31 July 2015

The majority of patients newly diagnosed with breast cancer are candidates to undergo what is known as breast conserving surgery, or lumpectomy. However, one challenge is obtaining a clear margin – a rim of normal tissue around the tumor. While we have gotten better at visualizing the extent of the tumor by using mammograms, ultrasound and MRI, none of these modalities can detect microscopic cancer cells. We know that a large or wide margin of normal tissue is no longer necessary, but we do aim for a margin clear of cancer cells to reduce the risk of recurrence. If the final pathology demonstrates that a surgical margin is positive (contains cancer cells at the edge of the tissue that was removed), it is generally recommended that the patient undergo another lumpectomy, known as a re-excision.

While there are various techniques to help reduce the rate of positive margins, re-excision rates can range from less than 10% to 50% or more, depending on the institution and the study. The American Society of Breast Surgeons recently convened a consensus conference to address this issue. The CALLER (Collaborative Attempt to Lower Lumpectomy Re-Operation Rates) Workshop evaluated various methods that surgeons can use to help reduce the rate of re-excision, and the results were published today in the Annals of Surgical Oncology.

Some of the techniques agreed upon to reduce repeat surgery rates were:

  • Minimally invasive (needle) biopsy rather than surgery to make the initial diagnosis
  • Multidisciplinary discussions prior to surgery including surgery, medical oncology radiation oncology, pathology and radiology
  • Specific surgical techniques to identify non-palpable (not able to be felt) tumors
  • Oncoplastic surgical techniques when appropriate to allow removal of larger areas of tissue and still have a good cosmetic result
  • Marking the different tumor margins (specimen orientation) – essentially marking “which way is up”
  • X-ray of the tissue removed in cases of non-palpable tumors, with surgeon review of the images
  • Consideration for “shave margins“, a technique where additional tissue is taken after the lumpectomy
  • Evaluation of the tissue removed by the pathologist in the operating room
  • Compliance with existing guidelines regarding the appropriate margin size

Re-excision rates shouldn’t be zero. Removing a larger amount of breast tissue often results in a worse cosmetic result. An acceptable rate is probably less than 20%. It is very reasonable for patients to ask their physicians what their average re-excision rate is prior to undergoing a lumpectomy.