Paraneoplastic syndromes are a group of rare disorders that develop in some people who have cancer. They are thought to occur when antibodies or white blood cells (also called T cells) in the immune system mistakenly attack normal cells in response to cancerous tumors (neoplasms).

Paraneoplastic syndromes can affect many parts of the body, including the nervous system (brain, spinal cord, and nerves), endocrine system, skin, blood, and joints. These disorders typically affect individuals with lung, breast, ovarian, or lymphatic cancer.

Paraneoplastic syndromes are sometimes related to myeloproliferative neoplasms (MPNs). MPNs are blood cancers that result from the body’s bone marrow making too many platelets, white blood cells, or red blood cells. Some types of MPNs have been associated with paraneoplastic syndromes as well. In fact, inflammation associated with paraneoplastic syndromes has been shown to accelerate the transition of MPNs to acute myeloid leukemia. However, solid cancers, such as small cell lung cancers, can also cause paraneoplastic syndromes.

What Are Paraneoplastic Syndromes?

Paraneoplastic syndromes are a group of disorders that are caused by an abnormal immune system response to cancerous tumors. There are many types of paraneoplastic syndromes, but their causes are relatively similar. In general, paraneoplastic syndromes are caused by the body’s immune system attacking itself. They are the result of an autoimmune response to cancer.

Paraneoplastic syndromes are not thought to be caused by the treatment of MPNs or other cancers. They are caused by the cancer itself. When your body fights against MPNs or cancer, it creates antibodies to destroy the tumor, but these antibodies can turn against your own body.

How Prevalent Are Paraneoplastic Syndromes?

According to the Cleveland Clinic, paraneoplastic syndromes develop in approximately 20 percent of people who have cancer. They occur most often in middle-aged people who have lung, ovarian, breast, or lymphatic cancer.

Are Certain Types of MPNs Associated With a Higher Risk for Paraneoplastic Syndromes?

Unfortunately, due to the rarity of these conditions, there is little information about which MPNs are associated with a higher risk of paraneoplastic syndromes. The most common MPN associated with paraneoplastic syndromes may be chronic myeloid leukemia.

In general, the most common cancers associated with paraneoplastic syndromes include:

• Lung cancer, especially small cell lung cancer
• Liver cancer
• Kidney cancer
• Leukemia
• Lymphoma
• Neural cancer
• Pancreatic cancer
• Stomach cancer
• Ovarian tumors
• Breast tumors

Symptoms of Paraneoplastic Syndromes

There are many symptoms associated with paraneoplastic syndromes. These symptoms can include fever, night sweats, weight loss, and loss of appetite. Less common symptoms include:

• High blood pressure
• Dizziness
• Difficulty with speech
• Weakness
• Weight gain
• Double vision
• Loss of coordination or sensation
• Slower reflexes
• Flushing (redness) of the skin
• Benign (non-cancerous) skin growths
• Itching

Examples of Paraneoplastic Syndromes

Paraneoplastic disorders of the nervous system (brain, spinal cord, and nerves) include:

• Lambert-Eaton myasthenic syndrome — A disorder of motor neurons and muscles that starts in the arms and legs and leads to progressive muscle weakness
• Stiff-person syndrome — A disorder characterized by muscle rigidity and spasms with heightened sensitivity to things like noise and touch
• Encephalitis — Inflammation of the brain and spinal cord
• Myasthenia gravis — A condition in which antibodies destroy communication between muscles and nerves
• Cerebellar degeneration — A condition in which brain cells in a region of the brain called the cerebellum die, affecting muscle control, speech, and balance
• Limbic or brain stem encephalitis — Inflammation of the limbic system (affecting memory, behavior, and emotion) or brain stem
• Neuromyotonia — Abnormal nerve impulses that cause continuous muscle fiber activity
• Opsoclonus — A nervous system disorder that mostly affects the eyes and causes rapid, irregular eye movements
• Sensory neuropathy — A loss of sensation throughout the body

Many other body systems can be affected. Paraneoplastic syndromes of the endocrine system include:

• Hypercalcemia — High blood calcium levels, which can cause kidney stones, bone weakness, lethargy, confusion, and stomach upset
• Syndrome of inappropriate antidiuretic hormone secretion — High vasopressin (antidiuretic) levels throughout the body, leading to water retention and reduced sodium levels in the blood
• Ectopic Cushing’s syndrome — High glucocorticoid hormone levels in the body, leading to weakness, headaches, “moon face” (a round, full face), and excessive fat around the abdomen
• Acromegaly — High growth hormone levels, which can cause abnormally large feet and hands, joint pain, and more prominent facial features
• Pulmonary carcinoid syndrome — Tumors of the lungs

Paraneoplastic disorders of the blood system include venous thromboembolism (deep vein thrombosis and pulmonary embolism) and Trousseau syndrome (a blood clotting disorder).

Joint or rheumatological paraneoplastic syndromes include hypertrophic pulmonary osteoarthropathy (clubbing of the fingers and painful, swollen joints) and inflammatory myopathies (chronic muscle inflammation and weakness).

Common skin (dermatological) symptoms of paraneoplastic syndrome include:

• Acanthosis nigricans — Darkening and thickening of the skin at creases and folds
• Dermatomyositis — Skin rash and muscle inflammation
• Leukocytoclastic vasculitis — Small blood vessel inflammation
• Paraneoplastic pemphigus — A blistering disease of the skin and mucous membranes
• Sweet’s syndrome — A fever and painful rash disorder affecting the face, neck, and arms

This list isn’t exhaustive. In fact, any symptom that occurs at sites far from a tumor or where it has spread that cannot be explained by the tumor itself can be considered a paraneoplastic syndrome.

Treatment and Prognosis of Paraneoplastic Syndromes

Effective diagnosis and treatment of paraneoplastic syndromes is important because these syndromes can affect clinical outcomes. This is, in part, because people may notice the symptoms of a paraneoplastic syndrome before they notice any symptoms from the underlying cancer. Paraneoplastic syndromes can be a clue to physicians to check the bone marrow for signs of MPNs or to look for another cancer in the body.

If someone has paraneoplastic syndromes, the syndromes can be treated in many different ways. The first is to treat the underlying cancer itself. There are many types of paraneoplastic syndrome-associated symptoms. Therefore, the treatment of the symptoms will vary depending on the body system affected.

Because these syndromes are related to inflammation and the autoimmune system, treatment options can include:

• Corticosteroids to reduce inflammation
• Intravenous immunoglobulins to boost healthy antibodies
• Immunosuppressants to help manage the immune system’s response
• Plasmapheresis to reduce the amount of antibodies in the blood
• Physical and speech therapy to help people speak and move better

Because paraneoplastic syndromes can vary from one individual to the next, the prognosis of these syndromes also varies. In some cases, symptoms can be easily managed. In other cases, they can be life-threatening. Ultimately, the presence of paraneoplastic syndromes can make the prognosis of the underlying cancer worse.

Talk With Others Who Understand

On myMPNteam, the social network for people with myeloproliferative neoplasms, more than 1,700 members come together to ask questions, give advice, and share their stories with others who understand life with MPNs.

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