Impact of residual microcalcifcations on prognosis after neoadjuvant chemotherapy in breast cancer patients

Background Residual microcalcifications after neoadjuvant chemotherapy (NAC) are challenging for deciding extent of surgery and questionable for impact on prognosis. We investigated changes in the extent and patterns of microcalcifications before and after NAC and correlated them with pathologic response. We also compared prognosis of patients depending on presence of residual microcalcifications after NAC. Methods A total of 323 patients with invasive breast carcinoma treated with neoadjuvant chemotherapy at Kangbuk Samsung Hospital and Samsung Medical center from March 2015 to September 2018 were included. Patients were divided into four groups according to pathologic response and residual microcalcifications. Non-pCR(w/mic) group was defined as breast non-pCR with residual microcalcifications. Non-pCR(w/o mic) group was breast non-pCR without residual microcalcifications. pCR(w/mic) group was breast pCR with residual microcalcifications. pCR(w/o mic) group was breast pCR without residual microcalcifications. The first aim of this study is to investigate changes in the extent and patterns of microcalcifications before and after NAC and to correlate them with pathologic response. The second aim is to evaluate oncologic outcomes of residual microcalcifications according to pathologic response after NAC. Results There were no statistical differences in the extent, morphology, and distribution of microcalcifications according to pathologic response and subtype after NAC (all p > 0.05). With a median follow-up time of 71 months, compared to pCR(w/o mic) group, the hazard ratios (95% confidence intervals) for regional recurrence were 5.190 (1.160-23.190) in non-pCR(w/mic) group and 5.970 (1.840-19.380) in non-pCR(w/o mic) group. Compared to pCR(w/o mic) group, the hazard ratios (95% CI) for distant metastasis were 8.520 (2.130-34.090) in non-pCR(w/mic) group, 9.120 (2.850-29.200) in non-pCR(w/o mic) group. Compared to pCR(w/o mic), the hazard ratio (95% CI) for distant metastasis in pCR(w/mic) group was 2.240 (0.230-21.500) without statistical significance (p = 0.486). Conclusions Regardless of residual microcalcifications, patients who achieved pCR showed favorable long term outcome compared to non-pCR group.