Presidential spokesman Tony Snow's malignant cancer has returned and spread to his liver and elsewhere in his body, shaken White House colleagues announced Tuesday. They said he told them he planned to fight the disease and return to work.

"He is not going to let this whip him, and he's upbeat," President Bush said of his press secretary. "And so my message to Tony is, 'Stay strong; a lot of people love you and care for you and will pray for you.'"

Snow, 51, had his colon removed in 2005 and underwent six months of chemotherapy after being diagnosed with colon cancer. He underwent surgery on Monday to remove a growth in his abdominal area, near the site of the original cancer.

Doctors determined the growth was cancerous and the cancer had metastasized, or spread, to the liver.

The news rocked the White House. Snow had gone into the surgery saying he felt fine, and recent blood tests and imaging scans had indicated no return of cancer. He had said he opted to remove the growth out of "aggressive sense of caution."

A former radio and TV commentator, Snow brought his star power and camera-ready charm to a beleaguered White House last May. He quickly became the public face of Bush's daily communications and has spoken openly — and emotionally — about being a cancer survivor.

He had recently reached the two-year mark of being free of cancer.

"He told me that he beat this thing before," said White House deputy press secretary Dana Perino, "and he intends to beat it again."

It is common for colon cancer patients to suffer a recurrence of cancer, particularly in the liver. Medical experts say advances in chemotherapy can allow people with the type of cancer Snow has to return to work and good health for years.

But experts declined to speculate on Snow specifically because many details of his condition are unknown. Among the unanswered questions are how far the cancer spread, how extensive the cancer in his liver is, and whether it can be surgically removed if it hasn't been already.

"This is a very treatable condition," said Dr. Allyson Ocean, a gastrointestinal oncologist at Weill Cornell Medical College. "Many patients, because of the therapies we have, are able to work and live full lives with quality while they're being treated. Anyone who looks at this as a death sentence is wrong."

Perino said Snow is feeling fine after his surgery and has pledged to fight the disease aggressively, likely with chemotherapy but perhaps with other treatments as well. He will be in the hospital recovering from the surgery, a major procedure, for about a week.

Perino broke into tears as she informed reporters Tuesday morning. She said Snow also gave her some instructions to pass on to reporters: "Tell them not to bug me." Throughout the day, lawmakers and members of the public sent good wishes to the White House.

Among them was Sen. John Edwards, a presidential candidate whose wife, Elizabeth, learned last week that her breast cancer had returned in an incurable but treatable form. Snow had publicly lauded her that day for dealing with her cancer without fear. At the time of those comments, Snow knew he was about to undergo more surgery of his own, although he did not know what the tests would show.

"Tony has been an incredible example for people living with cancer and cancer survivors," John Edwards said Tuesday.

Some 153,760 Americans will be diagnosed with colorectal cancer this year, and more than 52,000 will die of the disease.

How long they survive depends on how much of the liver is affected, and how many other parts of the body are, too.

In a small proportion of patients, the liver cancer is limited to a small enough area that it can be cut out. If surgery is not an option, doctors may try to curb the cancer's spread through the liver with radiofrequency ablation, using radiofrequency energy to blast the tumors.

Chemotherapy is a mainstay when the cancer has spread to more than one site, with the hope of controlling, even shrinking, tumors to prolong life.

It was unclear if or when Snow would return to his duties. Perino is leading the news briefings in his absence, which had been expected to be several weeks even before the discovery that his cancer had come back.

Snow and his wife, Jill, have three children, 10, 11 and 14.

"Tony Snow loves this job," Perino said. "He says it is the best job he's ever had in his life. He, in fact, has called it Communications Disneyland. And I think his intention, of course, is to come back. The president wants to have him back."