Tumor disease itself, food allergy, drug allergy or adverse reaction, radiation dermatitis and other reasons can lead to skin rash in tumor patients. Tumor disease itself: Tumor diseases such as breast cancer, blood system tumors can lead to skin rashes and ulcers. Food allergy: tumor patients eating spicy and stimulating food and food that is easy to trigger allergy can lead to skin rash. Drug Allergy or Adverse Reaction: After applying chemotherapy drugs, tumor patients may have skin rash due to allergy. Some patients have skin rashes due to the application of immunotherapy drugs, which enhance the immune response to their own tissues. In addition, some tumor-targeting drugs can affect the skin metabolism easily lead to rash. Radiation dermatitis: Skin damage of tumor patients after radiotherapy leads to radiation dermatitis, causing itchy skin rash. When tumor patients have skin rashes, they should go to regular hospitals in time to improve the examination and clarify the cause of the disease, and carry out treatment under the guidance of doctors. Normally, tumor patients should pay attention to their own diet and living habits, so as to better prevent the occurrence of skin rashes.