Changes in Ki-67 in Residual Tumor and Outcome of Primary Inflammatory Breast Cancer Treated With Trimodality Therapy

Background: Limited data are available on the prognostic role of Ki-67 changes in residual tumors after neoadjuvant chemotherapy in primary inflammatory breast cancer (IBC) patients treated with trimodality therapy. This study aims to evaluate changes in Ki-67 associated with disease-free survival (DFS) and overall survival (OS) in IBC patients without pathological complete response.

Patients and methods: We identified a cohort of primary IBC patients with matched pre- and posttreatment samples treated with anthracycline and taxane-based regimen. All patients had a pathological evaluation, including ER, PR, HER2 status, and Ki-67 expression performed both at diagnostic core biopsy and at final surgery. Kaplan-Meier and Cox proportional hazards methods were used to assess DFS and OS rates and their relationship with clinicopathological features.

Results: Two hundred and ten patients with stage III IBC were included. Sixty-three percent of residual tumors showed a decrease in Ki-67 positivity by at least 1%. The decrease of Ki-67 significantly correlated with better DFS (p = .001) and OS (P = .010) compared with no decrease, particularly in the luminal B-like and HER2-positive subgroups. The multivariate analysis showed that the decrease in Ki-67 level had a significant positive predictive value on DFS (HR = 0.47, 95% CI: 0.33-0.67; P< .001) and OS (HR = 0.59, 95% CI: 0.36-0.82; P= .004) in all IBC patients.

Conclusion: The decrease of Ki-67 expression after neoadjuvant chemotherapy has a prognostic significance in IBC patients with residual disease. Evaluation of Ki-67 changes may help to identify subgroups of patients with worse outcome to receive novel treatment in this setting.