Leptomeningeal carcinomatosis: Valerie Harper's diagnosis explained

Valerie Harper – of “The Mary Tyler Moore Show” and “Rhoda” fame – recently told People Magazine she was diagnosed with a terminal type of brain cancer known as leptomeningeal carcinomatosis.

One doctor said this is possibly a result of Harper’s lung cancer, which she battled in 2009.

“Five percent of cancer patients have this specific complication of cancer,” Dr. Isabelle Germano, professor of neurosurgery and director of the brain tumor program at Mt. Sinai Medical Center in New York City, told FoxNews.com.

Germano, who has not treated the 73-year-old actress, said while some cancer becomes metastatic in patients – spreading from one organ to another in the form of a bulk – this type of metastatic disease is different.

“The cancer went into the fluid that is surrounding the brain and the spine, and that condition is called leptomeningeal carcinomatosis,” Germano said. “It’s different than metastatic cancer, where the cells that are parting from the original cancer in the lungs; they are like little seeds, specks of dust floating in the fluid.”

The brain and spine are sheltered from the rest of the body by membranes known as meninges, which are essentially wrappings. The lepto meninges, which is the thinnest and closest to the brain, is where the particles are floating.

While typical metastases can be surgically cut out of an organ, there are millions and millions of cells floating around these membranes – and there’s no way to remove them all, Germano said. This makes the disease more serious.

Chemotherapy and radiation are used as treatments to prolong the patients’ life, and Germano added there is a lot of research being conducted on new drugs.  According to her, it is possible that one of those drugs could be more successful.

Germano said each patients’ symptoms will vary, but patients with this type of brain cancer may experience headaches, difficulty moving their eyes or mouth, trouble swallowing or a change in mental status.

Harper’s doctors have reportedly given the actress three months to live, which Germano said is “not too far off from realistic.”