Importance: Realizing the benefits of cancer screening requires testing of eligible individuals and processes to ensure follow-up of abnormal results.
Objective: To test interventions to improve timely follow-up of overdue abnormal breast, cervical, colorectal, and lung cancer screening results.
Design, Setting, And Participants: Pragmatic, cluster randomized clinical trial conducted at 44 primary care practices within 3 health networks in the US enrolling patients with at least 1 abnormal cancer screening test result not yet followed up between August 24, 2020, and December 13, 2021.