Types of Breast Cancer

The type, subtype, and stage of your breast cancer helps your doctors better understand your cancer and informs their recommendations when it comes to treatments. Understanding the unique characteristics of your breast cancer will allow you to take an active role in decision-making for your treatment plan.

Invasive Breast Cancers

Invasive Ductal Carcinoma is a cancer that begins in the ducts (passages that carry milk from the glands to the nipple) and has spread to the surrounding breast tissue. This is the most common type of breast cancer, accounting for approximately 70-80% of all breast cancers.

Invasive Lobular Carcinoma is a cancer that starts in the lobules (groups of glands that create milk) and has spread to breast tissue nearby.

Lobular Breast Cancer Alliance provides more information on invasive lobular carcinoma (ILC) and Living with Lobular Breast Cancer in Canada  is a private Facebook group that shares research and resources for those with ILC.

Reading suggestions from our blog:

• Lobular Breast Cancer: A Different Subtype
• Dense Breast Tissues and Lobular Cancer – Doubly Hard to Diagnose

Non-Invasive Breast Cancers

Ductal Carcinoma in Situ (DCIS) refers to abnormal cells found within the milk ducts that are considered non-invasive as the cells have not spread from the ducts to the surrounding breast tissue. This is an early form of cancer, often referred to as Stage 0, that in some cases could potentially become invasive and spread to other tissues.

Lobular Carcinoma in Situ (LCIS) refers to abnormal cells found within the lobules, the milk-producing glands, of the breast. Despite using the term “carcinoma”, LCIS is not considered breast cancer because the abnormal cells have not spread beyond the lobules into surrounding breast tissue. While it is uncommon for LCIS to turn into invasive cancer, this condition is linked to an increased risk of later developing invasive breast cancer. For more information on LCIS, visit our section on High-Risk Conditions. 

Special Types of Breast Cancer

Some invasive breast cancers may have further characteristics that make them unique and less common. Some features may make your breast cancer more or less aggressive and may impact your treatment options.

Inflammatory breast cancer is a rare form of breast cancer that causes the breast to appear red, swollen, and tender, often resembling an infection. It is an aggressive, locally advanced (breast cancer that has spread to the nearby tissues and/or lymph nodes, but not to the other organs) form of cancer that blocks the lymph vessels in the skin of the breast. Symptoms of inflammatory breast cancer can develop very quickly and are often similar to other disorders. If you notice rapid swelling, skin changes, or notice unusual sensations including pain or itching speak to your physician.

Reading suggestion from our blog:

• Here's what you need to know about inflammatory breast cancer

Secretory Breast Carcinoma is a cancer that occurs due to an over secretion of mucin in the tumor. It is considered a subtype of invasive ductal carcinoma but is prone to metastasis and local recurrence. It is a slow-growing cancer that is best to treat aggressively, and it represents less than 0.1% of all cases of invasive breast cancer. Possible treatment options include chemotherapy, radiation, and mastectomy; treatment decisions are made on an individual basis due to the rarity of this subtype of breast cancer.

Metaplastic breast cancer is a rare type of cancer that begins as one type of cancer cell that changes into another type of cancer cell. Less than one percent of breast cancers are metaplastic, and it can be treated with surgery, radiation, and chemotherapy.

Paget’s Disease of the Breast is a rare type of breast cancer that typically affects the nipple and surrounding areola. It often presents with symptoms such as itching, redness, and flaking or thickening of the nipple skin, which can be mistaken for benign skin conditions, like eczema. Paget’s disease is frequently associated with underlying ductal carcinoma behind the nipple.

Reading suggestions from our blog:

• My Eczema Turned Out to be Paget’s Disease – A Rare Breast Cancer

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