Breast Care A-Z · Condition · TNBC

Triple-negative breast cancer

also: TNBC, triple negative breast cancer, hormone-receptor-negative HER2-negative breast cancer

Triple-negative breast cancer is a type that lacks all three of the common treatment targets — oestrogen receptors, progesterone receptors, and HER2 — so it is treated mainly with chemotherapy rather than hormone or HER2-targeted drugs. You may have been told your cancer is triple-negative, or be reading to understand what receptor status means together.

Quick answers

Is triple-negative breast cancer worse than other types?

Historically yes — TNBC was associated with worse outcomes than ER-positive or HER2-positive subtypes. Modern treatment has improved outcomes substantially, particularly for early-stage TNBC. The triple-negative label by itself is no longer the prognostic mark it once was; size, grade, lymph node status, and response to treatment matter more.

Why doesn't hormone therapy work for TNBC?

Hormone therapy works by blocking the oestrogen signal that drives ER-positive cancers. TNBC cancers do not have the oestrogen receptor, so there is no signal to block. Tamoxifen and aromatase inhibitors are not used in TNBC.

Why is genetic testing recommended for TNBC?

TNBC has a higher chance of being associated with an inherited BRCA1 mutation than other breast cancer subtypes. A positive result changes treatment options (PARP inhibitors), informs surveillance for the other breast, and has implications for relatives. Testing is part of standard NHS and private practice for TNBC patients.

PLATE XLII · ONCOLOGY · MOLECULAR SUBTYPES triple-negative breast cancer TNBC · ER− PR− HER2− an aggressive molecular subtype defined by absent oestrogen, progesterone, and HER2 receptors, requiring cytotoxic and immunotherapy strategies 1 FIG 01 — MOLECULAR RECEPTOR DIAGRAM: TNBC BRCA1 pathway disrupted ER ER− PR PR− HER2− Basal-like phenotype → aggressive proliferation i oestrogen receptor (absent/ER−) ii progesterone receptor (PR−) iii HER2 receptor (absent/HER2−) iv BRCA1 pathway association v basal-like cytokeratin expression (CK5/6, CK14) BRCA1 ASSOCIATION TNBC and BRCA1: ~50% of TNBC harbour BRCA1 mutation BRCA1 carriers: ~70% develop TNBC PARP inhibitors: Active in BRCA-mutant TNBC TREATMENT STRATEGY Neoadjuvant chemo anthracycline + taxane Immunotherapy if PD-L1 CPS≥10 pembrolizumab PARP inhib. if BRCA-mut olaparib 2 FIG 02 — TNBC vs HORMONE RECEPTOR-POSITIVE BREAST CANCER TNBC HR+ breast cancer Receptors ER−/PR−/HER2− ER+ and/or PR+ Frequency ~15% ~75% Molecular subtype Basal-like Luminal A or B Grade Usually grade 3 Often grade 1–2 Ki67 High Lower Hormone therapy Not effective Yes (tamoxifen/AI) Chemotherapy Essential Selected 5-yr survival ~77% ~90%+ Recurrence pattern Early (1–3 yrs) Late (>5 yrs) BRCA association ~50% Rare 3 FIG 03 — TREATMENT OPTIONS: TNBC vs HR+ DISEASE Treatment TNBC HR+ disease Chemotherapy Backbone of treatment Selected cases Hormone therapy Not applicable Yes Anti-HER2 Not applicable If HER2+ Immunotherapy PD-L1 CPS≥10: pembrolizumab Not standard PARP inhibitors BRCA-mutant: olaparib (NICE TA886) Not applicable Antibody-drug conj. Sacituzumab govitecan Trastuzumab deruxtecan Neoadjuvant Standard (pCR ~40–60%) Selective Radiotherapy Post-surgery standard Post-surgery standard Surveillance 5-yr intensive Lifelong hormone therapy 4 FIG 04 — CLINICAL PATHWAY Diagnosis biopsy B5b receptor panel → Staging CT + bone scan → Neoadjuvant chemo ± immunotherapy ↓ Surgery WLE/mastectomy + SLNB ← Adjuvant therapy cape if residual olaparib (TA886, HER2−, post-chemo) ← Surveillance + genetic testing 5 FIG 05 — TNBC SUBTYPES AND THERAPIES Basal-like TNBC CK5/6+ · EGFR+ Most common subtype MOST COMMON BRCA1-associated Germline mutation PARP inhibitor eligible PARP ELIGIBLE PD-L1 CPS≥10 TNBC Immunotherapy eligible Pembrolizumab + chemo KEYNOTE-522 Neoadjuvant chemo Anthracycline + taxane pCR goal: ~40–60% STANDARD Olaparib (NICE TA886) BRCA-mutant TNBC OlympiA trial · adjuvant OLYMPIA Sacituzumab govitecan TROP2 ADC · mTNBC ADC THERAPY 6 FIG 06 — KEY STATISTICS ~15% of all breast cancers [1] ~77% 5-yr overall survival [2] ~50% BRCA1 association in TNBC [3] 40–60% pCR with neoadjuvant chemotherapy [4] 7 FIG 07 — REFERENCES 1. Lehmann BD et al. Identification of TNBC subtypes. J Clin Invest 2011;121:2750 2. Cancer Research UK. TNBC survival data 2024 3. Foulkes WD et al. Triple-negative breast cancer. NEJM 2010;363:1938 4. Schmid P et al. KEYNOTE-522. NEJM 2022;386:556 5. Tutt ANJ et al. OlympiA trial (olaparib). NEJM 2021;384:2394 Clinically authored by Dr Fiona Tsang-Wright , FRCS (Gen Surg) GMC 4549831 · ORCID 0000-0003-4801-026X
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Definition
Triple-negative breast cancer is a subtype of breast cancer in which the cancer cells test negative for all three of the standard treatment-targeting receptors — oestrogen receptor (ER), progesterone receptor (PR), and HER2 — meaning that hormone therapy and HER2-targeted antibodies do not work, and treatment relies primarily on chemotherapy and (in selected cases) immunotherapy and PARP inhibitors.

