In a meta-analysis reported in JAMA Surgery, Marinovich et al found that reoperation rates after breast-conserving surgery in women with breast cancer declined after the publication of the Society of Surgical Oncology/American Society for Radiation Oncology (SSO/ASTRO) Consensus Guideline on Margins for Breast-Conserving Surgery.
As stated by the investigators, “The 2014 publication of the SSO/ASTRO Consensus Guideline on Margins for Breast-Conserving Surgery recommended a negative margin definition of no ink on tumor. Adoption of this guideline would represent a major change in surgical practice that could lower the rates of reoperation.”
The meta-analysis included studies reported between January 2014 and July 2019 that compared reoperation rates in preguideline vs postguideline cohorts (actual change), retrospectively applied the SSO/ASTRO guideline to a preguideline cohort (projected change), or described economic outcomes associated with the guideline.
“This study found a decrease in reoperation rates after the publication of the SSO/ASTRO guideline; this reduction was greater at an institutional level than a population level, the latter reflecting the differences in guideline adoption between centers [in the population-based studies]. These early outcomes may be conservative estimates of longer-term implications.”— Marinovich et al
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A total of 30 studies, with a total of 599,016 participants, reported changes in reoperation rates. Studies included a median of 487 participants (range = 100–521,578). Of the 30 studies, 20 were from the United States, 6 from the United Kingdom, 3 from Canada, and 1 from Australia.
Among 21 studies of actual change, pooled odds ratios (ORs) indicated a significant reduction in reoperation in the 17 institution-based studies (OR = 0.62, 95% confidence interval [CI] = 0.52–0.74) and in the 9 population-based studies (OR = 0.76, 95% CI = 0.72–0.80). The likelihood of reduction in reoperation was significantly greater in the institution-based studies (P = .04).
Among the nine studies of projected changes (all institution-based), pooled odds ratios for reoperation were lower for preguideline margin thresholds of ≥ 2 mm (OR = 0.47, 95% CI = 0.40–0.56) vs 1 mm (OR = 0.85, 95% CI = 0.79–0.91), with the difference being significant (P < .001).
Studies of projected change in reoperation assumed that all women with close margins would avoid reoperation with the application of a no-ink-on-tumor threshold. However, the SSO/ASTRO guideline notes that clinical judgment based on patient and tumor factors would prompt reoperation in some patients even in cases in which a margin of no ink on a tumor is obtained. Thus, studies of projected change are likely to overestimate reductions in reoperation vs studies of actual change.
Findings in six studies estimating postguideline economic outcome indicated that application of the guideline appears to be cost-saving, with a median saving of U.S. $3,540 (range = $1,800–$25,650) per woman avoiding reoperation.
The investigators concluded, “This study found a decrease in reoperation rates after the publication of the SSO/ASTRO guideline; this reduction was greater at an institutional level than a population level, the latter reflecting the differences in guideline adoption between centers [in the population-based studies]. These early outcomes may be conservative estimates of longer-term implications.”
M. Luke Marinovich, PhD, of the School of Public Health, Curtin University, Bentley, Australia, is the corresponding author for the JAMA Surgery article.
Disclosure: The study was supported by the Western Australian Health Translation Network, the Australian Government’s Medical Research Future Fund, and the Australian National Breast Cancer Foundation. For full disclosures of the study authors, visit ascopubs.org.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.