Xiaodong Wu1,2, Yan Huang3, Yuan Li2, Qiang Wang2, Huoqiang Wang2, Lei Jiang4. 1. Medical College of Soochow University, Suzhou, 215123, China. 2. Department of Nuclear Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, 507 Zhengmin Road, Shanghai, 200433, China. 3. Department of Pathology, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, 200433, China. 4. Department of Nuclear Medicine, Shanghai Pulmonary Hospital, Tongji University School of Medicine, 507 Zhengmin Road, Shanghai, 200433, China. leijiang1031@163.com.
Abstract
OBJECTIVE: Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of non-small-cell lung cancer with poor prognosis. This study analyzed 18F-FDG PET/CT in PSC and possible correlations with the clinical and genetic findings. METHODS: Pre-operative 18F-FDG PET/CT findings and parameters of maximum standard uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of primary lesion (MTV-P, TLG-P), and combination of primary lesion and metastases (MTV-C, TLG-C) were retrospectively analyzed in 24 patients with PSC confirmed by post-operative pathology. Tumor location, size, TNM stage, serum tumor markers, histopathological features, and mutations were also reviewed. Furthermore, progression-free survival (PFS) of 24 patients was analyzed. RESULTS: All 24 enrolled patients (20 men; 4 women; age: 62 ± 9 years) had single PSC, including 8 spindle cell carcinomas and 16 pleomorphic carcinomas. Serum levels of tumor markers were found to be abnormally increased sporadically. Six patients had central PSC, and 18 had peripheral PSC (diameter: 41 ± 16 mm). Eighteen lesions were located in the upper lobes of bilateral lungs, and 22 showed necrosis. Five cases were at TNM stage I, 12 at stage II, and 7 at stage III. The primary tumors were FDG avid in the 24 cases, with SUVmax of 17.2 ± 10.6. There were no correlations of SUVmax with tumor location, size, TNM stage, or histopathological subtypes. Programmed cell death ligand 1 (PD-L1) expression was detected in 21 cases (positivity rate: 87.5%). SUVmax of 17 lesions with PD-L1 expression degree ≥ 50% was obviously higher than that < 50% (P < 0.05). Kirsten rat sarcoma viral oncogene homolog (KRAS) gene mutation was found in six cases, and their SUVmax was significantly higher than that without KRAS mutation (P < 0.05). Furthermore, the median PFS of the 24 patients was 14 months, and 12-month and 24-month PFS rates were 55.9% and 27.8%, respectively. Only TLG-P and KRAS mutations of primary lesions were significantly associated with PFS. CONCLUSIONS: PSC tended to present with intense 18F-FDG accumulation on PET/CT, and SUVmax was useful for assessing PD-L1 and KRAS expression of PSC. TLG-P and KRAS mutation were independent prognostic factors of PSC.
OBJECTIVE:Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of non-small-cell lung cancer with poor prognosis. This study analyzed 18F-FDG PET/CT in PSC and possible correlations with the clinical and genetic findings. METHODS: Pre-operative 18F-FDG PET/CT findings and parameters of maximum standard uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) of primary lesion (MTV-P, TLG-P), and combination of primary lesion and metastases (MTV-C, TLG-C) were retrospectively analyzed in 24 patients with PSC confirmed by post-operative pathology. Tumor location, size, TNM stage, serum tumor markers, histopathological features, and mutations were also reviewed. Furthermore, progression-free survival (PFS) of 24 patients was analyzed. RESULTS: All 24 enrolled patients (20 men; 4 women; age: 62 ± 9 years) had single PSC, including 8 spindle cell carcinomas and 16 pleomorphic carcinomas. Serum levels of tumor markers were found to be abnormally increased sporadically. Six patients had central PSC, and 18 had peripheral PSC (diameter: 41 ± 16 mm). Eighteen lesions were located in the upper lobes of bilateral lungs, and 22 showed necrosis. Five cases were at TNM stage I, 12 at stage II, and 7 at stage III. The primary tumors were FDG avid in the 24 cases, with SUVmax of 17.2 ± 10.6. There were no correlations of SUVmax with tumor location, size, TNM stage, or histopathological subtypes. Programmed cell death ligand 1 (PD-L1) expression was detected in 21 cases (positivity rate: 87.5%). SUVmax of 17 lesions with PD-L1 expression degree ≥ 50% was obviously higher than that < 50% (P < 0.05). Kirsten ratsarcoma viral oncogene homolog (KRAS) gene mutation was found in six cases, and their SUVmax was significantly higher than that without KRAS mutation (P < 0.05). Furthermore, the median PFS of the 24 patients was 14 months, and 12-month and 24-month PFS rates were 55.9% and 27.8%, respectively. Only TLG-P and KRAS mutations of primary lesions were significantly associated with PFS. CONCLUSIONS: PSC tended to present with intense 18F-FDG accumulation on PET/CT, and SUVmax was useful for assessing PD-L1 and KRAS expression of PSC. TLG-P and KRAS mutation were independent prognostic factors of PSC.