CA refers to cancer in medicine and is an abbreviation of the English word cancer. In clinical practice, Ca is commonly used to represent cancer, such as liver Ca, lung Ca, breast Ca, etc., which refer to liver cancer, lung cancer, breast cancer, etc. Usually when cancer is suspected but not fully diagnosed, it can only be said that there is a lump or occupying lesion in a certain part of the body, and then further biopsy is done to find the cancer cells to confirm the diagnosis before it can be called cancer. Cancer is a general term for all kinds of malignant tumors, and it can occur in all parts of the body. The characteristics of malignant tumors include rapid growth, invasive growth; easy metastasis and recurrence; in addition to the symptoms of the original disease, there can also be low fever, poor appetite, weight loss, anemia, infections and other systemic symptoms, and the rapid development of the disease can endanger the patient’s life if it is not treated in time.