COMPARISON OF METHODS TO REDUCE DOSE TO SWALLOWING-RELATED STRUCTURES IN HEAD AND NECK CANCER

Introduction: Emerging data suggest that reduction of dose to the larynx and pharyngeal constrictor may lower the risk of swallowing complications such as long-term gastrostomy dependence and aspiration. Organ avoidance becomes difficult when the primary tumor or involved nodes are present at the level of the larynx. Materials and Methods: Fifteen patients with Stage III-IV squamous cell carcinoma of the head and neck with high-dose target volume at the level of the larynx (but not involving the glottic larynx) were planned with whole-field IMRT (WF-IMRT), as well as a low anterior neck field dynamically matched to an IMRT plan (D-SCLV). Plans were compared with respect to coverage of targets and sparing of normal tissues including the larynx, inferior pharyngeal constrictor (IPC), parotid, and cord. Results: There was no significant difference between the two techniques in coverage of the high- or intermediate-dose planning target volumes (PTVs). Coverage of the elective nodal PTV was inferior with the D-SCLV technique, with a mean of 96.5% vs. 86.3% of the volume receiving the prescription dose (p=0.001) compared with WF-IMRT plans. However, the D-SCLV technique significantly reduced mean dose to the larynx (43.7 vs. 46.7 Gy, p = 0.05) and IPC (39.1 vs. 46.1 Gy, p = 0.002). There was no significant difference in dose to the parotid or cord. Conclusion: Given the steep dose responses seen in studies examining the association between swallowing toxicity and dose to the larynx and IPC, dose reductions using the D-SCLV technique may be clinically significant. (C) 2010 Elsevier Inc.