Volumetric response analysis during chemoradiation as predictive tool for optimizing treatment strategy in locally advanced unresectable NSCLC.
OBJECTIVE
To study the feasibility of measuring volumetric changes in the primary tumor on megavoltage-computed tomography (MVCT) during chemoradiation and to examine the correlation with local response.


METHODS
Fifteen consecutive patients with stage III, inoperable, locally advanced non-small cell lung cancer (NSCLC) were treated in a prospective dose escalation study protocol of concurrent chemoradiation. They were monitored for acute toxicity and evaluated with daily MVCT imaging. The volumetric changes were fitted to a negative exponential resulting in a regression coefficient (RC). Local response evaluation was done with positron emission tomography using the radio-labeled glucose analogue F18 fluorodeoxyglucose (FDG-PET).


RESULTS
The mean volume decrease (+/-standard deviation) was 73% (+/-18%). With a mean treatment time of 42days this treatment schedule resulted in a mean decrease of 1.74%/day. Of the 13 evaluable patients seven developed a metabolic complete remission (MCR). The mean RC of the patients with MCR is 0.050 versus a mean RC of 0.023 in non-responders (p=0.0074). Using a proposed cut-off value for the RC of 0.03 80% of the non-responders will be detected correctly while misclassifying 16.4% of patients who will eventually achieve an MCR. The total cumulative percentage of esophageal grade 3 or more toxicity was 46.7%.


CONCLUSIONS
The RC derived from volumetric analysis of daily MVCT is prognostic and predictive for local response in patients treated with chemoradiation for a locally advanced NSCLC. Because this treatment schedule is toxic in nearly half of the patient population, MVCT is a tool in the implementation of patient-individualized treatment strategies.
Department of Radiation Oncology, Universitair Ziekenhuis Brussel, Belgium. samuel.bral@uzbrussel.be
Samuel
S
Bral
Michaël
M
Duchateau
Mark
M
De Ridder
Hendrik
H
Everaert
Koen
K
Tournel
Denis
D
Schallier
Dirk
D
Verellen
Guy
G
Storme
D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D005240:Feasibility Studies; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000532:radiotherapy*; D008297:Male; D009367:Neoplasm Staging; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage; D012044:Regression Analysis; D014055:Tomography, Emission-Computed; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18