Cancer-associated pain is extremely common and is associated with significant physical and psychological suffering. Unfortunately,
pain associated with
cancer or its treatment is frequently under-treated, probably due to several factors, including
phobia of
opioids, under-reporting by patients, and under-diagnosis by healthcare workers. The most common etiology of
cancer pain is local
tumor invasion (primary or metastatic), involving inflammatory and neuropathic mechanisms; these have been reviewed in Part I. As malignant disease advances,
pain usually becomes more frequent and more intense. Additional expressions of orofacial
cancer pain include distant
tumor effects, involving paraneoplastic mechanisms.
Pain secondary to
cancer therapy varies with the treatment modalities used: Chemo-
radiotherapy protocols are typically associated with painful
mucositis and neurotoxicity. Surgical
therapies often result in nerve and tissue damage, leading, in the long term, to myofascial and
neuropathic pain syndromes. In the present article, 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. As a presenting symptom of orofacial
cancer, pain is often of low intensity and diagnostically unreliable. Diagnosis, treatment, and prevention of
pain in
cancer require knowledge of the presenting characteristics, factors, and mechanisms involved.