Using animal models to understand cancer pain in humans.

Cancer pain is not a single entity but a complex pain state involving different pain syndromes, with inflammatory, neuropathic, compressive, and ischaemic mechanisms. Current therapeutic regimens are based largely on opioids, although opioid treatment can lead to many side effects. Studies using animal models of cancer pain are aimed at understanding cancer pain and developing novel therapies. The most frequently reported models are of bone cancer pain, predominantly modelling pain associated with tumour growth within bone marrow. Here we summarise recent findings from studies using animal models of cancer pain and discuss the methodological quality of these studies.