Paraneoplastic syndrome is a collective term that denotes the disorders that develop due to the action of substances secreted by cancer cells. Here is a brief overview about the same.
According to statistics, around 8% of cancer patients develop paraneoplastic syndromes, that are rare disorders caused by substances secreted by the malignant tumor. In fact, the term encompasses a group of disorders that affect different organ systems. It has been observed that, these disorders are mostly associated with breast cancer, small cell lung cancer, blood cancer, gastric cancer, pancreatic cancer, and gynecologic malignancy.
Usually, these syndromes affect the endocrine, neurologic, dermatologic, rheumatologic, and hematologic systems. The symptoms may vary with the organ system that is affected. So, diagnosis of paraneoplastic syndrome is really difficult. Usually, these syndromes are diagnosed after the cancer is detected. In some cases, studying these symptoms may lead to diagnosis of the underlying cancer.
What Causes Paraneoplastic Syndrome?
The symptoms of paraneoplastic syndromes cannot be linked to the malignant tumor directly. In other words, the symptoms are not caused by the tumor itself. According to recent studies, cancerous tumors release certain substances, like hormones and peptides, that affect other organ systems and cause these syndromes. This explains conditions, like endocrine paraneoplastic syndromes.
The secretions of the tumor may disturb the immune system, which attacks normal body cells, mistaking them for cancer cells. For example, malignant tumors contain certain proteins that are like neuronal antigens in the nervous system. The immune system attacks the tumor as well as the nervous system, leading to damage of the latter. This leads to neurologic paraneoplastic syndromes. In short, these syndromes are caused by the action of secretions from cancerous tumors.
Types of Paraneoplastic Syndromes
As mentioned above, a cancerous growth in the body produces certain substances that can affect the organ systems. The type of underlying cancer and the nature of symptoms may vary from one patient to another. Given below are some of the common paraneoplastic syndromes.
Endocrine paraneoplastic syndrome includes conditions, like hypercalcemia, SIADH (syndrome of inappropriate antidiuretic hormone secretion), Cushing syndrome, carcinoid syndrome, hypoglycemia, etc.
When the secretions of the tumor affect the nervous system, the following conditions can be caused. They include limbic encephalitis, paraneoplastic cerebellar degeneration, myasthenia gravis, autonomic neuropathy, Lambert-Eaton myasthenia syndrome, and subacute (peripheral) sensory neuropathy.
Dermatologic and Rheumatologic Conditions
While the conditions relating to the skin include acanthosis nigricans, erythroderma, sweet syndrome, paraneoplastic pemphigus, leukocytoclastic vasculitis, pyoderma gangrenosum, necrolytic migratory erythema, and dermatomyositis; some of the common rheumatologic problems caused by cancerous tumors are hypertrophic osteoarthropathy and polymyalgia rheumatica.
As compared to other paraneoplastic conditions, hematological ones are rare, and are usually seen in those with advanced stages of cancer. Such conditions include eosinophilia, thrombocytosis, granulocytosis, nonbacterial thrombotic endocarditis, polycythemia, pure red cell aplasia, etc.
So there are different types of paraneoplastic syndromes. The symptoms may vary according to the condition. Those with dermatologic syndromes develop problems of the skin. For example, those with acanthosis nigricans may develop hyperpigmentation, along with a velvety texture. The condition is found to be more severe, when it develops in a cancer patient. When the eye and the retina are affected; conditions, like optic neuropathy, cancer-associated retinopathy, etc., develop.
In most cases, treatment for the underlying cancer is found to be effective for relieving these syndromes. Immunosuppression is another method of treating these conditions, as it reduces autoimmune response. This is mainly effective for neurologic, rheumatologic and hematologic neoplastic syndromes. For endocrine conditions, treatment is provided to correct the hormonal and electrolyte balance. The symptoms associated with some types of paraneoplastic disorders can be alleviated with plasmapheresis, a process that cleanses antibodies from the blood.
Disclaimer: This article is for informational purposes only, and should not be used as a replacement for expert medical advice. Visiting your physician is the safest way to diagnose and treat any health condition.