Abstract S3-08: Radioactive seed localization versus wire guided localization of nonpalpable invasive and in situ breast cancer: A Danish multicenter randomized controlled trial

Abstract

Background: The current standard method for locating nonpalpable breast lesions is wire guided localization (WGL) despite several methodological difficulties. Radioactive Seed Localization (RSL) has been developed to reduce these difficulties. The aim of this randomized trial was to compare the rate of positive resection margins between RSL and WGL in patients with nonpalpable invasive breast cancer (IBC) or ductal carcinoma in situ (DCIS). Material and Methods: Patients with nonpalpable IBC or DCIS visible on ultrasound were randomized to either of the two localization methods. Primary outcome was margin status at the final pathological evaluation. According to Danish standard in the study period margins were defined positive if cancer cells were found < 2mm from the inked margin. Secondary outcomes were duration of the surgical procedure, weight of the excised specimen and patient's pain perception. χ2-test, Fisher's exact test and Wilcoxon rank-sum test, respectively, were used to test differences between groups. Level of statistical significance was set to 5%. The average activity of seeds used in the trial was 1.70 MBq (range 0.7-3.27). Results: 413 cases representing 409 patients were randomized; 207 were allocated to RSL and 206 to WGL. 23 cases, who did not meet inclusion criteria, chose to withdraw, or had a change in surgical management, were excluded. The remaining 390 were included in the analysis. Patient, surgical and pathological characteristics between the two groups were alike, except for significantly more patients with DCIS in the WGL group (5.1% vs 0.5%). Significantly more cases in the WGL group (9.7%) needed additional localization compared to the RSL group (2.1%) (p=0.0014). In all cases but one in the RSL group, the index lesion was removed. Margins were positive in 23 cases (11.8%) in the RSL group compared to 26 cases (13.3%) in the WGL group. We were not able to detect a difference in margin status between the two groups (p=0.65). For IBC only, the number of positive margins was 22 (11.3%) in the RSL group and 21 (11.4%) in the WGL group (p=0.997). There was no difference between the two groups in the amount of tissue removed whether the analysis was done on the primary excision (p=0.18) or the total weight including intraoperative re-excisions (p=0.33). There was no difference in pain perception between the two groups whether patients who received local anesthesia were kept in the analysis (p=0.28) or excluded (p=0.91). Local anesthesia was used more frequently in the RSL group. Finally, there was no difference in the duration of the surgical procedure (p=0.12), the complication rate (p=0.89) or the identification rate for SN (p=1.0). Conclusions: We were not able to detect any differences considering positive margins, patient's pain perception or duration of the surgical procedure between the two localization methods. However, RSL offers a major logistic advantage, as the seed localization can be done several days before surgery without any risk or discomfort for the patient, with a low proportion of patients needing additional localization. So the RSL procedure has now been found preferable at our institutions. Citation Format: Langhans L, Tvedskov TF, Klausen TL, Jensen M-B, Talman M-L, Vejborg I, Benian C, Roslind A, Hermansen J, Oturai PS, Bentzon N, Kroman N. Radioactive seed localization versus wire guided localization of nonpalpable invasive and in situ breast cancer: A Danish multicenter randomized controlled trial [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr S3-08.