Cancer is also known as malignant tumor. In the early stage of cancer, there are often no precursor symptoms, but some patients may show some non-specific precursor symptoms, such as progressive weight loss, progressive loss of appetite, mental fatigue, and poor sleep. If you have any of these symptoms, you need to go to the hospital for medical checkups. Tumor markers for men or tumor markers for women should be tested, and imaging screening should be done. Therefore, systematic tests must be performed to find out the specific causes of these precursor symptoms, otherwise the treatment of early stage cancer will be delayed and many cancers are already in the middle and late stages when they are detected.