Nutritional Status of Patients with Cancer During Oncological Treatment—A Multicenter Cross-Sectional Study

Background: Malnutrition is a significant clinical problem in patients with cancer, occurring not only during hospitalization but also throughout the recovery phase. It brings severe health and economic consequences, affecting patients on both physical and psychological levels. The American Society for Parenteral and Enteral Nutrition (ASPEN) and the European Society for Clinical Nutrition and Metabolism (ESPEN) emphasize the critical importance of early detection of nutritional disorders and timely intervention in oncology populations. The aim of this study was to determine the prevalence of malnutrition and factors associated with malnutrition among hospitalized Polish oncology patients and to draw attention to the need for early nutritional assessment in patients with cancer so as to ensure appropriate nutritional care. Methods: A multicenter cross-sectional study was conducted in accordance with the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines among adult patients diagnosed with cancer and undergoing oncological treatment. Data collection involved a structured survey questionnaire, anthropometric measurements, and validated screening tools: Mini Nutritional Assessment (MNA), Nutritional Risk Screening Score 2002 (NRS 2002), and Subjective Global Assessment (SGA). Results: The study group comprised 560 patients with a mean age of 55 ± 13.95 years, including 59% women and 41% men. The mean duration of illness was 3.37 years. Advanced-stage cancer was present in 43% of participants, and 66% were undergoing chemotherapy. The mean Body Mass Index (BMI) for the study group was 23.14 kg/m2, with a mean MNA score of 16.23 points and a mean NRS 2002 score of 2.39 points. Based on Subjective Global Assessment, moderate malnutrition was identified in 45% of patients, whereas severe malnutrition was confirmed in 27% of the study population. Conclusions: The prevalence of malnutrition among oncology patients is high. Early screening and regular monitoring are essential for the prompt identification of patients at risk, enabling the implementation of appropriate nutritional therapy and the improvement of clinical outcomes.