was no evidence of a difference in pCR rate between patients with and without calcifications (62.0% vs 58.5%; P = .35). Conclusion: In patients with HER2-positive breast cancer, the absence of calcifications was associated with a higher pCR rate and a higher PPV for rCR at MRI for predicting pCR.