2 Indications and current treatments
2.1 Squamous dysplasia of the oesophagus consists of flat premalignant epithelial lesions that may progress to squamous cell carcinoma. The World Health Organization's (WHO) histologic classification of gastrointestinal tumours refers to squamous dysplasia as squamous intra‑epithelial neoplasia (defined as non‑invasive cytological or architectural alterations that may lead to development of invasive cancer) and categorises it as either low‑ or high‑grade. Low‑grade squamous dysplasia is associated with a low risk of progression to invasive squamous cell carcinoma, whereas high‑grade intra‑epithelial neoplasia carries a higher risk of progression.
2.2 Squamous cancer of the oesophagus can be treated by surgery (oesophagectomy) or chemoradiotherapy or a combination of these methods. When the disease is detected at an early pre‑invasive stage such as carcinoma in situ or high‑grade dysplasia, then endoscopic treatment is possible. Methods include removal by endoscopic mucosal resection or endoscopic submucosal dissection, and ablation using photodynamic therapy, argon plasma coagulation, laser ablation, cryotherapy or multipolar electrocoagulation.