Breast cancer
A malignant tumour of breast epithelium whose diagnosis, prognosis and treatment depend on whether it is in situ or invasive, its stage, grade and ER, PR and HER2 profile.
Definition
Breast cancer is a malignant tumour arising from the epithelium of the breast ducts or lobules. It may be in situ or invasive and is characterised further by histological grade, anatomical stage, ER/PR hormone-receptor status and HER2 status.
First principles
In situ and invasive disease are different clinical problems
Ductal carcinoma in situ is confined by the basement membrane and cannot metastasise as DCIS. Invasive carcinoma has breached the basement membrane and can spread to regional nodes and distant organs. The distinction changes staging, surgery, systemic treatment and prognosis.
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