Fish oil benefits have proven inhibitory effects against skin cancer, breast cancer, pancreatic cancer, colon cancer, prostate cancer, larynx cancer and lung cancer. Fish oil contains high amounts of omega-3 polyunsaturated fatty acids. Studies show that it can be used to prevent and treat cancer. Researchers found that a diet rich in fish oil had a significant lowering affect on cancers in animals as compared to high corn oil diets or low-fat diets. Expect fish oil to boost your immune system and change your hormone profile. This may be especially helpful in hormone-related cancers such as breast cancer. Eat a diet rich in fatty fish. Try grilling or baking salmon or mackerel to get more fish oil in your system. Supplement your diet by taking fish oil every day. It comes in soft gel and capsule form. You can find a product that contains omega-3 and omega-6 fatty acids, combining flax, fish and borage oils