Patient-physician sex concordance and real-world disparities in cancer treatment practices and outcomes in medical oncology

Background: Sex inequities in healthcare may be magnified in medical oncology, where patients and physicians often navigate life-limiting illnesses and intensive treatments. We examined the associations among patient-physician sex concordance, treatment practices, and cancer outcomes. Methods: This was a population-based, retrospective cohort study of adults diagnosed with stage II-IV lung or colon cancer in 2013-2020 in Alberta, Canada and referred to a medical oncologist. We classified patient-physician dyads as sex concordant (female-female, male-male) or discordant (female-male, male-female). We analyzed time-to-event data using Kaplan-Meier methods and associations with Cox and logistic regression models. Results: We identified 12,047 patients treated by 209 medical oncologists. Median overall survival (OS) was 19.6 months for concordant dyads and 21.6 for discordant (p=0.045), while median cancer-specific survival (CSS) was 24.1 and 26.1 months, respectively (p=0.27). Sex concordance was not independently associated with OS or CSS overall or in female patients. However, male stage IV patients treated by female physicians had lower OS and CSS (p=0.02). More female oncologists prescribed systemic therapy for stage II-III disease (25.8% vs. 22.6%, p=0.02), while more male oncologists prescribed for stage IV (64.7% vs. 57.9%, p<0.001). Conclusions: Cancer management and outcomes may be influenced by sex bias in specific patient-physician relationships.