Common questions The questions patients ask first

Is triple-negative breast cancer worse than other types?
Historically yes — TNBC was associated with worse outcomes than ER-positive or HER2-positive subtypes. Modern treatment has improved outcomes substantially, particularly for early-stage TNBC3. The triple-negative label by itself is no longer the prognostic mark it once was; size, grade, lymph node status, and response to treatment matter more.
Why doesn't hormone therapy work for TNBC?
Hormone therapy works by blocking the oestrogen signal that drives ER-positive cancers. TNBC cancers do not have the oestrogen receptor, so there is no signal to block. Tamoxifen and aromatase inhibitors are not used in TNBC.
Why is genetic testing recommended for TNBC?
TNBC has a higher chance of being associated with an inherited BRCA1 mutation than other breast cancer subtypes — around 11% of unselected TNBC patients carry a BRCA1 or BRCA2 mutation10. A positive result changes treatment options (PARP inhibitors)45, informs surveillance for the other breast, and has implications for relatives. Testing is part of standard NHS and private practice for TNBC patients.
Will I need a mastectomy?
Not necessarily. Surgical options for TNBC are decided in the same way as for any breast cancer — by the size and position of the cancer, and the patient's preference9. Many patients with early-stage TNBC have lumpectomy plus radiotherapy. Others have mastectomy, with or without reconstruction.

Triple-negative breast cancer is a subtype of breast cancer in which the cancer cells test negative for all three of the standard treatment-targeting receptors — oestrogen receptor (ER), progesterone receptor (PR), and HER2 — meaning that hormone therapy and HER2-targeted antibodies do not work, and treatment relies primarily on chemotherapy and (in selected cases) immunotherapy and PARP inhibitors1.

TNBC accounts for around 10–15% of breast cancers1. It tends to grow faster than other subtypes and presents at a younger age on average. Treatment options have expanded substantially in recent years — particularly with immunotherapy (pembrolizumab)3 and PARP inhibitors (olaparib4, talazoparib5 for BRCA carriers) — and outcomes for early-stage TNBC have improved alongside.

Orientation Why you might be reading about this

You may have been told that your cancer is triple-negative, or you are reading to understand what receptor status means in combination. The triple-negative label can be alarming when first heard, partly because it is associated with younger patients and faster-growing cancers. This page explains what TNBC is, how it differs from other receptor subtypes, and what the treatment options are.

Related terms: Oestrogen receptor · HER2 · Invasive ductal carcinoma · BRCA

Definition What “triple-negative” means

Modern breast cancer treatment is built around three key receptors that pathologists test on the biopsy or surgical specimen:

  • Oestrogen receptor (ER) — see oestrogen receptor.
  • Progesterone receptor (PR) — usually tested alongside ER.
  • HER2 — see HER2.

