Esophageal cancer refers to malignant lesions formed by abnormal proliferation of esophageal squamous or glandular epithelium. Its development generally passes through the stages of epithelial atypical hyperplasia, carcinoma in situ and invasive carcinoma. Esophageal squamous epithelial atypical hyperplasia is an important precancerous lesion of esophageal cancer, and it usually takes several years or even a dozen years from atypical hyperplasia to cancer. Because of this, some esophageal cancers can be detected early and can be completely cured. Patients with dysphagia or foreign body sensation should undergo gastroscopy as soon as possible to detect early esophageal cancer or precancerous lesions. The etiology of esophageal cancer is not fully understood. Environmental factors, genetic factors, human papillomavirus (HPV) infection, dietary patterns, nutritional status, deficiency of trace elements (molybdenum, etc.) and chronic mucosal damage are related to the occurrence of esophageal cancer. Consumption of vegetables containing contaminating fungal toxins such as aflatoxin, heterochromatin, deoxynivalenol, and high amounts of nitrosamines and secondary amines may lead to the occurrence of esophageal cancer. China is a region with a high incidence of esophageal cancer, ranking fourth in tumor deaths. Guangdong Chaoshan people have the habit of drinking Kung Fu tea, which may also be related to the high incidence of esophageal cancer. About the diagnosis of esophageal cancer Esophageal cancer is insidious and may be asymptomatic in early stage. Some patients have foreign body sensation in the esophagus, or slow or obstructive choking feeling when passing food. It may also show as burning, pinching or pulling pain behind the sternum when swallowing. Progressive esophageal cancer is often diagnosed with dysphagia, and the dysphagia develops progressively or even cannot eat at all. It is often accompanied by vomiting, epigastric pain, weight loss and other symptoms. Late stage of the disease may be accompanied by obvious malnutrition, emaciation and cachexia due to long-term lack of food intake, and complications such as cancer metastasis and compression may occur. Such as hoarseness caused by cancer compression of the recurrent laryngeal nerve, pain caused by bone metastasis; jaundice caused by liver metastasis and other symptoms. If the tumor invades adjacent organs and is complicated by perforation, it may also cause mediastinal abscess and pneumonia. During physical examination, a hard abdominal mass can be occasionally felt in the upper abdomen, or a swollen lymph node on the clavicle can be touched. The key to cure esophageal cancer is early detection and early treatment. Therefore, those who are over 50 years old and have stagnant feeling after eating or difficulty in swallowing should have gastroscopy in time. Middle and late stage cancer can be easily detected through medical history, symptoms and signs and laboratory examination; however, early stage cancer has no obvious clinical symptoms, limited lesions, mostly carcinoma in situ or intra-mucosal carcinoma, which has not invaded the muscle layer and has no lymph node metastasis, so endoscopy and tissue biopsy are needed to confirm the diagnosis. At the same time, it should be distinguished from esophageal cardia failure, gastroesophageal reflux disease and benign esophageal stricture to avoid misdiagnosis. Clinically, patients with symptoms suspicious of esophageal cancer should go to hospital for fruit gastroscopy as soon as possible. If no obvious lesions can be seen in gastroscopy, then they should be assured that esophageal cancer can be excluded. About precancerous lesions in esophagus Precancerous lesions is a pathological term, which refers to the precursor lesions of any tumor, and treatment of precancerous lesions can prevent the occurrence of esophageal cancer. Pathologically, it is also called atypical hyperplasia or heterogeneous hyperplasia. The occurrence of esophageal cancer is a gradual process, usually from simple epithelial hyperplasia to atypical hyperplasia, where grade I atypical hyperplasia refers to heterogeneous epithelial cells occupying the lower 1/3 layer of epithelial layer, grade II atypical hyperplasia refers to heterogeneous epithelial cells occupying the lower 2/3 layer of epithelial layer, and grade III atypical hyperplasia refers to heterogeneous epithelial cells involving the whole layer of epithelium. Grade III atypical hyperplasia is also known as intraepithelial neoplasia or carcinoma in situ, which can further develop into invasive carcinoma. Because of the high cancer rate of grade II and III atypical hyperplasia, grade II and III atypical hyperplasia are often regarded as precancerous lesions in clinical work, also known as high-grade intraepithelial neoplasia, which can be locally excised and often completely cured by endoscopic treatment. If gastroscopy reveals ulcer or erosion or tumor-like lesions in esophagus, one should go to the hospital to do pathological biopsy while examining gastroscopy, that is, to clamp a little bit of tissue under endoscopy for pathological examination to assess whether the period is pre-cancerous or early cancer in esophagus, or to determine whether the lesion should be followed up and reviewed in order to get the most timely treatment. About the treatment of esophageal cancer Early diagnosis and early treatment can improve the prognosis of esophageal cancer. High-grade intraepithelial neoplasia or early cancer of the esophagus can be resected by endoscopic debulking or local surgical resection, provided that ultrasound endoscopic evaluation is performed and careful pathological examination of the resected tissue is used to determine whether the endoscopic resection is clean. Chemotherapy is not required if there is no submucosal infiltration. If the margins are not clean, additional surgery with chemotherapy or radiotherapy is required. A comprehensive plan based on surgery or radiotherapy is emphasized for middle and advanced stage cancer. For upper esophageal cancer, surgery is difficult because of its proximity to the pharynx, so radiotherapy and chemotherapy are recommended; for middle and lower esophageal cancer, surgery is the main treatment, together with chemotherapy and other symptomatic supportive treatment. If the esophageal cancer has reached advanced stage and caused obvious esophageal stricture which is not suitable for surgical resection, esophageal stent can be placed to solve the patient’s feeding problem, and at the same time, chemotherapy, immunotherapy and Chinese medicine can be used to control tumor progression and prolong life.