Editing Breast cancer (section)

== '''Classification''' ==

* Non-invasive breast cancer
** DCIS - separate topic
** LCIS - separate topic
* Invasive epithelial cancers
** Invasive lobular carcinoma (10%)
*** Tends to permeate the breast in a single-file nature, so generally remains clinically occult and often escapes detection on mammography or physical examination until the disease is extensive
*** Loss of e-cadherin, single-file pattern, presence of small dis-cohesive tumour cells
*** Intermediate prognosis
** Invasive ductal carcinoma (50-70%)
*** Tends to grow as a cohesive mass
*** Appears as discrete abnormalities on mammograms and is often palpable as a discrete lump in the breast
*** Subtypes:
**** Invasive ductal carcinoma, not otherwise specified (50-70%)
**** Tubular carcinoma (2-3%)
***** Small glands lined by a single row of bland epithelium
***** Usually low-grade
***** Excellent prognosis
**** Mucinous or colloid carcinoma (2-3%)
***** Infiltrating cells secrete copious amounts of mucin and appear to float in this material
***** Usually low-grade
***** Excellent prognosis
**** Medullary carcinoma (5%)
***** Bizarre invasive cells with high-grade nuclear features, many mitoses and lack of an in-situ component
***** Pushes into the surrounding breast rather than infiltrating
***** Uniformly high-grade, triple negative
**** Invasive cribriform carcinoma (1-3%)
**** Invasive papillary carcinoma (1-2%)
**** Adenoid cystic carcinoma (1%)
**** Metaplastic carcinoma (1%)
***** Typically high-grade and triple-negative
***** Mostly node negative but still have high potential for de novo metastatic spread
* Mixed connective and epithelial tumours
** Phyllodes tumours, benign and malignant
** Carcinosarcoma
** Angiosarcoma
** Adenocarcinoma
* Multifocal - multiple tumours within the same quadrant
* Multicentric - multiple tumours in different quadrants