Saskatchewan Breast Cancer Connect

Breast Cancer Types

There are many breast cancer types. Breast cancer can be classified by their origin or by their hormone receptors.  

Classified by Origin 

  • Ductal carcinoma in situ (DCIS): considered non-invasive or pre-invasive breast cancer because the cells have not spread through the walls of the ducts into the surrounding breast tissue. 
  • Invasive Ductal Carcinoma  (IDC): starts in a milk duct of the breast, breaks through the wall of the duct, and grows into the fatty tissue of the breast. 
  • Invasive Lobular Carcinoma (ILC): starts in the milk-producing glands (lobules).


Classified by Hormone Receptors

  • Estrogen-positive (ER+) Breast cancer cells contain estrogen receptors. Breast cancers that are estrogen receptor-positive can be treated with hormone therapy drugs that lower estrogen levels or block estrogen receptors. 
  • Progesterone-positive (PR+) Breast cancer cells contain progesterone receptors. Breast cancers that are progesterone receptor-positive can be treated with hormone therapy drugs that block receptors. 
  • HER2-positive (HER2) Breast cancers that have too much of a growth-promoting protein called HER2/neu. HER2-positive cancers are more likely to benefit from drugs that target the HER2/neu protein, such as Herceptin® and Tykerb®.
  • Triple negative (TNBC) Breast cancer cells that don’t have estrogen or progesterone receptors and don’t have too much HER2 are called triple negative. Because the tumor cells don’t have hormone receptors, hormone therapy is not helpful in treating these cancers. Drugs that target HER2 aren’t helpful since these cancers don’t have too much HER2. 

There are also less common types of breast cancer. 

For more information, visit the following agencies and their resources:

Sources for Information

  • Triple Negative Breast Cancer Foundation

    The Triple Negative Breast Cancer Foundation® is dedicated to supporting TNBC-specific research and to providing meaningful programs and services to the TNBC community. 



    Willow provides free-of-cost support, insight and information to anyone affected by breast cancer or hereditary cancer. Willow recognizes that cancer affects all aspects of your life, and your loved ones' lives, in many ways. 

  • Living Beyond Breast Cancer

    LBBC is dedicated to assisting you, whether you are newly diagnosed, in treatment, recently completed treatment, are years beyond or are living with metastatic breast cancer. We are here to provide breast cancer information and support.


    Dedicated to providing the most reliable, complete, and up-to-date information about breast cancer to help women make sense of the complex medical information about breast cancer, so they can make the best decisions for their lives.