# Local-only language models over patient data (privacy by architecture)

Source: https://onco.cc/terms/local-llm-reasoning-layer/  
OnCo record `local-llm-reasoning-layer` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Running an open language model on the same machine as a patient's data, with code that blocks any network call, lets a system explain model outputs in words without the data ever leaving the room.

## Summary

A large language model is an AI model trained on vast text for generation and analysis (Wikipedia), and a clinical decision support system provides clinicians with knowledge and person-specific information in the workflow (Wikipedia). Cloud models cannot see identifiable patient data without agreements, so one design runs an open-weight model locally over a model's derived outputs only, with assertion-style guards that fail loudly if anything would be sent out or committed, and uses a cloud model only for cohort-level summaries of public findings. It is a privacy rule expressed as architecture, complementary to HIPAA and GDPR compliance.

## Fields

- Kind: Term
- Last checked: 2026-09-24
- Also known as: local-only LLM; on-device LLM; on-device language model; local language model; egress guard; egress guards; cohort briefing; LLM reasoning layer; no-network inference
- Tags: cansim-terms

## Notes

- Listed in the CanSim terms map 1.0.0 (docs/onco/terms.json, generated 2026-09-24), CC BY 4.0, attribution: CanSim project, an open, public-data-first cancer foundation-model programme; CanSim page path /terms/local-only-patient-reasoning-layer.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Large_language_model
- Wikipedia: clinical decision support system: https://en.wikipedia.org/wiki/Clinical_decision_support_system
- Wikipedia: https://en.wikipedia.org/wiki/Large_language_model

## Connected records

- terms: [Cancer AI vocabulary (CanSim terms map)](https://onco.cc/terms/cancer-ai-vocabulary/), [Controlled-access genomic data (dbGaP, EGA)](https://onco.cc/terms/controlled-access-data/), [HIPAA (Health Insurance Portability and Accountability Act)](https://onco.cc/terms/hipaa/), [Open weights, open code and gated models](https://onco.cc/terms/open-weights/), [Uncertainty quantification and confidence gates](https://onco.cc/terms/uncertainty-quantification/)

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