Imaging Factors That Influence Surgical Margins After Preoperative 125I Radioactive Seed Localization of Breast Lesions: Comparison With Wire Localization

Abstract

Objective: The objective of this study was to compare the potential influence of imaging variables on surgical margins after preoperative radioactive seed localization (RSL) and wire localization (WL) techniques.

Materials and methods: A total of 565 women with 660 breast lesions underwent RSL or WL between May 16, 2012, and May 30, 2013. Patient age, lesion type (mass, calcifications, mass with associated calcifications, other), lesion size, number of seeds or wires used, surgical margin status (close positive or negative margins), and reexcision and mastectomy rates were recorded.

Results: Of 660 lesions, 127 (19%) underwent RSL and 533 (81%) underwent WL preoperatively. Mean lesion size was 1.8 cm in the RSL group and 1.8 cm in the WL group (p = 0.35). No difference in lesion type was identified in the RSL and WL groups (p = 0.63). RSL with a single seed was used in 105 of 127 (83%) RSLs compared with WL with a single wire in 349 of 533 (65%) WLs (p = 0.0003). The number of cases with a close positive margin was similar for RSLs (26/127, 20%) and WLs (104/533, 20%) (p = 0.81). There was no difference between the RSL group and the WL group in close positive margin status (20% each, p = 0.81), reexcision rates (20% vs 16%, respectively; p = 0.36), or mastectomy rates (6% each, p = 0.96). Lesions containing calcifications were more likely to require more than one wire (odds ratio [OR], 4.44; 95% CI, 2.8-7.0) or more than one seed (OR, 7.03; 95% CI, 1.6-30.0) when compared with masses alone (p < 0.0001). Increasing lesion size and the presence of calcifications were significant predictors of positive margins, whereas the use of more than one wire or seed was not (OR, 0.9; 95% CI, 0.5-1.5) (p = 0.75).

Conclusion: Close positive margin, reexcision, and mastectomy rates remained similar in the WL group and RSL group. The presence of calcifications and increasing lesion size increased the odds of a close positive margin in both the WL and RSL groups, whereas the use of one versus more than one seed or wire did not.

Keywords: 125I seed localization; breast cancer; mammography; ultrasound-guided wire localization; wire localization.

Fig. 1

Photograph shows preloaded needle seed system used for radioactive seed localization. A = bioabsorbable glycolic lactide pellet interwoven with seed, B = 18-gauge needle, C = needle hub, D = security stopper, E = stylet.

Fig. 2

62-year-old woman with ductal carcinoma in situ (DCIS), high nuclear grade, and solid and cribriform subtype with comedonecrosis. A, Craniocaudal magnification mammogram shows calcifications (arrows) span 12- to 2-o'clock positions in superior breast. B, Craniocaudal spot mammographic view obtained during wire localization shows four Kopans localization needles used to bracket calcifications. Alphanumeric grid is used to perform localization. C, En bloc specimen radiograph shows removal of all four needles and calcifications. Additional tissue was obtained intraoperatively on basis of interpretation of margins of sliced specimen (not shown). Surgical margins were focally positive for DCIS (i.e., close positive margin). Patient underwent reexcision segmental mastectomy with negative final margins.

Fig. 3

50-year-old woman with right breast ductal carcinoma in situ, high nuclear grade, with comedonecrosis and associated microcalcifications. A, Lateromedial magnification mammogram shows calcifications (arrow) in inferior breast. B, Lateromedial mammogram confirms placement of three radioactive seeds to bracket calcifications (arrow) in posterior, inferior, and anterior directions and postbiopsy clip (arrowhead). C, En bloc specimen radiograph shows that seeds, clip (arrowhead), and residual calcifications have been removed from patient. Surgical margins were wide and negative.