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Breast

Breast Parallel Session 1

7: Routine Use of Cavity Shave Margins with Breast Conserving Surgery Lowers Re-Excision Rates in a High Volume, Large Group Practice

Friday, March 22, 2024
11:42am – 11:52am ET
Location: Georgia Ballroom
Disclosure(s):
Jeffery Chakedis, MD, FACS: No financial relationships to disclose
Introduction:

Routine use of cavity shave margins (CSM) after breast conserving surgery (BCS) for breast cancer was found in two randomized controlled trials to halve the rate of margin re-excision.  In a high-volume, large group-practice of 55 breast surgeons who treat 2,000 annually with BCS, routine CSM practice was instituted.  We conducted a prospective interventional study to evaulate the effects of routine CSM utilization on rates of margin re-excision.


Methods:

All adult female patients with a diagnosis of Stage 0-III breast cancer who underwent BCS were evaluated from September 1, 2018 through March 30, 2023.  Routine CSM was defined as at least four re-excised surfaces of the lumpectomy cavity. Three time periods were studied: Pre-intervention (Sept 2018 – June 2021), Transition (July 2021 – Jan 2022), and Post-intervention (Feb 2022 – March 2023). Margin re-excision rates were compared using chi-square test.


Results:

The trial enrolled 10,069 patients who had a median age of 64 (IQR 56-72), majority of cancers occurred in women of white race (56%) and were mostly invasive ductal (75.1%)  and early stage (T1 55.2% and T2 26.0%). During the study period routine cavity shave margin utilization increased by 170% (Overall  32.4%, Pre 20.7% to Post 56.9%, p< 0.001), Figure 1  Margin re-excision rates decreased by 28.1% (pre-18.3% to post-13.2%, p< 0.001) after CSM intervention.  BCS in which CSM were used had a significantly lower re-excision rate throughout the study (CSM: pre 14.3% and post 11.4%, no CSM: pre 19.4% and post 15.5%, < 0.001).  CSM utilization improved rates of re-excision for invasive breast cancer (pre- 12.8%, post 8.9%, p< 0.001) but did not effect ductal carcinoma in-situ (pre-27.6%, post-24.1%, p=0.36).  Mastectomy rates did not change throughout the study (pre-30.8% to post-32.2%, p=0.11). CSM were adopted by 26 surgeons (47%), CSM was not used or used selectively by 20 surgeons (36%), and 9 surgeons  (16%) routinely used CSM throughout the study.  Surgeons who adopted CSM  increased ultilization from 8% pre-intervention to 73% of BCS operations post-intervention.  Almost all CSM adopters (24/26 surgeons) had a decrease in re-excision rate and overall rates decreased by 36.8% (pre-21.3% to post-13.5%,p< 0.001)


Conclusions:

In a large group, high volume practice, cavity shave margins were adopted by half of surgeons in a two-year period and was succeful in signifcantly reducing re-excision rates by 37%.  This real-world experience corroborates clinical trial data that cavity shave margins are a practical and effective pratice to lower re-excision rates

Learning Objectives:

  • Identify methods for reducing re-excision rates for patients undergoing breast conserving surgery
  • Identify patients who are high risk for margin re-excision and may warrant additional methods for risk reduction
  • Describe the cavity shave margin technique and be able to incorporate it into their practice