Cancerous tumours of the breast

A cancerous tumour of the breast can grow into and destroy nearby tissue. It can also spread (metastasize) to other parts of the body. Cancerous tumours are also called malignant tumours.

Ductal carcinoma and lobular carcinoma

Nearly all breast cancers are adenocarcinomas. These tumours start in gland cells. The most common adenocarcinomas of the breast are:

  • ductal carcinoma (including ductal carcinoma in situ, or DCIS), which starts in the milk ducts
  • lobular carcinoma, which starts in the groups of glands that make milk (called lobules)

Doctors will classify these tumours as non-invasive or invasive. Non-invasive means that the cancer cells have not spread beyond the duct or gland where they started. Invasive means that the cancer cells have started to spread into the surrounding tissue.

Other types of breast cancer

The following types of cancer can also develop in the breast:

  • inflammatory breast cancer
  • Paget disease of the nipple
  • triple negative breast cancer

Rare breast tumours

The following cancerous tumours of the breast make up less than 1% of all breast cancers:

  • a type of non-Hodgkin lymphoma called diffuse large B-cell lymphoma
  • soft tissue sarcoma
  • melanoma
  • metaplastic tumours
  • adenoid cystic carcinoma
  • phylloides tumour
  • carcinosarcoma
  • basal-like breast cancer

Expert review and references

  • American Cancer Society. Breast Cancer. 2015:
  • Morrow M, Burstein HJ, and Harris JR . Malignant tumors of the breast. DeVita VT Jr, Lawrence TS, & Rosenberg SA. Cancer: Principles and Practice of Oncology. 10th ed. Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins; 2015: 79: 1117-1156.
  • National Cancer Institute. Breast Cancer Treatment for Health Professionals (PDQ®). 2015.

Ductal carcinoma

Nearly all women with ductal carcinoma in situ (DCIS) – an early stage of breast cancer – can be successfully treated. Learn about the 2 main subtypes of DCIS.

Lobular carcinoma

Lobular carcinoma in situ (LCIS) is a marker that a woman has an increased risk of developing invasive ductal or lobular breast cancer. Learn about LCIS.

Inflammatory breast cancer

Inflammatory breast cancer is less common and has very different symptoms than other breast cancers. Learn about symptoms, diagnosis and treatment.

Paget disease of the breast

Paget disease of the breast is a rare breast cancer that appears as a rash or skin change on the nipple. Learn about symptoms, diagnosis and treatment.

Triple-negative and basal-like breast cancers

Most triple-negative and basal-like breast cancers are aggressive tumours. Many are diagnosed at a later stage. Learn about these cancers and treatment.

Medical disclaimer

The information that the Canadian Cancer Society provides does not replace your relationship with your doctor. The information is for your general use, so be sure to talk to a qualified healthcare professional before making medical decisions or if you have questions about your health.

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