Objective: Single-center studies have demonstrated that resection of cavity shave margins (CSM) halves the rate of positive margins and re-excision in breast cancer patients undergoing partial mastectomy (PM). We sought to determine if these findings were externally generalizable across practice settings. Methods: In this multicenter randomized controlled trial occurring in 9 centers across the United States, stage 0–III breast cancer patients undergoing PM were randomly assigned to either have resection of CSM (“shave” group) or not (“no shave” group). Randomization occurred intraoperatively, after the surgeon had completed their standard PM. Primary outcome measures were positive margin and re-excision rates. Results: Between July 28, 2016 and April 13, 2018, 400 patients were enrolled in this trial. Four patients (2 in each arm) did not meet inclusion criteria after randomization, leaving 396 patients for analysis: 196 in the “shave” group and 200 to the “no shave” group. Median patient age was 65 years (range; 29–94). Groups were well matched at baseline for demographic and clinicopathologic factors. Prior to randomization, positive margin rates were similar in the “shave” and “no shave” groups (76/196 (38.8%) vs. 72/200 (36.0%), respectively, P = 0.604). After randomization, those in the “shave” group were significantly less likely than those in the “no shave” group to have positive margins (19/196 (9.7%) vs. 72/200 (36.0%), P < 0.001), and to require re-excision or mastectomy for margin clearance (17/196 (8.7%) vs. 47/200 (23.5%), P < 0.001). Conclusion: Resection of CSM significantly reduces positive margin and re-excision rates in patients undergoing PM.

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Background There are several techniques for localization of non-palpable breast tumors, but comparisons of these techniques in terms of margin positivity and volume of tissue resected are lacking. Methods Between 2011-2013 and 2016-2018, 2 randomized controlled trials involving 10 centers across the United States accrued 631 patients with stage 0-3 breast cancer, all of whom underwent breast conserving surgery. Of these, 522 had residual non-palpable tumors for which localization was required. The localization technique was left to the discretion of the individual surgeon. We compared margin positivity and volume of tissue resected between various localization techniques. Results The majority of the patients (n = 465; 89.1%) had wire localization (WL), 50 (9.6%) had radioactive seed (RS) localization, and 7 (1.3%) had Savi Scout (SS) localization. On bivariate analysis, there was no difference in terms of margin positivity (37.8% vs. 28.0% vs. 28.6%, P = .339) nor re-excision rates (13.3% vs. 12.0% vs. 14.3%, P = .961) for the WL, RS, and SS groups, respectively. Further, the volume of tissue removed was not significantly different between the 3 groups (71.9 cm3 vs. 55.8 cm3 vs. 86.6 cm3 for the WL, RS, and SS groups, respectively, P = .340). On multivariate analysis, margin status was affected by tumor size (OR = 1.336; 95% CI: 1.148-1.554, P<.001) but not by type of localization ( P = .670). Conclusions While there are a number of methods for tumor localization, choice of technique does not seem to influence volume of tissue resected nor margin status.

Background We sought to determine factors affecting time to surgery (TTS) to identify potential modifiable factors to improve timeliness of care. Methods Patients with clinical stage 0-3 breast cancer undergoing partial mastectomy in 2 clinical trials, conducted in ten centers across the US, were analyzed. No preoperative workup was mandated by the study; those receiving neoadjuvant therapy were excluded. Results The median TTS among the 583 patients in this cohort was 34 days (range: 1-289). Patient age, race, tumor palpability, and genomic subtype did not influence timeliness of care defined as TTS ≤30 days. Hispanic patients less likely to have a TTS ≤30 days ( P = .001). There was significant variation in TTS by surgeon ( P < .001); those practicing in an academic center more likely to have TTS ≤30 days than those in a community setting (55.1% vs 19.3%, P < .001). Patients who had a preoperative ultrasound had a similar TTS to those who did not (TTS ≤30 days 41.9% vs 51.9%, respectively, P = .109), but those who had a preoperative MRI had a significantly increased TTS (TTS ≤30 days 25.0% vs 50.9%, P < .001). On multivariate analysis, patient ethnicity was no longer significantly associated with TTS ≤30 ( P = .150). Rather, use of MRI (OR: .438; 95% CI: .287-.668, P < .001) and community practice type (OR: .324; 95% CI: .194-.541, P < .001) remained independent predictors of lower likelihood of TTS ≤30 days. Conclusions Preoperative MRI significantly increases time to surgery; surgeons should consider this in deciding on its use.

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