Metabolic tumor burden predicts for disease progression and death in lung cancer.
OBJECTIVE
In lung cancer, stage is an important prognostic factor for disease progression and survival. However, stage may be simply a surrogate for underlying tumor burden. Our purpose was to assess the prognostic value of tumor burden measured by 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) imaging.


METHODS
We identified 19 patients with lung cancer who had staging PET-CT scans before any therapy, and adequate follow-up (complete to time of progression for 18, and death for 15 of 19). Metabolically active tumor regions were segmented on pretreatment PET scans semi-automatically using custom software. We determined the relationship between times to progression (TTP) and death (OS) and two PET parameters: total metabolic tumor volume (MTV), and standardized uptake value (SUV).


RESULTS
The estimated median TTP and OS for the cohort were 9.3 months and 14.8 months. On multivariate Cox proportional hazards regression analysis, an increase in MTV of 25 ml (difference between the 75th and 25th percentiles) was associated with increased hazard of progression and of death (5.4-fold and 7.6-fold), statistically significant (p = 0.0014 and p = 0.001) after controlling for stage, treatment intent (definitive or palliative), age, Karnofsky performance status, and weight loss. We did not find a significant relationship between SUV and TTP or OS.


CONCLUSIONS
In this study, high tumor burden assessed by PET MTV is an independent poor prognostic feature in lung cancer, promising for stratifying patients in randomized trials and ultimately for selecting risk-adapted therapies. These results will need to be validated in larger cohorts with longer follow-up, and evaluated prospectively.
Lee
Percy
P
Department of Radiation Oncology, Stanford University, Stanford, CA 94305-5847, USA.
Weerasuriya
Dilani K
DK
Lavori
Philip W
PW
Quon
Andrew
A
Hara
Wendy
W
Maxim
Peter G
PG
Le
Quynh-Thu
QT
Wakelee
Heather A
HA
Donington
Jessica S
JS
Graves
Edward E
EE
Loo
Billy W
BW
D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging* / Q000401:mortality* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012044:Regression Analysis; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed; D047368:Tumor Burden
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18