Increased risk of second primary tumours in patients with oesophageal squamous cell carcinoma: a nationwide study in a Western population.

Approximately one in 20 patients with primary oesophageal squamous cell carcinoma have a second primary tumour in the upper aero digestive tract or stomach, either at the time of oesophageal squamous cell carcinoma diagnosis or at a later stage. As second primary tumours occur at an increased risk compared to the general population, prospective studies are necessary to investigate the yield and survival benefit of screening for second primary tumours in patients with oesophageal squamous cell carcinoma.