Repopulation of tumor cells after neoadjuvant chemotherapy in non-small cell lung cancer and head and neck cancer: A neglected factor.

Abstract

e18533 Background: Neoadjuvant chemotherapy (NAC) has been widely used to patients with locally advanced Non-Small Cell Lung Cancer (NSCLC) or Head and Neck Cancer(HNC).Less is known about repopulation in human cancer after chemotherapy. It is hypothesized that NAC might be the preceding stimulus to activate the epidermal growth factor receptor (EGFR), which may trigger cellular repopulation. We aim to ananlyze whether NAC could trigger repopulation of surviving cells and evaluate the potential role of EGFR in molecular mechanisms that underlie accelerated repopulation after chemotherapy. Methods: Fifty-two patients with locally advanced NSCLC (28 cases) and HNC(24 cases) were studied. received platinum-based NACImmunohistochemical expressions of ki67 and EGFR were measured from biopsy before NAC and surgical specimens after NAC. Spearman rank correlation analysis and Chi-square test was used to determine whether pretreatment clinicopathological characteristics and time between last day of last chemotherapy and surgery are predictive of tumor cells repopulation. Results: The median duration between the last day of last chemotherapy and surgery was 15 days (range, 1–53 days).Twenty-one (40%) of fifty-two patients showed an increased Ki67 proliferative index PI after chemotherapy.The increased PI were significantly associated with poor clinical response and longer interval between last chemotherapy and surgery. No significant relationship was found between the change of Ki67 and clinicopathological characteristics including the location of the tumor, clinical stage, and histological grade,as well as the change of EGFR expression. A delay greater than 14 days produced greater increases in Ki-67 change ( p =0.028) than lesser delays. Conclusions: Our results suggest that tumor cell repopulation may frequently occur in patients with longer interval,especially greater than 14 days between the last day of last chemotheraoy and surgery. Our results did not suggest a higher EGFR expression lead to increased proliferation.