Consultations et ponctions, pansements et prélèvements
Thibaut Voisin / Institut Curie
Not one breast cancer, but many
Breast cancer is a tumor that develops from the cells that form the mammary glands. The malignant cells multiply in an uncontrolled manner and form a tumor. This broad description harbors several different realities, however. Breast cancer is an extremely diverse disease, encompassing multiple types of tumor, which are treated differently.
Everything depends on the stage at which the cancer is detected.
- It is called a carcinoma in situ if the cancerous cells are confined to the level of the breast ducts or lobules.
- However, if the cancerous cells have crossed the so-called "basal" membrane of the ducts or lobules and invaded neighboring tissues, it is an infiltrating carcinoma. The cancerous cells may propagate either in the lymph nodes under the armpit, or through the veins. There is a risk of metastasis.
In addition, recent progress in genomics (the science of studying cancer at the genome level) today allows us to separate tumors into several types.
- Luminal A or B cancer: these are the most common forms. The cancer develops from the epithelial cells of the ducts or lobules. The “luminal A” cells have more estrogen receptors, whereas the “luminal B” cells have fewer estrogen receptors.
- HER2+ cancer: these cancerous cells have (more of) the HER2 receptor at their surface. When activated, this receptor causes significant cell proliferation.
- Basal-like cancer: thus named because its cells resemble the basal cells of the ducts, which bring milk to the ducts unlike the luminal cells.
- Triple-negative cancer: this is when the cancerous cells have no estrogen receptors and do not overexpress HER2.