A new PET/CT volumetric prognostic index for non-small cell lung cancer.
OBJECTIVE
Whole-body metabolic tumor volume (MTVWB) has been shown of prognostic value for non-small cell lung cancer (NSCLC) beyond that of TNM stage, age, gender, performance status, and treatment selection. The current TNM staging system does not incorporate tumor volumetric information. We propose a new PET/CT volumetric prognostic (PVP) index that combines the prognostic value of MTVWB and TNM stage.


METHODS
Based on 328 consecutive NSCLC patients with a baseline PET/CT scan before treatment, from which MTVWB was measured semi-automatically, we estimated hazard ratios (HRs) for ln(MTVWB) and TNM stage from a Cox proportional hazard regression model that consisted of only ln(MTVWB) and TNM stage as prognostic variables of overall survival. We used the regression coefficients, which gave rise to the HRs, as weights to formulate the PET/CT volumetric prognostic (PVP) index. We also compared the prognostic value of the PVP index against that of TNM stage alone and ln(MTVWB) alone with univariate and multivariate survival analyses and C-statistics.


RESULTS
Univariate analysis C-statistic for the PVP index (C=0.71) was statistically significantly greater than those for TNM stage alone (C=0.67, p<0.01) and for ln(MTVWB) alone (C=0.69, p=0.033). Multivariate analyses showed that the PVP index yielded significantly greater discriminatory power (C=0.74) than similar models based on either TNM stage (C=0.72, p<0.01) or ln(MTVWB) (C=0.73, p<0.01). Lower values of the PVP index were associated with significantly better overall survival (adjusted HR=2.70, 95%CI [2.16, 3.37]).


CONCLUSIONS
The PVP index provides a practical means for clinicians to combine the prognostic value of MTVWB and TNM stage and offers significantly better prognostic accuracy for overall survival of NSCLC patients than the current TNM staging system or metabolic tumor burden alone.
Department of Radiology, The University of Chicago, Chicago, IL 60637, United States; Department of Radiology, First Hospital of Lanzhou University, Lanzhou, Gansu 730000, China.
Hao
H
Zhang
Department of Public Health Sciences, The University of Chicago, Chicago, IL 60637, United States.
Kristen
K
Wroblewski
Department of Radiology, The University of Chicago, Chicago, IL 60637, United States.
Yulei
Y
Jiang
Department of Radiology, The University of Chicago, Chicago, IL 60637, United States.
Bill C
BC
Penney
Department of Radiology, The University of Chicago, Chicago, IL 60637, United States.
Daniel
D
Appelbaum
Cancer Registry, The University of Chicago, Chicago, IL 60637, United States.
Cassie A
CA
Simon
Section of Hematology Oncology of Department of Medicine, The University of Chicago, Chicago, IL 60637, United States.
Ravi
R
Salgia
Department of Radiology, The University of Chicago, Chicago, IL 60637, United States. Electronic address: ypu@radiology.bsd.uchicago.edu.
Yonglin
Y
Pu
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002289:Carcinoma, Non-Small-Cell Lung / Q000175:diagnosis* / Q000378:metabolism; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D011237:Predictive Value of Tests; D011379:Prognosis; D015996:Survival Rate; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden; D051598:Whole Body Imaging
(18)F-FDG PET/CT; Metabolic tumor volume (MTV); Non-small cell lung cancer (NSCLC); Prognosis; TNM stage; Tumor burden