Triple-negative breast cancer

Definition

Why it is unfavourable

• Definition: Triple-negative means: oestrogen receptor, progesterone receptor and HER2 are negative.
• Typical features: Characteristic features are young age at diagnosis, high grade, high Ki-67 and early visceral metastases.

• Breast cancer lacking oestrogen and progesterone receptors and making little or no HER2, i.e. negative for all three biomarkers.

Classification

• BRCA1-associated breast cancers fall mostly within the triple-negative group and overlap with the basal-like subtype.

Occurrence & epidemiology

Epidemiology

• About 15% of all breast cancers are triple-negative.
• Triple-negative breast cancer is often diagnosed at a younger age and is more common, and diagnosed earlier, in Black women.
• Women with changes in BRCA1 or BRCA2 are more frequently affected.

Aetiopathogenesis

Aetiology and pathogenesis

• The cause is unknown, and the other risk factors are the same as for other breast cancers.
• In a large series of BRCA2 carriers, 16% had triple-negative tumours.

Clinical features

• Triple-negative breast cancer is usually diagnosed at a later stage, grows more quickly and is more likely to recur than other invasive breast cancers.
• Because of its rapid growth it is rarely diagnosed as DCIS (stage 0) and is almost always invasive.
• Symptoms are the same as for most other breast cancers, but symptoms may also be absent.

Histology

• BRCA1-associated, mostly triple-negative carcinomas more often show medullary histology and a higher histological grade.

Diagnosis

• After imaging with mammography, ultrasound or MRI and biopsy, biomarker tests on tumour tissue reveal the triple-negative status.
• PET or CT serve to assess spread; staging combines the extent of spread, triple-negative status and tumour grade.
• Among women with triple-negative breast cancer, germline BRCA1 variants are found more often, particularly when diagnosed before the age of 50.

Keep learning in the app

Further reading (selection)

1. National Cancer Institute: What Is Triple-Negative Breast Cancer (TNBC)?
2. National Cancer Institute: BRCA1 and BRCA2 (PDQ®), health professional version
3. DocCheck Flexikon, Triple-negatives Mammakarzinom

Cross-references