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HR-positive breast cancer is the most common breast cancer, driven by oestrogen. It was treated for years with hormone-blocking pills, now joined by CDK4/6 inhibitors, PI3K-pathway drugs, degraders, and ADCs.
Hormone receptor-positive, HER2-negative breast cancer is about 70% of all breast cancers and the archetype of a hormone-driven, slow-evolving disease. Oestrogen receptor signalling drives proliferation, so endocrine therapy has been the backbone since tamoxifen (1977) and aromatase inhibitors (1990s); because recurrences can occur 10-20 years after diagnosis, therapy lasts 5-10 years and adherence is a major real-world determinant of outcome. Gene-expression assays (Oncotype DX, MammaPrint) now spare roughly 70% of node-negative and most postmenopausal node-positive patients chemotherapy, while adjuvant CDK4/6 inhibitors (abemaciclib, ribociclib) reduce recurrence in the high-risk minority.
Metastatic disease is treated as a sequence of endocrine-based combinations. First line is a CDK4/6 inhibitor plus endocrine therapy, with ribociclib and abemaciclib showing overall survival gains that palbociclib did not. Progression is increasingly managed by genotype: ESR1 mutations detected in ctDNA (30-40% after aromatase inhibitors) call for oral SERDs (elacestrant, imlunestrant) or the PROTAC vepdegestrant, and since September 2026 for camizestrant switched in at molecular progression; PIK3CA/AKT1/PTEN alterations (about 50%) call for inavolisib, capivasertib, or alpelisib; gedatolisib (2026) works in PIK3CA-wild-type disease. After endocrine options are exhausted, antibody-drug conjugates precede chemotherapy: T-DXd for the ~60% with HER2-low or ultralow expression, and the TROP2 ADCs sacituzumab govitecan and datopotamab deruxtecan.
Open problems are the evolution of resistance across this long sequence (CDK4/6, then endocrine, then ADC payload resistance), the absence of a validated test for late recurrence, toxicity and adherence over years of therapy, and translating ctDNA-guided decisions into proven survival gains. The near-term pipeline is defined by oral SERDs moving into the adjuvant setting (lidERA positive; CAMBRIA and EMBER-4 pending), CDK4-selective inhibitors, new HER2-low and TROP2 ADCs, and ctDNA-triggered switching, which the FDA endorsed over a negative advisory vote in 2026.
Averages across everyone diagnosed, often years ago. A median is the middle of a group: half the people counted lived longer than the figure shown, and some lived far longer. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
HR-positive, HER2-negative disease is 70.1 percent of American cases with a known receptor subtype (SEER 21, 2019 to 2023), so, if the same share holds elsewhere, of the order of 1.7 million of the 2,434,087 breast cancers diagnosed worldwide each year (GLOBOCAN 2024).
Averages across everyone diagnosed, often years ago. A median is the middle of a group: half the people counted lived longer than the figure shown, and some lived far longer. Your stage, subtype, age, fitness and the treatment you receive matter more than the average, and the numbers are improving quickly.
Most cancers start in the ducts and drain first to the axillary nodes, which is why the armpit is checked and a sentinel node is sampled.
Same organ: Triple-negative breast cancer (TNBC), Breast cancer (all types), HER2-positive breast cancer, Male breast cancer, Ductal carcinoma in situ (DCIS), High-risk early HR-positive breast cancer, HR-positive metastatic breast cancer after CDK4/6 inhibitors, HER2-low and HER2-ultralow metastatic breast cancer, Early HER2-positive breast cancer, HER2-positive breast cancer with brain metastases, Early triple-negative breast cancer, Metastatic triple-negative breast cancer, Basal-like 1 triple-negative breast cancer (BL1), Basal-like 2 triple-negative breast cancer (BL2), Mesenchymal triple-negative breast cancer (M), Mesenchymal stem-like triple-negative breast cancer (MSL), Luminal androgen receptor triple-negative breast cancer (LAR), Immunomodulatory triple-negative breast cancer (IM), Metaplastic breast carcinoma, Carcinoma with medullary pattern (medullary breast cancer), Adenoid cystic carcinoma of the breast, Apocrine carcinoma of the breast, Secretory carcinoma of the breast, BRCA-associated triple-negative breast cancer, Inflammatory breast cancer, Paget disease of the nipple, Phyllodes tumour of the breast, Invasive lobular carcinoma of the breast, Invasive breast carcinoma of no special type (invasive ductal carcinoma), Tubular carcinoma of the breast, Mucinous carcinoma of the breast, Papillary carcinomas of the breast (encapsulated, solid and invasive papillary), Invasive cribriform carcinoma of the breast, Invasive micropapillary carcinoma of the breast, Neuroendocrine neoplasms of the breast, Lobular carcinoma in situ (LCIS)
Most people reading this do not have advanced disease. The map describes what can happen over the whole course of the illness, across autopsy and registry series; today's staging scans find spread earlier, and each site has treatments, from focused radiotherapy for a few spots to drugs that reach the brain.
