Micrometastases

Micrometastases are tiny groups of cancer cells between 0.2 and 2 millimeters (the tip of a ball-point pen is about 1 millimeter) in size. Groups of cells smaller than 0.2 millimeters are called isolated tumor cells.

The cells that form micrometastases break off from the original breast cancer tumor and travel to another part of the body.

While breast cancer micrometastases can be anywhere in the body, doctors look for them in your lymph nodes because research shows that lymph node micrometastases are linked to a higher risk of recurrence (the cancer coming back) if left untreated. ¹

Because micrometastases are so small, they don’t cause any symptoms in the lymph nodes, such as a lump or swelling. Micrometastases can only be found by looking at lymph node tissue under a microscope.

If you’re diagnosed with breast cancer, your doctor usually removes some of the lymph nodes under your arm during mastectomy or lumpectomy. There are two types of lymph node surgery:

• Sponsor Message

  axillary lymph node dissection, which usually removes 10 or more lymph nodes

• Sponsor Message

  sentinel lymph node dissection, which removes the one or two lymph nodes closest to the cancer, though doctors sometimes remove more than two lymph nodes

After the lymph node(s) are removed, a pathologist examines them under a microscope to see if any cancer cells are present. 

If micrometastases are found in your lymph nodes, your doctor may recommend one or more treatments, depending in part on the characteristics of the breast cancer and the type of lymph node surgery you’ve had:

• Sponsor Message

  If you had sentinel lymph node dissection, axillary lymph node dissection may be recommended.

• Sponsor Message

  In some cases, radiation to the lymph nodes is recommended, even if you’ve had mastectomy. Decisions about radiation usually depend on the number of lymph nodes that have micrometastases in them.

• Sponsor Message

  Depending on the size and type of the cancer and number of micrometastases, chemotherapy may be recommended.

• Sponsor Message

  If the cancer is hormone receptor-positive, hormonal therapy is usually recommended.

• Sponsor Message

  If the cancer is HER2-positive, an anti-HER2 medicine is recommended, along with chemotherapy.