Invasive Breast Cancer (IDC/ILC)

Breast cancers that have spread into surrounding breast tissue are known as invasive breast cancer. There are different kinds of invasive breast cancer. Some kinds are more common than others.

Invasive ductal carcinoma

Invasive, or infiltrating, ductal carcinoma is the most common type of breast cancer. About 8 of 10 invasive breast cancers are invasive (or infiltrating) ductal carcinomas, which may be shortened to IDC.

IDC starts in the cells that line a milk duct in the breast, breaks through the wall of the duct, and grows into the nearby breast tissues. At this point, it may be able to spread (metastasize) to other parts of the body through the lymph system and bloodstream.

There are sub-types of invasive ductal carcinoma that are often named after cell features that can be seen under the microscope.

Some of these sub-types  might have better treatment outcomes than standard infiltrating ductal carcinoma. These include:

  • Adenoid cystic (or adenocystic) carcinoma
  • Low-grade adenosquamous carcinoma (this is a type of metaplastic carcinoma)
  • Medullary carcinoma
  • Mucinous (or colloid) carcinoma
  • Papillary carcinoma
  • Tubular carcinoma

Some sub-types have the same or maybe worse treatment outcomes than standard infiltrating ductal carcinoma. These include:

  • Metaplastic carcinoma (most types, including spindle cell and squamous)
  • Micropapillary carcinoma
  • Mixed carcinoma (has features of both invasive ductal and lobular)

For the most part, the sub-types are treated the same ways as standard IDC.

Invasive lobular carcinoma

Invasive lobular carcinoma (ILC) starts in the milk-producing glands (lobules). Like IDC, it can spread (metastasize) to other parts of the body. About 1  invasive breast cancer in 10  is an ILC. Invasive lobular carcinoma may be harder to detect on a mammogram than invasive ductal carcinoma.

Other types of invasive breast cancer

Less common types of invasive breast cancer are:

  • Inflammatory breast cancer
  • Paget disease of the nipple

Learn about treatments for invasive breast cancer

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: June 1, 2016 Last Revised: August 18, 2016

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