Cancer cells spread directly along the breast ducts and can involve the corresponding breast acini. Or spread to the adipose tissue along the tissue gap around the duct. As the cancer tissue continues to expand, it can even invade the pectoralis major muscle and chest wall

Advanced breast cancer can metastasize through blood vessels to tissues or organs such as lungs, bones, liver, adrenal glands, and brain.

First, it metastasizes to the ipsilateral axillary lymph node, and in the later stage, it can successively metastasize to the subclavian lymph node and retrogradely to the supraclavicular lymph node. Breast cancer located in the upper inner quadrant of the breast often metastasizes to the lymph nodes next to the internal mammary artery and further to the mediastinal lymph nodes. Occasionally, it may metastasize to the contralateral axillary lymph nodes. A small number of cases can be transferred to the contralateral axillary lymph node through the superficial lymphatic vessels of the chest wall or deep fascial lymphatic vessels.

Early stage: painless, solitary lump

Late stage: satellite nodules, fixed mass

Dimple sign: cumulative cooper's ligament

Nipple inversion: accumulated breast ducts

Orange peel sign: lymphatic involvement

Bloody serous discharge suggests early breast cancer

Lymphatic metastasis: first in the axilla of the affected side, later to the supraclavicular lymph nodes

Hematogenous metastasis: lung, bone, liver

Intraductal carcinoma, lobular carcinoma in situ, papillary eczematoid breast cancer

This type is early stage and has a better prognosis

Papillary carcinoma, medullary carcinoma, canalicular carcinoma, glandular cystic carcinoma, mucinous carcinoma, apocrine carcinoma, squamous cell carcinoma

This type is highly differentiated and has a good prognosis

Invasive lobular carcinoma, invasive ductal carcinoma, hard carcinoma, medullary carcinoma, simple carcinoma, adenocarcinoma

This type is poorly differentiated, has a poor prognosis, and is the most common

Breast-sparing breast cancer resection: Complete removal of the tumor and surrounding 1 to 2 cm of tissue

Modified radical mastectomy for breast cancer: retain the pectoralis major muscle and remove the pectoralis minor muscle; retain the pectoralis major and minor muscles

Radical mastectomy: removal of the entire breast, as well as the pectoralis major and minor muscles, armpits, and subclavian lymph nodes

Neoadjuvant chemotherapy TE: (paclitaxel etoposide intravenous drip) TEC regimen (docetaxel, epirubicin, cyclophosphamide) TAC regimen (docetaxel, pirarubicin, cyclophosphamide)

Endocrine therapy: goserelin, third-generation aromatase inhibitor, CDK4/6 inhibitor, PI3K/AKT signaling pathway inhibitor, growth factor receptor pathway inhibitor, androgen receptor inhibitor

Targeted therapy: targeting human epidermal growth factor receptor II, targeting epithelial growth factor receptor, targeting tyrosine kinase inhibitors, targeting vascular endothelial growth factor, targeting triple-negative breast cancer Cancer as a target

Radiotherapy: two-dimensional tangential radiotherapy, three-dimensional conformal radiotherapy, three-dimensional conformal intensity-modulated radiotherapy