Paraneoplastic syndrome

: A group of signs and symptoms caused by a substance produced by a tumor or in reaction to a tumor. Paraneoplastic syndromes can be due to a number of causes including hormones or other biologically active products made by the tumor, blockade of the effect of a normal hormone, autoimmunity, immune-complex production, and immune suppression. A well-known paraneoplastic syndrome is the syndrome of inappropriate antidiuretic hormone (ADH) secretion, which perturbs fluid balance, results in the inability to put out dilute urine, and causes nausea, vomiting, muscle cramps, confusion, and convulsions. Inappropriate ADH secretion can occur, for example, with oat-cell lung cancer, pancreatic cancer, prostate cancer, and Hodgkin's disease, as well as a number of other disorders. By definition, a paraneoplastic syndrome is not produced by the primary tumor itself or by its metastases, nor is it caused by compression, infection, nutritional deficiency, or treatment of the tumor. "Para-" is a prefix with many meanings including resembling, beyond, and apart from. "Neoplastic" means tumoral, pertaining to a tumor. "Paraneoplastic" thus means resembling a tumor, near tumoral, apart from a tumor.

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signs or symptoms that may occur in a patient with cancer but are not due directly to local effects of the cancer cells. Removal of the cancer usually leads to resolution of the problem. An example is myasthenia gravis secondary to a tumour of the thymus.

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a symptom-complex arising in a cancer-bearing patient that cannot be explained by local or distant spread of the tumor.