J. Howington

Utility of positron emission tomography- computed tomography in identification of residual nodal disease after chemoradiation for advanced head and neck cancer

Objectives: Planned neck dissection after chemoradiation (CR) is often advocated in patients with head and neck squamous cell cancer (HNSCC) with advanced nodal disease who demonstrate a clinical complete response to CR because identification of residual occult nodal disease is difficult. We sought to investigate the utility of positron emission tomography‐computed tomography (PET‐CT) in identifying patients with occult nodal disease after CR.

Effect of Comorbidity on Quality of Life and Treatment Selection in Patients with Squamous Cell Carcinoma of the Head and Neck

Objectives: Comorbidity is significantly associated with diminished survival and quality of life (QOL) after treatment of head and neck squamous cell carcinoma (HNSCC). We sought to determine whether comorbidity influenced pretreatment QOL scores and treatment selection in patients with HNSCC.

SU-E-T-166: Evaluation of Integral Dose in Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy for Head and Neck Cancer Patient

PURPOSE Volumetric Modulated Arc Therapy (VMAT) usually achieves higher conformity of radiation doses to targets and less delivery time than Intensity Modulated Radiation Therapy (IMRT). We hypothesized that VMAT will increase integral dose (ID) to patients which will decrease the count of white blood count (WBC) lymphocytes, and consequently has a subsequent impact on the immune system. The purpose of this study is to evaluate the ID to patients undergoing IMRT and VMAT for Head and Neck cancers and its impact on the immune system. METHODS As a pilot study, 30 head and neck patients who received 9-fields IMRT or 3-arcs Radip-Arcbased VMAT were included in this study. Ten of these patients who received the VMAT plans were re-planned using IMRT with the same objectives. ID was calculated for all cases. All patients also had a baseline WBC obtained prior to treatment, and 3 sets of labs drawn during the course of radiation treatment. RESULTS For the 10 re-planned patients, the mean ID was 13.3 Gy/voxel (range 10.2-17.5 Gy/voxel) for the 9-fields IMRT plans, and was 15.9 Gy/voxel (range 12.4-20.9 Gy/voxel) for the 3-Arc VMAT plan (p=0.01). The integral dose was significant correlated with reducing WBC count during RT even when controlling for concurrent chemotherapy (R square =0.56, p=0.008). CONCLUSION Although VMAT can deliver higher radiation dose conformality to targets, this benefit is achieved generally at the cost of greater integral doses to normal tissue outside the planning target volume (PTV). Lower WBC counts during RT were associated with higher Integral doses even when controlling for concurrent chemotherapy. This study is ongoing in our Institution to exam the impact of integral doses and WBC on overall survival.