A diagnosis of cancer is one of the most distressing events in life. It changes the course of everyday life and causes an existential crisis. This makes some clinicians think that depression is a normal reaction to a diagnosis of cancer. However, the body of evidence suggests that not all people diagnosed with cancer develop depression, but patients with cancer have an increased rate of depression. This presentation will try to combine the latest data on depression and cancer, including the mechanisms underlying depression in these patients and the impact of psychiatric diagnosis on the outcome of cancer. We will then focus on the implications of these data on the diagnosis and management of depression in the clinical setting.