Canadian Cancer Society logo

Breast cancer

You are here: 

Malignant tumours of the breast

Malignant tumours of the breast are cancerous growths that have the potential to spread (metastasize) to other parts of the body.


The most common type of malignant breast tumour is adenocarcinoma. Nearly all breast cancers start in the glandular tissue in the breast, in either the milk ducts or the milk glands. Most adenocarcinomas occur in the upper, outer part of the breast.

There are 2 main types of adenocarcinoma:

  • ductal carcinoma – begins in the lining of the milk ducts of the breast
  • lobular carcinoma – begins in the milk glands (lobules) of the breast

Ductal carcinoma and lobular carcinoma are also classified according to whether they are:

Other types of malignant breast tumours

There are other less common types of malignant breast tumours:


Dr Bruno Gagnon Integrating palliative care into advanced cancer care

Read more

How can you stop cancer before it starts?

It's My Life! icon

Discover how your lifestyle choices can affect cancer risk and how you can take action with our interactive tool – It’s My Life!

Learn more