What are precancerous lesions? Cancer can be categorized into three stages: precancerous lesions, carcinoma in situ and invasive carcinoma. It is an extremely long process for a normal cell in the human body to start proliferating and become completely cancerous. When you find abnormal proliferation of this cell, it has the possibility of becoming cancerous, and if it continues to develop, it may develop into cancer, this process is called precancerous lesions. Precancerous lesions are caused by multiple factors, such as chronic inflammation, poor lifestyle and genetic factors. All cancers go through precancerous lesions, but not all precancerous lesions have the potential to turn into cancer; most of them may remain in a stable state, some may even return to normal, and a small number of them will eventually evolve into cancer. Therefore, recognizing precancerous lesions and actively detecting and treating them are important measures for cancer prevention. At present, there are the following common precancerous lesions. (1) Colorectal adenoma: It is very common and can be single or multiple. Especially hereditary familial adenomatous polyposis (FAP), the probability of cancer is 100%. (2) Ulcerative colitis: is an inflammatory bowel disease. The intestinal mucosa can be repeatedly ulcerated and proliferated, and the probability of intestinal adenocarcinoma is very high if left untreated. (3) Proliferative fibrocystic degeneration of the breast: it is mainly due to the proliferation of the ductal and alveolar epithelium of the breast lobules leading to cystic dilatation. If the pathology at this time shows papillary hyperplasia of ductal epithelium, the probability of cancer is higher. It is common in women around 40 years of age. (4) Cervical columnar epithelial ectasia (cervical erosion) with atypical epithelial hyperplasia: Cervical columnar epithelial ectasia (cervical erosion) is a condition in which the squamous epithelium of the cervix at the junction of the cervix and the vagina is necrotic and exfoliated to be replaced by the columnar epithelium, which is known as cervical erosion because it is pink in color and resembles the occurrence of a mucosal defect. Routinely, this is a normal physiological phenomenon and is reversible. However, this alternate phenomenon may develop into squamous cell carcinoma if it occurs frequently and is accompanied by HPV infection, which in turn leads to atypical hyperplasia of the epithelium. (5) Chronic atrophic gastritis and gastric ulcer: both may progress to gastric cancer. However, the probability is 1%. (6) Cirrhosis of the liver: usually caused by chronic hepatitis B, it may further develop into hepatocellular carcinoma. (7) Chronic skin ulcers: if the ulcers on the skin surface are left untreated for a long time, the squamous epithelium of the epidermis proliferates under the long-term chronic stimulation, and cancer may occur. (8) Mucous membrane leukoplakia: the common site is in the oral cavity or vulva pubis. Due to the overgrowth and keratinization of squamous epithelium, it can be manifested as white patches called mucosal leukoplakia. If not treated in time, the probability of developing into squamous cell carcinoma is very high. What are the early warning signs of cancer? Overall, the early signs of cancer can be summarized into five major points. (1) Lumps: painless, progressively increasing lumps in any part of the body, such as palpable lumps on skin, neck, tongue and throat, breast, abdomen, bones, etc., which can be big or small, single or multiple, with normal skin color and no pain or itch; or existing moles or warts on the skin, which change in a short period of time, such as deepening or lightening of the color, rapid growth, itching, oozing, and ulceration, especially on the soles of the feet, palms of the hands, or in the skin, or in the skin of the body. (2) Pain: Long-term and persistent aggravation of pain. (2) Aches and pains: Pain that continues to worsen over a long period of time. Headache: Progressively worsening, with nausea, vomiting (projectile vomiting is more critical), and blurred vision. Neck pain: pain, pressure, tightness and hardness in the neck, facial edema, which may be caused by the tumor compressing the superior vena cava causing obstruction of blood return. Chest pain: burning sensation behind the sternum, difficulty in swallowing things, pain, these may be manifestations of esophageal cancer, cardia cancer and stomach cancer. Bone pain: gradually aggravating localized pain, which may be skeletal system dysfunction, pathological fracture, hypercalcemia. (3) Blood: besides normal menstruation in women, it can be unexplained and prolonged bleeding from any organ. Hemoptysis and blood in sputum: excluding temporary bleeding caused by dry weather or overwork, it may be a manifestation of lung cancer. Blood in urine: the presence of hematuria, especially painless hematuria, may be bladder cancer or kidney cancer. Postmenopausal vaginal bleeding: vaginal bleeding after menopause in women may be a manifestation of cervical cancer Blood in stool: if it is accompanied by change in bowel habit, urgency and heaviness, it may be an early manifestation of colorectal tumor. Unexplained nosebleed: excluding secondary nosebleed caused by trauma, external force, dry weather or high blood pressure, it may be nasopharyngeal cancer, blood system disease, etc. (4) Fever: persistent fever, especially low-grade fever. Children should be alert to blood system tumors; adults should be alert to liver cancer, kidney cancer and other tumors. (5) Loss: unexplained weight loss in a short period of time with progressive decline (exclude hyperthyroidism, diabetes mellitus) If any of the above phenomena occurs, please do not ignore it, and it is recommended to undergo early screening for cancer in time to exclude health risks. How can we prevent cancer? Early detection, early diagnosis and early treatment are the key to preventing cancer. Timely detection and treatment of precancerous lesions and early-stage cancer can nip the disease in the bud, thus effectively improving the survival rate of cancer patients. For example, if breast cancer is detected at an early stage and surgically removed, the 5-year survival rate can reach more than 85%, but if it is detected only when it has infiltrated and metastasized, the 5-year survival rate after treatment may only be 5%. However, if it is found only when it develops infiltration and metastasis, the survival rate after treatment may only be 5%. It takes years or even decades for a cancer cell to develop from sprouting to proliferation and then to penetrate the basement membrane and infiltrate into the deeper layers. Therefore, we need to do the following in our daily life. (1) Regular self-examination and periodic health checkups. (2) Actively respond to and participate in cancer screening services provided by the government or regular medical institutions. Cancer screening is different from health checkups and should be done in a specialized oncology department for targeted tumor screening. (3) Actively treat pre-cancerous lesions and conduct regular follow-up and testing for susceptible and high-risk groups.