RESUMEN
RATIONALE: Individuals afflicted with achalasia of the cardia (AC) are more susceptible to the development of esophageal cancer (EC). However, the presence of esophageal retention obscured observation, making it difficult to detect EC early, which leads to misdiagnosis and poor prognosis in AC patients with EC. Besides, the persistence of high-risk factors may have contributed to the rapid progression of EC shortly after per-oral endoscopic myotomy (POEM). Therefore, it is imperative to alert clinicians to this extremely rare and instructive early-onset cancer. PATIENT CONCERNS: The patient was a 67-year-old male who developed dysphagia 3 years ago without obvious causes, with intermittent onset and aggravating trend, accompanied by weight loss. He usually eats high-temperature foods and pickled foods, and has a family history of esophageal squamous cell carcinoma. DIAGNOSIS AND INTERVENTIONS: The patient was initially diagnosed with AC 2 years ago and subsequently underwent POEM surgery. One year after surgery, he was found to have mid-upper EC during follow-up and underwent partial esophagectomy in time. OUTCOMES: The patient's symptoms have significantly improved with weight gain, and he is still adhering to regular follow-up and endoscopic examination. LESSONS: In rare cases, EC develops early in patients with achalasia after POEM surgery. To avoid missed diagnosis, a comprehensive examination to improve the accuracy to diagnose achalasia and identify possible early-onset cancer is very important in clinical practice. Especially for patients with AC who have a family history of EC or other high-risk factors may develop EC early after POEM surgery. Therefore, regular endoscopic follow-up after POEM surgery is essential.