Biopsy Basics: Luminal A & Luminal B

In looking at the Luminal A and Luminal B breast cancer sub-types, we’ve summarised excerpts from a variety of expert sources into which we’ve included links for you to follow for deeper insights.

advocates for breast cancer_biopsy_luminal a and b
{ original cellular images courtesy of }



Luminal A and Luminal B types:

  • The luminal types are estrogen receptor (ER)–positive.
  • The gene expression patterns of these cancers are similar to normal cells that line the breast ducts and glands (the inside of a duct or gland is called its lumen).
  • Luminal A cancers are low grade, tend to grow fairly slowly, and have the best prognosis.
  • Luminal B cancers generally grow somewhat faster than luminal A cancers and their outlook is not as good.

READ MORE:American Cancer Society‘s Detailed Guide to Breast Cancer Classifying 



Luminal A — the least aggressive and most common subtype — accounts for 42% to 59% of all breast cancers, according to background information in the study.

Luminal B typically occurs in younger women and accounts for about 10% of all breast cancers.

Current research suggests that luminal A and luminal B cancers are two completely different diseases, and work is being performed to better distinguish between these two disease types so as to deliver more effective therapy to individual patients.

(Quite medically technical article!) READ MORE:→ The Oncologist‘s New Developments in Hormone Receptor–Positive Disease


Luminal A:

  • These cancers grow slowly.
  • When cancers turn up on screening mammograms, they are most often Luminal A.
  • They have a cure rate of more than 90% and generally can be treated with limited surgery and radiation.
  • Chemotherapy is usually not necessary.

Luminal B:

  • Compared to Luminal A, these cancers are more likely to grow aggressively
  • Can spread into blood vessels and the lymph system.
  • Not as aggressive as Basal and HER2-positive cancers.
  • Luminal B cancers can be challenging to remove completely, so a second surgery is sometimes necessary to achieve clear surgical margins around the tumor with no cancer cells.

READ MORE: Know Your Breast Cancer‘s How Genomic Tests for ‘Subtypes’ Help Target Treatment


Luminal A

  • Luminal A breast cancer cells can remain in a single location without spreading into the lymph system or blood stream.
  • Because Luminal A breast cancers are so slow-growing and unlikely to spread, there is a risk of overtreatment.
  • Luminal A breast cancers can generally be cured without chemotherapy, using limited surgery alone or in combination with radiation therapy.
  • Left untreated, there is a possibility that Luminal A cancers can develop into Luminal B cancers.

Luminal B

  • Unlike Luminal A cancers, which are situated in a specific site, Luminal B cancers can manifest in multiple sites within a particular region of the breast, with normal breast tissue existing in between.
  • In these instances, mammography often underestimates the size of primary cancers and fails to detect secondary cancers.
  • Magnetic resonance imaging (MRI) can help to more accurately measure and detect Luminal B cancers.
  • Treatments for Luminal B breast cancers can include limited surgery, mastectomy, radiation therapy and chemotherapy.
  • Recommended treatment options available to each woman will vary based on a range of personal factors regarding her disease and her risk factors.

READ MORE: Breastlink‘s Types of Breast Cancer



ARTICLE: Understanding Your Pathology Report


VIDEO: Understanding Pathology for Breast Cancer