Correlation of quantified metabolic activity in nonsmall cell lung cancer with tumor size and tumor pathological characteristics

The aim of this study was to evaluate the relationship between maximum standardized uptake value (SUV(max)) with tumor size and tumor pathological characteristics as well as suggesting equations between SUV(max) and tumor size in patients with nonsmall cell lung cancer (NSCLC) to help differentiate between pathology types. We retrospectively analyzed the fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) findings of 98 patients with NSCLC. Statistical differences were considered significant when P < .05. Correlation between SUV(max) and other variables was determined by Pearson and Spearman correlation. Both linear and nonlinear regression analysis were used to determine equations between SUV(max) and tumor size to help differentiate between pathology types. The mean SUV(max) in patients with squamous cell carcinoma was significantly higher than that of adenocarcinoma (21.35 ± 1.73 vs 13.75 ± 0.89, P = .000). The results of regression analysis indicated that among all equations determined with relative accuracy, the “cubic equation” has the highest accuracy when considering the relationship between SUV(max) and tumor size in patients with adenocarcinoma. In patients with squamous cell carcinoma, the most accurate equation was obtained using the “quadratic equation.” There was a significant correlation between SUV(max) and tumor differentiation and tumor size in patients with adenocarcinoma. SUV(max) of patients with squamous cell carcinoma also had a significant correlation with tumor size. Overall SUV(max) of patients with NSCLC could be predicted by tumor size value. In patients with squamous cell carcinoma compared with those with adenocarcinoma, SUV(max) with less accuracy can be determined by tumor size. Linear regression analysis line slope can be used as an index for distinguishing adenocarcinoma from squamous cell carcinoma.