When breast cancer is removed by surgery (during a surgical biopsy, lumpectomy or mastectomy), a rim of normal tissue surrounding the tumor is also removed. This rim is called a margin. It helps show whether or not all of the tumor was removed.
With a mastectomy, the whole breast is removed during surgery. Whether the margins contain cancer cells does not usually affect your treatment.
Learn more about mastectomy and tumor margins.
A pathologist studies the tissue removed during surgery (including the margins) under a microscope. He/she determines whether or not the margins contain cancer cells.
Negative (also called “clean,” “not involved” or “clear”) margins
Positive (also called "involved") margins
Learn more about microcalcifications.
Read Komen advocate Peggy Johnson’s blog on her involvement in an expert panel’s recommendations on assessing margins.
You should get your results about a week after surgery.
In rare cases after a mastectomy, the deep margin (the margin closest to the chest wall) or skin margin contains cancer cells. In these cases, more surgery and/or radiation therapy may be recommended.
Learn more about radiation therapy.
Breast Cancer Surgery