Supplementary Material for: Esophageal cancer secondary to achalasia: a case series study

Background
Achalasia is the most common primary motility disorder of the esophageal body and lower esophageal sphincter, and it has been reported to be associated with esophageal cancers (ECs). However, owing to the rarity of achalasia, details of ECs secondary to achalasia are not well investigated.
Aims
Summarize the clinical characteristics of esophageal cancer(EC) secondary to achalasia, improve understanding of achalasia combined with esophageal cancer, and further reduce the risk of ECs.
Methods
Retrospective statistics were conducted on patients with ECs secondary to achalasia in our hospital from 2009 to 2023. All patients with achalasia were characterized initially according to the primary treatment and then any following therapeutic interventions were also considered in the study.Characteristics of ECs and treatment courses were also analyzed.
Results
we present a case series comprised of five patients with achalasia who presented with esophageal cancer. Three of the patients diagnosed with achalasia were treated by endoscopy or operation to improve symptoms. One patient was treated by pneumatic dilation.All were histologically diagnosed as squamous cell carcinoma. The validity period of endoscopic treatment has been lost in all patients. The erosions were all distributed over the thoracic esophagus.
Conclusion
The high relative risk of ECs was demonstrated in achalasia patients, even in the treated achalasia patients. Therefore, surveillance endoscopy may be recommended regularly in the treated patients.