Cancer pain syndromes and pharmacotherapy of cancer pain

Cancer-related pain afflicts some 9 million people worldwide annually. Pain is usually a direct result of tumor in 75%-80% of patients; it is caused by anticancer treatments in 15%-19% of patients and is unrelated to cancer and its treatments in 3%-5%. This coincidental pain is related to debility, decubitus (nociceptive) and post-herpetic neuralgia (neuropathic-peripheral and central). Pain is also caused by diagnostic procedure used in cancer treatment. Numerous distinct cancer pain syndromes have been recognized and described (1-3).