Invasive carcinoma of the breast

This condition is the result of atypical neoplastic cells (as seen in DCIS/LCIS) crossing the basement membrane (i.e. invasive).  This infiltration of the normal parenchyma increases the risk of metastasis and mortality.

Epidemiology

• Commonest female cancer and commonest cause of female cancer deaths
• Incidence is on the increase (at the moment 1 in 9 women will develop breast cancer at some stage)

Risk factors

• Age; geography; genes (BRCA); oestrogens (HRT carries a small risk- more likely to be high levels occuring naturally)
• Length of reproductive life (early menarche/late menopause- again, hormone dependent); nulliparity; age of 1st child (the later the pregnancy the more risk); obesity; FHx/PMHx

Aetiology

• Genes
  • BRCA 1/2
  • FHx
• Hormones (oestrogens)
  • No. of menstrual cycles
  • (Exogenous hormones)
• Environment
  • Smoking, diet etc

Pathological Types

• Invasive carcinoma can arise from different tissues within the breast:
  • Ductal (70%)
  • Lobular (10)
  • Mucinous (2%)
  • Medullary (3%)
  • Tubular (2%)
  • Others e.g. cribiform/papillary
  • Mixed

Prognosis and Predictive factors

• Grade (Degree of differentiation) (1-3)
  • Tubular differentiation (/3)
  • Nuclear pleomorphism (/3)
  • Mitotic activity (/3)
    • If =<5 – 1; if >5/=<7 – 2; if >7 – 3
• Stage (TNM)
• Completeness of excision
• ER/Her2 status
  • Oestrogen receptor positive cancers are potentially responsive to anti-oestrogens (tamoxifen) and/or aromatase inhibitors (eg letrazole- more used in post-menopausal/obese women)
  • Human epidermal growth factor receptor 2 (her2) positive cancers are a potential target for trastuzimab (herceptin) (around 15% of all cancers)
• Nottingham Prognostic Index
  • 0.2 × tumour size (cm) + Grade + Lymph node status (from TNM)
    • <3.4 has a good prognosis (similar to population survival)
    • 3.41-5.4 have a medium survival (42% at 5 years)
    • >5.41 have a poor prognosis (13% 5 year survival)

Treatment

Mix of surgery, radiotherapy, chemotherapy and hormonal therapy depending on the severity.