title: Locoregional recurrence by molecular subtype after multicatheter interstitial accelerated partial breast irradiation: Results from the Pooled Registry Of Multicatheter Interstitial Sites research group.
abstract: To determine in breast tumor recurrence (IBTR) and regional nodal recurrence (RNR) rates for women treated with multicatheter interstitial accelerated partial breast irradiation.
  
  
  
  Data from five institutions were collected for patients treated from 1992 to 2013. We report outcomes of 582 breast cancers with ≥1 year of followup. Molecular subtype approximation was performed using estrogen receptor, progesterone receptor, Her2, and grade. The Kaplan-Meier method was used to calculate overall survival, IBTR, RNR, and distant recurrence rates. Univariate and multivariate Cox proportional hazard models were performed to estimate risks of IBTR and RNR.
  
  
  
  With a median followup time of 5.4 years, the 5-year IBTR rate was 4.7% overall, 3.5% for Luminal A, 4.1% for Luminal B, 5.2% for Luminal Her2, 13.3% for Her2, and 11.3% for triple-negative breast cancer. Positive surgical margins and high grade were associated with increased risk for IBTR, as was Her2 subtype in comparison with Luminal A subtype. Other individual subtypes comparisons did not show a significant difference. Analysis of Luminal A vs. all other subtypes demonstrated lower IBTR risk for Luminal A (5-year IBTR 3.5% vs. 7.3%, p = 0.02). The 5-year RNR rate was 2.1% overall, 0.3% for Luminal A, 4.6% for Luminal B, 2.6% for Luminal Her2, 34.5% for Her2, and 2.3% for triple-negative breast cancer. RNR risk was higher for women with Her2 compared to the other four subtypes and for Luminal B compared to Luminal A subtype.
  
  
  
  Molecular subtype influences IBTR and RNR rates in women treated with multicatheter interstitial accelerated partial breast irradiation.
authors.affiliation: Department of Human Oncology, University of Wisconsin, Madison, WI. Electronic address: anderson@humonc.wisc.edu.
authors.forename: Bethany M
authors.initials: BM
authors.lastname: Anderson
authors.affiliation: Department of Radiation Oncology, UCLA Health, Los Angeles, CA.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Kamrava
authors.affiliation: Department of Radiation Oncology, UCLA Health, Los Angeles, CA.
authors.forename: Pin-Chieh
authors.initials: PC
authors.lastname: Wang
authors.affiliation: Department of Radiation Oncology, William Beaumont Hospital, William Beaumont School of Medicine, Oakland University, Royal Oak, MI.
authors.forename: Peter
authors.initials: P
authors.lastname: Chen
authors.affiliation: Department of Radiation Oncology, UCLA Health, Los Angeles, CA.
authors.forename: D Jeffrey
authors.initials: DJ
authors.lastname: Demanes
authors.affiliation: Gamma West Cancer Services, Salt Lake Regional Medical Center, Salt Lake City, UT.
authors.forename: John K
authors.initials: JK
authors.lastname: Hayes
authors.affiliation: Arizona Breast Cancer Specialists, Scottsdale, AZ.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Kuske
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001918:Brachytherapy / Q000379:methods*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D008207:Lymphatic Metastasis; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000378:metabolism* / Q000473:pathology; D009367:Neoplasm Staging; D016016:Proportional Hazards Models; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D011960:Receptors, Estrogen / Q000378:metabolism; D011980:Receptors, Progesterone / Q000378:metabolism; D012042:Registries
chemical_list: D014408:Biomarkers, Tumor; D018719:Erb-b2 Receptor Tyrosine Kinases; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone; C508053:ERBB2 protein, human
keywords: Brachytherapy; Breast cancer; Molecular subtype; Multicatheter