By Karen Weintraub
As many as 30 percent of breast cancer patients have a second surgery because doctors worry they didn't remove enough of the tumor the first time. But many of those repeat surgeries may be unnecessary, according to an essay published earlier this month in The New England Journal of Medicine.
One of the authors of that report, Dr. Stuart Schnitt, director of anatomic pathology at Beth Israel Deaconess Medical Center, spoke with me today about why he thinks these surgeries aren't needed.
KW: It's long been clear that lumpectomies are as good as mastectomies at preventing breast cancer from spreading. But doctors still don’t agree on the proper margins, that is, on how much of the tumor needs to be removed to prevent that spread?
SS: What constitutes an adequate negative margin has been a matter of debate for 20 years. Some surgeons say, "as long as there’s no tumor at the edge, I don’t care how close it is, it’s not a positive margin." Others say: it’s got to be at least 1, 2 or 5 mm. But none of that is based on any data.
The other major thing is that the rules we went by 20 years ago have changed.
Now, most patients get the combination of lumpectomy and radiation therapy with some form of systemic therapy, either hormonal therapy or chemotherapy or both. Overall, local recurrence rates today are much lower than they were 20 years ago. Some of the ideas people still carry on are from early days of lumpectomy and radiation therapy when people didn’t get effective systemic therapy.
How much disagreement is there about the margins?
A couple of studies have looked at surgeons' and radiation oncologists’ definitions of what constitutes a negative margin. The bottom line is there is no distance about which 50 percent or more agree is an adequate margin.
What should that margin be, then?
We really don’t know what the right number should be, because there aren’t evidence-based data on which to make a decision. The problem is, some clinicians carry around this notion that every patient in order to be eligible for breast conserving therapy has to have tumor X distance away from the margin and the X really depends on what institution they’re at. Some places say, they have to have at least a 2 mm margin in every direction on every specimen.
And, if those arbitrary margins aren’t reached, the patient is sent in for a second surgery? The consequence of this kind of thinking is that a lot patients undergo second surgery [solely] in order to get wider margins. One of the purposes of this [New England Journal] article is to make people rethink that, and perhaps consider the possiblity that you don’t need some predetermined margin distance in every patient
Is it appropriate to perform repeat surgery on anyone?
If the tumor went to the margin of the [first] specimen, that’s not a good thing. That’s probably the most important predictor of a local recurrence in the breast. Those patients should definitely undergo re-excision to get a negative margin. But if the patient has an initial negative margin of a millimeter, there’s no good data to say that the patient should undergo a re-excision to increase that margin to 2 mm, to 5 mm. The data suggest that increasing the margin doesn’t necessarily result in lower rates of local recurrence.
So the idea of margins – removing as much of the tumor as possible – isn't wrong?
Even when we have negative margins, a lot of patients have residual cancer in the breast, which is why we irradiate the breast in the first place.
Obviously, a second surgery is costly for both patients and the healthcare system.
The complication rate is relatively low, but not zero. [A second surgery] adds cost, it adds time, it adds delay to the time before they can begin radiation. It adds cost to the healthcare system. If some of these are unnecessary, it’s good to try to scale back on that.
So, as a patient, is it better to look for doctors who never do these re-excisions? Is the number of repeat surgeries reflective of quality?
[A recent study showed that] the frequency with which surgeons did re-excisions ranged from 0 to 70 percent. For doctors who never did re-excisions, it’s probably because they did big whopping incisions in the first place. The question is what kind of cosmetic result do the patients get? If a patient has half her breast removed because the surgeon never does a re-excision, the cosmetic result is going to be awful.
The whole idea of lumpectomy is to take out enough tissue to leave the patient with a very low chance of the tumor recurring in the breast, but not take out so much that it results in a bad cosmetic outcome. My impression in talking to surgeons about why they do things certain ways – it’s sort of like: that’s the way I was taught. But the way they were taught may not have been based on anything.
Without good data, how is a doctor to decide what kind of margin is enough, or a patient to agree to a second surgery?
One way to answer [this] would be with a prospective randomized trial – but it would be absolutely impossible to do a trial to answer the question: how big a margin do you need? Because we’ve gotten so good at treating patients, the recurrence rates are really low, so you would need a huge number of patients to have enough recurrences so that you could stratify the analysis by margin width, tumor characteristics and various forms of therapy. Another option is that [the National Institutes of Health] puts together a consensus panel – there’s a critical review of data and panel issues guidelines indicating how people should treat patients. [But] you’re going to be left with the fact that whatever consensus statement that’s made, is going to be made based on pretty flimsy evidence.
This interview has been edited and condensed.
This program aired on July 31, 2012. The audio for this program is not available.