Breast Cancer Classification

Topic Overview

Breast cancer is the abnormal growth of the cells that line the ducts and lobes of the breast. The classification of breast cancer is based on:

  • Whether the cancer started in the ducts or the lobules of the breast.
  • Whether the breast cancer cells have invaded other tissue in the breast.
  • What the cancer cells look like under the microscope.

Classification also takes into consideration such information as how rapidly the cancer cells are multiplying (tumor grade) and whether breast cancer cells are present in the nearby lymph nodes.

The following classifications describe the most common types of breast cancer.

  • In situ: A tumor that hasn't spread beyond the area where it began is called in situ.
    • Lobular carcinoma in situ (LCIS): Although not a true cancer, LCIS increases a woman's risk of developing cancer. For this reason, it's important for women with LCIS to have a physical exam 2 or 3 times a year, as well as a mammogram every year.
    • Ductal carcinoma in situ (DCIS): This is a precancerous condition also called Stage 0 breast cancer. It is noninvasive and is confined to the ducts. Almost all women who have DCIS can be successfully treated. The best way to detect DCIS is with a mammogram.
  • Infiltrating (invasive) ductal carcinoma (IDC): This cancer starts in a milk duct, breaks through the wall of the duct, and invades the fatty tissue of the breast. From there, it can spread to other parts of the body. IDC is the most common type of breast cancer, accounting for nearly 80% of cases.
  • Infiltrating (invasive) lobular carcinoma (ILC): This cancer starts in the mammary, or milk, glands (lobules) and can spread to other parts of the body. About 10% of breast cancers are this type.

Credits

By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer Douglas A. Stewart, MD - Medical Oncology
Last Revised June 28, 2011

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

© 1995-2013 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.

Decision Points

Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.

You'll find Decision Points to help you answer questions about:

Interactive Tools

Get started learning more about your health!

Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.

Symptom Checker

Feeling under the weather?

Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.

Symptom Checker