Correlation of Pre-treatment FDG Uptake to Therapeutic Response and Relapse in Patients with Small Cell Lung Cancer

Seo, Young Soon; Kwon, Seong Young; Jeong, Shin Young; Song, Ho Chun; Min, Jung Joon; Kim, Kyu Sik; Kim, Young Chul; Bom, Hee Seung

Abstract

PURPOSE: We evaluated correlation of 18F-FDG uptakes, therapeutic response and relapse in pre-treatment 18F-FDG PET/CT in patients with SCLC.
MATERIALS AND METHODS
We included 26 patients with pathologically proven small cell lung cancer. Total 102 lesions (26 lungs, 69 lymph nodes and 8 metastatic lesions) were evaluated. All patients underwent 18F-FDG PET/CT for staging. The maxSUV was used as a parameter of 18F-FDG uptake. The patients were divided into responders and non-responders according to response criteria on chest CT scan after 3 cycles of chemotherapy. We compared maxSUV between two groups by using independent t-test. To access correlation with 18F-FDG uptake and relapse, maxSUV and interval time to relapse was analyzed by correlation analysis. The cutoff value of maxSUV was evaluated by ROC curve.
RESULTS
Twelve-one patients (81%) were responders and five patients were non-responders on follow-up chest CT scan. The mean maxSUV of main lung lesions in responders and non-responders were 14.15+/-3.72 and 9.17+/-2.15, respectively. The maxSUV in the responders was significantly lower than that in non-responders (p<0.05). According to ROC curve, point of cut that predicts therapeutic response was 8.98 with 100% sensitivity and 57% specificity. The correlation analysis between 18F-FDG uptakes and interval time to relapse showed a significant negative correlation (p<0.05, r=-0.757).
CONCLUSION
The pre-treatment 18F-FDG uptake of responders was significantly lower than that of non-responders. Patients with high 18F-FDG uptake in pre-treatment 18F-FDG PET/CT relapse earlier.