Prognostic Significance of Total Metabolic Tumor Volume on Baseline 18F-FDG PET/CT in Patients with Lung Adenocarcinoma: Further Stratification of the Ninth Edition of TNM Staging Subgroups

Background: This study aimed to investigate the prognostic value of baseline total metabolic tumor volume (TMTV) on 18F-fluorodeoxyglucose positron emission tomography/computed tomography and its potential for further stratification within the ninth tumor-node-metastasis (TNM) staging system in patients with lung adenocarcinoma (LUAD).

Methods: A cohort of 384 patients with LUAD who had undergone pretreatment PET/CT were included in this retrospective study. The optimal cutoff value for TMTV was determined through analysis of time-dependent receiver operating characteristic curves. The analysis of overall survival (OS) was conducted utilizing Kaplan-Meier curves. Predictive capacity was evaluated using the C statistic.

Results: The optimal cutoff value for TMTV was 40.13 ml. The survival rates of patients varied significantly across stages I (n = 164), II (n = 37), III (n = 46), and IV (n = 137); however, there was no statistically significant difference between stages II and III (P = 0.440). In stages II-IV, the 2-year OS rates for patients with TMTV less than 40.13 ml were significantly higher at 81.7 and 86.7%, respectively, compared with patients with TMTV greater than equal to 40.13 ml who had rates of only 56.5 and 42.5%. No patients with stage I presented TMTV greater than or equal to 40.13 ml, and the 2-year OS rate was 98.3%. The C index did not reveal a significant difference between TNM and TMTV in their predictive ability for OS (0.83 vs. 0.85, P = 0.159).

Conclusion: The TNM staging system demonstrates robust prognostic utility in patients with LUAD, while the incorporation of baseline TMTV may offer additional risk stratification within distinct TNM stages.