Improving mortality prediction after radiotherapy with large language model structuring of large-scale unstructured electronic health records

Abstract

Background and purpose: Avoiding unnecessary radiotherapy (RT) in patients with limited life expectancy requires accurate selection. Traditional survival models based on structured data often lack precision. Large language models (LLMs) offer a novel approach to structuring unstructured electronic health record (EHR) data, potentially improving survival predictions by integrating comprehensive clinical information. Materials and methods: We analyzed structured and unstructured data from 34,276 RT-treated patients at Yonsei Cancer Center. An open-source LLM structured unstructured EHR data using single-shot learning. External validation included 852 patients from Yongin Severance Hospital. We compared the LLM's performance against a domain-specific medical LLM and a smaller variant. Survival prediction models using statistical, machine-learning, and deep-learning approaches incorporated both structured and LLM-structured data. Results: The open-source LLM structured unstructured EHR data with 87.5 % accuracy, outperforming the domain-specific medical LLM (35.8 %). Larger LLMs were more effective in structuring clinically relevant features, such as general condition and disease extent, which correlated with survival. Incorporating LLM-structured features improved the deep learning model's C-index from 0.737 to 0.820 (internal validation) and from 0.779 to 0.842 (external validation). Risk stratification was also enhanced, with clearer differentiation among low-, intermediate-, and high-risk groups (p < 0.001). Additionally, models became more interpretable, as key LLM-structured features aligned with statistically significant predictors traditionally identified from structured data. Conclusion: General-domain LLMs, despite not being fine-tuned for medical data, can effectively structure large-scale unstructured EHRs, significantly improving survival prediction accuracy and model interpretability. The RT-Surv framework highlights the potential of LLMs to enhance clinical decision-making and optimize RT treatment.