Surgeon characteristics and receipt of adjuvant radiotherapy in women with breast cancer

Background Adjuvant radiotherapy following breast conservation surgery (BCS) is considered to be an indicator of quality of care for the majority of women with breast cancer, but many women do not receive adjuvant radiotherapy. We investigated the association of surgeon-related factors with receipt of adjuvant radiotherapy after BCS. Methods We used the linked Surveillance, Epidemiology and End Results (SEER)-Medicare database to identify women aged 65 years or older with stage I/II breast cancer who were diagnosed between 1991 and 2002 and underwent BCS. We collected demographic and clinical data from SEER and treatment information from Medicare claims data. The American Medical Association Masterfile was used to obtain information on surgeons' characteristics, including sex, medical school location (United States or elsewhere), and type of degree (MD or Doctorate in Osteopathic Medicine [DO]). The associations of patient (age, race, rural vs urban residence, comorbidities, marital status), tumor (hormone receptor status, grade, stage), and surgeon-related factors with receipt of adjuvant radiotherapy were analyzed using Generalized Estimating Equations to control for clustering. All statistical tests were two-sided. Results Of 29 760 women in our sample, 22 207 (75%) received radiotherapy. Patients who received adjuvant radiotherapy were younger, had fewer comorbidities, and were more likely to be white, married, from an urban area, and diagnosed in a later year compared with those who did not. They were also more likely to have a surgeon who was female (79% vs 73%), had an MD degree ( 75% vs 68%), or was US trained ( 75% vs 70%). The multivariable analysis confirmed the association of radiotherapy with having a surgeon who was female (odds ratio [OR] = 1.13; 95% confidence interval [CI] = 1.06 to 1.27), had an MD degree (OR = 1.55; 95% CI = 1.24 to 1.91), was US trained ( OR = 1.12; 95% CI = 1.01 to 1.25), or had more than 15 patients (OR = 1.18; 95% CI = 1.10 to 1.28). Conclusions Surgeon characteristics were associated with patients' receipt of adjuvant radiotherapy after BCS after controlling for patient and tumor characteristics, although the individual effect sizes were small for surgeon sex, location of training, and type of medical degree. More research is warranted to confirm the associations to determine whether they reflect surgeon behavior, patient response, or physician-patient interactions.