Most cancers test positive for at least one of these:

  • ER-positive — responds to hormone therapy.
  • HER2-positive — responds to HER2-targeted antibodies (trastuzumab, pertuzumab, and others).

A triple-negative cancer tests negative for all three1. The receptor-targeted treatments that work for other subtypes do not work for TNBC. Treatment relies on chemotherapy and, in recent years, immunotherapy3 and PARP inhibitors4.

Who gets it Who gets TNBC

TNBC is more common in:

  • Younger patients — the average age at TNBC diagnosis is younger than for other subtypes, with a meaningful proportion of patients under 501.
  • Black women — TNBC has a higher prevalence in some ethnic groups, including Black women in UK and US data1.
  • BRCA1 carriers — most BRCA1-associated breast cancers are triple-negative12.
  • Patients with no known family history — TNBC is often sporadic; family history is not always present10.

These associations are statistical, not deterministic — TNBC occurs across all ages and ethnic groups.

Treatment Treatment

The TNBC treatment pathway has evolved substantially in the past five years9.

Surgery

Standard principles apply: lumpectomy plus radiotherapy, or mastectomy with or without reconstruction, decided by the cancer’s size, position, and patient preference9. Sentinel lymph node biopsy is part of the operation. The triple-negative status itself does not dictate the type of surgery — the size and biology of the cancer do.

Chemotherapy

Chemotherapy is the mainstay of systemic treatment for TNBC1. It is given either:

  • Neoadjuvant (before surgery) — increasingly the preferred sequence for TNBC larger than ~2 cm, because it allows assessment of how the cancer responds9. Pathological complete response (pCR) — no residual cancer in the operation specimen — is associated with excellent long-term outcomes7, while residual disease guides further treatment8.
  • Adjuvant (after surgery) — for smaller cancers operated on first, or where neoadjuvant treatment was not feasible.

Immunotherapy

Pembrolizumab (Keytruda) — added to chemotherapy for stage II-III TNBC, both neoadjuvant and adjuvant. Substantially improves event-free survival, with a side-effect profile that includes immune-related effects on thyroid, skin, and other organs that need monitoring3.

PARP inhibitors

Olaparib is given as adjuvant treatment for BRCA-mutation-carrier patients with high-risk early-stage TNBC, after standard chemotherapy4. Talazoparib is used in advanced disease5. PARP inhibitors exploit a vulnerability in BRCA-mutant cells and have changed the outlook for BRCA-associated TNBC.

Targeted antibody-drug conjugates

Sacituzumab govitecan (Trodelvy) — used in advanced or metastatic TNBC, an antibody-drug conjugate that delivers chemotherapy specifically to TNBC cells6.

For early-stage TNBC, the multimodal approach (chemotherapy + immunotherapy + surgery + radiotherapy + PARP inhibitor where applicable) has produced meaningful improvements in outcomes over the last decade.

Outlook Outlook

The TNBC label was once considered uniformly unfavourable. Modern outcomes are more nuanced:

  • Early-stage TNBC treated with current standards (neoadjuvant chemo-immunotherapy plus surgery plus radiotherapy) has outcomes increasingly comparable to other early-stage subtypes3.
  • Pathological complete response on neoadjuvant treatment predicts excellent long-term outcomes7.
  • Residual disease after neoadjuvant treatment prompts additional adjuvant treatment (capecitabine8, olaparib for BRCA carriers4).
  • Advanced TNBC has a less favourable outlook than other subtypes, but the recent additions of immunotherapy, PARP inhibitors5, and antibody-drug conjugates6 have meaningfully extended treatment options.

The recurrence pattern for TNBC tends to be earlier (within the first 3–5 years)1 than for ER-positive cancers, which can have late recurrences.

Why it matters Why genetic testing matters

For TNBC, genetic testing is part of standard care because:

  • BRCA1 mutations are present in around 10–20% of TNBC cases110 — meaningful for treatment decisions (PARP inhibitors)4.
  • PALB2 and other genes can also be relevant10.
  • A confirmed mutation has implications for the patient’s relatives2 and for risk-reducing options for the unaffected breast.

For more on what testing involves, see BRCA.

