Referral Network Increases Physicians' Adoption of Active Surveillance for Localized Prostate Cancer: A Cross-Sectional Study Using SEER-Medicare.

Physicians' referral networks influence the information they obtain from peers and how fast they adopt new treatment modality. This study employs a cross-sectional design. We examined how urologists' referral network connections via primary care physicians influence the adoption of active surveillance for localized prostate cancer, using SEER-Medicare data (2001-2015). We developed a referral network index to measure urologists' connections outside their practice. Multinomial logistic regression estimated the likelihood of active surveillance adoption, adjusting for patient, urologist, and market factors. Findings revealed that each standard deviation increase in a urologist's referral network index was associated with a 1.90 percentage point rise in the likelihood of adopting active surveillance, with a more pronounced effect observed post-2010. The study concludes that primary care physicians may function as critical "information hubs," accelerating the diffusion of new treatment modalities among urologists, particularly following clinical guideline updates.