The forbidden foods for cancer patients are mainly spicy, cold, greasy and other highly stimulating foods. As diet has a close relationship with the occurrence and development of tumor, necessary contraindications are needed. Cancer should avoid spicy food, such as chili, pepper, garlic, onion, etc. Such food may lead to severe stimulation of gastrointestinal mucosa of cancer patients, nausea and vomiting, abdominal pain and diarrhea and other symptoms. Cancer should also avoid raw and cold foods, including ice cream, raw fish, oysters, celery, cucumber, etc. Such foods may have adverse effects on the digestive system after entering the gastrointestinal tract. Cancer patients have poorer body functions, and foods such as fatty meat, walnuts, sesame seeds, peanuts, etc. will bring greater digestive pressure to the gastrointestinal tract of cancer patients, which will easily lead to indigestion and affect the recovery of the body. Pay attention to reasonable diet and follow doctor’s advice.