How Surgical Margins Affect Breast Cancer Treatment Decisions

Choosing Between Lumpectomy and Mastectomy

When your breast biopsy reveals cancer and you're faced with the decision between a lumpectomy and a mastectomy, you may be feeling pretty stressed and confused. What are the real differences between these procedures and which is best for you personally?

You may find yourself going back and forth and back and forth again while you make your choice between a lumpectomy and a mastectomy. You may also find that opinions differ, whether it is the opinion of your surgeon or a friend. Why the controversy? And why is it important to understand the concept of surgical margins?

Because both you and your surgeon want to be on the same page. On one side of the issue is the desire to keep your breast, or as much of your breast as possible. On the other side is the importance of getting all of the cancer and having good surgical margins. Understanding more about surgical margins can help you get a better handle on which may get you closer to a cure.

Get Some Expert Advice on Lumpectomy vs. Mastectomy

If you're facing this decision—lumpectomy or mastectomy—you will need to know how the state of your surgical margins comes into the total equation. Start by reading this excerpt from UpToDate to see why surgical margins are important for you.

Microscopic Examination of the Tumor: A Discussion on Surgery Options

"Microscopic examination of the tissue removed during a biopsy or during surgery may identify features that influence the recommendation for BCT [breast conserving therapy] versus mastectomy. One of these features is the presence of residual cancer cells at the edges of the tumor (the surgical margins). If residual cancer cells are present despite a large amount of tissue being removed, mastectomy may be preferable."

Getting the Message About Surgical Margins

Surgical Margins, Clear
Surgical Margins, Clear. Illustration © Pam Stephan

What Are Surgical Margins?

When your tumor is biopsied or surgically removed, your surgeon takes out more than just the tumor—some tissue around the tumor is also taken. This border of tissue between the outer edge of the sample and the tumor is called the surgical margin.

After your surgeon removes the tissue, it is carefully enclosed in a container and sent to the pathology lab. The pathologist uses a special ink to cover the outer edge of the entire tissue sample. Then the sample is sliced into thin sections and examined under a microscope. The edges, as well as the margins, are checked to see if any cancer cells have strayed outside the tumor and, if so, how far they have gone.

Understanding Terms Doctors Use to Describe Surgical Margins

Surgical Margins, Positive
Surgical Margins, Positive. Illustration © Pam Stephan

There are general guidelines, but the definition of negative or clear margins may vary from one hospital or clinic to another. These three terms are used to describe the margins:

  • Negative Margin: No cancer cells at the outer inked edge of the tissue
  • Positive Margin: Cancer cells or tumor extends to the edge of the sample
  • Close Margin: Any situation in between negative and positive

When Surgical Margins Contain Cancer

Surgical Margins, Close
Surgical Margins, Close. Illustration

Close margins after a lumpectomy might be treated by another surgical procedure, called a re-excision. Your surgeon would return to the original site and remove additional tissue to try and get negative (clear) margins. If that is successful, radiation treatment may be in line for you.

Some women with close margins choose to have a mastectomy, rather than undergo one or possibly two more surgeries. Positive margins may indicate the presence of invasive breast cancer, and you may need to have a mastectomy in order to be sure that all cancer has been removed and to prevent a recurrence.

Negative Margins and Treatment Decisions

If you've had a biopsy, your tumor is small (under 4 centimeters), and your surgical margins are clear, then a lumpectomy may be all the breast surgery that you need (although, you may still elect for a mastectomy). If a lumpectomy is chosen, radiation therapy to the remaining breast is offered to prevent recurrent cancer.

Your lymph node status must also be checked; if your lymph nodes are free of disease, you likely won't need radiation treatment to that location after surgery. If they are not clear, your oncologist may recommend radiation. When you have completed radiation, if required, and if you had estrogen-sensitive cancer, then you would take hormonal therapy for at least five years, and often ten, to prevent a recurrence elsewhere in your body.

Take-Home Message

You need to know if your surgical margins were negative, positive, or close. This, along with cancer type, stage and lymph node status, will help you and your doctor choose the most effective treatment for you.

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