# Gene-expression assay → chemotherapy omission

Source: https://onco.cc/pairings/genomic-assay-to-chemo-omission/  
OnCo record `genomic-assay-to-chemo-omission` (Pairing). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A gene test on the tumour decides who can skip chemotherapy without losing protection.

## Summary

This diagnostic-therapeutic pairing uses a gene-expression assay on the tumour, chiefly Oncotype DX and also MammaPrint, to decide which women with HR-positive, HER2-negative breast cancer can safely omit adjuvant cytotoxic chemotherapy. Proliferation- and oestrogen-receptor-related gene expression predicts both chemosensitivity and prognosis better than clinical and pathological factors alone. TAILORx in node-negative disease and RxPONDER in postmenopausal women with one to three involved nodes found no chemotherapy benefit at a recurrence score of 25 or below, and MINDACT with MammaPrint concurs; together these are three large prospective trials. Premenopausal women with intermediate scores still gain from chemotherapy, possibly through ovarian suppression.

## Fields

- Kind: Pairing
- Last checked: 2026-09-07
- Pairs: Oncotype DX + Cytotoxic chemotherapy
- Type: diagnostic-therapeutic
- Rationale: Proliferation and ER-related gene expression predicts chemosensitivity and prognosis better than clinicopathologic factors alone.
- Evidence: Three large prospective trials (>20,000 women).

## Sources

- ClinicalTrials.gov NCT00310180: TAILORx: https://clinicaltrials.gov/study/NCT00310180
- ClinicalTrials.gov NCT01272037: RxPONDER (SWOG S1007): https://clinicaltrials.gov/study/NCT01272037

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- drugs: [MammaPrint (70-gene signature)](https://onco.cc/drugs/mammaprint/), [Oncotype DX](https://onco.cc/drugs/oncotype-dx/)
- trials: [RxPONDER (SWOG S1007)](https://onco.cc/trials/rxponder/), [TAILORx](https://onco.cc/trials/tailorx/)
- technologies: [Cytotoxic chemotherapy](https://onco.cc/technologies/cytotoxic-chemotherapy/)

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