Nutrient Recommendations for Cancer Patients Treated with Pelvic Radiotherapy, with or without Comorbidities.

Radiotherapy is one of the main treatment options used in pelvic cancers. Ionizing radiation induces damage to surrounding tissues, resulting in disruption of normal physiological functions and symptoms such as diarrhea, tenesmus, incontinence, and rectal bleeding, which can all significantly alter the patient's quality of life. These patients are at increased risk of developing protein-calorie malnutrition and micronutrient deficiencies. Therefore, designing a proper nutritional intervention plan, with an optimal proportion of protein, fat, and carbohydrates, is required to reduce or even reverse the patients' poor nutritional status, increase their tolerance and response to oncology treatment, decrease the rate of complications and improve their quality of life. The aim of this review was to establish a nutritional plan that includes recommendations on macronutrient proportions and micronutrient intake in patients receiving pelvic radiotherapy. The following nutritional plan has been recommended in the literature: Energy: 28-31 kcal/kg/day, using the Harris-Benedict formula adjusted for body weight in obese patients; protein: 20-30%; fat: 30-40%; and carbohydrates: 40-50%. The maintenance of adequate levels of Vitamin D, Vitamin E, Vitamin A, calcium, magnesium, thiamin, riboflavin, and niacin must be emphasized. Physical activity must also be increased to maintain muscle mass. Nutrient requirements must be established in an integral manner, considering the patient's age, nutritional status, and the presence of comorbidities. Unnecessary dietary restrictions should be avoided to ensure an adequate nutritional status.