Whole-body metabolic tumour volume of 18F-FDG PET/CT improves the prediction of prognosis in small cell lung cancer

We investigated whether the whole-body metabolic tumour volume (WBMTV) measured by F-18-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) can improve the prediction of prognosis in patients with small cell lung cancer (SCLC). We reviewed 106 consecutive patients (mean age 67 years, range 42-89 years, limited stage 45 patients, extensive stage 61 patients) with pathologically proven SCLC who underwent pretreatment FDG PET/CT. WBMTV and maximum standardized uptake value (SUVmax) were measured in all malignant lesions. The Cox proportional hazards model was used with age, sex, performance status, lactate dehydrogenase (LDH), treatment, stage, SUVmax and WBMTV to predict overall survival (OS) and progression-free survival (PFS). Subgroup analysis was performed using WBMTV combined with conventional staging and tumour node metastasis (TNM) staging. The uni- and multivariate analyses showed that both stage and WBMTV were independent prognostic factors for death and progression. Patients with high WBMTV were associated with poor prognosis compared with patients with low WBMTV [hazard ratio = 2.11 (95% confidence interval 1.31-3.39) for death (p = 0.002) and 1.80 (95% confidence interval 1.16-2.80) for progression (p = 0.009)]. Incorporation of conventional staging and WBMTV could classify four subgroups with different prognoses (log-rank test, p < 0.001). Incorporation of TNM staging and WBMTV could classify six subgroups with different prognoses (log-rank test, p < 0.001). WBMTV is an independent predictor for progression and death in patients with SCLC. Incorporation of WBMTV with TNM staging can provide a more detailed prediction of prognosis than WBMTV with conventional staging as well as tumour staging alone.