Occurrence of cancer pain

Occurrence of cancer pain is highly variable and incom-pletely understood. Surveys are not population-based, are characterized by small heterogeneous samples, and provide sketchy data on etiology of pain, pain syndromes, and clin-ical or demographic factors. Moreover, the multiple dimen-sions of pain have not been thoroughly elucidated. Cancer-related pain is caused by the following: 1) direct tumor involvement, 2) diagnostic/therapeutic procedures, and 3) side effects or toxicities of treatment. Individuals may have more than one type of cancer-related pain simultaneously. Occurrence rates range from 14 % to 100%, and between 33 and 50 % of patients experience pain at some point in the cancer trajectory. Rates are higher (e.g., 70%–100%) in palliative care or pain management settings. Few research-ers have focused solely on specific causes of pain in specifi