The early symptoms of malignant tumors are generally not obvious and specific. If patients do not take targeted examination and treatment when early symptoms appear, it is easy to let the disease have a chance to develop and deteriorate. (1) Skin pigmented nevus with itching, hair loss, oozing, erosion or surface cracking, sudden enlargement. (2) Localized ulcers and hard nodules in the mouth that do not heal for a long time. (3) Non-resolving lumps or swollen lymph nodes can be palpated in any part of the body without obvious redness, swelling or pain, and the swelling is progressively enlarged. (4) Chronic skin ulcers, fistulas and sinus tracts with nodules or crater-like changes at their edges, or with foul odor (5) Unilateral tonsils with progressive enlargement, no obvious fever and pain, and no improvement by anti-infection treatment, should be alerted to tonsil cancer. (6) Unexplained unilateral tinnitus, hearing loss, nasal congestion and migraine, accompanied by blood in the first sputum in the morning, should be considered as possible nasopharyngeal carcinoma. (7) Enlarged mass in the anterior neck area with hard texture, accompanied by unexplained hoarseness, which becomes more and more severe and does not improve with treatment, should be considered as thyroid cancer. (8) Fixed chest pain, cough, blood in sputum, and a history of smoking should be considered as lung cancer. (9) Eating, especially dry and hard food, with obstructive feeling on the side, or erratic rebellion, retrosternal discomfort, stabbing pain or foreign body feeling in the esophagus should be considered as esophageal cancer. (10) If there is a history of gastric ulcer and regular pain in the upper abdomen is disturbed and painful at night, accompanied by loss of appetite, emaciation, anemia or black stool, the possibility of malignant change of gastric ulcer should be noted. (11) History of hepatitis or long-term alcohol consumption, recent discomfort in the liver area, weakness, weight loss with gastrointestinal symptoms, and palpable mass in the right upper abdomen, consider whether it is hepatocellular carcinoma. (12) Painless progressive yellow staining of skin and sclera without fever or history of hepatitis should be considered as pancreatic head cancer or pot belly cancer. (13) Painless, intermittent hematuria, after excluding urinary tuberculosis, should consider whether there is a urinary tract tumor. (14) Change in stool habit, stool with mucus, bloody stool or thinning of stool sticks, feeling of anal drop, and multiple polyps in the colon should be considered for rectal cancer or colon cancer by anal finger diagnosis or fiberoptic colonoscopy. (15) Vaginal bleeding outside menstruation or after menopause, especially vaginal bleeding after sexual intercourse, especially for those with cervical erosion and chronic cervicitis, cervical smear examination should be performed to consider the possibility of cervical cancer. (16) Pre-existing prepuce or prepuce with local roughness, desquamation or nodular swelling of glans without obvious pain is often a manifestation of penile cancer. (17) Headache, nausea, vomiting, visual disturbance and unstable walking should be considered whether there is intracranial occupying lesion, and cranial CT examination should be performed to clarify the diagnosis. (18) Children or adolescents with recurrent bleeding spots on the skin and mucous membranes, anemia or fever, enlarged liver and spleen, and bone marrow image by bone marrow aspiration can clarify the possibility of leukemia. (19) The presence of hard masses in the breast, adhesion to the skin, nipple retraction and nipple overflow should alert the possibility of breast cancer. (20) Intractable pain in the upper abdomen, which is aggravated when lying down or supine and relieved when sitting up or bending the upper body forward, should alert to pancreatic cancer or metastatic cancer of the pancreas.