Neuropathic pain in cancer.

Cancer-related neuropathic pain is common; it can be disease related or related to the acute or chronic effects of cancer treatment. For example, chemotherapy-induced peripheral neuropathy occurs in 90% of patients receiving neurotoxic chemotherapy. Cancer treatments have become more effective; patients are living longer with cancer and there are more cancer survivors. However, side-effects (particularly neuropathy) have become more problematic. The key to management of cancer-related neuropathy is a considered assessment, remembering not to miss the opportunity of reversing the cause of the pain with appropriate oncological management. An increasing range of oncological therapies are available, including radiotherapy, chemotherapy, hormonal therapy, or one of the evolving approaches (e.g. immune therapies). Patients are often elderly and with comorbidities; therefore, all treatment decisions have to be made carefully and reviewed appropriately. Cancer pain is often of mixed aetiology or, if purely neuropathic, may be one of several pains experienced by a patient. For these reasons, opioids are used more frequently in patients with cancer-related neuropathic pain. Standard guidelines for the use of anticonvulsants (e.g. pregabalin and gabapentin), antidepressants (e.g. duloxetine and tricyclics), and topical treatments (e.g. capsaicin and lidocaine) may be applicable, but there is a lack of good-quality clinical trials in cancer-related neuropathic pain. Choice is dictated not just by age, drug interactions, and comorbidities, but also by the coexistence of many symptoms in patients with cancer. Treating more than one symptom with a particular neuropathic pain agent can avoid polypharmacy.