09/07/2012 02:14 pm ET Updated Oct 15, 2012

Arlen Specter Non-Hodgkin's Lymphoma: What Is The Former Senator's Condition?

In this June 6, 2009 file photo, Pennsylvania Sen. Arlen Specter, D-Pa., addresses the Pennsylvania Democratic State Committe
In this June 6, 2009 file photo, Pennsylvania Sen. Arlen Specter, D-Pa., addresses the Pennsylvania Democratic State Committee Meeting in Pittsburgh. Specter, Pennsylvania's longest serving U.S. Senator, is hosting a pilot episode of a public affairs show that airs Friday, Jan. 13, 2012 on Maryland Public Television. (AP Photo/Gene J. Puskar, File)

Arlen Specter, the former U.S. senator, has been diagnosed with non-Hodgkin's lymphoma, according to news reports.

Specter, 82, has already battled Hodgkin's disease in the past, and is now receiving treatments at a hospital in Philadelphia for the cancer, the Associated Press reported.

"It's another battle I intend to win," Specter wrote in a statement, as reported by the Associated Press. "I'm grateful for all the well wishes I've received."

Non-Hodgkin's lymphoma -- also known as non-Hodgkin lymphoma -- is the seventh most common cancer in the United States, according to the Leukemia and Lymphoma Society.

Survival rates for the cancer have significantly increased over the last 50 years, with about 69.5 percent of all people, of all races, surviving the cancer between 2001 and 2007, the Leukemia and Lymphoma Society reported. However, it remains the ninth most common cause of death from cancer.

There are estimated to be 70,130 new cases of the cancer this year, and 18,940 deaths, according to the National Cancer Institute.

Non-Hodgkin's lymphoma is cancer of the lymph tissue. The lymph tissue contains white blood cells called lymphocytes; in cases of non-Hodgkin's lymphoma, these lymphocytes are abnormal and grow uncontrollably, the Mayo Clinic explained. The cancer is separated into two main types of cells: B cells, which produce antibodies to boost the body's defenses; and T cells, which are responsible for directly attacking pathogens. Most of the time, non-Hodgkin's lymphoma takes form in B cells.

The cancer is also classified by grades, depending on how fast it grows -- a low grade cancer means that it grows slowly, while a high grade cancer means it grows quickly, the A.D.A.M. Medical Encyclopedia explained.

Researchers aren't sure exactly how non-Hodgkin's lymphoma is caused, but there are some factors that can increase the risk of it including certain medications, some infections (such as Epstein-Barr virus and HIV), increasing age, and possibly even some types of chemicals (like insect or weed killers), according to the Mayo Clinic.

Treatments for the cancer usually involve chemotherapy or radiation, according to the A.D.A.M. Medical Encyclopedia. However, not all cases may require treatment since the cancer can be slow-growing, the Mayo Clinic said. In these instances, watchful waiting by your doctor may be the best route to take.