Neuropathic Caner Pain: Is It Linked to the Recurrence of Cancer?

This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http:// creativecommons.org/licenses/by-nc/3.0/), which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. Cancer is a significant public health problem in every country. The World Health Organization reported that there were 14.1 million new cancer cases, 8.2 million cancer deaths, and 32.6 million people living with cancer (within 5 years of diagnosis) worldwide in 2012 [1]. The number of cancer survivors will increase due to improvement in cancer screening, advancement of cancer treatment, and the aging of the population [2,3]. Pain is a common symptom in cancer survivors [4]. In a systemic review [5], the reported incidence of pain was 33% to 64%. About one-third of the patients with pain presented their pain as moderate to severe. They may have acute and chronic pain related to direct tumor involvement , diagnostic or therapeutic procedures, or adverse effects of cancer treatment. They may also experience pain unrelated to cancer. Cancer pain can be classified predominant type of pain: either nociceptive or neuropathic. In clinical situation, cancer pain patients commonly experience more than one type of pain. They may represent both nociceptive and neuropathic features, rather than distinct elements of a single process. Neuropathic pain is defined as " pain arising as a direct consequence of a lesion or disease affecting the somato-sensory system " [6]. Neuropathic cancer pain (NCP) is common and can be caused by direct tumor damage or as a consequence of cancer-directed therapy. In a recent systemic review, the prevalence of patients with NCP ranged from 19%-39.1%, including mixed pain as well as pure neuropathic pain. And, the causes of neuropathic cancer pain were cancer itself (64%), treatment of cancer (20.3%), related to cancer (3.5%), unrelated to the cancer (10.2%), and unknown origin (2%) [7]. Clinical characteristics of NCP include spontaneous burning, stabbing, or lancinating characteristics, hyperalgesia, and allodynia. Whatever the etiology of NCP is, it definitely arises from changes initiating in the damaged nerves, which in turn alter spinal cord and brain function, leading to altered plasticity at a number of sites [8]. The management of NCP may be therapeutically challenging. The pharmacotherapy, using combination of drugs with different mechanisms of action is a main therapeutic strategy. However, multimodal treatment, employing pharmacological therapy, non-pharmacological techniques, and psychological support, may be required to improve the …