# Endocrine resistance

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

## TL;DR

When hormone therapy stops controlling a hormone-driven breast cancer, either quickly (primary) or after years (acquired).

## Summary

Primary resistance: relapse within 2 years of adjuvant ET or progression within 6 months of first-line metastatic ET. Secondary: later relapse or progression. Mechanisms: ESR1 mutations, PI3K/AKT/mTOR activation, cyclin D1/CDK4 amplification, RB loss, FGFR1 amplification, HER2 activation, lineage plasticity. Determines eligibility for INAVO120-type regimens (relapse on/within 12 months of adjuvant ET).

## Fields

- Kind: Term
- Last checked: 2026-09-07
- Also known as: endocrine-resistant

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Hormone_therapy_(oncology)
- Wikipedia: https://en.wikipedia.org/wiki/Hormone_therapy_(oncology)

## Connected records

- cancers: [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/)
- targets: [CDK4/6](https://onco.cc/targets/cdk4-6/), [Estrogen receptor (ERα)](https://onco.cc/targets/estrogen-receptor/), [PIK3CA / PI3K-alpha](https://onco.cc/targets/pik3ca/)
- terms: [Aromatase inhibitor](https://onco.cc/terms/aromatase-inhibitor/), [Hormone receptor status (ER / PR)](https://onco.cc/terms/hormone-receptor-status/), [Hyperglycaemia (PI3K/AKT inhibitor class effect)](https://onco.cc/terms/hyperglycaemia/), [mCRPC and mHSPC (castration-resistant vs hormone-sensitive prostate cancer)](https://onco.cc/terms/mcrpc-mhspc/), [Receptor conversion: when the receptors change between the primary and a recurrence](https://onco.cc/terms/receptor-conversion-breast/), [Selective oestrogen receptor degrader (SERD)](https://onco.cc/terms/serd/)
- bottlenecks: [Acquired resistance to every therapy](https://onco.cc/bottlenecks/b-resistance/)
- pathways: [The cell-cycle engine (cyclins & CDKs)](https://onco.cc/pathways/cell-cycle-engine-cdks/)

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JSON: https://onco.cc/api/v1/entities/endocrine-resistance.json