According to an investigation in the February 1 issue of JAMA, surgery to remove additional tissue (reexcision) is required in almost 1 in 4 women who undergo a partial mastectomy for breast cancer treatment. In addition, there is considerable surgeon and institutional difference in the rate of reexcisions that have nothing to do with patients' characteristics.

In the U.S., the current environment of health care reform requests transparency of health care outcomes and increasing hospital and physician accountability.

The researchers explain:

"Breast-conserving therapy, or partial mastectomy, is one of the most commonly performed cancer operations in the United States. Currently, there are no readily identifiable quality measures that allow for meaningful comparisons of breast cancer surgical outcomes among treating surgeons and hospitals."

A "Partial mastectomy" is when the surgeon removes the breast tumor, plus a small amount of healthy tissue surrounding it. If this is not done properly, further surgery will be required later on.

For the patients, these additional operations can cause significant psychological, economic and physical stress and delay use of recommended supplemental therapies.

The researchers say:

"Thus, the effect of reexcision on altering a patient's initial treatment of choice is significant."

In order to measure the difference in reexcision rates between hospitals and surgeons treating individuals with similar clinical conditions, Laurence E. McCahill, M.D., of the Richard J. Lacks Cancer Center, Van Andel Research Institute, and Michigan State University, Grand Rapids, Mich, and team conducted an investigation between 2003 and 2008. The researchers gathered data from electronic medical records, and chart abstraction of surgical, radiology, pathology and outpatient records. The study involved 2,206 women with 2,220 newly identified invasive breast cancer undergoing their first partial mastectomy from the University of Vermont, Marshfield Clinic, Kaiser Permanente Colorado, and Group Health.

92.8% of women with reported race/ethnicity were non-Hispanic white and the average age for patients was 62 years old. The researchers found that 22.9% (509 patients) underwent additional surgery on the affected breast.
  • 454 (89.2%) of these 509 patients underwent a single reexcision
  • 9.2% (48 patients) underwent two reexcisions
  • 1.4% (7 patients) underwent 3 reexcisions
  • while a total of 190 patients (8.5%) underwent a total mastectomy
The researchers explain:

"Reexcision rates for margin status following initial surgery were 85.9 percent for initial positive margins [cancer cells at the edge of the removed tissue], 47.9 percent for less than 1.0 mm margins, 20.2 percent for 1.0 to 1.9 mm margins, and 6.3 percent for 2.0 to 2.9 mm margins. For patients with negative margins [no cancer cells at the outer edge of the tissue that was removed], reexcision rates varied widely among surgeons (range, 0 percent - 70 percent) and institutions (range, 1.7 percent - 20.9 percent). Reexcision rates were not associated with surgeon procedure volume after adjusting for case mix."

Among Institutions, the team also found difference in the reexcision of positive margins, with rates ranging from 73.7% and 93.5%. The authors explain that these rates may reflect institutional variation in surgeons' regional variation in interpretation of the required criteria for reexcision and training.

The researchers conclude:

"Our study highlights the value of multi-centre observational studies in demonstrating variability in health care across geographic regions and different health systems, with uniform data collection instruments. The long-term effect of this variability is beyond the scope of our study, but it is feasible that outcomes such as local recurrence and even overall survival could be affected by variability in initial surgical care.

Even in the absence of effects on local control, the wide level of unexplained clinical variation itself represents a potential barrier to high-quality and cost-effective care of patients with breast cancer. Continued comparative effectiveness research of breast cancer surgery requires further attention to better determine the association of initial surgical care with long-term patient outcomes."

Associated report in the same journal

In an associated report, Monica Morrow, M.D., of the Memorial Sloan-Kettering Cancer Center, New York, and Steven J. Katz, M.D., M.P.H., of the University of Michigan. Ann Arbor comment:

"The article by McCahill et all underscores the challenge in developing surgical quality indicators for patients with cancer, especially for procedures with very low risk of major complications. While there is strong evidence that positive margins are associated with an increased rate of local recurrence, a substantial number of reexcisions are performed among patients with negative margins to obtain a more widely clear margin.

There is no consensus among surgeons and radiation oncologists as to what constitutes an optimal negative margin width because the question has not been addressed in prospective randomized trials. The observational design used in the McCahill et all study is valuable for illuminating the nature of potential quality gaps but cannot be used to inform the validity of candidate quality measures."

Written by Grace Rattue