ResearchResearch paperReinforcement Learning · Large Language Models1 source · Oct 18, 2026

CasePlay: Self-Play Reinforcement Learning from Case Reports for Medical Reasoning

Reinforcement learning (RL) is a promising way to improve the clinical reasoning abilities of large language models (LLMs), but current pipelines often rely on expert-labeled questions or costly synthetic-data generation.

Key points

  • We study whether document-grounded self-play can convert these reports into effective RL training signals.
  • We identify two challenges that limit existing self-play methods in this setting: knowledge-point fixation}, where the proposer repeatedly asks about a narrow set of salient clues in a source report, and difficulty-quality mismatch, where appropriately difficult questions may still be poorly formed or shallow, limiting their value for reasoner training.
  • Extensive experiments across seven medically related benchmarks demonstrate that CasePlay outperforms existing self-play baselines and improves the SFT warm-start model by 3.1 points on average, highlighted by a 6.3-point gain on LiveClin.
  • This approach offers an effective path toward continually improving medical reasoning ability through self-play RL.

Sources (1)

  • [1]CasePlay: Self-Play Reinforcement Learning from Case Reports for Medical Reasoning
    arXiv (AI, ML, NLP, CV, robotics, multi-agent) · Oct 18, 02:06 AM
    Reinforcement learning (RL) is a promising way to improve the clinical reasoning abilities of large language models (LLMs), but current pipelines often rely on expert-labeled questions or costly synthetic-data generation.
    We study whether document-grounded self-play can convert these reports into effective RL training signals.

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