Esophageal Circumferential Dose-Length Histogram Parameters to Predict Dysphagia in Patients Receiving Thoracic...

Chemoradiation for locally advanced non-small cell lung cancer can cause severe esophagitis. Techniques to spare the contralateral esophagus may mitigate toxicity, but traditional dose-volume histograms (DVH) do not capture the degree of circumferential irradiation. We evaluated dose-length histogram (DLH) parameters as predictors of dysphagia compared with DVH metrics.

We retrospectively reviewed patients treated with definitive thoracic radiation therapy from 2019 to 2023. Descriptive statistics described the cohort. Clinician-reported (National Cancer Institute Common Terminology Criteria for Adverse Events [CTCAE] v.4) and patient-reported outcomes (PRO)-CTCAE v.1 dysphagia within 120 days of treatment start were collected prospectively. The McNemar test compared dichotomized scores. The length of esophageal full-circumferential (L_Fdose) and partial-circumferential irradiation (L_Pdose) was defined as the length of the esophagus with ≥90% and ≥50% circumference exposure to threshold radiation doses, respectively. Spearman correlation examined relationships between L_Fdose, L_Pdose, and volumetric (V_dose) parameters. Associations between L_Fdose, L_Pdose, and V_dose, and grade ≥2 dysphagia were evaluated using univariate logistic regression. Likelihood ratio tests assessed model fit.

Of 107 patients, 86.9% (93) had non-small cell lung cancer, all received ≥60 Gy (median, 63 Gy; range, 60-70 Gy), and 94.4% (101) received concurrent chemotherapy. Patients and physicians reported rates of grade ≥2 dysphagia differently: 17 (15.9%) and 6 (5.6%), respectively (P = .0015). Each 0.5 cm increase in the length of partial-circumference esophagus receiving ≥55 Gy (L_P55) and 60 Gy (L_P60) resulted in increased odds of PRO-CTCAE dysphagia by 8% and 9%, respectively. Each 0.5 cm increase in full-circumference esophagus receiving ≥60 Gy (L_F60) resulted in 11% increased odds of PRO-CTCAE dysphagia. Esophageal DLH parameters, L_P55 and L_P60, correlated with the esophageal V₆₀ volumetric parameter strongly (ρ = 0.751 and 0.729, respectively). No DVH or DLH parameter predicted grade ≥2 CTCAE dysphagia.

Esophageal DLH metrics assessing partial- or full-circumferential esophageal irradiation, specifically L_P55, L_P60, and L_F60, are associated with patient-reported dysphagia and complement traditional DVH parameters.