What is a paraneoplastic syndrome?

A paraneoplastic syndrome is a set of signs and symptoms that occur in people with a cancerous tumor. They develop when a malignant tumor releases a substance (hormone/protein) which affects a certain body system or when the body’s immune system releases a substance (antibody) meant to kill the tumor but also damages healthy body cells (autoimmune response).

Depending on which part of the body these substances affect, they can damage brain and muscle functions. In many cases, if the symptoms are recognized as a paraneoplastic syndrome early, it can help the doctor find malignant (cancerous) tumors in an early stage when they are most treatable.

How many people are affected by paraneoplastic syndromes?

Paraneoplastic syndromes develop in roughly 20% of people who have cancer. They occur most often in middle-aged people with breast, lymphatic, lung, or ovarian cancer.

What are the risk factors for paraneoplastic syndromes?

Risk factors include age, a previous cancer diagnosis or a family history of certain cancers. The types of cancer most likely to cause paraneoplastic syndromes are:

  • Breast
  • Gastric (stomach)
  • Leukemia
  • Lymphoma
  • Lung, especially small cell lung cancer
  • Ovarian
  • Pancreatic
  • Renal (kidney)

What causes paraneoplastic syndromes?

Some cancerous tumors produce chemicals which can direct certain organs in your body to work in an abnormal way. This produces signs and symptoms which would not occur in an otherwise healthy individual. If left untreated, this can lead to permanent damage of the organ system. Furthermore, your immune system can make a substance (antibody) which helps certain cells recognize tumor cells that should be killed. Sometimes the signals get crossed and these cells attack healthy tissues instead, leading to signs and symptoms not expected in a previously healthy individual.

What are the symptoms of paraneoplastic syndromes?

Symptoms of paraneoplastic syndromes vary depending on the organ systems affected. In more than half of cases, the symptoms appear before a person receives a cancer diagnosis. These syndromes' symptoms may include fever, loss of appetite and weight, and night sweats.

Less commonly, people experience other paraneoplastic syndromes, including:

  • Endocrine syndromes, which can cause:
    • High blood pressure
    • Weakness
    • Weight gain
  • Neurologic syndromes, with symptoms such as:
    • Dizziness
    • Double vision
    • Reduced reflexes, sensation, or coordination
    • Speech difficulty
    • Weakness
  • Skin syndromes, which may produce:
    • Flushing (redness)
    • Itching
    • Benign (non-cancerous) skin growths

Last reviewed by a Cleveland Clinic medical professional on 04/22/2019.


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