Does 18F FDG PET/CT paramaters predict histopathologic response to the neoadjuvant therapy in patients with non-small cell lung cancer?

Objective: Progression-free and overall survival are better correlated with metabolically active tumor volume (MTV) and total lesion glycolysis (TLG), as compared to the maximum standardized uptake value (SUVmax) in NSCLC patients. In this study, we aimed to evaluate the correlation between the PET-CT parameters and histopathologic tumor regression score in non-small cell lung cancer(NSCLC) patients after treatment with neoadjuvant chemotherapy.(1) Methods: This retrospective study evaluated stage III lung cancer patients who were treated with neoadjuvant chemotherapy followed by surgical resection at a single institution between 2014 and 2018. The 3-dimensional volumes of interest were drawn in primary tumor and largest lymph node on the pretreatment examination and corresponding location on the post-treatment examination to obtain a pre- and post-treatment SUVmax, SUVmean, MTV and TLG. All hematoxylin- and eosin-stained surgery specimens were assessed based on a 4-tiered scale. Results: Patients who had lower than 10% histologic response established higher values of SUVmax, in tumor as compared to good responders in basal PET CT assessment (p:0.014). Patients who established higher than 10% pathologic response showed higher reduction rates in terms of SUVmax (p:0.002), mean tumor volume (p:0.024), and total lesion glycolysis (p:0.009). The overall survival for patients with <10% histologic response was 15.26 months while the patients with good histologic response had 35.36 months and the difference was statistical significance (p<0.001). Due to univariate analysis, the higher SUVmax, TLG and MTV reduction have been found in association with better overall survival. Conclusion: PET CT parameters may be useful to predict histopathologic response for NSCLC patients who received neoadjuvant chemotherapy.