Effectiveness of prognostic nutritional index in predicting overall survival and evaluating immunotherapy response in anaplastic thyroid carcinoma

Background The prognostic value of nutritional status in anaplastic thyroid carcinoma (ATC) remains unclear. The Prognostic Nutritional Index (PNI) is a reliable indicator of overall nutritional and immune status, and it has emerged as a significant prognostic factor in various malignancies. This study aimed to explore the utility of PNI in ATC. Methods We systematically reviewed ATC patients in our institute from January 2000 to June 2023 and categorized them into high and low PNI groups based on the median PNI value. Kaplan–Meier analysis and Cox regression were employed to assess the impact of PNI on overall survival, while ROC curve analysis evaluated the predictive value of PNI. Mimics software was used for three-dimensional reconstruction of pre- and post-immunotherapy tumor volumes, enabling the assessment of treatment response. Results A total of 77 ATC patients were included in this study. Low baseline PNI was associated with significantly shorter overall survival (1-year survival rate: 5.26% vs 30.77%; median survival time: 5.30 months vs 8.87 months). The 1-year, 2-year, and 3-year AUC values for PNI were 0.82, 0.79, and 0.77, respectively. In the multivariate analysis, both PNI and tumor size emerged as independent prognostic factors for patient overall survival. Among ATC patients receiving 2–3 cycles of immunotherapy, an increase in post-treatment PNI levels was positively correlated with a reduction in tumor volume. Conclusion PNI is an independent predictor of overall survival and holds the potential to serve as a valuable indicator for assessing and predicting immunotherapy efficacy in ATC patients.