Sherman Hemsley, the 74-year-old actor best known for his role as George Jefferson on "The Jeffersons," passed away last month because of a complication of lung cancer, according to news reports.

TMZ reported that, specifically, Hemsley's cause of death was a rare condition called superior vena cava syndrome.

Superior vena cava syndrome occurs when the superior vena cava -- one of the body's major veins -- is obstructed, most commonly because of a cancer or tumor. The superior vena cava is responsible for returning blood to the heart that comes from the upper part of the body, according to the National Cancer Institute.

The most common cancers that cause superior vena cava syndrome are lung cancer -- what Hemsley had -- and non-Hodgkin lymphoma, the National Cancer Institute reported. Usually, the condition is a sign of tumor spread.

The condition can also be a result of non-cancerous causes, like infection, vein inflammation, goiters, aneurysm of the aorta or blood clots, according to the A.D.A.M. Medical Encyclopedia.

Symptoms of the condition depend on how bad the blockage is in the superior vena cava, according to the Yale School of Medicine. Symptoms include problems breathing, swelling of the upper body and face, coughing and chest pain.

A number of tests such as bronchoscopy, chest X-ray, ultrasound and angiography may be used to see if there is a blockage of the superior vena cava, the National Institutes of Health reported. Treatments are meant to stop the blockage, and may include radiation or chemotherapy so that the tumor shrinks, or putting the patient on pills or steroids for swelling, according to the NIH.

TMZ reported that Hemsley was advised to undergo chemotherapy or radiation before he passed away.

Lung cancer is the most common cause of cancer death in the United States, with 158,592 people dying from the condition in 2008, according to the Centers for Disease Control and Prevention.

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