Abstract P2-12-08: Rates of re-excision surgery after implementation of consensus guidelines on margins for breast- conserving surgery in stage I and II invasive breast cancer: A Nova Scotian experience
Bibliographic record
Abstract
Abstract Background: In Canada, most women with early invasive breast cancer will be treated with breast-conserving surgery (BCS). The proportion of patients requiring re-excision surgery after BCS varies province to province. Until recently, there was no universally accepted definition for adequate margin width following BCS. The Society of Surgical Oncology (SSO) and American Society for Radiation Oncology (ASTRO) published consensus guidelines in 2014 to help regulate practice. The objective of this study was to determine the proportion of patients undergoing re-excision surgery before and after guideline implementation at our institution. Methods: We performed a retrospective review of all patients with invasive breast cancer and/or ductal carcinoma in situ (DCIS) who underwent re-excision surgery between October 1, 2010- October 31, 2011 (pre-guideline) and October 1, 2014- May 30, 2016 (post-guideline). The proportion of patients requiring re-excision surgery was calculated for each time period and patient characteristics and clinical outcomes were compared. Results: There were 188 patients identified who underwent BCS in the pre-guideline time period and 411 patients in the post-guideline time period. The proportion of patients undergoing re-excision surgery significantly decreased from 13.8 % to 7.8 % after guideline implementation (p = 0.02). Patient characteristics were similar between those who underwent re-excision before and after guideline implementation. In patients requiring re-excision surgery, histological and pathological features were similar between time periods. Margin width and indication for re-excision surgery varied between time periods. Among women who had re-excision surgery in the pre-guideline group, most (50%) had an invasive cancer margin > 1 mm. However, after guideline implementation, a frankly positive invasive cancer margin was the most common indication for re-excision surgery (65%). No significant differences in clinical outcomes were observed between patients who underwent re-excision surgery before and after guideline implementation. Conclusion: The proportion of patients undergoing re-excision surgery after BCS has significantly decreased after SSO-ASTRO guideline implementation at our institution. This data suggests that among women with invasive breast cancer and/or DCIS, the implementation of SSO-ASTRO guidelines has led to a 43.5% decline in re-excision surgery. Citation Format: Drohan AE, Helyer LK. Rates of re-excision surgery after implementation of consensus guidelines on margins for breast- conserving surgery in stage I and II invasive breast cancer: A Nova Scotian experience [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P2-12-08.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.003 | 0.015 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".