PHILADELPHIA (AP) — Former Sen. Arlen Specter, who has already survived two bouts of Hodgkin's disease, is now battling non-Hodgkin's lymphoma, according to his son's law firm.

A statement released Friday said Specter, 82, had been released from a Philadelphia hospital but was expected to return there for additional treatment.

Specter said in a statement last week that he was again fighting cancer.

"It's another battle I intend to win," Specter wrote. "I'm grateful for all the well wishes I've received."

Specter, who was Pennsylvania's longest-serving senator before losing a primary in 2010, has overcome Hodgkin's disease, a cancer of the lymphatic system, twice since 2005. He also has survived a brain tumor and cardiac arrest after bypass surgery.

Non-Hodgkin's lymphoma is a broad description for a number of blood cancers primarily affecting white blood cells in the lymph tissue. It can be treated with radiation or chemotherapy.

Specter's 30-year Senate career ended after he switched from the Republican Party to the Democratic Party and lost the subsequent primary, and Pennsylvania voters elected conservative Republican Pat Toomey, then a congressman, to replace him.