Updated: 3:37 p.m.

Sen. Frank Lautenberg (D-N.J.) has been diagnosed with lymphoma of the stomach and will undergo chemotherapy over the next few months, according to a statement released by his office Friday.

“We expect a full and complete recovery for Senator Lautenberg,” Dr. James Holland, Lautenberg’s physician, said in the statement, which detailed a treatment regimen that will include chemotherapy every three weeks at Mount Sinai Medical Center in New York.

Lautenberg, 86, was taken by ambulance to the hospital Monday after falling at his Cliffside, N.J., home, and he underwent surgery for a bleeding ulcer earlier in the week.

Lautenberg, who was elected to a fifth term in 2008, is not expected to return to work this week and will miss the Senate’s Monday evening procedural vote on the first in a series of jobs bills. But colleagues expect Lautenberg to periodically return to Washington to cast votes as he battles cancer.

“Frank Lautenberg is my friend and partner in the Senate, and if there’s one thing I know about him, it’s that he is New Jersey tough,” Lautenberg’s home-state colleague Sen. Bob Menendez (D) said in a statement Friday. “Between his strength and his doctor’s statements, I am confident that he won’t miss a beat in continuing his crucial work in the Senate.”

Aides maintain that Lautenberg will continue to serve and not step down from office. If Lautenberg were to retire midterm, New Jersey law states that Republican Gov. Chris Christie could select a replacement or call for a special election.

“I’m encouraged by the positive statements of his doctors, and I am confident that Frank will be back in the Senate fighting for New Jersey soon,” Senate Majority Leader Harry Reid (D-Nev.) said in a statement. “I wish him and his family all the best as he recovers.”