Paraneoplastic syndromes are rare groups of symptoms that affect some people with cancer. These symptoms aren’t directly caused by the spread of cancer but by:

  • hormones and signaling molecules produced by tumors
  • a mistargeted immune system reaction that damages your nervous system

Lung cancer is the most common type of cancer connected with paraneoplastic syndromes. Although the prevalence of these conditions isn’t well known, limited evidence has found that they occur in about 10 percent of lung cancers. They’re particularly common in people with small cell lung cancer.

Continue reading to learn more about paraneoplastic syndromes and how they relate to lung cancer.

Paraneoplastic syndromes are groups of symptoms that can appear in some people with cancer. They aren’t directly caused by the spread of cancer cells. It’s thought that the two main causes are the production of hormones or other signaling molecules by cancer cells and a misdirected autoimmune response.

Damage caused to your nervous system by your immune system can far exceed the damage caused by cancer.

In a 2019 study, researchers found that lung cancer was the most common type of cancer that lead to paraneoplastic syndromes. The next most common types of cancers were breast cancer and lymphoma.

The two main categories of lung cancer are:

In a 2017 study, researchers found that paraneoplastic syndromes were nearly 5 times more common in people with NSCLC and 8 times higher in SCLC compared with the general population.

In about 60 percent of people, paraneoplastic syndrome symptoms start before cancer is diagnosed. Symptoms can develop over days to months.

Paraneoplastic syndromes are subdivided into various syndromes depending on the symptoms you experience.

Syndrome of inappropriate ADH secretion (SIADH) and hypercalcemia are the most common syndromes seen in people with lung cancer.

Paraneoplastic syndromes can cause symptoms that affect your:

  • endocrine system
  • nervous system
  • blood
  • muscles and bones
  • skin
  • other body parts

Syndromes associated with lung cancer include:


About 8 to 12 percent of people with lung cancer are thought to develop hypercalcemia or high blood calcium at some point. Symptoms can include:


SIADH is characterized by the release of antidiuretic hormone by areas that normally don’t release it, causing too much sodium to pass through your urine. The abnormal release of antidiuretic hormone is seen in 10 to 45 percent of people with SCLC and about 1 percent of people with NSCLC.

Symptoms can include:

Ectopic Cushing’s syndrome

Up to 50 percent of people with lung cancer have elevated levels of adrenocorticotropic hormone (ACTH), or ectopic Cushing’s syndrome. It’s almost always caused by SCLC or bronchial carcinoids.

Elevated levels of ACTH stimulates the production of too much cortisol, leading to symptoms such as:

  • weight gain
  • rounded face
  • increased fat around neck
  • decreased strength
  • fragile and thin skin
  • easing bruising
  • slow healing


Abnormal release of growth hormone-releasing hormone (GHRH) by cancer cells can cause acromegaly, or the overproduction of growth hormone. It’s usually caused by bronchial carcinoids or squamous cell carcinomas and, less frequently, SCLC.

Symptoms include:

  • larger and swollen hands and feet
  • larger lips, nose, and tongue
  • bone changes, such as jutting brow and lower jaw
  • thick, coarse, or oily skin
  • sweating and increased skin odor
  • deeper voice
  • skin tags
  • headache
  • joint aches
  • vision problems

Pulmonary carcinoid syndrome

Less than 5 percent of people with bronchopulmonary tumors develop pulmonary carcinoid syndrome. This syndrome is characterized by excessive serotonin release from tumor cells. This can lead to:

Limbic encephalitis

Limbic encephalitis is most associated with SCLC. It’s characterized by:

  • changes in mood or memory
  • changes in cognitive function
  • seizures

Lambert-Eaton myasthenia syndrome (LEMS)

LEMS is caused by a decrease of the neurotransmitter acetylcholine into the space between your nerves and muscles.

The primary symptom is muscle weakness, usually in the lower limbs starting from the pelvis. Weakness of the upper body is usually milder.

Subacute cerebellar degeneration

Subacute cerebellar degeneration is usually caused by SCLC. Symptoms include:

  • nausea
  • vomiting
  • vertigo
  • gait changes
  • lack of muscle control

Subacute sensory neuropathy

Subacute sensory neuropathy is a collection of neurological symptoms that start with a loss of joint sensation and loss of being able to perceive vibrations. It usually progresses within 12 weeks to impaired temperature sensation and shock-like pain.

Acanthosis nigricans

Acanthosis nigricans is the thickening and hyperpigmentation of your skin in areas where skin rubs together, such as your armpits or neck folds. Less often, people with this syndrome develop oral sores.

Hypertrophic pulmonary osteoarthropathy (HPO)

HPO causes clubbing of the fingers and toes and painful joints and bones on both sides. It’s most often associated with lung cancer.

Inflammatory myopathies

Myopathies are conditions that affect your ability to control your muscles. They’re associated with painless muscle weakness. One type called dermatomyositis is associated with:

  • a purple rash
  • purple raised areas of skin on the backs of your hands
  • light sensitivity (less common)


Hypercoagulability is the tendency for blood clots to form. A form called venous thromboembolism forms in 3 percent of people with lung cancer. People with lung cancer are 20 times more likely to develop venous thromboembolism than somebody in the general population.

Nephrotic syndrome

Nephrotic syndrome is a group of symptoms that indicate your kidneys aren’t functioning properly. The most common form of this syndrome in people with lung cancer is membranous glomerulopathy, which manifests as:

Older people are generally at a higher risk of paraneoplastic syndromes. They can be associated with any type of cancer but are most common in people with:

Since the trigger for paraneoplastic syndromes is cancer, first-line treatment centers around treating existing tumors. Remission often follows surgical removal of the tumor.

Other treatment options include:

It’s not known how to prevent paraneoplastic syndromes but taking general steps to avoid cancer can minimize your risk.

Cigarette smoking is the top risk factor for the development of lung cancer and is linked to up to 90 percent of lung cancer deaths.

If you suspect you may have a neoplastic syndrome, it’s important to seek immediate medical attention.

For some people, developing symptoms of a paraneoplastic syndrome indicates undiagnosed cancer or a returning cancer after remission.

Paraneoplastic syndromes are groups of symptoms that can develop in people with cancer. They’re not caused by the cancer itself but by a misdirected response to the cancer by your immune system and the release of hormones and signaling molecules from cancer cells.

Lung cancer is the most common type of cancer associated with paraneoplastic syndrome. Often, symptoms begin before cancer diagnosis.

If you think you may have a paraneoplastic syndrome, it’s critical to see your doctor. While the presence of a paraneoplastic syndrome doesn’t mean you have cancer, your doctor can screen you and determine next steps.