Background: Cancer is the leading cause of death in US prisons. Incarcerated patients with cancer have 92% higher 5-year mortality than the general population with cancer, but little is known about how to improve cancer screening, diagnosis and treatment in this high-risk population. Methods: We conducted interviews with state prison medical directors and primary care clinicians, and medical, radiation and gynecologic oncologists who coordinate or provide cancer care for individuals incarcerated in prison. Participants were recruited via 1) email invitation to participants at a correctional health conference, 2) purposeful sampling using targeted emails to clinicians in prison systems selected for diversity in size, geography and correctional health model (e.g., contracted care), and 3) snowball sampling of individuals from research and participant networks. Participants were interviewed about 1) logistics of cancer care delivery from screening and treatment through end-of-life care, 2) barriers and facilitators to cancer care delivery, and 3) evidence-based strategies to facilitate cancer care in prisons, including best practices. Interview transcripts were analyzed using mixed inductive/deductive thematic content analysis to identify emerging themes. Results: 34 participants from 16 prison systems were interviewed (10 medical directors, 6 PCPs, 14 oncologists, 4 other). Participants reported prison clinicians coordinate most cancer care (e.g., screening, diagnosis and symptom management), while cancer treatment largely occurs in community or academic facilities outside of prison. Common barriers identified included underscreening / delays in diagnosis, complex logistical coordination, poor communication (between patients and oncologists, and prison clinicians and oncologists), inadequate symptom management, dehumanizing practices, loss-to-follow-up after release and that patients often come from marginalized populations. Common facilitators were better access to insurance, cancer screening, and general medical and cancer care than incarcerated patients might receive before/after incarceration. Participants identified multiple ways to improve cancer screening (creating enforceable standards, increasing continuing medical education, implementing electronic medical record reminders, reducing logistical barriers), cancer treatment (implementing navigators within prisons and cancer centers, prioritizing care with oncologist input, keeping care in prisons, decarceration), and transitions to the community (Medicaid activation prior to release, community partnerships to facilitate care transitions). Conclusions: Incarceration imposes multiple barriers to cancer care delivery, but clinicians identified numerous tools to improve cancer care in prison. Future studies should test and optimize these strategies to improve cancer outcomes for incarcerated patients.