# Cell composition confound (tumour versus stroma and immune cells)

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

## TL;DR

Because a tumour sample is a mix of cancer, stromal and immune cells, a difference between two samples may only reflect a different mix of cells.

## Summary

The tumour microenvironment, as Wikipedia describes it, is the ecosystem of cancer cells, stromal tissue, immune cells and extracellular matrix around a tumour. Any measurement on the whole sample (bulk expression, methylation, a region of a spatial section) averages over that mix, so an apparent risk or subtype difference between regions or patients can be a composition difference rather than a change in the cancer cells themselves. Deconvolution and purity estimates are the usual corrections.

## Fields

- Kind: Term
- Last checked: 2026-09-24
- Also known as: cell composition confound; cell-mix confound; stromal contamination; immune infiltration confound
- 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/cell-composition-confound.

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Tumor_microenvironment
- Wikipedia: https://en.wikipedia.org/wiki/Tumor_microenvironment

## Connected records

- terms: [Cancer AI vocabulary (CanSim terms map)](https://onco.cc/terms/cancer-ai-vocabulary/), [Microenvironment and inflammation: tumours as wounds that do not heal](https://onco.cc/terms/microenvironment-inflammation-theory/), [Stroma-rich and desmoplastic tumours in molecular data](https://onco.cc/terms/desmoplastic-stroma-rich/), [Tumour purity](https://onco.cc/terms/tumour-purity/)

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JSON: https://onco.cc/api/v1/entities/cell-composition-confound.json