What is an Adequate Margin for Breast-Conserving Surgery? Surgeon Attitudes and Correlates

Re-excision is common in breast-conserving surgery (BCS), partly due to lack of consensus on margin definitions. A population-based surgeon sample was used to determine current attitudes toward margin width and identify characteristics associated with margin choice.

Breast cancer patients treated from 2005 to 2007 were identified from Los Angeles and Detroit Surveillance, Epidemiology, and End Results (SEER) registries. Pathology reports were used to identify their surgeons, who were surveyed (n = 418). Response rate was 74.6% (n = 312). Mean surgeon age was 51.9 years, 17.8% were female, and mean number of years in practice was 18.5.

Wide variation in margin selection was noted among surgeons, and did not differ for invasive cancer and ductal carcinoma in situ (DCIS). In a scenario of T1 invasive cancer, 11% of surgeons endorsed margins of tumor not touching ink (TNTI), 42% of 1–2 mm, 28% of ≥5 mm, and 19% >1 cm as precluding need for re-excision before radiotherapy. On multivariate analysis, having 50% or more of practice devoted to breast cancer independently predicted smaller margin choice (p = 0.03). For a patient with a 1.4-cm grade 2 estrogen receptor (ER)-positive DCIS without radiotherapy (RT) planned, 3% of surgeons chose TNTI, 12% 1–2 mm, 25% ≥5 mm, and 61% >1 cm as sufficient without re-excision. In the scenario of DCIS without RT, breast specialization independently predicted larger margin choice (p = 0.03). Gender and years in practice were not predictive of margin choice.

Wide variation in BCS margin definition exists. Variation is similar for invasive cancer and DCIS with RT, with more specialized surgeons choosing smaller margins. In DCIS without RT, more specialized surgeons favored larger margins. A standardized margin definition may significantly affect re-excision rates.