Supine positioning reduces lung volumes irradiated in patients treated for esophageal cancer

Purpose: Investigators at our institution recently described that irradiating increased volumes of lung preoperatively with concurrent chemotherapy led to significantly increased postoperative pulmonary complications. This is a pilot study to determine the effect of supine vs prone treatment positions on the volume of lung irradiated for esophageal cancer patients. Methods and Materials: Ten patients prospective!)- underwent 3-D treatment planning supine and prone. A goal dose of 50.4 Gy/ 28fx was prescribed to the PTY The responsible clinician delineated target and normal tissue volumes. The "best" plans in each position were compared. Results: All esophageal lesions were distal. The median GTV was 75cm'(25-260cm'). The percent of total lung volume irradiated to a given dose in supine patients was significantly lower than the volume irradiated in prone patients (P s 0.032). The median percent of total lung volume irradiated to lOGy, 20Gy, 30Gy, 40Gy, and 50Gy for prone patients was 44% (29-52%), 23% (21-28%), 17% (10-19%), 14% (4-15%) and 6% (2-9%), respectively. This compared to 38% (20-53%), 18% (9-31%), 13% (5-18%), 10% (3-12%) and 3% (1-5%) for the supine position. Volumes of heart irradiated to the same doses for prone and supine were 93% (80-98%), 71% (61-85%), 66% (42-81%), 62% (24-78%), and 32% (0-19%), vs 92% (76-100%), 77% (61-92%), 68% (46-66%), 57% (30-83%), and 26% (19-35%) respectively. The percent of total heart volume irradiated to 50Gy was significantly higher in supine patients (P = 0.03). Spinal cord doses were usually higher in the supine position, but no plan had any portion of cord 50Gy. Conclusions: Three-D conformai RT for esophageal cancer in the supine position significantly reduced lung volume irradiated compared to prone positioning. Spinal cord and heart volumes irradiated tended to be slightly increased in the supine position. While these data strongly suggest supine positioning is superior, we reserve final recommendations until our prospective study is completed.