In advanced stage of lung cancer, red spots on body may be due to lung cancer skin metastasis, chemotherapy side effect or skin disease. 1. Lung cancer skin metastasis: when lung cancer skin metastasis occurs, cancer tissues can destroy subcutaneous blood vessels, leading to bleeding, thus red spots appear on the body, which usually do not protrude from the surface of skin, but are local color changes of skin. 2. Side effect of chemotherapy: chemotherapy drugs will cause bone marrow inhibition, which will reduce the platelet of cancer patients and impair their coagulation function, resulting in red dots on the body, mostly due to subcutaneous bleeding. 3. Skin disease: It may be caused by heat rash (also known as prickly heat) or contact with allergic substances in the elderly who have been bedridden for a long time. Such red spots may protrude from the surface of the skin. If red spots appear on the body, it is recommended to communicate with the attending physician in time and treat them actively to avoid delaying the condition.