Effective communication is a requirement in the teamwork necessary for improved coordination to deliver patient-centered, value-based cancer care. Communication is particularly important when care providers are geographically distributed or work across organizations. We review organizational and teams research on communication to highlight psychological safety as a key determinant of high-quality communication within teams. We first present the concept of psychological safety, findings about its communication effects for teamwork, and factors that affect it. We focus on five factors applicable to cancer care delivery: familiarity, clinical hierarchy-related status differences, geographic dispersion, boundary spanning, and leader behavior. To illustrate how these factors facilitate or hinder psychologically safe communication and teamwork in cancer care, we review the case of a patient as she experiences the treatment-planning process for early-stage breast cancer in a community setting. Our analysis is summarized in a key principle: Teamwork in cancer care requires high-quality communication, which depends on psychological safety for all team members, clinicians and patients alike. We conclude with a discussion of the implications of psychological safety in clinical care and suggestions for future research.