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Understanding Variability in the Rate of Additional Surgery after Partial Mastectomy

Laurence McCahill, MD
Department of Surgery
Michigan State University
East Lansing, MI
Richard J. Lacks Cancer Center and Van Andel Research Institute
Grand Rapids, MI

What's the problem?

Breast cancer surgery is a commonly performed operation that is generally the first step in breast cancer treatment. The quality with which this surgery is performed and the patient's outcomes have a major impact on all future steps in care. However, at present, no readily identifiable quality measures exist to compare breast cancer surgical outcomes across surgeons and hospitals.

Breast-conserving therapy, or partial mastectomy, is a good example of this lack of data. Partial mastectomy is one of the most frequent cancer surgeries in the United States. An estimated 60% to 75% of women with breast cancer undergo partial mastectomy as their initial treatment. The goal of the surgery is to achieve an adequate rim of normal tissue, or surgical margin, around the breast cancer while maintaining the maximum cosmetic appearance of the breast. Failure to achieve an adequate surgical margin requires additional surgery later. These reexcision procedures cause considerable psychological, physical, and economic stress for patients and delay the start of recommended supplemental treatments. Nearly one in four women who undergo partial mastectomy have a second surgery afterword. For almost half of these women, the second procedure is a total mastectomy.

Despite the frequency of this surgery, little is known about the extent to which reexcision rates vary across institutions and surgeons or about the factors that influence the likelihood of a second surgery. Detailing the variability and defining predictors of reexcision would help investigators evaluate the utility of reexcision as a meaningful breast cancer surgery quality measure.

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How has this research addressed the problem?

Dr. McCahill and his colleagues developed a Breast Cancer Surgical Outcomes (BRCASO) research consortium, which combined expertise in cancer surgery outcomes assessment from the University of Vermont (UVM) with expertise in cancer-related effectiveness research from three sites within the NCI-funded Cancer Research Network (CRN). The three sites were Kaiser Permanente, Colorado; Group Health, western Washington state; and Marshfield Clinic, Wisconsin.

The study pooled data on 2,206 women who had a breast-conserving first surgical procedure between 2003 and 2008. The average age for patients was 62 years, and 93% of patients with reported race/ethnicity were non-Hispanic white. Overall, 23% of the sample, or 509 patients, had one or more reexcisions on the affected breast.

A total of 14 percent of the overall sample, or 311 women, had positive margins (some tumor cells left at the site of surgery) after their initial surgery. Of these women, 86%, or 267 women, underwent reexcision. The percentage of women with positive margins who underwent reexcision differed considerably across institutions and surgeons, with the rate varying from 74% to 94% among institutions. Nearly half the patients with pathologically clear margins of less than 1mm had reexcision and one-fifth of patients with clear margins between 1 and 1.9mm underwent reexcision. Reexcision rates overall varied from 0% to 70% among individual surgeons. These results illustrated an important area in which consensus is lacking - the appropriate size of a surgical margin that should be considered "clear."

These significant variations in reexcision rates cannot be entirely explained by patients' clinical characteristics. However, study results did point to a number of potentially relevant factors. These include the type of breast cancer, institutional variations in surgeons' training, other differences across surgeons, regional variation in interpreting criteria for reexcision, and differences in perceived risk of recurrence.

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Significance of the research & results

Although considerable research has been conducted on access to surgical cancer care, little has been done on the quality of surgical care. This study, which was funded under the 2009 American Recovery and Reinvestment Act (ARRA), represents a critical step in opening up this unexplored area.

Dr. McCahill and his team also used an innovative approach in studying this issue. Creating the research consortium allowed the team to pool detailed data across the UVM and CRN researchers' separate data systems and develop a multicenter electronic breast cancer surgery outcomes database. This database gave Dr. McCahill and his colleagues a new capacity to ask, and begin to answer, key questions about breast cancer surgery outcomes.

Finally, the results of this study have important public health implications, for they point the way to additional studies that may help to resolve current controversies in breast cancer management. These controversies result in tens of thousands of surgeries annually, exacting a high personal and financial cost for women and our nation but without a clear impact on cancer recurrence or patient survival.

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Recent related publications of interest

Aiello Bowles EJ, Feigelson HS, Barney T, Broecker K, Sterrett A, Bischoff K, Engel J, Gundersen G, Sheehey-Jones J, Single R, Onitilo A, James TA, McCahill LE. Improving quality of breast cancer surgery through development of a national breast cancer surgical outcomes (BRCASO) research database. BMC Cancer 2012 Apr 3;12:136. [View Abstract]

McCahill LE, Single RM, Aiello Bowles EJ, Feigelson HS, James TA, Barney T, Engel JM, Onitilo AA. Variability in reexcision following breast conservation surgery. JAMA 2012 Feb 1;307(5):467-75. [View Abstract]

Morrow M, Harris JR, Schnitt SJ. Surgical margins in lumpectomy for breast cancer--bigger is not better. N Engl J Med 2012 Jul 5;367(1):79-82. [Look up in PubMed]

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Last Modified: 03 Sep 2013