Clinical utilities of FDG-PET/CT in small cell lung cancer

Objectives Small cell lung cancer (SCLC) has the most aggressive clinical course of pulmonary tumor and is treated in a different way from non-SCLC. However, the clinical value of FDG-PET/CT is not well established in SCLC patients. The purpose of this study was to evaluate clinical usefulness of FDG-PET/CT in SCLC.

Methods A total of 22 consecutive patients (pts) (20 males, 2 females, age 70.5±8.6) with histologically-proven SCLC who underwent FDG-PET/CT exam were included in this study. Fifteen pts underwent PET/CT scan prior to treatment, while 10 pts underwent scan after treatment. Among them, 3 pts underwent both pre- and post-treatment scans. The findings of PET/CT images were analyzed visually, and compared with the final diagnosis obtained after at least 6 months’ follow-up.

Results Before treatment, intense FDG uptake (SUV=8.3±2.8) was seen in all of the primary tumors. The initial stages were limited disease in 9 pts and extensive disease in 6 pts. Although primary or metastatic tumors were equally visualized on PET/CT and CT images in 10 pts, discordant findings between PET/CT and CT were observed in 5 pts: FDG-avid bone metastases (mets) were missed on CT in 4 pts, and MRI-positive brain mets were missed on PET/CT in 1 pt. After treatment, discordant findings between PET/CT and CT were observed in 7 pts. PET/CT clarified inconclusive finding on CT images in 5 pts. FDG-avid bone mets were missed on CT in 1 pt, and MRI-positive brain mets were missed on PET/CT in 1 pt.

Conclusions FDG-PET/CT was useful in evaluating primary, metastatic and recurrent SCLC. FDG-PET/CT had additional value over CT because distant mets to bone, etc. could be missed only with CT images.