ARTEMIS: a pilot study comparing AI-based and expert therapeutic decisions in simulated clinical cases of neuroendocrine neoplasms

: Neuroendocrine neoplasms (NENs) are rare and heterogeneous malignancies requiring multidisciplinary management. Large language models (LLMs) are emerging as decision-support tools, but their role in therapeutic decision-making is largely unexplored. ARTEMIS was a pilot cross-sectional study comparing three configurations-a baseline GPT, a customised GPT with static domain knowledge (GPTs), and a retrieval-augmented GPT (RAG)-against a panel of nine Italian NEN experts using twenty simulated, non-surgical cases. The primary endpoint was non-inferiority for systemic therapy recommendations; secondary endpoints included completeness, explicit uncertainty, parsimony of additional tests, costs, and variability metrics. RAG and GPTs achieved 70.0% agreement versus the expert benchmark (63.8%), meeting the exploratory -10% non-inferiority margin but not the stricter -5% threshold. Baseline GPT reached 60.0% and was not non-inferior. All AI systems consistently produced complete recommendations and expressed uncertainty more often than experts; RAG tended to propose fewer additional tests and lower associated costs. Experts showed greater variability than AI systems, and Ki-67 correlated with disagreement, indicating biological aggressiveness as a source of uncertainty. This exploratory study suggests that LLMs can approximate expert therapeutic reasoning under controlled conditions, but concordance remains limited and external validation in real-world settings is needed before clinical use.