What are Paraneoplastic Syndromes?

Paraneoplastic Syndromes in People with Lung Cancer

image of cancer cells in the body
What are paraneoplastic syndromes?. istockphoto.com

Definition: Paraneoplastic Syndrome

Paraneoplastic syndrome is a set of symptoms that occur as a result of a tumor being present in the body, but not secondary to the cancer itself. Paraneoplastic symptoms occur as a result of the body's immune response to a tumor, or substances secreted by tumor cells.

Paraneoplastic Syndrome in Lung Cancer

Paraneoplastic syndromes occur in around 10 percent of people with lung cancer.

They can involve virtually any body system (discussed more below) and are symptoms that are not ordinarily associated with lung cancer. Symptoms from these syndromes may be the first symptoms of a lung cancer, arising well before symptoms of the cancer itself.

Most Common Types

There are a multitude of paraneoplastic symptoms seen with lung cancer, but the 2 most common include:

  • Hypercalcemia with squamous cell carcinoma of the lungs
  • Syndrome of Inappropriate ADH (SIADH)  secretion with small cell lung cancer

Hypercalcemia as a Paraneoplastic Symptom

Hypercalcemia as a paraneoplastic syndrome occurs most commonly with squamous cell carcinoma of the lungs, a form of non-small cell lung cancer. Hypercalcemia refers to an elevated level of calcium in the blood.  Hypercalcemia with lung cancer can be caused by a combination of the cancer secreting a hormone known as parathyroid hormone protein, plus calcium that is released by the breakdown of bone due to cancer being present in the bone.

Symptoms can include thirst, muscle weakness, loss of appetite, confusion, abdominal pain, and depression. The best way to treat hypercalcemia is by treating the cancer itself, but making sure people get enough fluids is very important both for the symptoms, and because this syndrome often causes serious kidney damage.

Syndrome of Inappropriate ADH Secretion (SIADH)

SIADH occurs most commonly with small cell lung cancer, and is characterized by a low level of sodium in the blood (hyponatremia.) Symptoms can include headaches, muscle weakness, memory loss, and fatigue, but if it occurs very fast or is very severe can cause seizures and loss of consciousness. The best way to treat SIADH is to treat the cancer, and one study found that treating small cell lung cancer with chemotherapy could reduce the symptoms in up to 80 percent of people. Specific treatments for hyponatremia (low sodium) due to SIADH may include restricting water intake or using other fluids or medications.

Other Paraneoplastic Syndromes and Lung Cancer

Paraneoplastic syndromes can affect nearly any region of the body and cause many different symptoms. Some of the more common syndromes involve the brain, endocrine system, skin, kidneys, eyes, bones, and blood cells. Since these symptoms may occur before a lung cancer is diagnosed, it can be very frustrating as doctors look for the causes.

A few more examples of these syndromes that may occur in lung cancer include:

  • Cushing's syndrome - An elevated level of cortisol in the blood can cause swelling, high blood pressure, a "moon faced" appearance, and stretch marks (like women may develop in pregnancy.) 
  • Acromegaly - In this syndrome, a lung cancer may make a hormone like growth hormone, which in adults can result in the growth of the hands and feet.
  • Polymyositis/dermatomyositis - An inflammation of the skin and soft tissues may occur, especially with squamous cell lung cancer.
  • Neurological syndromes - There are several neurological syndromes that can represent paraneoplastic syndromes with lung cancer, with one example being cerebellar ataxia - inflammation of the brain resulting in lack or coordination.
  • Paraneolplastic glomerulopathy is a kidney disorder that may be present with lung cancer as a paraneoplastic syndrome.

Treatments

Paraneoplastic syndromes vary widely in their symptoms, and there may even be several causes of one of these specific syndromes, so treatment will be individual for each one. Overall, the best treatment for all of these - especially since the substances causing these symptoms is usually produced by cancer cells or by the body in reaction to cancer cells - is treating the underlying cancer. Thankfully, treatments for lung cancer - even advanced lung cancer - have improved in the last few years, and progress is being made even in the more difficult to treat cancers such as squamous cell carcinoma of the lungs and small cell lung cancer.

Sources:

Pelosof, L, and D. Gerber. Paraneoplastic syndromes: an approach to diagnosis and treatment. Mayo Clinic Proceedings. 2010. 85(9):838-54.

Kanaji, N., Watanabe, N., Kita, N. et al Paraneoplastic syndromes associated with lung cancer. World Journal of Clinical Oncology. 2014. 5(3):197-223.

Continue Reading