Medullary Carcinoma Characteristics and Treatments

How is medullary breast cancer different than other breast cancers?

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Medullary carcinoma of the breast is an uncommon form of breast cancer. It is a type of invasive ductal carcinoma (IDC) and takes it name from its color, which is close to the color of brain tissue, or medulla. It starts in your milk ducts, with large cancer cells that look very different from healthy cells.

Medullary carcinoma is not a common diagnosis. Medullary carcinoma accounts for only 3 percent to 5 percent of all breast cancers. It can be difficult to distinguish from invasive ductal carcinoma and there are some cancers that have some but not all features of medullary carcinoma. Due to this overlap, doctors sometimes treat medullary carcinoma more aggressively, perhaps, than needed, given its good prognosis.   It is most common in women in their late 40s and early 50s.


Medullary carcinoma cells tend to form a clear boundary between the tumor and healthy tissue right next to them - they are less invasive than some other breast cancer cells. Under the microscope, the cells are large and very abnormal and aggressive appearing, but they tend not to act as aggressive as they look.

There are often many immune cells (such as lymphocytes) at the edges of these tumors, suggesting that the immune system is working to fight off the tumor.

When a breast cancer has the appearance of medullary carcinoma but does not fit all criteria, you may hear your tumor called "atypical medullary carcinoma." These atypical cancers are often treated more like other breast cancers, in other words, more aggressively.

Signs and Symptoms

Medullary carcinoma of the breast may not always feel like a lump, but rather, like a thick, spongy area of breast tissue. It may first be noted as a pain, redness, or a swelling in your breast. Since the cells for medullary carcinoma are large and tend to stay together and expand in one place, the tumor may feel rather smooth-sided, like a breast cyst. This is one reason that it's very important to have any lump in your breast examined, even if it feels like a simple cyst.

Tests for Diagnosis

Medullary breast cancers do not always show up on a mammogram and are often discovered first when someone feels a lump.  A breast ultrasound may be done as well. The only way to distinguish medullary carcinoma from other forms of breast cancer is through a biopsy.  A tissue sample is usually taken by open surgical or stereotactic breast biopsy.


Most medullary carcinomas are small and can be easily treated with surgery. They are less likely than other breast cancers to spread to the lymph nodes, and some doctors consider surgery alone to be adequate treatment for these tumors (most of which are less than 1 inch in size.) Treatments may include:

  • Surgery: Surgery is performed for the majority of people with this form of breast cancer and can be either a lumpectomy or a mastectomy, depending upon the location of the tumor and personal preferences.
  • Chemotherapy: Since most of these tumors are small and seldom spread to lymph nodes, chemotherapy is often only needed for tumors larger than an inch in size. That said, many of these tumors overlap - have characteristics - of other types of breast cancer, and therefore may be treated more aggressively.
  • Radiation therapy: Again, radiation therapy is used less often than with other forms of breast cancer, but may be used in individual cases.
  • Hormone therapy: Hormone therapy is also used less often with medullary carcinoma, as many of these tumors are hormone receptor negative. In one study, 68% of these tumors were negative for estrogen receptors and 86 percent were negative for progesterone receptors.
  • Herceptin is used rarely with this type of cancer as most of these tumors are HER2 negative.  In one study over 80 percent of the tumors were negative for HER2 receptors.


    Medullary carcinoma tends to have high-grade appearing cells that act in a slow-growing fashion. They are less likely to spread to lymph nodes than other breast cancers and overall have an excellent prognosis.  In one large study, the overall survival rate at 2 years was 98.2 percent. The recurrence rate beyond this is also very low compared to other types of breast cancer.

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