title: Can breast cancer register data on recommended adjuvant treatment be used as a proxy for actually given treatment?
abstract: OBJECTIVE
  To study agreement between recommended adjuvant treatment after primary breast cancer (BC) surgery from the clinical based National Breast Cancer Register and initiated adjuvant treatment from medical records; factors associated with agreement; and reasons for discontinuation or change of planned treatment.
  
  
  METHODS
  Included were 970 women who had undergone BC surgery, aged 20-63 years, living in Stockholm County, and literate in Swedish.
  
  
  METHODS
  Distant metastases, pre-surgical chemotherapy, and/or a previous BC diagnosis. Information on clinical tumor stage, surgical treatment, recommended adjuvant radiotherapy, chemotherapy, and endocrine therapy was obtained from the BC register. Type of initiated adjuvant treatments, if treatment plan was followed, and reasons for discontinuation were extracted from medical records.
  
  
  RESULTS
  The register had high completeness and agreement was high, 94-96%, (κ 0.801-0.908) for all types of treatment. Disagreement regarding radiotherapy and chemotherapy was associated with having ≥1 lymph node metastases and more extended axillary surgery, and for radiotherapy also more extended breast surgery. There were no such associations with age, tumor size, or invasiveness. None of these factors were associated with disagreement regarding recommended versus initiated endocrine therapy. Endocrine therapy was most often discontinued (24%), mostly due to toxicity which was also the most common reason for discontinuation of chemotherapy.
  
  
  CONCLUSIONS
  Swedish register data on recommended treatment has high validity in women aged 24-63 years, with limited BC, and demonstrates utility as a proxy for initiated treatment in this group. This is of interest since extracting data from medical records is resource demanding.
authors.affiliation: Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden; Sophiahemmet University, Box 5605, 114 86 Stockholm, Sweden. Electronic address: agneta.wennman-larsen@ki.se.
authors.forename: Agneta
authors.initials: A
authors.lastname: Wennman-Larsen
authors.affiliation: Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden; Department of Social Work, Karolinska University Hospital, 141 86 Stockholm, Sweden; Division of Social Work, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 171 77 Stockholm, Sweden.
authors.forename: Marie I
authors.initials: MI
authors.lastname: Nilsson
authors.affiliation: Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden; Red Cross University College, Teknikringen 1, 114 28 Stockholm, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Saboonchi
authors.affiliation: Division of Social Work, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, 171 77 Stockholm, Sweden.
authors.forename: Mariann
authors.initials: M
authors.lastname: Olsson
authors.affiliation: Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Alexanderson
authors.affiliation: Department of Oncology-Pathology, Karolinska Institutet, 171 77 Stockholm, Sweden; Department of Oncology, Karolinska University Hospital, 171 76 Stockholm, Sweden.
authors.forename: Tommy
authors.initials: T
authors.lastname: Fornander
authors.affiliation: Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 77 Stockholm, Sweden; Department of Breast and Endocrine Surgery, Karolinska University Hospital, 171 76 Stockholm, Sweden.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Sandelin
authors.affiliation: Division of Insurance Medicine, Department of Clinical Neuroscience, Karolinska Institutet, 171 77 Stockholm, Sweden.
authors.forename: Lena-Marie
authors.initials: LM
authors.lastname: Petersson
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000628:therapy*; D002277:Carcinoma / Q000453:epidemiology / Q000473:pathology / Q000628:therapy*; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D008408:Mastectomy; D008875:Middle Aged; D018714:Radiotherapy, Adjuvant; D012042:Registries; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: Breast cancer; Chemotherapy; Endocrine therapy; Radiotherapy; Recommended adjuvant treatment; Register data