The relationship between prognostic nutritional index at the time of diagnosis, and treatment response and prognosis in patients with lung cancer

Objective: Many parameters such as disease stage, patient performance status, weight loss and nutritional status in lung cancer affect the prognosis of the disease. In this study, we aimed to investigate the relationship between Prognostic Nutritional Index (PNI) which was calculated with hematological and biochemical parameters, and treatment response and prognosis of the patients diagnosed with lung cancer and followed-up in our clinic. Method: 482 patients who were treated and followed-up in the Department of Medical Oncology, Faculty of Medicine, Dokuz Eylul University between 2010-2017 and met the criteria of our study were included in the study. Demographic data as well as prognostic nutritional index of each patient were calculated at the time of diagnosis and in the post-treatment period. Prognostic Nutritional Index was calculated as follows: (PNI) = (serum albumin level (g/dl) × 10) + (total lymphocyte count (mm3) × 0.005). The index calculated before the treatment was expressed as PNI1 and the recalculated index after the treatment was expressed as PNI2. The difference between these two indexes (PNI2-PNI1) was indicated as PNIf. In addition, Glasgow Prognostic Score (GPS) was calculated using C-reactive protein and albumin values. The effects of PNI and other parameters on treatment response and survival were evaluated. WHO response evaluation criteria were used in the evaluation of treatment response, while Kaplan-Meier survival analysis was used in survival analysis. The variables considered as significant in the univariate analysis were introduced into the Cox regression with the "Forward Likelihood Ratio" method. Results: A total of 482 patients were evaluated and 79 of them were the patients with non-small cell lung cancer (NSCLC) and 403 patients were diagnosed with small cell lung cancer (SCLC). The mean follow-up period of the whole patient group was 24.5 months and the median survival time was 24 months. There was a statistically significant difference between mortality rates and patient age>64, male gender, small cell lung cancer (SCLC) type of cancer, the inability to apply surgical treatment and radiotherapy, and inability to treat with concurrent chemoradiotherapy in the univariate analysis for the factors affecting the prognosis in all patient groups. Similarly, both the overall survival (p <0.001, p <0.001, p:0.009 and p <0.001, respectively) and progression-free survival (p <0.001, p<0.001, p: 0.007, and p <0.001, respectively) were longer in the groups PNI1, PN2, PNIf with high scores and in the group without GPS cachexia. In the Cox regression analysis, the independent variables which statistically significantly affected the survival time were included the type of cancer, serum albumin level, surgical treatment, the ability to apply surgical treatment, applicability to radiotherapy, GPS and PNI2 score (p= 0,031, p: 0,015, p <0.001, p: 0.001, p <0.001 and p <0.001, respectively). The overall survival was longer in the patients whose initial PNI1 values were > 45 and the post-treatment PNI2 values did not decrease (>45). However, the overall survival was significantly shorter in the patients whose initial PNI1 values were <45 and PNI2 values persisted at this level and PNI2 values were <45 after the treatment although their initial PNI1 values were >45. While a positive correlation between PNI1 and response is found, there was no significant relationship was found between PNIf, GPS and treatment response when the factors in response to treatment were evaluated in 267 patients with locally advanced/metastatic NSCLC and 73 patients with SCLC. Conclusion: The results obtained in our study suggested that PNI can be used dynamically as a marker for the evaluation of general nutritional status, prognosis and predicting treatment response in the patients with lung cancer. Keywords: Lung Cancer, Prognostic Nutritional Index, Glasgow Prognostic Score