Rates of re-excision after initial breast-conserving surgery for invasive breast cancer vary greatly across surgeons and across medical centers, according to a report in the Feb. 1 issue of JAMA.
These variations are only partly explained by the basic clinical and demographic factors that dictate treatment decisions, such as tumor size and patient age. The remaining reasons for the profound differences in re-excision rates remain unexplained.
Dr. Laurence E. McCahill
Nevertheless, these variations certainly are a barrier to consistent, high-quality, cost-effective care for breast cancer. "Outcomes such as local recurrence and even overall survival could be affected by variability in initial surgical care," said Dr. Laurence E. McCahill of the Richard J. Lacks Cancer Center, Van Andel Research Institute, and department of surgery at Michigan State University, Grand Rapids, and his associates.
Noting that "currently, there are no readily identifiable quality measures that allow for meaningful comparisons of breast cancer surgical outcomes among treating surgeons and hospitals," the investigators examined re-excision rates across four geographically diverse health systems. Their chief goal was to determine whether significant variations existed, which would in turn determine whether the re-excision rate is a meaningful measure of surgical quality.
They assessed detailed data on initial and subsequent surgeries for invasive ductal carcinoma or invasive lobular carcinoma in 2,206 women who underwent an initial breast-conserving procedure for incident cancer.
Overall, 509 patients (23%) underwent re-excision of the affected breast during 5 years of follow-up. A total of 454 women had a single re-excision, 48 had two re-excisions, and 7 had three re-excisions. Approximately 9% of the study subjects (190 women) underwent total mastectomy after the initial breast-conserving surgery.
The rate of re-excision varied greatly from one surgeon to another, ranging from 0% to 70%. This implies that patients with the same clinical presentations are likely to undergo re-excision based on who is doing their procedure, not on their clinical traits, the investigators said (JAMA 2012;307:467-75).
This study was designed to determine whether such variations exist, not the reasons why they exist. But the researchers suggested that "differences in surgical training, surgeon confidence in their operative technique in localizing tumors, utilization of intraoperative assessment of margins, and surgeon’s and pathologist’s coordination of specimen orientation and margin interpretation" may all play a role.
Surprisingly, the volume of procedures a surgeon performs did not affect his or her re-excision rate in this study, so surgical experience may not play an important role in these variations, Dr. McCahill and his colleagues added.
The rate of re-excision also varied greatly from one medical center to another, ranging from 1.7% at the center with the lowest rate to 21% at the center with the highest rate. In particular, the rate of re-excision for cases with positive margins ranged from 74% to 94%. Any variation in this statistic is surprising because positive margins are known to correlate with local recurrence and are "almost always" re-excised, the researchers said.
Again, this study was not designed to determine why re-excision rates differ so greatly between medical centers, but the investigators suggested that "institutional variation in surgeon’s training, regional variation in interpretation of the required criteria for [re-excision], or both" may account, at least in part, for the variation.
The need for re-excision in patients who have negative (pathologically clear) margins at the initial surgery is controversial, because "there is no clear consensus on the appropriate distance required for a clear margin to be deemed adequate." So perhaps it should not be surprising that almost half of the re-excisions (242 of the 509) in this study were performed in patients who had negative margins, the researchers said.
One major limitation of this study was that some factors that greatly influence treatment decisions, including patient preferences, were not included in the data and so could not be factored into the analysis, they noted.
This study was funded by the National Institutes of Health under the American Recovery and Reinvestment Act. The authors reported no financial conflicts of interest.