Correlation between maximum standardized uptake values on FDG-PET and microenvironmental factors in patients with clinical stage IA radiologic pure-solid lung adenocarcinoma.

OBJECTIVES

The purpose of this study was to investigate whether fluorodeoxyglucose (FDG) accumulation is associated with the expression of microenvironmental factors in radiological pure-solid lung adenocarcinoma.

METHODS

We selected 50 cases involving patients with clinical stage IA radiological pure-solid lung adenocarcinoma who were examined with 18 F-FDG positron emission tomography (18 F-FDG PET) prior to surgery and whose FDG-PET maximal standardized uptake values (SUVmax) were calculated. Tumor specimens were analyzed by immunohistochemistry (IHC) for phosphorylated AKT (pAKT), glucose transporter type 1 (GLUT-1), carbonic anhydrase IX (CA IX), podoplanin-positive cancer associated fibroblasts (PDPN + CAFs), and CD204-positive tumor-associated macrophages (CD204+ TAMs). We compared the clinicopathological characteristics and the immunophenotypes between two groups with high and low SUVmax.

RESULTS

A multivariate analysis revealed that SUVmax was an independently significant prognostic factor (P = .03). The 5-year overall survival (OS) and recurrence free survival (RFS) rates of the SUV max high and low groups were 68.0% versus 100% ((P = .002; OS) 54.3% versus 90.8% (P < .001; RFS)), respectively. Vascular invasion, pleural invasion, and the prevalence of solid predominant subtype tumors were more frequent in the SUVmax high group. Additionally, the expression levels of GLUT-1 and pAKT in cancer cells were significantly higher in this group (P < .001, and P < .001 respectively). Furthermore, the numbers of the tumor-promoting stromal cells, i.e., PDPN + CAFs and CD204+ TAMs, were also significantly higher in the SUVmax high group (P = .001, and P < .001 respectively).

CONCLUSION

Our results indicated that a close association exists between the SUVmax and expressions of not only metabolism associated markers in cancer cells but also of tumor promoting markers in stromal cells among patients with clinical stage IA adenocarcinoma with radiologically pure-solid nodules.