Nearly one-fourth of women who undergo a partial mastectomy have a second surgery to remove additional tissue, and there is substantial surgeon and institutional variation in the rate of reexcisions that cannot be explained by patients’ clinical characteristics.

Investigators reached this conclusion after conducting an observational study of breast surgery performed between 2003 and 2008 at four medical institutions (JAMA. 2012;307[5]:467-475). Of 2,206 women (mean age 62 years) with 2,220 newly identified invasive breast cancers who underwent a partial mastectomy, 509 of them (22.9%) had additional surgery. Most patients (454, or 89.2%) had one reexcision, 48 women (9.4%) had two reexcisions, and seven women (1.4%) had three reexcisions.Of the full group of women, 190 (8.5%) eventually had a total mastectomy.

Failure to achieve appropriate surgical margins (the rim of normal tissue around the cancerous tissue) after initial partial mastectomy results in the need for more surgery. Reexcision rates for margin status after the first operation were as follows:

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  • 85.9% for initial positive margins
  • 47.9% for margins of less than 1.0 mm
  • 20.2% for margins of 1.0 to 1.9 mm
  • 6.3% for margins of 2.0 to 2.9 mm.

Reexcision rates varied widely among surgeons and institutions for patients with negative surgical margins. The great variation in reexcision rates could not be explained by a patient’s medical or treatment history.

As the investigators point out, partial mastectomy is the most commonly performed procedure for invasive breast cancer, and cancer recurrence as well as the patient’s overall survival could possibly be affected by differences in initial surgical care.

“The wide level of unexplained clinical variation itself represents a potential barrier to high-quality and cost-effective care of patients with breast cancer,” cautioned study leader Laurence E. McCahill, MD, director of surgical oncology at The Lacks Cancer Center in Grand Rapids, Michigan, in a statement describing his group’s findings.