Breast cancer

Lancet. 2021 May 8;397(10286):1750-1769. doi: 10.1016/S0140-6736(20)32381-3. Epub 2021 Apr 1.


Breast cancer is still the most common cancer worldwide. But the way breast cancer is viewed has changed drastically since its molecular hallmarks were extensively characterised, now including immunohistochemical markers (eg, ER, PR, HER2 [ERBB2], and proliferation marker protein Ki-67 [MKI67]), genomic markers (eg, BRCA1, BRCA2, and PIK3CA), and immunomarkers (eg, tumour-infiltrating lymphocytes and PD-L1). New biomarker combinations are the basis for increasingly complex diagnostic algorithms. Neoadjuvant combination therapy, often including targeted agents, is a standard of care (especially in HER2-positive and triple-negative breast cancer), and the basis for de-escalation of surgery in the breast and axilla and for risk-adapted post-neoadjuvant strategies. Radiotherapy remains an important cornerstone of breast cancer therapy, but de-escalation schemes have become the standard of care. ER-positive tumours are treated with 5-10 years of endocrine therapy and chemotherapy, based on an individual risk assessment. For metastatic breast cancer, standard therapy options include targeted approaches such as CDK4 and CDK6 inhibitors, PI3K inhibitors, PARP inhibitors, and anti-PD-L1 immunotherapy, depending on tumour type and molecular profile. This range of treatment options reflects the complexity of breast cancer therapy today.

Publication types

  • Review

MeSH terms

  • Adult
  • B7-H1 Antigen / metabolism
  • Biomarkers, Tumor / metabolism*
  • Breast Neoplasms / epidemiology*
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / therapy
  • Class I Phosphatidylinositol 3-Kinases / metabolism
  • Combined Modality Therapy / methods
  • Drug Therapy / methods
  • Female
  • Hormones / therapeutic use
  • Humans
  • Immunohistochemistry / methods*
  • Immunotherapy / methods
  • Incidence
  • Ki-67 Antigen / metabolism
  • Lymphocytes, Tumor-Infiltrating / immunology
  • Middle Aged
  • Neoadjuvant Therapy
  • Neoplasm Metastasis / drug therapy
  • Radiotherapy / methods
  • Receptor, ErbB-2 / metabolism
  • Risk Factors
  • Triple Negative Breast Neoplasms / drug therapy*


  • B7-H1 Antigen
  • Biomarkers, Tumor
  • CD274 protein, human
  • Hormones
  • Ki-67 Antigen
  • MKI67 protein, human
  • Class I Phosphatidylinositol 3-Kinases
  • PIK3CA protein, human
  • ERBB2 protein, human
  • Receptor, ErbB-2