The cause of purple spots on the body of patients with advanced stomach cancer is usually due to the disorder of the coagulation system. Besides, there are possibilities of hyperpigmentation and skin petechiae. 1. Stomach Cancer It is a common malignant tumor of digestive system, and the disease can be caused by heredity, bad dietary habits and other factors. With the development of tumor and anti-tumor treatment, the balance of fibrinolytic system in patient’s body can be damaged, and one of the manifestations is the obstacle of coagulation system. At this time, when the skin capillaries rupture without timely coagulation, it can lead to purple spots on the patient’s body. As distant metastasis occurs in this period, the condition is complicated and the chance of surgery is small. Non-surgical therapies, such as radiotherapy, targeted therapy, immunotherapy and other therapies, are often used to prolong patients’ survival and improve their quality of life. 2. Pigmentation Abnormal metabolism of cancer patients leads to abnormal pigmentation, which is patchy and discontinuous, and then occurs gradually and slowly. 3. Skin ecchymosis The fragility of capillaries increases, and all kinds of inconspicuous injuries can lead to the rupture of superficial subcutaneous capillaries, resulting in petechiae. Purple spots appearing on the body in the late stage of gastric cancer may also be caused by other reasons, so it is suggested that patients should consult the hospital in time.