The pharmacological management of cancer pain. Part 1: The role of non opioid and adjuvant drugs.

The incidence of pain among 5,410 patients at various stages of the disease was 51%, whereas among 9,007 patients with advanced metastatic or at terminal phase of cancer was 74% [1]. Furthermore, published data show that among advanced cancer patients with pain, the symptom is moderate to severe in about 40%-50% and very severe or excruciating in 25%30% [2-4] and that most advanced-cancer patients have two or more types and/or etiologies of cancerrelated pain [3-8]. One-third of adults and children with metastatic cancer report pain that interferes with and reduces their activity level and requires the use of analgesics [9]. The frequency of chronic cancer pain is related to the initial cancer site and varies from 85% (bone) to 5% (leukemia) [4]. Foley [4] found that among 143 cancer in patients referred for pain therapy, the pain was due to cancer in 78% and to cancer therapy in 19%. The nociceptive stimulus may be somatic (e.g., metastatic to bone, pleura involvement), visceral (e.g., distended bowel proximal to obstruction) or neuropathic as a result of aberrant processes in the peripheral or central nervous system that result from injury to neural pathways. Some of these neuropathic pains are due to deafferentation and may result from rumor infiltration of nerves (e.g., brachial plexopathy due to Pancoast's tumor) or surgical intervention (e.g., phantom limb pain). Table 1 summarizes various cancer-related pain syndromes. Assessment of cancer pain is essential in evaluating the current status of the patient, the pain and its impact on the patient as well as the efficacy of pain therapy over time. Different types of pain evaluation are available, as per the review by Chapman and Syrjala [10] and other papers [11-13]. Table 1. Pain syndromes in cancer patients.