Management of pain in cancer patients with depression and cognitive deterioration.

Patients with cancer are burdened with pain, ranging in prevalence from 14 to 100% in this population, and with comorbid behavioural symptoms such as depression and cognitive decline. However, the complex relationships between cancer pain, depression and cognitive decline, as well as their causes, still need to be clarified. Here, the existing literature on pain and its relationships with depression and cognitive decline in adult patients with cancer is reviewed, in order to understand the impact of pain on these interrelated symptoms, and the importance of its correct assessment and management. From the literature, it emerges that pain in cancer patients has a multidimensional phenomenology, which is the final product of a complex process involving emotional, cognitive, and sensory components. There is a substantial agreement that cancer patients with pain are at higher risk of having depression and cognitive decline. However, it is still controversial if these symptoms may fit into the same cluster, due to the paucity of studies exploring the simultaneous impact of pain on the psychological and cognitive well-being of patients with cancer, which would be consequential on their treatment and management. Finally, recent advances in immunology/oncology have provided novel insights into the pathophysiologic mechanisms supposedly underlying pain-related symptoms. Particularly, immune dysfunction may represent a common pathogenic ground of pain, depression and cognitive decline in cancer patients. In clinical practice, an appropriate assessment of pain should take into account the relationships with depression and cognitive decline, in order to develop more personalised and effective therapies for its management.