Cancer is one of the leading causes of morbidity and mortality worldwide. The World Cancer Research Fund determined that the diet and nutrition conditions of the individuals are modifiable risk factors in the development of several cancers and a predominant component in the recovery and effectiveness of the treatments. Nutritional intervention is critical, but nutritional support is not widely accessible to all individuals, leading to potential nutritional risk and nutrition wasting. A multidisciplinary approach with targeted nutrition is vital to improve the quality of care in oncology. Cachexia management remains a challenge in clinical practice and malnutrition is accepted as a significant negative predictive and prognostic factor in all cancer patients. The importance of metabolic interactions within the tumours are crucial and the mechanisms by which dietary factors might increase or decrease therapeutic intervention are key factors to unravel the nutrition influences in cellular and molecular processes in cancer.