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Additional Surgery after Breast-Conserving Surgery Varies Widely

A new study has found that the number of women who have one or more additional surgeries to remove suspected residual tumor tissue (re-excisions) following breast-conserving surgery (BCS) for breast cancer varies widely across surgeons and hospitals. Although researchers, led by Dr. Laurence E. McCahill from the Richard J. Lacks Cancer Center in Grand Rapids, MI, could not determine whether this variation affected rates of tumor recurrence, "the wide level of unexplained clinical variation itself represents a potential barrier to high-quality and cost-effective care," the authors wrote in a report that appeared February 1, 2012, in the Journal of the American Medical Association.

The researchers pooled data on women with breast cancer diagnosed between 2003 and 2008 who had undergone a first BCS procedure at the University of Vermont or at one of three sites in the HMO Cancer Research Network (Group Health, Kaiser Permanente Colorado, and Marshfield Clinic). Of the 2,206 women eligible for inclusion in the study, 509, or 23 percent, had one or more breast surgeries after the initial BCS. Of these women, 190, or about 8.5 percent of those who underwent initial BCS, had a total mastectomy.

A total of 311 women, or 14 percent, had positive margins (some tumor cells left at the site of surgery, as determined by a pathologist) after their initial surgery, but only about 86 percent of those women underwent re-excision. "This finding is notable given that positive margins…have been correlated with a long-term increased risk of local recurrence," the authors stated.

The percentage of women with positive margins who underwent re-excision differed among institutions, from 73.7 percent to 93.5 percent. The re-excision rates also varied substantially among individual surgeons, from zero percent to 70 percent. Whether these variations were influenced by pathological features of the tumors, clinical factors such as whether women received radiation therapy, or preferences of individual women could not be determined from the study.

Currently, the authors explained, there is no consensus about the appropriate size of a surgical margin around a tumor to be considered "clear." As a result, in this study, nearly half of patients with pathologically clear margins that were less than 1 mm wide and one-fifth of patients with clear margins between 1 and 1.9 mm underwent re-excision.

"I think it’s clear that we have to do more clinical research to really understand what’s behind this variation: how much of it is clinically appropriate—including where patient preference may be driving some of that variation—and how much of it is really driven by factors that could be mediated by things like better education and better resources in the operating suites," commented Dr. Steven Clauser, chief of the Outcomes Research Branch in NCI’s Division of Cancer Control and Population Sciences.