Cancer does not occur immediately, but evolves gradually due to atypical proliferation of normal cells at the lesion. Common precursors of cancer are: Oral white spot is the precursor of oral cancer, in which the patient feels roughness and astringency in the local area, and white plaques can be seen with naked eyes, which mostly occurs in lips, tongue, palate, gums and other parts of the body. Gastric polyps Often have mild pain and discomfort in the upper abdomen, 95% of patients have lack or low gastric acid, and symptoms such as nausea, anorexia, dyspepsia, diarrhea, etc. Meanwhile, intermittent or persistent bloody stools occur. Yao Li, Department of Integrative Medicine, Nongsanji Hospital, Kashgar, Xinjiang, China Esophageal epithelial atypical hyperplasia Patients have vague pain, burning or foreign body sensation behind the sternum when swallowing food. With staining method under esophagoscopy, the site and range of lesion can be clarified, suggesting that it is a precancerous manifestation of esophageal cancer. Liver lesions If there is hepatitis B, hepatitis C or history of cirrhosis for 10 years, such as sudden onset of vague pain in liver area, dry mouth, insomnia, bleeding from gums and nasal cavity, accompanied by epigastric fullness and discomfort in liver area; generalized joint pain, especially obvious in waist and back, accompanied by anorexia and irritability; recurrent diarrhea, accompanied by dyspepsia and bloating, and gradual loss of weight, it is necessary to be alerted to cancerous lesion possibility. Vulvovaginal leukoplakia (white lesion of vulva): It occurs on the vulva, with dry, atrophied and whitish skin, itching and burning sensation, and severe pain when urine impregnates the vulvovaginal lesion, which needs to be considered as a cancerous lesion. Proliferative endometriosis Mostly seen in older women who are childless or infertile, and accompanied by obesity, high blood pressure, diabetes mellitus, manifested by irregular vaginal bleeding, delayed menopause, menstrual disorders in the pre-menopausal and menopausal periods, and the above symptoms need to be considered for the possibility of uterine cancer.