Nearly one in four women who undergo a partial mastectomy for treatment of breast cancer have a subsequent re-excision, and there is substantial surgeon and institutional variation in the rate of re-excisions that cannot be explained by patients' clinical characteristics, according to a study in the Feb. 1 issue of JAMA.
The current environment of healthcare reform in the United States calls for increasing physician and hospital accountability and transparency of healthcare outcomes, the authors wrote as background information in the study.
"Breast-conserving therapy, or partial mastectomy, is one of the most commonly performed cancer operations in the United States," they wrote. "Currently, there are no readily identifiable quality measures that allow for meaningful comparisons of breast cancer surgical outcomes among treating surgeons and hospitals."
Partial mastectomy is optimally performed by achieving adequate surgical margins (the rim of normal tissue around the breast cancer) during the initial surgical resection while maintaining maximum cosmetic appearance of the breast. Failure to achieve appropriate margins at the initial operation will require additional surgery.
These additional operations can produce considerable psychological, physical and economic stress for patients and delay use of recommended supplemental therapies. "Thus, the effect of re-excision on altering a patient's initial treatment of choice is significant," the authors wrote.
Laurence E. McCahill, MD, of the Richard J. Lacks Cancer Center, Van Andel Institute and Michigan State University, and colleagues conducted a study between 2003 and 2008 to measure variation in re-excision rates across hospitals and surgeons treating patients with similar clinical conditions.
The study included women with invasive breast cancer undergoing partial mastectomy from four institutions: a university hospital (the University of Vermont) and three large health plans (Kaiser Permanente Colorado, Group Health and Marshfield Clinic). Data were obtained from electronic medical records and chart abstraction of surgical, pathology, radiology and outpatient records.
The study included 2,206 women with 2,220 newly identified invasive breast cancers who underwent a breast-conserving first surgical procedure. The average age for patients was 62, and 92.8% of patients with reported race/ethnicity were non-Hispanic white. Overall, 509 patients (22.9%) underwent at least one re-excision on the affected breast. Among all patients undergoing initial breast conservation, a total mastectomy was subsequently performed in 190 patients (8.5%).
The authors wrote that re-excision rates following initial surgery were 85.9% for initial positive margins (cancer cells at the edge of the removed tissue), 47.9% for margins less than 1 millimeter, 20.2% for 1 to 1.9 mm margins and 6.3% for 2-2.9 mm margins.
Nearly half the patients in the study who underwent re-excision did so despite having negative margins, meaning no cancer cells were found at the outer edge of the removed tissue, The researchers did not specify why these patients underwent re-excision, but noted tumor size, study site and a known preoperative malignant diagnosis all remained significantly associated with re-excision in those cases.
Re-excision rates in those cases varied widely among surgeons, ranging from 0% to 70%, and among institutions, ranging from 1.7% to 20.9%. After adjusting for case mix, the rates were not associated with the number of procedures a surgeon performed.
The researchers also observed variation in the re-excision of positive margins among institutions, with rates ranging between 73.7% and 93.5%. This disparity may reflect institutional variation in surgeons' training, regional variation in interpretation of the required criteria for re-excision or a combination of both issues, they wrote.
"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," the authors wrote.
"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," they said. "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."
To read the study, visit http://bit.ly/ysE3Nx.
