As the New York Times and other news organizations are reporting, a study published in the Journal of the American Medical Association, found that nearly one in four women who have a lumpectomy to treat their breast cancer require another surgery to remove additional tissue.
The data come from an observational study of breast surgery performed between 2003 and 2008 at four institutions. The research team's goal was to see if they could use the number of operations a woman undergoes as a potential measure of quality of care. To make this assessment, the researchers looked at how many women required a second surgery because the pathology report showed that there was a not a "clean margin." Margin is a term of art used to describe whether there are cancer cells right at the edge of the tissue that has been removed. The idea is that having only normal cells present would indicate that the entire tumor was removed, while the presence of cancer cells would indicate that the surgeon might have cut through the tumor and left cells behind.
The study's findings imply that some surgeons are not performing high-quality operations. But I don't think that's really what this study tells us. To be sure, it's important to evaluate how well breast surgeons do their work. But I don't believe that a surgeon's re-excision rate is a good indicator of their skill or judgment.
One of the big problems in breast surgery is the fact that we don't have a good map of the anatomy of the breast. Yes, believe it or not, we know more about the molecular biology of the breast cancer cell than we do about the pattern and number of holes there are for milk to emerge from the nipple!
The breast is formed of six to nine ductal systems, which are distributed throughout the breast like branches of a tree. All breast cancer starts in these milk ducts (lobules which make the milk hang off the ducts like leaves). Like tree branches, the ductal systems are not all the same size or shape, and they are not evenly distributed. You cannot see them on mammography or MRI and they are not visible to the surgeon during surgery.
When a woman has invasive breast cancer, the tumor will present as a lump. These are pretty easy to remove, although the tumor can sometimes have a tail that we can't feel. Along with an invasive cancer, there will also be ductal carcinoma in situ (DCIS), which are the precancerous cells that are still contained in the ducts.
Although DCIS can be initially diagnosed with microcalcifications on a mammogram, the calcifications do not outline the whole area of involvement. There is no imaging tool that can tell the surgeon how much DCIS is present before the surgery, and a surgeon cannot see it or feel for it during the surgery. We do the best we can but often leave some behind. These cells can only be seen when the tissue is examined under the microscope later, which is why it can be potentially overlooked.
Secondly, the technique used to identify whether or not a surgeon has obtained clean margins is very crude. It involves taking what in essence is a "wad" of fat (think chicken fat) and painting it with India ink and then taking tangential slices. In reality, it would take 2,000 slides to look at every margin of a 2 cm piece of tissue, but we do about 10! In other words, the chance of missing something is high. For this reason, surgeons are leery of assuming all the margins are clean and tend to make decisions based on the pathology instead.
Finally, although it should be the most important, there is the patient choice. Some surgeons may try to do breast conservation, if the patient desires it, only to find that the disease is more extensive than thought and a mastectomy is necessary. In other instances, a women or surgeon may decide prior to surgery that if the surgeon has any questions about whether clean margins have been obtained, they will go straight to mastectomy.
While I am a great believer in outcome measures, I don't think this area of breast cancer has been sufficiently defined to use these types of measures to determine quality of care. A woman with breast cancer needs to find a surgeon who she is comfortable with, and who she trusts. She should not make that decision based on the surgeon's re-excision rate, because it is not a good indicator of quality of care and having surgeons and pathologist articulate new guidelines will not improve the situation. What we desperately need is better imaging, which will allow us to map the ductal anatomy and the extent of disease accurately ahead of time and direct an informed operation rather than what is in essence an exploratory one.
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