House Rep. Joaquin Castro underwent surgery Monday to remove tumors from his gastrointestinal tract, he said.

Castro, who represents Texas' 20th Congressional District, said in a statement that the tumors, which doctors discovered last summer in a series of tests, were small and slow-growing and did not present any symptoms.

"My prognosis is good," he said. "I expect to be home recovering in Texas for several weeks before returning to Washington to continue my work on behalf of the people of my hometown, San Antonio."

"Thank you to the doctors, nurses, and medical staff at MD Anderson Cancer Center and the University of Texas Health Science Center San Antonio for their care and treatment, and thank you to my family for their love and support," he said.

Gastrointestinal neuroendocrine tumors are a type of cancer that forms in the gastrointestinal tract, which includes the colon, rectum, stomach and small intestine, according to the National Cancer Institute.

The GI tract is part of the body's digestive system, and is responsible for digesting food, absorbing nutrients from food and excreting waste.