title: Breast-conserving therapy versus mastectomy in T1-2N2 stage breast cancer: a population-based study on 10-year overall, relative, and distant metastasis-free survival in 3071 patients.
abstract: Our previous study demonstrated breast-conserving surgery with radiation therapy (BCT) to be at least equivalent to mastectomy in T1-2N0-1 breast cancer. Yet, 10-year survival rates after BCT and mastectomy with radiation therapy (MAST) in T1-2N2 breast cancer specifically have not been examined. Our study aimed to determine 10-year overall (OS), relative (RS), and distant metastasis-free survival (DMFS) in T1-2N2 breast cancer after BCT and MAST, stratified for T category.
  
  
  
  All women diagnosed with primary invasive T1-2N2 breast cancer in 2000-2004, treated with BCT or MAST, both with axillary dissection and RT, were selected from the Netherlands Cancer Registry. Ten-year OS and DMFS were estimated using multivariable Cox regression. Excess mortality ratios (EMR) were calculated to estimate RS, using life tables of the general population. OS and RS were determined on the whole cohort, and DMFS on the 2003 cohort with completed follow-up. Missing data were imputed.
  
  
  
  Of 3071 patients, 1055 (34.4 %) received BCT and 2016 (65.7 %) MAST. BCT and MAST showed equal 10-year OS and RS. After stratification, BCT was significantly associated with improved 10-year OS [HRadjusted0.82 (95 % CI 0.71-0.96)] and RS (EMRadjusted0.81 (95 % CI 0.67-0.97]) in T2N2, but not in T1N2. Ten-year DMFS was equal for both treatments [HRadjusted0.87 (95 % CI 0.64-1.18)] in the 2003 cohort (n = 594), which was representative for the full cohort.
  
  
  
  BCT showed at least equal 10-year OS, RS, and DMFS compared to MAST. These results confirm that BCT is a good treatment option in T1-2N2 breast cancer.
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation, P.O. Box 19079, 3501 DB, Utrecht, The Netherlands. M.vanMaaren@iknl.nl.
authors.forename: M C
authors.initials: MC
authors.lastname: van Maaren
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation, P.O. Box 19079, 3501 DB, Utrecht, The Netherlands.
authors.forename: L
authors.initials: L
authors.lastname: de Munck
authors.affiliation: Department of Radiation Oncology, Medical Spectrum Twente, P.O. Box 50000, 7500 KA, Enschede, The Netherlands.
authors.forename: J J
authors.initials: JJ
authors.lastname: Jobsen
authors.affiliation: Department of Radiation Oncology, Radboud University Medical Center, P.O. Box 9101, 6500 HB, Nijmegen, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Poortmans
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, University of Groningen, P.O. Box 30001, 9700 RB, Groningen, The Netherlands.
authors.forename: G H
authors.initials: GH
authors.lastname: de Bock
authors.affiliation: Department of Research, Netherlands Comprehensive Cancer Organisation, P.O. Box 19079, 3501 DB, Utrecht, The Netherlands.|Department of Health Technology & Services Research, MIRA Institute for Biomedical Technology and Technical Medicine, University of Twente, P.O. Box 217, 7500 AE, Enschede, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Siesling
authors.affiliation: Department of Surgical Oncology, Canisius Wilhelmina Hospital, P.O. Box 9015, 6500 GS, Nijmegen, The Netherlands.
authors.forename: L J A
authors.initials: LJA
authors.lastname: Strobbe
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000453:epidemiology / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008408:Mastectomy / Q000379:methods; D015412:Mastectomy, Segmental / Q000379:methods; D008875:Middle Aged; D060787:Neoplasm Grading; D009367:Neoplasm Staging; D009426:Netherlands / Q000453:epidemiology; D011159:Population Surveillance; D012042:Registries; D016019:Survival Analysis; D016896:Treatment Outcome; D055815:Young Adult
keywords: Breast cancer; Breast-conserving surgery; Distant metastasis-free survival; Mastectomy; Overall survival; Radiation therapy; Relative survival