Exploring the Relationship of Radiation Dose Exposed to the Length of Esophagus and Weight Loss in Patients with Lung Cancer

Purpose: We investigate whether esophageal dose–length parameters (L_dose) can robustly predict significant weight loss—≥5% weight loss during radiation therapy (RT) compared with the weight before RT—in patients with lung cancer treated with definitive intent. Methods and Materials: Patients with lung cancer treated with conventionally fractionated RT between 2010 and 2018 were retrospectively identified. L_Fdose and L_Pdose, the length of full- and partial-circumferential esophagus receiving greater than a threshold dose in Gy, respectively, were created. Multivariate logistic regression examined the associations between individual L_dose and weight loss after adjusting for clinical parameters and correcting for multiple comparisons. Ridge logistic regression examined the relative importance of L_dose compared with dose–volume (V_dose), mean dose (D_mean), and clinical parameters in determining weight loss. Univariate logistic regression examined the unadjusted probability of weight loss for important L_dose parameters. Results: Among the 214 patients identified, median age was 66.9 years (range, 31.5-88.9 years), 50.5% (n = 108) were male, 68.2% (n = 146) had stage III lung cancer, median RT dose was 63 Gy (range, 60-66 Gy), and 88.3% (n = 189) received concurrent chemotherapy. Esophagus lengths receiving high full-circumferential (L_F50-L_F60) and high partial-circumferential doses (L_P60) were associated with significant weight loss (P ≤ .05). L_F65 and L_P65 reached near significance (P = .06 and. 053, respectively). L_F65 > L_F60 > L_P65 were the most important dose parameters in determining weight loss compared with other L_dose, V_dose, and D_mean parameters. Conclusions: Esophageal L_dose parameters are an efficient way of interpreting complex dose parameters in relation to weight loss toxicity among patients with lung cancer receiving definitive RT.