We can call dietary as diet therapy. As it is a method giving the proper nutrition to the patient prescribed by the doctors. Treatment of the patient involves food for better condition of the health. In the case of cancer patients diet is very important to survive for a long period. Taking the right kind of the food before and after cancer treatment is very important. As the cancer patient should need all the vitamins as well as nutrition. When the body is not provided with the proper nutrition then the patient is going to suffer with the malnutrition. In some conditions, the tumours in our body make chemicals that distract the way of nutrients usage. Cancer and the cancer treatment make the patient harder to consume the nutrition and vitamin. The side effects caused by the treatment of cancer in eating.