Endocrine therapy (SERMs, AIs, SERDs)
Pills that block or remove oestrogen signalling, the mainstay of treatment for hormone-driven breast cancer for 50 years.
Tamoxifen (SERM), aromatase inhibitors (letrozole, anastrozole, exemestane), fulvestrant (injectable SERD), oral SERDs (elacestrant, imlunestrant approved 2025, camizestrant), and the PROTAC vepdegestrant (2026). Ovarian function suppression (goserelin) for premenopausal women. Five to ten years of adjuvant therapy halves recurrence; adherence is a major real-world problem.
How it works
Compete for ER (SERM), deplete oestrogen (AI), or degrade ER (SERD, PROTAC).
- Oral, effective, cheap (generics)
- ESR1 mutations; menopausal symptoms, bone loss, adherence
Camizestrant is an oral oestrogen-receptor degrader approved in September 2026 for a new kind of decision: switching treatment when a blood test shows resistance developing, before the cancer visibly grows.
Elacestrant was the first oral oestrogen-receptor degrader (2023), for ESR1-mutant breast cancer detected by blood test.
Exemestane is a steroidal aromatase inhibitor, the partner of everolimus and the agent tested with ovarian suppression in young women.
Fulvestrant is a monthly injection that destroys the oestrogen receptor; it is the standard partner for many targeted drugs after hormone therapy stops working.
Giredestrant is Roche's oral SERD: it failed to beat an aromatase inhibitor in first-line metastatic disease but succeeded after surgery and after CDK4/6 failure.
Monthly or 3-monthly injections that switch off the ovaries, letting premenopausal women use aromatase inhibitors and lowering recurrence in higher-risk cases.
Imlunestrant is Lilly's oral oestrogen-receptor degrader, approved in 2025 for ESR1-mutant breast cancer and shown to work with abemaciclib regardless of mutation.
Daily pills that stop the body making oestrogen after menopause, the backbone of hormone therapy for most breast cancers.
Leuprolide is the injectable that shuts off testosterone production, the foundation of hormone therapy for prostate cancer since the 1980s; it is also used for ovarian suppression in premenopausal breast cancer.
Progesterone-like hormones that can reverse early endometrial cancer in women who want to keep their uterus, and control advanced hormone-sensitive disease.
The original targeted cancer drug (1977): a pill that blocks oestrogen's effect on breast cancer and halves recurrence, still essential for premenopausal women.
Vepdegestrant is the first PROTAC ever approved (2026): a pill that tags the oestrogen receptor for destruction, for breast cancers with ESR1 mutations.
Ribociclib is a second adjuvant CDK4/6 option, and the only one with data in node-negative stage II disease. Roughly 3 in 100 patients avoid a relapse or death at three years, so the decision depends heavily on individual risk, tolerance of a three-year oral drug, and cost. Whether the benefit persists after treatment ends, as it did with abemaciclib, needs longer follow-up.
Women with hormone-receptor-positive, HER2-negative breast cancer that has spread to lymph nodes and has other high-risk features can now be offered two years of abemaciclib alongside their hormone therapy, with a durable reduction in relapse. It does not apply to node-negative or low-risk disease, and the diarrhoea and cost are real trade-offs to discuss.
Men diagnosed with prostate cancer that has already spread, or that is locally advanced and high risk, should start abiraterone (or another androgen-receptor pathway inhibitor) at the same time as testosterone suppression rather than waiting for resistance. This roughly halves the risk of death over several years. The same platform later showed that docetaxel chemotherapy and, in high-volume metastatic disease, triple therapy also help, and that abiraterone benefits men with high-risk disease treated with radiotherapy.
For women at raised risk, a 5-year course of tamoxifen offers long-lasting protection against the commonest kind of breast cancer. Uptake is low because of side effects and fear of rare serious harms; low-dose tamoxifen (TAM-01) is now being tested to improve the balance. It has not been shown to save lives.
Latest papers
topQuery for this technology: (TITLE:"endocrine therapy" OR ABSTRACT:"endocrine therapy" OR TITLE:"aromatase inhibitor" OR ABSTRACT:"aromatase inhibitor" OR TITLE:"oral SERD" OR ABSTRACT:"oral SERD") AND breast. Results are unfiltered search hits about Endocrine therapy (SERMs, AIs, SERDs), not a curated reading list.
Pages like this
not linked directly; found by shared links- TermOvarian function suppression (OFS)
Shares Goserelin / leuprolide (ovarian function suppression), Exemestane, Leuprolide (leuprorelin) and GnRH agonists, SOFT & TEXT.
- InstitutionBreast International Group (BIG)
Shares Austrian Breast & Colorectal Cancer Study Group, Edinburgh Cancer Centre / CRUK Scotland Centre, GEICAM Spanish Breast Cancer Group, Comprehensive Cancer Center Vienna – Medical University of Vienna / AKH.
- TermOral SERD
Shares Imlunestrant, Giredestrant, Fulvestrant, Camizestrant.
- ProductPalbociclib
Shares CDK4/6 inhibitor + endocrine therapy, Austrian Breast & Colorectal Cancer Study Group, GEICAM Spanish Breast Cancer Group, Comprehensive Cancer Center Vienna – Medical University of Vienna / AKH.
- TermESR1 mutation
Shares Imlunestrant, Vepdegestrant, Camizestrant, Elacestrant.
- TechnologyAndrogen deprivation & AR pathway inhibitors
Shares Cardiometabolic screening and treatment for survivors on long-term hormone therapy, Agonist and antagonist, Leuprolide (leuprorelin) and GnRH agonists, STAMPEDE: adding abiraterone to hormone therapy at diagnosis of advanced prostate cancer.
- TermEndocrine resistance
Shares Aromatase inhibitor, Hormone receptor status (ER / PR), Selective oestrogen receptor degrader (SERD), The cell-cycle engine (cyclins & CDKs).
- ProductAbemaciclib
Shares CDK4/6 inhibitor + endocrine therapy, GLP-1 receptor agonists as adjuvant weight-loss therapy in HR-positive breast cancer, monarchE: two years of abemaciclib after surgery in high-risk, hormone-receptor-positive early breast cancer, The cell-cycle engine (cyclins & CDKs).