Despite being critical to models of coordinated care, the relationship and communication between primary care providers (PCPs) and cancer specialists throughout the cancer continuum is poorly understood. Using pre-defined search terms, we conducted a systematic review of the literature in three databases to examine the relationship and communication between PCPs and cancer specialists. Among 301 articles identified, 35 met all inclusion criteria and were reviewed in-depth. We integrated findings from qualitative, quantitative, and disaggregated mixed methods studies using meta-synthesis. Six themes were identified and incorporated into a preliminary conceptual model of the PCP-cancer specialist relationship: (1) poor and delayed communication between PCPs and cancer specialists, (2) cancer specialists’ endorsement of a specialist-based model of care, (3) PCPs’ belief that they play an important role in the cancer continuum, (4) PCPs’ willingness to participate in the cancer continuum, (5) cancer specialists’ and PCPs’ uncertainty regarding the PCP’s oncology knowledge/experience, and (6) discrepancies between PCPs and cancer specialists regarding roles. These data indicate a pervasive need for improved communication, delineation and coordination of responsibilities between PCPs and cancer specialists. Future interventions aimed at these deficiencies may improve patient and physician satisfaction and cancer care coordination.