Purpose: We sought to determine whether physician-level characteristics were associated with 21-gene recurrence score (RS) genomic testing to evaluate recurrence risk and benefit of adjuvant chemotherapy in patients with estrogen receptor-positive, node-negative breast cancer.
Methods: Retrospective cohort study of a nationally representative sample of Medicare beneficiaries using Surveillance, Epidemiology, and End Results program-Medicare data linked with the American Medical Association physician master file. The main outcome was receipt of genomic testing within 1 year of diagnosis as a function of physician-level factors.
Results: A total of 24,463 patients met the study criteria; they received care from 3172 surgeons and 2475 medical oncologists. Of 4124 tests ordered, 70% were ordered by a medical oncologist and 16% by a surgeon. In multivariable regression models, multiple variables were associated with receipt of testing, including having a medical oncologist (odds ratio [OR] 2.77; 95% CI 2.00-3.82), a surgeon specializing in surgical oncology (OR 1.20; 95% CI 1.09-1.31), and a female medical oncologist (OR 1.10; 95% CI 1.02-1.20). Having a medical oncologist with 5 or more years in practice was associated with lower odds of testing (OR 0.83; 95% CI 0.76-0.92). Surgical procedures performed at academic centers were associated with higher odds of testing (OR 1.11; 95% CI 1.02-1.20).
Conclusions: Although most RS testing was ordered by medical oncologists, physicians in other specialties ordered roughly one-third of the tests. Physician characteristics, including gender and time in practice, were associated with receiving testing, creating opportunities for targeting interventions to help patients receive optimal care.
Keywords: Adjuvant; Biomarkers; Breast neoplasms; Chemotherapy; Gene expression profiling; Genetic testing; Physicians’; Practice patterns; SEER program; Tumor.