Evaluation of the Relationship Between Prognostic Nutritional Index and Postoperative Complications in Patients Undergoing Oncologic Surgery: A Retrospective Cohort Study

Anorexia, malnutrition, and cachexia are commonly observed in patients undergoing oncologic surgery . Although these issues are more pronounced in advanced-stage disease, they can also occur in early-stage malignancies and adversely affect treatment outcomes. Various methods and tests are used to assess patients' nutritional status, including the Malnutrition Universal Screening Tool (MUST) for community screening, the Nutritional Risk Screening (NRS) for hospitalized patients, and the Mini Nutritional Assessment (MNA) for elderly patients. Some of these tools are simple, consisting of only a few parameters, while others are more complex, incorporating clinical, laboratory, and technological measurements . Examples of these scales include the Subjective Global Assessment (SGA) and the Patient-Generated Subjective Global Assessment (PG-SGA) . Nutritional assessment methods have generally been reported to be useful in predicting treatment response, tolerance, and prognosis.

One such tool, the Prognostic Nutritional Index (PNI), was first proposed by Onodera et al. as a novel prognostic score based on systemic inflammation, calculated using the combination of lymphocyte count and serum albumin levels. PNI is relatively simple, relies on fewer parameters, and is easy to apply . It is calculated using the formula:

PNI=Serum albumin (g/L)+(5×Total lymphocyte count [109/L])PNI=Serum albumin (g/L)+(5×Total lymphocyte count [109/L])

Onodera et al. demonstrated that PNI values above 45 can be used reliably, although the optimal cut-off value may vary . Hypoalbuminemia is an independent predictor of in-hospital and long-term adverse outcomes . Serum albumin (SA) is a negative marker of inflammation, as its concentration decreases in the presence of inflammatory processes . It also serves as an abundant and important circulating antioxidant, participating in ligand binding and free radical scavenging activities . Lymphocyte count reflects immune function; low lymphocyte levels have been associated with pre-existing immunosuppression, leading to inadequate immune responses in cardiovascular diseases. Patients with lymphopenia are more likely to develop endothelial dysfunction, platelet activation, and thrombogenesis. Total lymphocyte count (TLC) is an immuno-inflammatory biomarker, and lymphopenia is more likely to develop in the setting of inflammation-associated lymphocyte apoptosis .

PNI has been used as a prognostic marker in various malignancies, pulmonary embolism, and other diseases. It has been shown to be an effective indicator of nutritional and immunological status in cancer patients and to influence patient prognosis through local immune responses . Although the predictive value of PNI has been studied for postoperative mortality, treatment response, and prognosis in different oncologic surgeries, there is no study evaluating its prognostic role across all patients undergoing oncologic surgery . This study aims to assess the impact of PNI on postoperative outcomes in patients undergoing various oncologic surgical procedures.