Hi there! One of the best ways to help keep your immunity up is to focus on nutrient-dense foods that are high in protein, healthy fats, and provide adequate calories or energy throughout the day. Opt for small, frequent meals or nutrient dense smoothies throughout the day and keep your favorite healthy snacks handy! A diet comprised mainly of fruits and veggies, whole grains, beans, peas, lentils, nuts and plant-based fats is best for people with a history of cancer. Limiting refined grains, added sugars, red meat and alcohol offers additional protection. You may also want to check out this blog post, "Stock Your Kitchen With These Cancer Fighting Foods": https://www.nutriliving.com/blog/stock-your-kitchen-with-these-cancer-fighting-foods
I also encourage you to seek out a registered dietitian in your area that specializes in oncology as they will be able to offer customized nutritional recommendations based on your specific health history and dietary needs.