title: Physician's peer exposure and the adoption of a new cancer treatment modality.
abstract: BACKGROUND
  New technologies, often with limited evidence to support their effectiveness, frequently diffuse into clinical practice and increase the costs of cancer care. The authors studied whether physician peer exposure was associated with the subsequent adoption of a new approach to adjuvant radiotherapy (brachytherapy) for the treatment of women with early-stage breast cancer.
  
  
  METHODS
  A retrospective cohort study was performed using Surveillance, Epidemiology, and End Results (SEER)-Medicare data. Data from 2003 through 2004 were used to classify surgeons as early brachytherapy adopters and, among non-early adopters, whether they shared patients with early adopters (peer exposure). Data from 2005 through 2006 were used to examine whether women were more likely to receive brachytherapy if their surgeons were exposed to early adopters.
  
  
  RESULTS
  Overall, the percentage of women receiving brachytherapy increased from 3.2% in 2003 through 2004 to 4.7% in 2005 through 2006. In this latter period, a total of 2087 patients were assigned to 328 non-early adopting surgeons. In unadjusted analyses, patients whose surgeons were connected to early adopters during 2003 through 2004 were found to be significantly more likely to receive brachytherapy in 2005 through 2006 compared with those whose surgeons were not connected to early adopters (8.0% vs 4.1%; P = .003). In adjusted analyses, the predicted probability of receiving brachytherapy among patients whose surgeon did have an early-adopting peer was 3.9% versus 1.0% among those whose surgeons did not have an early-adopting peer (P = .03).
  
  
  CONCLUSIONS
  Exposure to peers who were early adopters of brachytherapy was found to be associated with a surgeon's subsequent uptake of brachytherapy. The results of the current study provide an example of a novel approach to examining the diffusion of innovation in cancer care.
authors.affiliation: Department of Medicine, Johns Hopkins School of Medicine, Baltimore, Maryland.|Departments of Epidemiology and Health Policy and Management, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland.
authors.forename: Craig Evan
authors.initials: CE
authors.lastname: Pollack
authors.affiliation: Cancer Outcomes, Public Policy and Effectiveness Research (COPPER) Center, Yale Cancer Center, Yale School of Medicine, New Haven, Connecticut.|Section of General Internal Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut.
authors.forename: Pamela R
authors.initials: PR
authors.lastname: Soulos
authors.affiliation: Cancer Outcomes, Public Policy and Effectiveness Research (COPPER) Center, Yale Cancer Center, Yale School of Medicine, New Haven, Connecticut.|Section of General Internal Medicine, Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut.
authors.forename: Cary P
authors.initials: CP
authors.lastname: Gross
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001918:Brachytherapy; D001943:Breast Neoplasms / Q000628:therapy*; D015331:Cohort Studies; D005260:Female; D006801:Humans; D016015:Logistic Models; D015412:Mastectomy, Segmental; D010820:Physicians; D012189:Retrospective Studies
keywords: brachytherapy; breast cancer; diffusion of innovation; physician patient-sharing networks