Pre-cancerous lesions are changes in the skin or tissue of the body that may develop into cancer. They are caused by damage to cells from environmental factors such as sun exposure, smoking, or other carcinogens. Pre-cancerous lesions can be found through a biopsy or physical examination, and are typically removed to prevent further damage. Treatment may involve surgery, chemotherapy, or radiation therapy, depending on the size and location of the lesion. It is important to be aware of any changes in the body and to have regular check-ups to ensure that pre-cancerous lesions are identified and treated quickly.