Margins … Ugh!
Complete excision of breast cancer is the goal of surgery. Obtaining clear, microscopic margins can be a challenge. Having involved margins occurs in 25-30% of cases, thus requiring a second operation (re-excision). The challenge is not based on the technical aspects of surgery, but the fact that disease as a margin is most often microscopic; thus, not visible or visual. It takes a pathologist to determine the status of margins.
Not obtaining clear margins occurs with both mastectomy and lumpectomy (partial mastectomy). It is a more common issue with a lumpectomy. Even when margins are clear, radiation is typically an adjuvant (after surgery) therapy, so as to address any residual microscopic cancer cells. Following mastectomy, radiation is not typically offered with clear margins, because the amount of residual breast cancer is next to zero.
So, what is a clear margin? It is now readily accepted for invasive cancer, that as long as there are no tumor cells seen microscopically at the edge of a specimen (called: No Ink On Tumor) margins are clear and recurrence rates (after radiation) is comprable to a mastectomy. While there is a continued debate and discussion as to what constitutes a clear margin for “pure” noninvasive cancer or DCIS (ductal carcinoma in situ) it seems as though the consensus will require at least a 2 mm margin, depending on whether or not radiation is planned (a discussion for another blog!).
What can be done intraoperatively, to assure clear margins?
- Clinical assessment: the specimen is evaluated by it’s appearance physically and the feel grossly.
- Specimen radiograph: Drs. Brown and Gold will use an intraoperative mammogram of the surgical specimen, in hopes of assessing (radiographically) the margins.
- Margin Probe: under certain circumstances, margin status can be tested intraoperatively using a special hand held probe. While this method does have some limitations, it has been shown that under certain circumstances re-excision rates are < 10%. https://www.compbreastcare.com/margins/
- Shaved Margins: Yale University has published results of a trial where patients either had margins assessed by traditional methods OR had all margins addressed at the time of original surgery (shaved margin technique) and demonstrated a reduction in re-excision rates. In the soon to open SHAVE2 Trial, Dr. Brown and Gold will be offering this technique to their patients interested in breast conservation (lumpectomy).
- Intraoperative Margin Assessment: margin assessment by pathology during surgery is another method attempting to reduce re-excision rates. While this method does not guarentee a clear margin, it has been done.
So, the struggle continues. What you can’t see or feel is difficult to completely remove. While we continue to look for methods to reduce re-excision rates, it is important to undertand that a patients prognosis is not related to whether they have had a second surgery. Complete excision of the mass as well as adjuvant therapy are all keys to overall survival/prognosis.