Paraneoplastic syndromes in patients with nasopharyngeal cancer.

Paraneoplastic syndromes (PNS) represent the clinical manifestation of the remote and indirect effects produced by tumor metabolites or other products. Paraneoplastic effects are not directly mediated by tumor invasion of normal tissue, or by the disruption of normal function of the involved organ, or by distant metastases. More than 260 cases of nasopharyngeal carcinoma (NPC) associated with PNS have been reported in the literature. These syndromes can be divided into six main groups: cutaneous or dermatologic, endocrine, hematologic, osteoarticular or rheumatologic, neurologic, and ocular. The most common dermatologic manifestation is dermatomyositis, while the syndrome of inappropriate secretion of antidiuretic hormone and occasionally Cushing's syndrome due to ectopic ACTH production are the endocrinologic manifestations. Tumor fever and leukemoid reaction, osteoarticular or rheumatic syndromes, including clubbing of the fingers and toes, sensory neuropathy and demyelinating motor polyneuropathy, and rarely optic neuritis represent the most prominent examples of the other groups of syndromes. PNS may occur before the NPC is manifest, or while it is in an occult stage, and thus the possibility of NPC should be considered in patients with these various disorders. While some PNS will respond to direct treatment, most often the PNS subsides in parallel to response of the NPC, and thus may be useful for monitoring tumor response or recurrence.