Glandular precursor lesions generally refer to precancerous lesions, and common precancerous lesions mainly include mucosal leukoplakia, junctional nevus, chronic atrophic gastritis, and lung glandular precursor lesions. Mucosal leukoplakia: Mucosal leukoplakia is one of the common precancerous lesions, which is a white patch appearing on the surface of mucous membranes, and is mainly characterized by hyperkeratosis of the superficial layer of mucous membrane epithelium. Mucosal leukoplakia has always been regarded as a precancerous lesion, with 20% to 30% developing into cancer. Some studies now show that mucosal leukoplakia is mostly harmless, with only a few developing malignant changes, with an average incidence of about 4%. Mucosal leukoplakia occurs mainly in two areas, the oral cavity and the vulva. Junctional nevus: A junctional nevus is a black or brown rash that is slightly elevated, round, and has a clear border. Junctional nevus can appear on any part of the body, especially palmoplantar and external genitalia. Junctional nevus has the tendency of malignant transformation and can be transformed into malignant melanoma under the effect of certain factors. Chronic atrophic gastritis: Chronic atrophic gastritis is a very common gastric disorder, accounting for 10% to 30% of all chronic gastritis. Chronic atrophic gastritis is a precancerous lesion that can induce cancer, and long-term irritation from chronic gastritis can lead to cellular carcinogenesis. Precancerous lesions are not cancerous, and therefore should not be equated with cancer. 4. Lung glandular precursor lesion: it is carcinoma in situ and atypical neoplastic hyperplasia in the classification of lung epithelial tumor. If it is analyzed and judged to be precursor lesion of lung glands, which does not belong to the category of cancer, surgical resection may not be needed urgently, and it can be followed up and observed for the time being according to the doctor’s instruction, and then surgical treatment can be carried out if necessary. Glandular precursor lesions in the lungs may develop into adenocarcinoma. If it is a glandular precursor lesion, it can be followed up through dynamic observation, and according to the changes of the lesion observed in the course of the follow-up, corresponding measures can be taken according to the doctor’s instructions.