Cost-effectiveness of sponge cytology test vs endoscopy for esophageal squamous cell carcinoma screening in high-risk areas

Figure 1 Markov model structure illustrating the natural history and treatment-related transitions of esophageal squamous cell carcinoma. Red boxes represent disease health states, including healthy, mild dysplasia, moderate dysplasia, severe dysplasia/carcinoma in situ, early esophageal cancer, and advanced esophageal cancer, while the blue box denotes the treatment state. Solid arrows indicate allowed disease progression between adjacent health states, whereas self-loop arrows represent remaining in the same state within a cycle. Dashed arrows indicate transitions following treatment, including return to the Healthy state after successful treatment of dysplasia/carcinoma in situ and post-treatment transitions from cancer states. Once esophageal squamous cell carcinoma has developed, backward transitions to pre-cancerous states are not permitted. Death is modeled as an absorbing state applicable to all disease stages, as indicated in the figure.