Adenocarcinoma is a malignant tumor that originates from the glandular epithelium. The causes of adenocarcinoma are not fully understood, and the degree of malignancy and five-year survival rate vary among adenocarcinomas with different degrees of differentiation. Usually, the higher the differentiation of adenocarcinoma, the less malignant it is, and the better the treatment effect. 1. Breast cancer: It often appears as a painless breast lump, and some patients may have cellulite or ulceration on the surface of the breast, and the diagnosis is confirmed by biopsy of the lump and tumor markers. The main factors affecting the prognosis are lymph node metastasis and whether there is a chance of surgery. 2. Lung adenocarcinoma: Early stage shows irritating dry cough and later may show symptoms such as blood in sputum and chest pain. The treatment is usually surgical, which depends on the extent of the lesion, but all aim to maximize the removal of the lesion and reduce the possibility of recurrence while protecting the normal lung tissue. Generally speaking, lung adenocarcinoma is more difficult to treat and has a poor prognosis; 3. Gastrointestinal adenocarcinoma: Gastrointestinal tumors usually have atypical symptoms in the early stage, but can be detected by gastrointestinal microscopy. Early intra-mucosal adenocarcinoma can often be removed minimally invasively through endoscopy, and mid- to late-stage GI adenocarcinoma can be treated through surgery if metastasis has not occurred. With the development of GI endoscopy, the probability of early detection and treatment of GI adenocarcinoma is also increasing, so the five-year survival rate of GI adenocarcinoma is generally higher. Besides, there are prostate cancer, uterine cancer, pancreatic cancer, etc. The prevention and early detection of adenocarcinoma can be achieved through regular medical checkups and routine screening for high-risk groups. If adenocarcinoma is diagnosed, you should follow the medical advice and actively cooperate with the treatment.