Correlation between Semi-Quantitative F-18-FDG PET/CT Parameters and Ki-67 Expression in Small Cell Lung Cancer

Abstract

Purpose The aimof this study was to evaluate the relationship between semiquantitative parameters on F-18-FDG PET/CT including maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) and the expression level of Ki-67 in small-cell lung cancer (SCLC). Methods Ninety-four consecutive patients with SCLC were enrolled in this study. They underwent F-18-FDG PET/CT for initial evaluation of SCLC, and we measured SUVmax, avgSUVmean, MTVsum, and TLGtotal on F-18-FDG PET/CT images. The protein expression of Ki-67 was examined by immunohistochemical staining. Results Significant correlations were found between the MTVsum and Ki-67 labeling index (r=0.254, p=0.014) and the TLGtotal and Ki-67 labeling index (r=0.239, p=0.020). No correlation was found between the SUVmax and Ki-67 labeling index (r=0.116, p=0.264) and the avgSUVmean and Ki-67 labeling index (r=0.031, p=0.770). Dividing the Ki-67 expression level into three categories, it was suggested that increasing Ki-67 expression level caused a stepwise increase in the MTVsum and TLGtotal. (p=0.028 and 0.039, respectively), but not the SUVmax and avgSUVmean (p=0.526 and 0.729, respectively). Conclusion In conclusion, the volume-based parameters of F-18-FDG PET/CT correlate with immunohistochemical staining of Ki-67 in SCLC. Measurement of the MTVsum and TLGtotal by F-18-FDG PET/CT might be a simple, non-invasive, and useful method to determine the proliferative potential of cancer cells.