Value of volume-based early metabolic response in patients with unresectable thymic epithelial tumor.
We conducted this study to investigate the value of early metabolic responses assessed by (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) in predicting prognosis and monitoring treatment response in patients with unresectable thymic epithelial tumors (TETs).



Study subjects were selected from the prospective dataset of a phase II clinical trial for cisplatin plus Cremorphor EL-free paclitaxel. A total of thirty patients with unresectable TETs who underwent baseline and early post treatment scan after two cycles of chemotherapy were enrolled (22 Male; mean age 55.0±15.0years). Metabolic parameters including metabolic tumor volume (MTV) and total lesion glycolysis (TLG) of the tumor lesions were measured.



Multivariate analysis using Cox proportional hazards regression model showed that percent decrease of MTV (HR=0.995 by 1% decrease, P=0.037) and TLG (HR=0.996 by 1% decrease, P=0.044) were significant predictors of progression-free survival (PFS). Receiver operating characteristic curve identified an 88.0% decrease in MTV and a 92.0% decrease in TLG as the optimal cut-off value for disease progression. Responders with ≥88% of ΔMTV and ≥92% of Δ TLG had significantly longer PFS than non-responders (P=0.012, 0.026, respectively).



The percent decrease in MTV and TLG of tumor lesions measured by early post treatment FDG PET/CT significantly associated with disease progression in this study. Early metabolic response based on these volumetric parameters has the potential to monitor treatment response and predict prognosis in patients with unresectable TETs.
Departments of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Seung Hwan
SH
Moon
Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea; Division of Hematology-Oncology, Department of Medicine, Veterans Health Service Medical Center, Seoul, Republic of Korea.
Hae Su
HS
Kim
Departments of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Young Seok
YS
Cho
Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Jong-Mu
JM
Sun
Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Jin Seok
JS
Ahn
Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Keunchil
K
Park
Departments of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Byung-Tae
BT
Kim
Division of Hematology-Oncology, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: silkahn@skku.edu.
Myung-Ju
MJ
Ahn
Departments of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea. Electronic address: khnm.lee@samsung.com.
Kyung-Han
KH
Lee
D000328:Adult; D000368:Aged; D018450:Disease Progression; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009375:Neoplasms, Glandular and Epithelial / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D049268:Positron-Emission Tomography / Q000379:methods*; D011379:Prognosis; D011446:Prospective Studies; D012189:Retrospective Studies; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D016896:Treatment Outcome
D019788:Fluorodeoxyglucose F18
(18)F-FDG; Positron emission tomography; Prognosis; Thymic epithelial tumor