Paraneoplastic Syndromes Health Article

Definition

Paraneoplastic syndromes (PS) are rare disorders triggered by the immune system's response to cancer cells, or by remote effects of tumor-derived factors. These syndromes are believed to occur when cancer-fighting anti-bodies or white blood cells, known as T-cells, mistakenly attack normal body cells. These disorders typically affect middle-aged to older people and are most common in patients with lung, ovarian, lymphatic, or breast cancer.

Description

Paraneoplastic syndromes are defined as clinical syndromes involving non-cancerous effects in the body that accompany malignant disease, and can affect any part of the nervous system from the cerebral cortex to peripheral nerves and muscles. In a broad sense, these syndromes are collections of symptoms that result from substances produced by the tumor, occurring far away from the tumor itself. When a tumor arises, the body may produce antibodies to fight it, by binding to and helping in the destruction of tumor cells. Unfortunately, in some cases, these antibodies cross-react with normal tissues and destroy them, which may stimulate the onset of PS. However, not all PS are associated with such antibodies.

Neurological symptoms generally develop over a period of days to weeks, and usually occur prior to the discovery of cancer, which can complicate diagnosis. In these cases, additional information should raise the possibility that the patient may have a hidden cancer and that neurological symptoms could be paraneoplastic. Symptoms include fatigue, weakness, muscular pain in upper arms, difficulty walking, burning, numbness or tingling sensations in the limbs (peripheral paresthesia), dry mouth, sexual function difficulty, and drooping eyelids.

Neurological signs may include dementia with or without brain stem signs, rapid and irregular eye movements, and ophthalmoplegia (weakness or paralysis in muscles that move the eye). Paraneoplastic syndromes involving the nervous system include: Lambert-Eaton myasthenic syndrome (LEMS), stiff person syndrome (SPS), encephalomyelitis (inflammation of the brain and spinal cord), myasthenia gravis (MG), cerebellar degeneration (CD), limbic and/or brain stem encephalitis, neuromyotonia, opsoclonus myoclonus (OM), and sensory neuropathy.

Demographics

Most paraneoplastic syndromes are rare, affecting less than 1% of persons with cancer. Exceptions include LEMS, which affects about 3% of patients with small-cell lung cancer; MG, which affects about 15% of persons with thymoma; and demyelinating peripheral neuropathy, which affects about 50% of patients with the rare osteosclerotic form of plasmacytoma. No race, age, or sex preference has been reported.