Patient that undergo chemotherapy and radiotherapy are at risk of weight loss during treatment which can impact quality of life and survival. Patients with the most symptoms were associated with weight loss, a lower quality of life and lower performance status. This can be important as will determine which group the patient will be part of if there is recurrence of the cancer and how to treat it.The main adverse effect of chemo- and radio-therapy is diarrhea and it may impact the treatment of the cancer (eg. The dose of the next treatment is reduced). The ESPEN guidelines suggest that there is no effect of enteral nutrition on tumor response to chemotherapy. Studies have supported ESPEN and ASPEN guidelines.For the management of chemotherapy induced diarrhea the suggested steps are to use fluid resuscitation and medication. An overview of the underlying mechanisms of diarrhea is given in order to better address the cause of it. As of now there are no dietary strategies to decrease the toxicity of chemotherapy.