At consultation What to discuss at consultation

If your cancer is triple-negative:

  • The treatment sequence — most commonly neoadjuvant chemotherapy plus immunotherapy, then surgery, then radiotherapy39.
  • Genetic testing — usually offered as part of the pathway, given the higher chance of finding a BRCA mutation10.
  • Clinical trial options — TNBC has been a focus of clinical trial activity, and trial enrollment is sometimes recommended.
  • Reconstruction planning — most options remain available, though radiotherapy after mastectomy can shift the choice towards delayed rather than immediate reconstruction.

Resources Further reading

Sources & guidance

Every figure on this page is anchored to a published source. Tap a number in the text or below to jump to the reference.

  1. review Bianchini G, Balko JM, Mayer IA, Sanders ME, Gianni L. Triple-negative breast cancer: challenges and opportunities of a heterogeneous disease. Nature Reviews Clinical Oncology. 2016 ;13(11):674-690 doi:10.1038/nrclinonc.2016.66 Cited for: TNBC prevalence (~10-15%), recurrence pattern, BRCA1 association, biology overview.
  2. cohort Kuchenbaecker KB, Hopper JL, Barnes DR, et al. Risks of Breast, Ovarian, and Contralateral Breast Cancer for BRCA1 and BRCA2 Mutation Carriers. JAMA. 2017 ;317(23):2402-2416 doi:10.1001/jama.2017.7112 Cited for: Lifetime breast cancer risk in BRCA1 (~72%) and BRCA2 (~69%) carriers; relevance to TNBC subset.
  3. rct Schmid P, Cortes J, Dent R, et al. Event-free Survival with Pembrolizumab in Early Triple-Negative Breast Cancer. New England Journal of Medicine. 2022 ;386(6):556-567 doi:10.1056/NEJMoa2112651 Cited for: KEYNOTE-522: pembrolizumab + chemotherapy improves event-free survival in stage II-III TNBC.
  4. rct Tutt ANJ, Garber JE, Kaufman B, et al. Adjuvant Olaparib for Patients with BRCA1- or BRCA2-Mutated Breast Cancer. New England Journal of Medicine. 2021 ;384(25):2394-2405 doi:10.1056/NEJMoa2105215 Cited for: OlympiA trial: adjuvant olaparib for BRCA-mutated high-risk early breast cancer.
  5. rct Litton JK, Rugo HS, Ettl J, et al. Talazoparib in Patients with Advanced Breast Cancer and a Germline BRCA Mutation. New England Journal of Medicine. 2018 ;379(8):753-763 doi:10.1056/NEJMoa1802905 Cited for: EMBRACA trial: talazoparib for advanced BRCA-mutated breast cancer.
  6. rct Bardia A, Hurvitz SA, Tolaney SM, et al. Sacituzumab Govitecan in Metastatic Triple-Negative Breast Cancer. New England Journal of Medicine. 2021 ;384(16):1529-1541 doi:10.1056/NEJMoa2028485 Cited for: ASCENT trial: sacituzumab govitecan for metastatic TNBC after prior therapies.
  7. meta_analysis Cortazar P, Zhang L, Untch M, et al. Pathological complete response and long-term clinical benefit in breast cancer: the CTNeoBC pooled analysis. Lancet. 2014 ;384(9938):164-172 doi:10.1016/S0140-6736(13)62422-8 Cited for: CTNeoBC pooled analysis: pCR after neoadjuvant chemotherapy predicts long-term outcomes, particularly in TNBC.
  8. rct Masuda N, Lee SJ, Ohtani S, et al. Adjuvant Capecitabine for Breast Cancer after Preoperative Chemotherapy. New England Journal of Medicine. 2017 ;376(22):2147-2159 doi:10.1056/NEJMoa1612645 Cited for: CREATE-X trial: adjuvant capecitabine improves survival for residual disease after neoadjuvant chemotherapy, with stronger benefit in TNBC.
  9. guideline National Institute for Health and Care Excellence. Early and locally advanced breast cancer: diagnosis and management (NG101). NICE. 2018 https://www.nice.org.uk/guidance/ng101 Cited for: UK guideline for surgical and systemic management of early and locally advanced breast cancer including TNBC pathway.
  10. cohort Couch FJ, Hart SN, Sharma P, et al. Inherited mutations in 17 breast cancer susceptibility genes among a large triple-negative breast cancer cohort unselected for family history of breast cancer. Journal of Clinical Oncology. 2015 ;33(4):304-311 doi:10.1200/JCO.2014.57.1414 Cited for: BRCA1/BRCA2 mutation frequency in unselected TNBC cohort (~11%).