Shaves off the Cavity or Specimen in Lumpectomy for Breast Cancer

Re-excision for positive margins (margins where tumor is positive) after breast conserving surgery (BCS) is common and burdensome for breast cancer patients. Routine shave margins can reduce positive margins and re-excision rates. Cavity shaving margin (CSM) removes margins from the lumpectomy cavity edges, whereas specimen shave margin (SSM) requires ex vivo removal of margins from the resected specimen.

We assessed breast cancer patients undergoing BCS who received CSM or SSM procedures from 2017 to 2019. CSM and SSM techniques were compared by analyzing positive rates of primary and final shaved margins, re-excision rates, and tissue volumes removed.

Of 116 patients included in this study, 57 underwent CSM and 59 underwent SSM. Primary margins were positive or close in 19 CSM patients and 21 SSM patients (33% versus 36%; P = 0.798). Seventeen CSM patients had a tumor in shaved margin specimens, compared to four patients for SSM (30% versus 7%; P < 0.001); however, final shave margins were similar (5% versus 5%; P = 0.983). Volumes of shave specimens were higher with SSM (40.7 versus 13.4 cm³; P < 0.001), but there was no significant difference in the total volume removed (146.8 versus 134.4 cm³; P = 0.540). For tumors 2 cm or larger, the total volume removed (140 versus 206 cm³; P = 0.432) and rates of final margin positivity (7.5% versus 0%; P = 0.684) were similar for both techniques.

CSM and SSM are effective techniques for achieving low re-excision rates. Our findings suggest that surgeons performing either CSM or SSM may maintain operative preferences and achieve similar results.