title: Pattern of ipsilateral breast tumor recurrence after breast-conserving therapy.
abstract: OBJECTIVE
  To analyze the incidence and prognostic factors of ipsilateral breast tumor recurrence (IBTR) after breast-conserving therapy (BCT) in a large, population-based, single-center study with long-term follow-up.
  
  
  METHODS
  We analyzed 3595 cases in which BCT was performed in 3824 women with stage I or II breast cancer. The incidence of IBTR was analyzed over time and was based on IBTR as first event.
  
  
  RESULTS
  The 15-year local relapse-free survival was 90.9%. The hazard estimates for IBTR showed a time course with 2 peaks, the first at approximately 5 years and the second, twice as high, at 12 years. Stratifying subjects by age and margin status showed that, for women ≤40 years old with negative margins, adjuvant systemic therapy led to a 5-fold reduced risk of recurrence compared to none, and the presence of lymph vascular space invasion (LVSI) had a 3-fold increased risk compared to its absence. For women >40 years old, the presence of LVSI (hazard ratio [HR] 2.5) and the presence of lobular carcinoma in situ in the lumpectomy specimen (HR 2.3) were the only 2 risk factors.
  
  
  CONCLUSIONS
  We demonstrated a pattern in risk of IBTR over time, with 2 peaks, first at approximately 5 years and a second, much higher peak at approximately 12 years, especially for women ≤40 years old. For women ≤40 years old with tumor-free resection margins, we noted that the absence of adjuvant systemic therapy and the presence of LVSI were independent prognostic factors of IBTR. For women >40 years old, the presence of LVSI and the presence of lobular carcinoma in situ were independent risk factors.
authors.affiliation: Department of Radiation Oncology, Medisch Spectrum Twente, Enschede, The Netherlands. Electronic address: j.jobsen@mst.nl.
authors.forename: Jan
authors.initials: J
authors.lastname: Jobsen
authors.affiliation: Department of Epidemiology, Medisch Spectrum Twente, Enschede, The Netherlands; Department of Research Methodology, Measurement, and Data Analysis, Faculty of Behavioral Science, University of Twente, Enschede, The Netherlands.
authors.forename: Job
authors.initials: J
authors.lastname: van der Palen
authors.affiliation: Laboratory for Pathology Oost Nederland, Hengelo, The Netherlands.
authors.forename: Sietske
authors.initials: S
authors.lastname: Riemersma
authors.affiliation: Department of Surgery, Ziekenhuis Groep Twente, Hengelo, The Netherlands.
authors.forename: Harald
authors.initials: H
authors.lastname: Heijmans
authors.affiliation: Department of Radiation Oncology, Medisch Spectrum Twente, Enschede, The Netherlands.
authors.forename: Francisca
authors.initials: F
authors.lastname: Ong
authors.affiliation: Department of Radiation Oncology, Leiden University Medical Centre, Leiden, The Netherlands; Radiotherapy Centre West, Medical Centre Haaglanden, The Hague, The Netherlands.
authors.forename: Henk
authors.initials: H
authors.lastname: Struikmans
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001365:Axilla; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D002278:Carcinoma in Situ / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D018275:Carcinoma, Lobular / Q000453:epidemiology* / Q000473:pathology / Q000628:therapy; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D015994:Incidence; D008197:Lymph Node Excision; D008198:Lymph Nodes / Q000473:pathology; D015412:Mastectomy, Segmental; D008875:Middle Aged; D060787:Neoplasm Grading; D009361:Neoplasm Invasiveness / Q000473:pathology; D018365:Neoplasm, Residual; D016609:Neoplasms, Second Primary / Q000453:epidemiology* / Q000473:pathology; D016016:Proportional Hazards Models; D011446:Prospective Studies; D013997:Time Factors