Purpose: To evaluate the prognostic value of FDG PET/CT metabolic parameter compared to clinico-pathological risk factors in surgical margin-negative stage IA non-small cell lung cancer (NSCLC) patients.
Methods: 167 patients with consecutive FDG PET/CT scans from 2009 to 2015 performed for staging of NSCLC stage IA with plans for curative surgery were retrospectively reviewed. Maximum standardized uptake value (SUVmax) of primary tumor and mean SUV of liver were acquired from PET/CT. Tumor-to-liver SUV ratio (TLR) was calculated. Charts were reviewed to obtain basic patient characteristics (age, sex, smoking history, LDH, histologic subtype) and high-risk factors for adjuvant chemotherapy (tumor size, poorly differentiation, vascular invasion, and sub-lobar resection). Patients were dichotomized into two groups using optimal cut-off from receiver operating characteristic curve analysis of TLR to predict recurrence. Statistical analysis was done using Cox regression analysis and Kaplan-Meier method. Factors with P < 0.2 in univariate analysis were included in multivariate analysis.
Results: Recurrence rate was 12.6% (21/167). Median disease-free survival (DFS) was 47.2 months while 2-year and 5-year DFS rates were 93% and 86%, respectively. The optimal cut-off for TLR was 2.3. In univariate analysis, P value of sex, vascular invasion, and TLR were less than 0.2. In multivariable analysis, high TLR was the only factor that showed significant association with tumor recurrence (hazard ratio 3.795, P = 0.0048).
Conclusions: TLR was an independent prognostic factor for recurrence and TLR could be an important risk factor to be considered in decision-making for adjuvant chemotherapy, even for those with stage IA NSCLC.
Keywords: Carcinoma; Non-small cell lung; Positron emission tomography–computed tomography; Prognosis; Stage IA.