Purpose: A number of studies have demonstrated that 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is effective for staging of lung cancer. However, the efficacy of FDG-PET for staging lung cancer after neoadjuvant treatment is still controversial. This study compared FDG-PET and computed tomography (CT) for lung cancer staging, and evaluated the ability of the two methods to predict the pathologic response of the primary tumor to neoadjuvant treatment.
Patients and methods: Twenty-two patients who underwent neoadjuvant treatment followed by surgery were investigated. Eighteen patients received chemoradiotherapy and four patients received chemotherapy only. One hundred and three lymph node stations in the 22 patients were evaluated by FDG-PET and CT. The pathologic responses of the tumors were compared by FDG-uptake and tumor size on CT for the 15 patients who underwent FDG-PET and CT both before and after neoadjuvant treatment.
Results: There was no significant difference in the ability of FDG-PET or CT to predict residual viable tumor. Although positive predictive value by FDG-PET (0.29) was lower than that by CT (0.64) (p=0.04) in the mediastinal lymph nodes, there were no statistically significant differences in the other results of lymph nodes by FDG-PET and CT. Both decrease in FDG-uptake and decrease in tumor size by CT after neoadjuvant treatment correlated significantly with pathologic response in the 15 patients (p=0.003 and 0.009, respectively).
Conclusion: FDG-PET did not appear to offer any advantages over CT for lymph node staging or for predicting the pathologic response after neoadjuvant treatment of non-small cell lung cancer.