{"entity":{"id":"organ-of-origin-signal","kind":"term","name":"Tissue-of-origin signal in tumour data","aka":["organ-of-origin signal","tissue-of-origin signal","tissue of origin","organ of origin","cell-of-origin signal","tissue-only floor","type-only floor"],"tldr":"A tumour's molecular profile is dominated by the organ it came from, so a model can look impressive by recognising the organ and must be judged against a baseline that knows only that.","summary":"The TCGA Pan-Cancer Atlas classification paper found that cell of origin dominates the molecular clustering of ten thousand tumours across thirty-three types. Expression, methylation and even mutation patterns encode the tissue so strongly that a pan-cancer survival or drug-response model gets much of its apparent accuracy from the tissue label; the honest comparison is a tissue-only or cancer-type-only baseline, and within-type (stratified) metrics. The same signal is what classifiers exploit to assign a primary site to cancers of unknown primary (Wikipedia).","asOf":"2026-09-24","wikipedia":"https://en.wikipedia.org/wiki/Cancer_of_unknown_primary_origin","links":[{"label":"Hoadley et al., Cell-of-Origin Patterns Dominate the Molecular Classification of 10,000 Tumors from 33 Types of Cancer (Cell 2018)","url":"https://doi.org/10.1016/j.cell.2018.03.022"},{"label":"Wikipedia","url":"https://en.wikipedia.org/wiki/Cancer_of_unknown_primary_origin"}],"tags":["cansim-terms"],"related":["cancer-ai-vocabulary"],"cancers":["cancer-of-unknown-primary"],"sections":[],"technologies":[],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":["concordance-index","clinical-covariates","gene-co-expression"],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"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/organ-of-origin-signal."],"provenance":{"editedBy":"OnCo CanSim terms wave (Wikipedia summaries, standards and project pages, GDC and FDA pages, Europe PMC)","editedOn":"2026-09-24","note":"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"},"category":"Cancer biology"},"route":"/terms/organ-of-origin-signal/","neighbours":{"term":[{"id":"accuracy-f1","kind":"term","name":"Accuracy, macro-F1 and confusion matrices","route":"/terms/accuracy-f1/"},{"id":"concordance-index","kind":"term","name":"C-index (concordance index), Harrell's and Uno's","route":"/terms/concordance-index/"},{"id":"cancer-ai-vocabulary","kind":"term","name":"Cancer AI vocabulary (CanSim terms map)","route":"/terms/cancer-ai-vocabulary/"},{"id":"clinical-covariates","kind":"term","name":"Clinical covariates (age, stage, nodes, treatment flags)","route":"/terms/clinical-covariates/"},{"id":"methylation-arrays","kind":"term","name":"DNA methylation arrays and beta values (450k, EPIC)","route":"/terms/methylation-arrays/"},{"id":"gene-co-expression","kind":"term","name":"Gene co-expression structure","route":"/terms/gene-co-expression/"}],"cancer":[{"id":"cancer-of-unknown-primary","kind":"cancer","name":"Cancer of unknown primary (CUP)","route":"/cancers/cancer-of-unknown-primary/"}]}}