title: Is a higher boost dose of radiation necessary after breast-conserving therapy for patients with breast cancer with final close or positive margins?
abstract: To determine rates of loco-regional recurrence (LRR), distant failure and overall survival for patients with breast cancer treated with breast-conserving therapy (BCT) with a close or positive surgical margin (C/PM) treated with standard dose boost radiation compared with a higher boost of radiation. We retrospectively studied 1476 patients with T1-T3 invasive breast cancer treated with BCT between 1992 and 2009. Median age was 57 years. Patients were divided into three groups: Group I included 1197 patients (81 %) with negative margins who received a standard boost (median 60 Gy) total dose to the lumpectomy cavity; Group II included 116 patients (8 %) with C/PM who received a standard boost (median 60 Gy); and Group III included 163 patients (11 %) with C/PM who received a higher boost (median 68 Gy). Biological subtypes (e.g., ER, PR, HER2/neu) were available for 858 patients (58 %) and were also assessed for any relationship to LRR rate. The Kaplan-Meier, Cox-regression, and log-rank tests were used to estimate rates of LRR and the significance of risk factors. Median follow-up was 8.6 years. The overall 5- and 10-year cumulative incidences of LRR were 2.1 % (95 % CI 0.8-2.1 %) and 4.5 % (95 % CI 3.4-6.0 %), respectively. The 5- and 10-year cumulative incidences of LRR for Group I (negative margins + standard boost) were 1.9 and 4.4 %; for Group II (C/PM + standard boost) were 3.9 and 7.0 %; and for Group III (C/PM + higher boost) were 2.9 and 3.8 %, respectively. No statistically significant differences in LRR rates were found among the three groups (p = 0.4). Similar results were obtained for distant failure (p = 0.3) and overall survival (p = 0.4). On multivariate analysis, tumor grade (p = 0.03), systemic-therapy (p = 0.005), node positivity (p = 0.05), young age (p = 0.001), and biological subtype (p = 0.04) were statistically significantly associated with higher LRR. Higher boost dose and margin positivity were not significant. Our data suggest that the 10-year risk of local recurrence for patients with close or positive margins receiving a standard boost was 7 % compared to 3.8 % for those receiving a higher boost; however, this difference was not significant. A higher boost dose did not significantly improve local control, nor did margins impact LRR risk in our cohort of patients.
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 3 Building, 100 Blossom St., Boston, MA, 02114, USA.|Family Medicine Residency Program, Mercy Health, Toledo, OH, 43604, USA.
authors.forename: Betro T
authors.initials: BT
authors.lastname: Sadek
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 3 Building, 100 Blossom St., Boston, MA, 02114, USA.|Department of Dermatology, SUNY Downstate Medical Center, Brooklyn, NY, 11203, USA.
authors.forename: Gelareh
authors.initials: G
authors.lastname: Homayounfar
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 3 Building, 100 Blossom St., Boston, MA, 02114, USA.
authors.forename: Rita F
authors.initials: RF
authors.lastname: Abi Raad
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 3 Building, 100 Blossom St., Boston, MA, 02114, USA.|Statistics Section, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Niemierko
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 3 Building, 100 Blossom St., Boston, MA, 02114, USA.|Department of Internal Medicine, Marshals University, Huntington, WV, 25701, USA.
authors.forename: Mina N
authors.initials: MN
authors.lastname: Shenouda
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 3 Building, 100 Blossom St., Boston, MA, 02114, USA.|Department of Internal Medicine, University of Toledo, Toledo, OH, 43614, USA.
authors.forename: Amany R
authors.initials: AR
authors.lastname: Keruakous
authors.affiliation: Department of Surgical Oncology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, 02114, USA.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Specht
authors.affiliation: Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, Cox 3 Building, 100 Blossom St., Boston, MA, 02114, USA. ataghian@partners.org.
authors.forename: Alphonse G
authors.initials: AG
authors.lastname: Taghian
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D015412:Mastectomy, Segmental; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D009367:Neoplasm Staging; D018365:Neoplasm, Residual / Q000473:pathology / Q000532:radiotherapy* / Q000601:surgery; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human
keywords: Breast cancer; Close/positive margins; Higher radiation boost; Lumpectomy