Histological Subtypes of Lung Adenocarcinoma Have Differential 18F-Fluorodeoxyglucose Uptakes on the Positron Emission Tomography/Computed Tomography Scan

Introduction: Previous studies have shown that lung squamous cell carcinoma has higher (18)F-fluorodeoxyglucose (FDG) uptake on positron emission tomography (PET) than adenocarcinoma. We hypothesized that histological subtypes of lung adenocarcinoma were also different in (18)F-FDG uptake. Methods: Patients who had preoperative PET/computed tomography (CT) scan and had undergone complete resection for lung adenocarcinoma between April 2007 and December 2009 were enrolled in this study. Because of the limitation of spatial resolution on PET/CT, tumors less than 1 cm were excluded for analysis. Two independent classification systems were used to categorize histological subtypes of adenocarcinoma; one was modified from the current World Health Organization classification and the other used the morphological features of the terminal respiratory unit (TRU). The maximal standardized uptake value (SUVmax) on PET/CT and the glucose transporter type 1 (GLUT-1) expression of the tumors were measured and correlated to the histology of lung adenocarcinoma. Results: One hundred fifty-two patients with 153 primary lung adenocarcinomas were included. There was a significant difference in SUVmax among different histological subtypes. Namely, solid predominant adenocarcinomas had significantly higher SUVmax than those with other predominant histology (p < 0.001), and TRU-type adenocarcinomas had significantly lower SUVmax than non-TRU-type adenocarcinomas (p < 0.001). Consistently, GLUT-1 expression was higher in tumors with a solid growth pattern than those without (p < 0.001) and in tumors with non-TRU type than TRU type (p < 0.001). Conclusions: The histological subtypes of lung adenocarcinomas differ in GLUT-1 expression and (18)F-FDG uptake on the PET/CT scan, suggesting that histological subtyping not only has morphological but also biological implications.