Joost L.M. Jongen

More than half of all chronic cancer pain arises from metastases to bone, and bone cancer pain is one of the most difficult of all persistent pain states to fully control. Several tumor types including sarcomas and breast, prostate, and lung carcinomas grow in or preferentially metastasize to the skeleton where they proliferate, and induce significant bone remodeling, bone destruction, and cancer pain. Many of these tumors express the isoenzyme cycloxygenase-2 (COX-2), which is involved in the synthesis of prostaglandins. To begin to define the role COX-2 plays in driving bone cancer pain, we used an in vivo model where murine osteolytic 2472 sarcoma cells were injected and confined to the intramedullary space of the femur in male C3HHeJ mice. After tumor implantation, mice develop ongoing and movement-evoked bone cancer pain-related behaviors, extensive tumor-induced bone resorption, infiltration of the marrow space by tumor cells, and stereotypic neurochemical alterations in the spinal cord reflective of a persistent pain state. Thus, after injection of tumor cells, bone destruction is first evident at day 6, and pain-related behaviors are maximal at day 14. A selective COX-2 inhibitor was administered either acutely [NS398; 100 mg/kg, i.p.] on day 14 or chronically in chow [MF. tricyclic; 0.015%, p.o.] from day 6 to day 14 after tumor implantation. Acute administration of a selective COX-2 inhibitor attenuated both ongoing and movement-evoked bone cancer pain, whereas chronic inhibition of COX-2 significantly reduced ongoing and movement-evoked pain behaviors, and reduced tumor burden, osteoclastogenesis, and bone destruction by >50%. The present results suggest that chronic administration of a COX-2 inhibitor blocks prostaglandin synthesis at multiple sites, and may have significant clinical utility in the management of bone cancer and bone cancer pain.

BACKGROUND: Pain in Guillain-Barré syndrome (GBS) may be pronounced and is often overlooked. OBJECTIVES: To obtain detailed information about pain in GBS and its clinical variants. METHODS: This was a prospective cohort study in 156 patients with GBS (including 18 patients with Miller Fisher syndrome [MFS]). We assessed the location, type, and intensity of pain using questionnaires at standard time points during a 1-year follow-up. Pain data were compared to other clinical features and serology. RESULTS: Pain was reported in the 2 weeks preceding weakness in 36% of patients, 66% reported pain in the acute phase (first 3 weeks after inclusion), and 38% reported pain after 1 year. In the majority of patients, the intensity of pain was moderate to severe. Longitudinal analysis showed high mean pain intensity scores during the entire follow-up. Pain occurred in the whole spectrum of GBS. The mean pain intensity was predominantly high in patients with GBS (non-MFS), patients with sensory disturbances, and severely affected patients. Only during later stages of disease, severity of weakness and disability were significantly correlated with intensity of pain. CONCLUSIONS: Pain is a common and often severe symptom in the whole spectrum of GBS (including MFS, mildly affected, and pure motor patients). As it frequently occurs as the first symptom, but may even last for at least 1 year, pain in GBS requires full attention. It is likely that sensory nerve fiber involvement results in more severe pain.

Chemotherapy-induced peripheral neuropathy (CIPN) is a common major dose-limiting side effect of many chemotherapeutic agents, including platinum compounds, taxanes, vinca alkaloids, thalidomide and newer agents such as bortezomib. The incidence and degree of neuropathy depends on the type of cytotoxic drug, the duration of administration, cumulative dose and pre-existing peripheral neuropathy. Because of increasing survival rates of patients treated with neurotoxic agents, CIPN is accompanied by a significant decrease in the patient's quality of life among cancer survivors. Therefore, several neuroprotective strategies, including calcium/magnesium infusion, amifostine, gluthatione, glutamine, acetyl-L-carnitine and erythropoietin as most promising, have been investigated to decrease the neurotoxicity without compromising anti-tumour efficacy. However, clinical evidence for the efficacy of these drugs is sparse. In this review we will give an outline of the neurotoxic effects of chemotherapeutic agents, their clinical manifestations and potential neuroprotective strategies.