Relationship between primary lesion metabolic parameters and clinical stage in lung cancer.

OBJECTIVES: The relation of PET-derived parameters as maximum standardized uptake value (SUVmax), total lesion glycolysis (TLG), metabolic tumor volume (MTV) with clinical stage in lung cancer and correlation of SUVmax of primary tumor and that of metastatic lesion was studied in lung cancer patients.

MATERIALS AND METHODS: Patients with lung cancer who were referred for FDG PET/CT were included in the study.

RESULTS: PET/CT scans and pathology reports of 168 patients were assessed. A total of 146 (86.9%) of these patients had a diagnosis of non-small cell lung cancer (NSCLC) and 22 (13.1%) had small cell lung cancer (SCLC). Metabolic parameters such as SUVmax, TLG and MTV showed significant differences in all the stages in NSCLC patients (p<0.001). However, after tumors sizes <25 mm were excluded, no significant differences in SUVmax between stages were observed. No significant differences were found between these metabolic parameters and limited or extended disease SCLC. Tumor diameter correlated with primary tumor SUVmax and significant correlations between primary lesion SUVmax and metastatic lesion SUVmax were found.

CONCLUSIONS: Although differences were found regarding indices between stages of NSCLC cases, SUVmax differences between stages seem to be caused by underestimation of SUVmax in small lesions. Other glucose metabolism indexes such as MTV and TLG show promising results in terms of prognostic stratification. Future studies are needed for better understanding of their contribution to clinical cases.