The Diminishing Impact of Margin Definitions and Width on Local Recurrence Rates following Breast-Conserving Therapy...

Area of Science:

• Oncology
• Surgical Oncology
• Breast Cancer Research

Background:

• Optimal tumor-free margin definition and width for breast-conserving therapy (BCT) in early-stage invasive cancers is crucial.
• Previous meta-analyses and guidelines have addressed margin width, but treatment improvements over time necessitate updated assessments.
• The impact of margins on local recurrence (LR) rates requires re-evaluation in light of evolving treatment modalities.

Purpose of the Study:

• To conduct an updated meta-analysis assessing the effect of treatment improvements on the relationship between margin status and local recurrence (LR) rates.
• To evaluate how changes in breast cancer treatment over time have influenced the significance of margin width in predicting local recurrence.
• To provide current evidence to inform management guidelines for breast-conserving therapy.

Main Methods:

• Systematic literature review of 38 studies including 54,502 patients treated between 1968 and 2010.
• Inclusion criteria focused on BCT, minimum 50-month follow-up, explicit margin status definitions, and LR data.
• Bayesian logistic regression model used for data pooling to assess LR risk in relation to margin status and enrollment periods.

Main Results:

• Median follow-up was 7.25 years.
• Absolute LR rates declined across all margin width cohorts over time.
• The difference in LR rates between negative margin groups was less than 1% in the most recent period, indicating a diminished impact of margin width.

Conclusions:

• Supports the "no tumor on ink" guideline for most patients, based on an analysis of over 54,000 patients.
• The impact of margin width on local recurrence rates has substantially decreased over time.
• Older studies may have limited relevance for current breast cancer management guidelines due to treatment advancements.