What helpsCDK4/6 inhibitors with endocrine therapy first, then drugs matched to ESR1 or PIK3CA/AKT changes found in a blood test, then T-DXd or TROP2 ADCs; bone-protecting drugs keep the skeleton strong for years.
Background: Circulating tumour DNA (ctDNA), Organ tropism: seed and soil. Also on OnCo: Atlas of advanced disease · How cancer spreads: the metastasis stages.
65-75% of patients with advanced disease develop bone metastases. Often the first and only site for years.
Invasive lobular carcinoma favours serosal and gynaecological sites.
Also on OnCo: Symptoms and red flags · Early detection roadmap.
Mammography ± tomosynthesis; supplemental MRI for dense breasts or high risk; core biopsy with ER/PR/HER2/Ki-67; AI-assisted reading being deployed.
Genomic assay (Oncotype DX RS ≤25 node-negative or postmenopausal 1-3 nodes; MammaPrint low risk) → endocrine therapy alone; premenopausal RS 16-25 or high clinical risk → chemotherapy or OFS-based escalation.
Postmenopausal: aromatase inhibitor 5-10 years (or tamoxifen → AI switch). Premenopausal: tamoxifen 5-10 years; add OFS (+ AI or tamoxifen) for higher-risk or chemotherapy-treated women (SOFT/TEXT).
Abemaciclib 2 years for node-positive high-risk (monarchE); ribociclib 3 years for stage II-III including node-negative high-risk (NATALEE). Palbociclib not effective (PALLAS/PENELOPE-B). Olaparib 1 year if gBRCA (OlympiA).
Extended AI to 10 years for higher-risk (MA.17R, NSABP B-42); adjuvant giredestrant positive in lidERA (2025, not yet approved); CAMBRIA (camizestrant) and EMBER-4 (imlunestrant) ongoing.
CDK4/6 inhibitor + aromatase inhibitor (or fulvestrant): ribociclib or abemaciclib preferred where OS data are valued; palbociclib acceptable. Premenopausal: add OFS. For relapse on/within 12 months of adjuvant ET with PIK3CA mutation: inavolisib + palbociclib + fulvestrant (INAVO120).
Serial ctDNA; on emergent ESR1 mutation before radiographic progression, switch AI → camizestrant and continue the CDK4/6 inhibitor (SERENA-6; accelerated approval 4 Sep 2026).
ESR1-mutant: elacestrant, imlunestrant (± abemaciclib), or vepdegestrant. PIK3CA/AKT1/PTEN: capivasertib + fulvestrant; alpelisib + fulvestrant. Any genotype after CDK4/6: gedatolisib + palbociclib + fulvestrant (PIK3CA-wild-type, 2026); everolimus + exemestane or giredestrant (filed); abemaciclib switch (postMONARCH, modest).
HER2-low or ultralow (~60%): T-DXd (DESTINY-Breast06 chemotherapy-naive; DESTINY-Breast04 after chemotherapy). HER2-zero: sacituzumab govitecan or Dato-DXd after chemotherapy (TROPiCS-02, TROPION-Breast01).
Sequential single-agent chemotherapy (capecitabine, taxanes, eribulin, vinorelbine); olaparib/talazoparib if gBRCA; clinical trials; supportive and palliative care integrated early.
Bisphosphonate or denosumab for bone metastases and AI-induced bone loss; adjuvant bisphosphonates in postmenopausal women; exercise, cardio-oncology, and adherence support.
Trials recruiting now, the landmark trials, the trials held by this cancer's subtypes, the key papers and what they mean, the latest literature, and the milestones year by year.
The molecular landscape: the targets and how often each appears, the pathways, the mechanics stages and the preclinical models.
Cases by country, the UK and NHS pathway and other country lenses, the expert centres with trials on record, and the centres named on this cancer's subtypes.
The decisions you may face, the aids that walk through them, the warnings on record, the first sixty days and the questions to ask.
Everything in development, the medicines held by this cancer's subtypes, the open problems and what is being done about them, the roadmaps, and what changed on this record.
Every connected record, the notes, the JSON, Markdown and RDF twins, and where the record came from and when it was checked.