Objectives: To determine the prognostic utility of a volumetric threshold for gross tumor volume (GTV) of the primary and nodal disease when accounting for the TNM classification in head and neck cancer (HNC) patients treated with definitive radiotherapy (RT).
Materials and Methods: From 2004 to 2011, 79 HNC patients were treated to a median dose of 70 Gy, using intensity-modulated RT in 78.5% and 3-dimensional conformal RT in 21.5% with 83.5% receiving concurrent chemotherapy. Primary (GTV-P) and nodal (GTV-N) GTVs were derived from computed tomography (CT)-based contours for RT planning, of which 89.7% were aided by positron emission tomography-computed tomography. Local (LC), nodal (NC), distant (DC) control, and overall survival (OS) were assessed using the Kaplan-Meier product-limit method.
Results: With a median follow-up of 27.1 months GTV-P, threshold of <32.9 mL (mean value) compared with ≥32.9 mL, correlated with improved 2-year LC (96.2% vs. 63.9%, P<0.0001), NC (100% vs. 69.2%, P<0.0001), DC (87.9% vs. 64.2%, P=0.001), and OS (88.4% vs. 58.6%, P=0.001). GTV-P demonstrated its prognostic utility in multivariate analyses when adjusted for tumor category, cancer site, and chemotherapy regimen. Nodal GTV (mean, 34.0 mL) was not predictive of nodal control and survival.
Conclusions: A volumetric threshold of the primary tumor may be used as an independent prognostic factor in patients with HNC undergoing definitive RT.
Departments of *Radiation Oncology
‡Otolaryngology, Boston Medical Center, Boston University School of Medicine, Boston, MA
Present address: Paul B. Romesser, Department of Radiation Oncology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065.
Presented in part at the 53rd Annual Meeting of the American Society for Radiation Oncology, October 2 to 6, 2011, Miami Beach, FL.
The authors declare no conflicts of interest.
Reprints: Minh T. Truong, MD, Department of Radiation Oncology, Boston Medical Center, Boston University School of Medicine, 830 Harrison Ave, Moakley Building LL 238, Boston, MA 02118. E-mail: firstname.lastname@example.org.