Many women with early-stage breast cancer will choose to undergo breast conservation surgery or lumpectomy as the initial step in the local treatment of their cancer. This has the advantage of preserving a woman's own breast, with minimal cosmetic changes and minimal recovery time after surgery. When coupled with radiation therapy it is equivalent to mastectomy in survival rates.
During a lumpectomy, the surgeon’s goal is to take out all the breast cancer, plus a rim of normal tissue around it. This is to be sure all cancer has been removed. Once removed, the tumor and surrounding tissue are stained with a special ink so that the outer edges, or margins, are clearly visible under a microscope. During or after surgery, a pathologist looks at the tissue that’s been removed to make sure there are no cancer cells in the margin. A clear, negative, or clean margin means there are no cancer cells at the outer edge of tissue that was removed. A positive margin means that cancer cells come right out to the edge of the removed tissue and have ink on them. A positive margin at the time of lumpectomy, however, does increase the chance of local recurrence and would require additional surgery, known as a ‘re-excision’ to remove a larger margin of cancer-free tissue.
To establish a standard for lumpectomy margins, the American Society for Radiation Oncology (ASTRO) and the Society of Surgical Oncology (SSO) reviewed a number of studies. The groups issued new guidelines in 2014 saying that clear margins, no matter how small as long as there was no ink on the cancer tumor, should be the standard for lumpectomy surgery.
