Clinical implications of the tumor volume reduction rate in head-and-neck cancer during definitive intensity-modulated radiotherapy for organ preservation.
OBJECTIVE
To investigate the prognostic value of the volume reduction rate (VRR) in patients with head-and-neck cancer treated with intensity-modulated radiotherapy (IMRT).


METHODS
Seventy-six patients with oropharyngeal cancer (OPC) and another 76 with hypopharyngeal cancer (HPC) were enrolled in volumetric analysis. All patients received allocated radiotherapy courses. Adaptive computed tomography was done 4 to 5 weeks after the start of IMRT. Primary tumor volume measurement was derived using separate images for the pretreatment gross tumor volume (pGTV) and the interval gross tumor volume.


RESULTS
In the OPC group, the pGTV ranged from 6.6 to 242.6 mL (mean, 49.9 mL), whereas the value of the VRR ranged from 0.014 to 0.74 (mean, 0.43). In HPC patients, the pGTV ranged from 4.1 to 152.4 mL (mean, 35.6 mL), whereas the VRR ranged from -1.15 to 0.79 (mean, 0.33). Multivariate analysis of the primary tumor relapse-free survival for OPC revealed three prognostic factors: T4 tumor (p = 0.0001, hazard ratio 7.38), pGTV ≥20 mL (p = 0.01, hazard ratio 10.61), and VRR <0.5 (p = 0.001, hazard ratio 6.49). Multivariate analysis of the primary tumor relapse-free survival for HPC showed two prognostic factors: pGTV ≥30 mL (p = 0.001, hazard ratio 2.87) and VRR <0.5 (p = 0.03, hazard ratio 2.25).


CONCLUSIONS
The VRR is an outcome predictor for local control in OPC and HPC patients treated with IMRT. Those with large tumor volumes or a VRR <0.5 should be considered for a salvage operation or a dose-escalation scheme.
Yang
Shih-Neng
SN
Department of Radiation Oncology, China Medical University, Taichung, Taiwan.
Liao
Chih-Ying
CY
Chen
Shang-Wen
SW
Liang
Ji-An
JA
Tsai
Ming-Hsui
MH
Hua
Chun-Hung
CH
Lin
Fang-Jen
FJ
D000328:Adult; D000368:Aged; D002294:Carcinoma, Squamous Cell / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007012:Hypopharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009959:Oropharyngeal Neoplasms / Q000000981:diagnostic imaging / Q000401:mortality / Q000473:pathology / Q000532:radiotherapy*; D011379:Prognosis; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D047368:Tumor Burden / Q000528:radiation effects*