Shared Identity and Patient Care: Adherence to Guideline-Recommended Biomarker Testing in Chronic Myeloid Leukemia

Disparities in adherence to guideline-recommended cancer monitoring persist, with historically disadvantaged populations receiving less frequent testing. Although primary care physicians (PCPs) play a central role in long-term cancer care, and oncologists directly oversee treatment, the influence of shared identity with either clinician type on biomarker testing adherence remains underexplored. This study examines whether patient-physician concordance in race/ethnicity and gender-specifically with PCPs and oncologists-is associated with adherence to BCR::ABL1 testing in chronic myeloid leukemia (CML).

We analyzed electronic health record data of 425 patients with CML diagnosed between 2007 and 2019, 385 PCPs, and 113 oncologists from an integrated health care system. We defined concordance by shared race/ethnicity, gender, and their combination between patients and each physician type. Biomarker testing adherence was measured as the proportion of guideline-recommended BCR::ABL1 tests completed annually. Linear mixed-effects models assessed associations, adjusting for demographic, clinical, socioeconomic, and care-seeking factors. Random intercepts for patients and physicians were included to account for individual baseline adherence levels and variability in practice patterns across both PCPs and oncologists.

Over a 7-year follow-up, patient-PCP race/ethnicity and gender concordance was associated with a 4.8 percentage point (pp) increase in biomarker testing adherence in a given year (95% CI, 1.1-8.5; P=.012), with stronger effects among historically disadvantaged patients (6.6 pp; P=.03). Gender concordance alone showed a modest association (3.5 pp; P=.04). In contrast, no statistically significant associations were found for patient-oncologist concordance across any dimension (race/ethnicity: -1.4 pp; 95% CI, -5.8 to 2.9; P=.53; gender: 0.5 pp; 95% CI, -2.5 to 3.6; P=.73; combined race/ethnicity and gender: -1.1 pp; 95% CI, -6.2 to 3.9; P=.68).

Shared identity with PCPs-but not oncologists-was associated with improved adherence to molecular monitoring guidelines in CML. In chronic cancer care within integrated health care systems, PCPs are well positioned to reinforce oncology-driven testing plans. These findings highlight the importance of fostering patient-centered relationships and promoting workforce diversity in primary care, particularly given that historically disadvantaged patients experienced the greatest gains in adherence.