title: Early breast cancer with positive margins: excellent local control with an upfront brachytherapy boost.
abstract: Standard breast conservation therapy consists of lumpectomy and whole breast radiation with boost. The effectiveness of radiation in cases of positive margins is controversial. Two potential treatment-related factors are time to initiation of radiation and localization of the boost. Here, we examine long-term outcomes of positive margin cases treated with an upfront interstitial brachytherapy boost. This particular treatment arrangement may reduce those treatment-related effects on local control. Historically, a low dose interstitial implant was a common boost technique. One approach administered the boost before external beam. A review of 521 cases treated at our institution was conducted. Patients were selected for this study if they received an upfront brachytherapy boost and had close or positive margins. Forty-four breast cancers were identified. Median follow-up of survivors was 11.3 years (8.1-21.7). Implant was performed at lumpectomy (12) or axillary dissection (32). Margin statuses were: focal carcinoma at ink (37), multifocal carcinoma at ink (1), carcinoma <1 mm from ink (2), and DCIS at ink (4). Median tumor size was 1.2 cm (0.5-3.5 cm). Ten patients had nodal involvement. Total median dose was 60 Gy (58.6-65.3 Gy). Median boost dose was 15 Gy (12-20.3 Gy). Lumpectomy to boost interval was median of 3 weeks (0-10.8). No ipsilateral breast recurrences or second primaries were identified. Four developed contralateral breast cancer. Eleven are deceased, four from breast cancer-all from metastasis. 12-year Kaplan-Meier estimates were: overall survival 78 ± 7 %, cause specific survival 93 ± 4 %, and recurrence-free survival 82 ± 6 %. Univariate analysis identified nodal disease as significant for cause specific survival (log rank p = 0.005). No ipsilateral breast recurrences were found. Early administered radiation and accurate boost localization were identified as suspected treatment-related factors for local recurrence. When these two treatment-related factors are minimized, long-term local control rates do not suffer.
authors.affiliation: UNM Cancer Center, The University of New Mexico, Albuquerque, NM 87131-0001, USA. tschroeder@salud.unm.edu
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Schroeder
authors.forename: Ben
authors.initials: B
authors.lastname: Liem
authors.forename: Sagus
authors.initials: S
authors.lastname: Sampath
authors.forename: William R
authors.initials: WR
authors.lastname: Thompson
authors.forename: Janet
authors.initials: J
authors.lastname: Longhurst
authors.forename: Melanie
authors.initials: M
authors.lastname: Royce
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D001943:Breast Neoplasms / Q000401:mortality / Q000532:radiotherapy*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000401:mortality / Q000532:radiotherapy*; D003131:Combined Modality Therapy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008875:Middle Aged; D020360:Neoadjuvant Therapy; D012189:Retrospective Studies