Large Language Models as Decision Support in Breast Cancer Management: A Comparison with Multidisciplinary Team Decision-Making

Background/Objectives: Breast cancer management relies on multidisciplinary team (MDT) decisions that integrate clinical, radiological, pathological, and patient-related factors. Large language models (LLMs) may support such decisions, but evidence based on real-world cases remains limited.

Methods

We evaluated the agreement between ChatGPT-5.5 (OpenAI, San Francisco, CA, USA) and real MDT management of patients with invasive breast cancer. In this single-center, retrospective, proof-of-concept study, standardized preoperative clinical vignettes for 86 patients with invasive breast carcinoma were independently evaluated by GPT-5.5 (frozen prompt, Medium reasoning mode, Web Search enabled). AI-generated recommendations were compared with the MDT reference standard across eight therapeutic domains (four surgical, four non-surgical), yielding 688 individual decisions. Agreement was summarized descriptively and with Cohen’s κ.