Meeting Minutes (Academic Deep Dive)
[Editor’s Note] At the recent American Society of Clinical Oncology (ASCO) Annual Meeting, Professor Anees B. Chagpar, a Professor of Surgery at the Yale School of Medicine, delivered an important special report titled "Does resection of cavity shave margins impact survival in breast cancer patients?". Based on the famous SHAVE and SHAVE2 randomized controlled trials, the report explored the advantages of Cavity Shave Margins (CSM) in breast-conserving surgery (BCS) regarding the reduction of positive margin rates and re-excision rates. For the first time, it disclosed detailed long-term impacts on patients' 5-year local recurrence (LR) rates, disease-free survival (DFS), and overall survival (OS), providing key evidence-based support for treatment de-escalation and multi-modal synergy in the field of breast surgery.01 Clinical Challenges of Margin Management: Starting from the SHAVE Research Background
In breast-conserving surgery for breast cancer, ensuring negative margins is a core requirement for reducing local recurrence (LR). However, traditional margin assessment methods often lead to extremely high re-excision rates. Re-excision not only increases the psychological burden and medical costs for patients but may also negatively impact breast aesthetic outcomes. Professor Anees B. Chagpar pointed out that to address this challenge, the academic community launched the SHAVE series of studies. Data previously published in the New England Journal of Medicine (NEJM) and Annals of Surgery have already confirmed that routinely performing cavity shave margins during breast-conserving surgery (i.e., taking an additional “shave” of tissue from the surrounding cavity walls after the primary tumor specimen has been removed) can significantly improve surgical quality. The core focus of this report is: can this optimization of surgical technique be translated into long-term survival benefits for patients?
02 Study Design and Methodology: Integrated Analysis of Single-center SHAVE and Multi-center SHAVE2
To obtain more statistically powerful conclusions, the research team integrated data from the SHAVE and SHAVE2 trials. • SHAVE Trial: A single-center study conducted at Yale from October 2011 to November 2013, involving 235 patients. • SHAVE2 Trial: A multi-center study conducted from June 2016 to April 2018, covering 9 centers across the United States, including academic centers and community hospitals, involving 396 patients. Inclusion Criteria and Intervention Process: The inclusion criteria for both trials were consistent, requiring patients to be ≥18 years old, planning to undergo partial mastectomy, and having disease staged from Stage 0 to III. The study adopted a highly innovative “intraoperative randomization” model: after the surgeon completed what they considered their “best” breast-conserving surgery (including reviewing specimen radiographs and performing selective margin re-excisions as needed), only when they believed the margins were satisfactory and were ready to suture was the randomization envelope opened. Patients were randomly assigned to:
- CSM Group (Shave Group): Taking additional cavity shave margins around the entire cavity.
- Control Group (No Shave Group): Suturing the cavity directly without further additional shaves.
03 Surgical Result Review: The “Halved Benefit” of Positive Margin and Re-excision Rates
The integrated data from the two studies, totaling 631 patients, showed no statistical difference between the two groups in terms of baseline demographic characteristics (such as age, tumor size, positive margin rate before randomization, etc.). However, the surgical outcomes after randomization showed significant differences: • Decrease in Positive Margin Rate: In the CSM group, the final positive margin rate after randomization was reduced by more than 50% compared to the control group, with high statistical significance (P < 0.001). • Detection of Occult Disease: Notably, among patients initially judged to have negative margins and randomized to the CSM group, occult cancerous lesions were found in the additionally resected cavity shave tissue in approximately 13.3% of cases. • Reduction in Re-excision Rates: The benefit was directly reflected in the frequency of re-excisions. Because intraoperative CSM reduced the risk of positive margins, the re-excision rate in the CSM group was significantly lower than that in the control group, with a risk reduction also exceeding 50%.
04 Long-term Prognosis Follow-up: Survival Analysis under Five-Year Follow-up Data
The highlight of this ASCO report is the long-term prognostic data with a median follow-up time of 60.4 months (5 years). Professor Chagpar presented comparison results based on the Cox regression model to evaluate the impact of surgical technique improvement on long-term outcomes: • Local Recurrence (LR) Rate: At the 5-year time point, no statistically significant difference in the risk of local recurrence was observed between the CSM group and the control group. • Disease-Free Survival (DFS): The 5-year DFS rates were highly similar between the two groups, with survival curves showing significant overlap. • Overall Survival (OS): Similarly, the 5-year OS rates for the CSM group and the control group were basically consistent. Professor Chagpar emphasized that although CSM significantly reduced post-operative histopathological positive margins and cleared 13.3% of potential occult lesions, in the context of modern multidisciplinary treatment (especially adjuvant radiotherapy), this local “thoroughness” did not translate directly into an extension of survival.
05 The Key to Driving Survival: The Value of Radiotherapy in Multivariate Regression
Analysis To further explore independent prognostic factors affecting patient DFS, the research team constructed a multivariate analysis model covering randomization grouping (CSM vs. No Shave), final margin status (positive vs. negative), and whether radiotherapy was received. The study found: • After including systemic therapy (chemotherapy, endocrine therapy) in the model, the results remained stable. • The only significant predictor: Radiotherapy was the only intervention capable of independently predicting improved DFS for patients. • Regardless of whether the patient underwent cavity shave margins, and regardless of how their final margin status reached negative, standardized postoperative radiotherapy played a “decisive” role in preventing local recurrence and ensuring long-term survival.
06 Clinical Significance and Outlook: The Balance Point between Surgical De-escalation and Precision Treatment
In her summary, Professor Anees B. Chagpar pointed out that the clinical value of CSM (Cavity Shave Margins) is primarily reflected in the optimization of the surgical level rather than changes in survival outcomes. Core conclusions are as follows:
- Clinical Practice Recommendation: For surgeons aiming to reduce re-excision rates and alleviate patients’ psychological and financial burdens, CSM remains an extremely effective technical tool. It can reduce the risk of re-excision by more than 50%.
- Survival Benefit Assessment: Under conditions of comprehensive adjuvant radiotherapy and systemic therapy, it may be difficult to further improve 5-year survival indicators solely by expanding the scope of local surgery (such as CSM).
- Future Direction: This study provides supporting evidence for the “de-escalation” discussion in breast cancer surgical treatment. With the arrival of the era of precision treatment, how to identify those patients who can achieve excellent prognosis even without re-excision and by relying solely on radiotherapy is a focus of future clinical exploration.
Expert Commentary:
This study, through a follow-up of up to 60 months, confirms that the long-term prognosis of breast cancer patients depends more on the combined effects of systemic therapy and local radiotherapy rather than minor adjustments to the scope of a single surgical resection. As a tool for optimizing the surgical process, the significance of CSM lies in improving the “success rate of the first operation” rather than acting as a means to change the biological outcome of the disease. In clinical decision-making, doctors should comprehensively consider whether to implement cavity shave margins based on the patient’s requirements for breast aesthetics, tolerance for a second surgery, and cooperation with adjuvant treatment plans.
