Precancerous lesions are not cancer, nor are they in the early stages of cancer. Precancerous lesions are reversible and most of them do not turn into cancer. “Precancerous lesion” is actually the name of pathology diagnosis, which is the migration stage of transition from benign to malignant lesion. Under the long-term effect of different carcinogenic factors, normal cells in human body firstly show an increase in the number of cells, but the cell morphology has not yet changed, which is called “simple hyperplasia” in pathology. Subsequently, while the number increases, the difference between the cell morphology and that of the tissue of origin will gradually worsen and enter the precursor stage of cancer, that is, precancerous lesions. No cancer cells can be detected in any precancerous lesions. The most common precancerous lesions are eight kinds: first, mucosal leukoplakia, mainly leukoplakia of the mucosa of the oral cavity, digestive tract, vagina and other tissues; second, atrophic gastritis; third, cervical erosion, mainly severe cervical erosion; fourth, cystic hyperplasia of the breast; fifth, senile solar keratosis; sixth, pigmented dry skin disease; seven, gastrointestinal polyps, especially familial and multiple polyps; and eighth, certain benign tumors. Although all malignant tumors have precancerous stages, the reverse is true, only a small percentage of precancerous lesions may evolve into cancer, and the chances of this are high and low for different tumors. These 8 types of precancerous lesions can almost always be clearly diagnosed through clinical and histopathological diagnosis. The causative mechanism of cancer is complex, often the result of multiple complex factors, as well as the interaction of internal and external factors. It usually takes about 10 years for precancerous lesions to develop into invasive cancer. If precancerous lesions are found only, there is no need to panic, and one should actively operate if surgical treatment is needed, and take the initiative to review regularly if regular review is needed. In addition, it should be pointed out that due to misunderstanding or fear of cancer, the definition of precancerous lesions has been expanded, and many non-pre-cancerous lesions have been treated as precancerous lesions, such as general skin moles and warts, common peptic ulcers and chronic gastritis, etc., which cannot be classified as precancerous lesions in general. Do not worry and carry a heavy burden of thought. Long-term mental stress can lower the immunity of the body and even promote the normal cells in the body to become cancerous.