Judy C. Boughey, MD: Talking With Patients About Mastectomy vs Breast-Conserving Surgery

For patients that are pursuing breast conserving surgery, it's always important to ensure that we can resect the tumor and obtain clean or negative margins around the tumor before we proceed on to radiation therapy. If we can't obtain negative margins, then mastectomy would be the preferred recommendation. This very much comes down to the size of the tumor in relation to the size of the breast, and in particular for patients with multiple ipsilateral breast cancer, if they have two or three distinct sites, then we need to resect those two or three distinct sites, two negative margins, and still maintain enough of a breast volume and shape to make that a functional cosmetic breast that's appropriate for the patient. Really, that decision about being able to conserve the breast versus needing to recommend a mastectomy is very much dependent on the extent of the disease within the breast, the ability to resect its clean margins and maintain enough breast tissue. Tumor to breast volume ratio is probably the biggest determinant.

If a patient is interested in breast conserving therapy and based on the imaging and examination it looks like that patient would be a reasonable candidate for breast conserving therapy, at most institutions, the surgeon would take that patient to the operating room to perform the lumpectomy, resect the tissue, and submit it to pathology. Institutions vary based on their ability to assess margins intraoperatively, and if we are able to identify any positive margins intraoperatively, they can be re-excised at that same operation, but for most institutions, we have to wait for the final pathology, which will be available usually several days to a week or two later.

If there are still positive margins on the final pathology, then the discussion with the patient would be, do we go back and re-excise that margin or do we now need to convert to a mastectomy? Some institutions can do this intraoperatively, but for the majority of patients, it's much more straightforward to proceed to the operating room, do the lumpectomy, wait for the final pathology. If we have clean margins, then that's great, and if there are positive margins, then we need to have further discussion with the patient about a second operation for re-excision or conversion to mastectomy.

For patients with multiple ipsilateral breast cancer, if we're considering breast conserving surgery, most appropriate patients would be those that have two separate small foci of disease. If either focus of disease is greater than five centimeters, those patients were not enrolled in the clinical trial. If the disease involved more than two quadrants of the breast, those patients were also not eligible for the clinical trial. You really want two distinctly separate sites of disease, neither of which is overwhelmingly large, so that both areas can be resected and maintain enough breast tissue that it's worthy of preserving the breast. Those patients that have more extensive disease, any lesion that's greater than five centimeters or maybe four or five lesions in the breast, are still recommended to undergo a mastectomy.

For all patients treated with breast conserving surgery, the recommendation is that they also have adjuvant radiation therapy. The surgery and the radiation together is what constitutes breast conserving therapy. In the ACOSAG Z11102 clinical trial, the protocol required whole breast radiation with a boost to each of the lumpectomy sites. That would be the recommendation for multiple ipsilateral breast cancer would be surgery followed by whole breast radiation with a lumpectomy site boost. For those patients that have ER positive disease, the study also showed better local recurrence rates in those patients treated with adjuvant endocrine therapy, which is also the standard of care for patients with unifocal breast cancer that is ER positive.

One of the interesting unplanned findings from the study was that the patients that did not have a pre-operative breast MRI had a higher local recurrence rate than those patients that did have a pre-operative breast MRI. Now, as I mentioned, this was an unplanned secondary analysis and the cohort of patients without a pre-operative breast MRI was small. It was only 15 patients, but three of these patients did recur. While we can't make definitive recommendations based on this, I think in my practice, if I see a patient that I know has two foci of disease and is motivated and interested in breast conserving surgery, that is really a patient where I would seriously consider getting a preoperative breast MRI to evaluate for the extent of disease, make sure that there aren't additional foci before proceeding to the operating room for breast conserving surgery.