A paraneoplastic syndrome is a rare condition that is instigated by an alteration in your immune system response to a neoplasm. Neoplasm is a cancerous tumor. It is seen as a clinical syndrome in patients with cancer, involving nonmetastatic systemic effects. In other words, a paraneoplastic syndrome is a symptom attributed to by substance is produced by the tumor that occurs remotely from the tumor itself. Some of the symptoms may be endocrine, neuromuscular or musculoskeletal, cardiovascular, cutaneous, hematologic, gastrointestinal, renal, or miscellaneous in nature. Paraneoplastic disorders are more common in middle-aged to older people as well as in individuals with lung, ovarian, lymphatic, or breast cancer as well as other various cancers. 
How Common Is Paraneoplastic Syndrome Or Is It A Rare Disease?
Many cancer patients usually exhibit signs of central nervous system involvement. Paraneoplastic syndromes are often the first or most prominent manifestation of cancer. So, when a patient without a discovered cancer presents any particular paraneoplastic syndrome, it is vital that a diagnosis of cancer should be considered and investigated.
As earlier mentioned, paraneoplastic syndromes are more common in middle-aged to older people. The median age of the onset of these syndromes is 65 years. As per American studies, female patients seem to be more prone compared to men, even when cases of gender-specific tumors such as breast, ovary, prostate, and testes are not considered. Generally speaking, paraneoplastic syndromes are quite rare, and only about 0.01% of cancer patients are likely to develop any of the conditions.
Nevertheless, some malignancies are more likely to be associated with paraneoplastic syndromes. For example, about 30% of patients with thymoma have some form of neurological autoimmunity, mostly myasthenia gravis, and small-cell carcinomas, mostly arising in the lungs, is linked to one or more paraneoplastic syndromes in up to 3% of cases. On the other hand, there are those malignancies with a less likelihood of involvement with paraneoplastic syndromes. They include; non-small-cell lung, renal, uterine, and melanotic skin cancers.
Adding to that, approximately 10% of patients with plasma cell disorders, and accompanied by malignant monoclonal gammopathies are affected by a paraneoplastic peripheral neuropathy. For patients with the rare form of myeloma, i.e. osteosclerotic myeloma, more than half of them develop a severe predominantly motor paraneoplastic peripheral neuropathy. The incidence of paraneoplastic syndromes in hematological tumors is very low, except in cases of Hodgkin’s disease, of which are below 1%. Myasthenia gravis and Lamberton-Eaton myasthenic syndrome (LEMS) is the most common paraneoplastic syndromes in individuals with solid tumors. Myasthenia gravis occurs in 15% of individuals with thymoma whereas LEMS occurs in 3% of individuals with small cell lung cancer. For other forms of solid tumors, the incidences of paraneoplastic syndromes are below 1%.
The Manifestation Of Paraneoplastic Syndromes
Paraneoplastic syndromes are usually neurological, thus affect the nervous system, including the brain, spinal cord, nerves and/or muscles. Paraneoplastic is a word, in this case, that means that the neurological implication, in patients with cancer is not caused by the tumor itself, but by the immunological response triggered by the undiscovered tumor.
The pathophysiology behind paraneoplastic syndromes is linked to how the body’s normal immunological system interprets the tumor that is as an invasion. Therefore, your immune system triggers the antibodies and lymphocytes to fight against the tumor. When this occurs, your own immune system can turn against healthy normal cells, causing collateral damage to the nervous system, which can sometimes be severe. For many patients, the immune response can result in greater nervous system damage than that done to the tumor. While some of the effects of paraneoplastic syndromes can remit entirely, some of them can also be permanent effects.
Paraneoplastic syndromes are rare disorders that often occur in patients with cancer. They are usually an indication of an underlying tumor that is undiscovered and needs to be diagnosed. Although paraneoplastic syndromes are common in cancer patients, it does not necessarily mean that all cancer patients are susceptible to the ailments. As a matter of fact, less than 1% of patients with tumors have paraneoplastic syndromes, but some forms of cancers have a higher likelihood of development of these disorders.
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