Cancer is a scary disease which can be cured by using different methods. It may cause several complications like: Pain Fatigue Difficulty breathing Nausea Diarrhea or constipation Weight loss Chemical changes in your body Brain and nervous system problems Unusual immune system reactions to cancer Cancer that spreads Cancer that returnsCancer treatment is very painful. Keep yourself healthy to prevent cancer. The doctors have identified some ways to reduce cancer risk, such as: Maintain a healthy weight Exercise most days of the week Eat a healthy diet Avoid excessive sun exposure Stop smoking Schedule cancer screening exams Ask your doctor about immunizations