Being diagnosed with and treated for cancer is highly stressful and potentially traumatic. An extensive literature has evaluated the prevalence, predictors, and correlates of cancer-related post-traumatic stress disorder (PTSD) symptoms and diagnoses. In this qualitative review of cancer-related PTSD literature, we highlight conceptual, methodological, and diagnostic issues, and identify clinical implications and areas for future research. Cancer-related PTSD has been documented in a minority of patients with cancer and their family members, is positively associated with other indices of distress and reduced quality of life, and has several correlates and risk factors (eg, prior trauma history, pre-existing psychiatric conditions, poor social support). The literature on treatment of cancer-related PTSD is sparse. Existing literature on cancer-related PTSD has used DSM-IV-TR diagnostic criteria; the revised DSM-5 PTSD criteria have important implications for the assessment of cancer-related distress. Application of PTSD diagnosis to patients with cancer has been critiqued on conceptual and methodological grounds, and important differential diagnosis considerations should be taken into account. Psychosocial assessment of patients with cancer should include careful evaluation of pre-cancer diagnosis trauma and psychiatric history, and diagnostic interviewing should consider concurrent conditions (eg, adjustment disorder). Treatment of cancer-related PTSD should be approached with caution and be informed by existing evidence-based approaches for traumatic stress.