18 F-FDG PET/CT in lung adenosquamous carcinoma and its correlation with clinicopathological features and prognosis

Lung adenosquamous carcinoma (ASC) is a rare histological subtype of non-small cell lung cancer (NSCLC). Due to its rarity, the studies about 18F-FDG PET/CT in this kind of pulmonary tumor were quite limited. Thus, this study investigated 18F-FDG PET/CT findings in ASC and its correlation with clinicopathological features and clinical outcomes. Preoperative 18F-FDG PET/CT findings and parameters of maximum standard uptake value (SUVmax), metabolic tumor volume and total lesion glycolysis of primary lesion (MTV-P, TLG-P), combination of primary lesion and metastases (MTV-C, TLG-C), and clinicopathological features were retrospectively investigated in patients with ASC. Moreover, progression-free survival (PFS) was also analyzed. All 41 patients (25 men; 16 women; age: 60 ± 7 years) had single ASC with the mean diameter of 33 ± 14 mm. Six lesions were located centrally and 35 peripherally. Serum tumor markers were abnormally increased sporadically. Twenty-two cases were at TNM stage I, 9 at II, and 10 at III. The primary tumors were FDG-avid in all cases, with the average SUVmax of 11.5 ± 6.0. SUVmax was significantly associated with tumor location, size, and TNM stage (P < 0.05). Forty-one lesions were subgrouped into 23 AC-predominant and 18 SCC-predominant lesions, and significant differences were observed for age, tumor size, and SUVmax in two groups (P < 0.05). The median PFS of 41 cases was 19 months, and 12-month and 24-month PFS rates were 72.1% and 36.1%, respectively. SUVmax, MTV-P, and TLG-C were significantly associated with PFS (P < 0.05). ASC of the lung displayed high SUVmax on 18F-FDG PET/CT, which was associated with tumor location, size, TNM stage, and predominant histologic component. Moreover, metabolic parameters of 18F-FDG PET/CT were independent prognostic factors of this rare lung malignancy.