The mechanisms involved, and possible treatment targets, in
orofacial pain due to
cancer are poorly understood. The aim of the first of this two-part series is to review the involved pathophysiological mechanisms and explore their possible roles in the orofacial region. However, there is a lack of relevant research in the trigeminal region, and we have therefore applied data accumulated from experiments on
cancer pain mechanisms in rodent spinal models. In the second part, we review the clinical presentation of
cancer-associated
orofacial pain at various stages: initial diagnosis, during
therapy (chemo-,
radiotherapy, surgery), and in the post-
therapy period. In the present article, we provide a brief outline of trigeminal functional neuro-anatomy and
pain-modulatory pathways. Tissue destruction by invasive
tumors (or
metastases) induces
inflammation and nerve damage, with attendant
acute pain. In some cases,
chronic pain, involving inflammatory and neuropathic mechanisms, may ensue. Distant, painful effects of
tumors include paraneoplastic neuropathic syndromes and effects secondary to the release of factors by the
tumor (
growth factors,
cytokines, and
enzymes). Additionally,
pain is frequent in
cancer management protocols (surgery,
chemotherapy, and
radiotherapy). Understanding the mechanisms involved in
cancer-related
orofacial pain will enhance patient management.