Whenever Dr. Aislinn Vaughan or Dr. Julie Margenthaler perform lumpectomies, each predicts a roughly 20-to-30 percent chance the patient will have to undergo a second operation to remove stray or undetected cancer cells left behind.

Vaughan is medical director of SSM Breast Care, and Margenthaler is an associate professor of surgery at Washington University Medical School. Both mentioned their repeat surgery rates in discussing a study recently published in the Journal of the American Medical Association.

It found that the rates of secondary surgery for breast cancer, in four hospitals in various parts of the country, differed considerably from hospital to hospital -- ranging from 1.7 percent to 20.9 percent. The study's lead author, Dr. Laurence E. McCahill, assistant director of the Lacks Cancer Center in Grand Rapids, Mich., says differing opinions among surgeons "is probably leading to quite a lot of variability in care women receive."

In an interview with JAMA News, he said, "We need to get down to a more acceptable range of re-excision, down to (between) 5 percent to 20 percent in the next five to 20 years. But I'm not trying to say re-excisions are bad. Surgeons are concerned about using re-excisions as a quality measure; we don't want people to just take more" tissue during the initial surgery.

That study suggested that about half of women who had second operations might not have needed them but got them because there is no excision guideline for lumpectomies.

The two local doctors say coming up with a guideline is elusive because surgeons don't agree on the margin of healthy tissue that needs to be removed around a tumor to help prevent repeat surgery. Following a lumpectomy, a pathologist uses an ink to cover the outer area of sample tissue taken from the patient, then measures the distance between the tumor and the outer edge.

The operation results in what's called a negative margin if no cancer cells are found at the edge of the inked tissue. A positive margin means the tumor extends to the edge of the sample. The margin usually determines whether the surgeon will perform a second operation.

Judging quality of care

The JAMA article has fueled an even bigger debate about the pros and cons of using re-excision or repeat surgery rates as a measure for judging quality of care.

A second operation is not a good measure of the effectiveness of the treatment, stressed two local surgeons. They say gauges, ranging from low rates of recurrence of a tumor to high rates of survival, are better markers of success in the fight against breast cancer.

"The reality is that (repeat surgery) is not a good quality measure because there is no right answer to what is an adequate margin," Vaughan says. "I can remove half of someone's breast and make sure I get a negative margin, but I haven't done anything to help (preserve their appearance). We like to try to save the breast when we can" if it doesn't affect the survival rate.

"The point of a lumpectomy is really cosmesis (preservation of appearance); otherwise, everybody would have a mastectomy. If you take a lot of tissue, like a third of the breast, you're going to have horrible cosmesis. But if you take too little, you're going to have close margins."

Surgeons appear to be dealing with what amounts to inexact science in spite of the fact that women have been undergoing lumpectomies for at least three decades. Vaughan says the challenge involves "figuring out the balance between doing a safe cancer operation but also having a good outcome for the patient."

If re-excision rates are made a quality measure, she says, some surgeons will quit offering lumpectomies "because they are going to be afraid it's going to drive up their re-excision rate. They would be more likely to recommend a mastectomy to keep their re-excision rate low. It would make the numbers look better."

Margenthaler also thinks that a focus on re-excisions would distort the picture because some surgeons may be offering lumpectomies only to "very favorable candidates and their re-excision rates may be low," depending on the health of patients.

Still, says Margenthaler, there needs to be "some guidelines of good quality evidence to at least give some common ground definitions -- what would be a sufficient margin."

Even so, she says guidelines "would not completely eradicate the need for going back because that's just the nature of how breast cancer is. It's not a perfectly round area. Sometimes there are little extensions that you can't appreciate by the naked eye or even in the pictures we do during the surgery. But I think we should be able to come up with some general guidelines that would help structure this better."

Chances for second surgery

Although the JAMA study cites re-excision rates ranging from 1.7 percent to 20.9 percent, Margenthaler said data compiled by Siteman Cancer Center show a range between 20 percent and 30 percent. She adds that if the rate were 5 percent, "I'm going to be doing very large lumpectomies. That's not necessarily best for the patient. You have to strike a balance between taking enough tissue to remove the cancer and taking just enough so that you leave her with a good cosmetic result."

Vaughan said the re-excision rate is between 25 percent and 30 percent at SSM. "It not only varies from one (hospital) system to another, it varies from one surgeon to another because surgeons have different thresholds on what is an adequate margin."

Asked if her patients have second thoughts upon learning that a second surgery might be needed, Vaughan said the rates she cited were "fairly common and very well tolerated with very low risks. A year or two down the road, patients don't remember that they had to have two procedures to get where they are. We do excellent breast cancer care."

She adds that "the biggest thing we need to emphasize is that women get their yearly mammograms because that's the only way we can find these cancers at the earliest, most treatable stages."

Margenthaler says women might not be surprised that there's up to a 30 percent chance they will need additional surgery because "I basically explain to them why this can happen because there are microscopic extensions that may not be appreciated on the day of surgery, and I explain that this is a bit of a trade-off for breast conservation."

She adds that "as long as you are upfront with the patient before the surgery and clearly give her a reasonable range of what you see in your own practice, there is a lot of understanding when (re-excision) does happen because you've prepared them for that possibility."