Identification of a Suitable Subgroup for Radiation Dose Escalation in Definitive Concurrent Chemoradiation Therapy for Nonmetastatic Esophageal Squamous Cell Carcinoma.

Purpose: Dose escalation may only be suitable for some patients with esophageal cancer (EC) undergoing concurrent chemoradiotherapy (CCRT). This study aimed to identify specific subgroups of patients for whom dose escalation was most beneficial.

Materials and methods: Between January 2008 and December 2022, 187 patients with EC underwent CCRT; 94 patients received high-dose (HD) radiotherapy (RT; >64.8 Gy), and 93 patients received low-dose (LD) RT. We developed a model on the basis of clinical and radiomic features to compare the predicted survival probabilities of patients with EC receiving HD- and LD-RT. Patients suitable for HD-RT could be identified. We validated our findings of a suitable HD subgroup by evaluating the actual overall survival (OS) across different subgroups in the testing set.

Results: Our model comprised HD and LD submodels, each predicting patient survival under their respective RT doses. The HD and LD submodels achieved concordance indexes of 0.78 and 0.75 in their respective testing sets. The average areas under the receiver operating characteristic curve over years 1-3 were 0.890 and 0.807 in the HD and LD testing sets, respectively. By comparing patients' predicted survival under HD- and LD-RT in the model, we classified the patients in the testing set into the HD-suitable (HDS) subgroup and the HD-unsuitable subgroup. In the subgroup analysis, HD-RT led to a better OS benefit for the identified HDS subgroup compared with LD-RT (P = .014). Among the HD-treated patients, the HDS subgroup showed better OS than did patients identified as unsuitable (P < .001).

Conclusion: We identified a suitable subgroup of patients with EC who might benefit from HD-RT. This model could aid clinicians in prescribing RT doses.