Risk-stratifying capacity of PET/CT metabolic tumor volume in stage IIIA non-small cell lung cancer

Abstract

Objectives Stage IIIA non-small cell lung cancer (NSCLC) is heterogeneous in tumor burden, and its treatment is variable. Whole-body metabolic tumor volume (MTVWB) has been shown to be an independent prognostic index for overall survival (OS). However, the potential of MTVWB to risk-stratify stage IIIA NSCLC has previously been unknown. If we can identify subgroups within the stage exhibiting significant OS differences using MTVWB, MTVWB may lead to adjustments in patients’ risk profile evaluations and may, therefore, influence clinical decision making regarding treatment. We estimated the risk-stratifying capacity of MTVWB in stage IIIA by comparing OS of stratified stage IIIA with stage IIB and IIIB NSCLC. Methods We performed a retrospective review of 330 patients with clinical stage IIB, IIIA, and IIIB NSCLC diagnosed between 2004 and 2014. The patients’ clinical TNM stage, initial MTVWB, and long-term survival data were collected. Patients with TNM stage IIIA disease were stratified by MTVWB. The optimal MTVWB cutoff value for stage IIIA patients was calculated using sequential log-rank tests. Univariate and multivariate cox regression analyses and Kaplan-Meier OS analysis with log-rank tests were performed. Results The optimal MTVWB cut-point was 29.2 mL for the risk-stratification of stage IIIA. We identified statistically significant differences in OS between stage IIB and IIIA patients (p < 0.01), between IIIA and IIIB patients (p < 0.01), and between the stage IIIA patients with low MTVWB(below 29.2 mL) and the stage IIIA patients with high MTVWB(above 29.2 mL) (p < 0.01). There was no OS difference between the low MTVWB stage IIIA and the cohort of stage IIB patients (p = 0.485), or between the high MTVWB stage IIIA patients and the cohort of stage IIIB patients (p = 0.459). Similar risk-stratification capacity of MTVWB was observed in a large range of cutoff values from 15 to 55 mL in stage IIIA patients. Conclusions Using MTVWB cutoff points ranging from 15 to 55 mL with an optimal value of 29.2 mL, stage IIIA NSCLC may be effectively stratified into subgroups with no significant survival difference from stages IIB or IIIB NSCLC. This may result in more accurate survival estimation and more appropriate risk adapted treatment selection in stage IIIA NSCLC.

Greater reduction in mid-treatment FDG-PET volume may be associated with worse survival in non-small cell lung cancer

“…Studies on the survival effect of baseline MTV are relatively limited. Investigators from the University of Chicago concluded that PET-MTV was more important than AJCC staging, and PET-MTV can further predict survival for each stage group such as IIIA [20,21]. Another study reported that a smaller MTV on FDG-PET was associated with epidermal growth factor receptor (EGFR) mutations and better survival [22].…”

Developing and validating a novel metabolic tumor volume risk stratification system for supplementing non-small cell lung cancer staging

“…From the database of our institutional Cancer Center Cancer Registry, we found 2,510 patients with NSCLC who were diagnosed with pathological confirmation and treated at our institution from January 2004 to December 2014. Part of this patient population was previously analyzed for different purposes and reported [2–5, 15, 16]. The patients were enrolled based on the following inclusion criteria: 1) had undergone a baseline FDG PET/CT with PET positive tumor, 2) had no evidence of brain metastasis, and 3) did not have concurrent diagnosis or a history of other primary cancer[17].…”

“…However, it cannot be easily used clinically as an interval measurement. Although MTV wb has been used for risk stratification within TNM stages[3, 6, 7, 13–16], the MTV wb cutoff points in various studies were different for the same TNM stages due to heterogeneity of the tumor burden[6, 7, 16]. Based on the independent prognostic value of the MTVwb and the variation of the patient survival within the same TNM stage, we hypothesized that the MTVwb could be used clinically to supplement NSCLC staging through risk stratification, and so developed and validated a novel MTVwb risk stratification system for use in conjunction with the TNM staging system and other prognostic variables.…”

PET-Based Volumetric Biomarkers for Risk Stratification of Non-Small Cell Lung Cancer Patients

“…Another study including only NSCLC patients in stage III reported the use of whole-body MTV to stratify patients for the adoption of the most appropriate therapeutic strategy [ 58 ]. The authors found that volume-based PET parameters may help to choose whether a patient in stage IIIA should receive a more aggressive treatment than that for stage IIIB or a less intensive regimen than that for stage IIB.…”