POSTED: 10:48 p.m. EDT, March 27, 2007

WASHINGTON (CNN) -- Doctors have removed a small, malignant growth from presidential spokesman Tony Snow's abdomen, but they determined the cancer had spread to his liver, the White House said Tuesday.

Snow, 51, told reporters during a Friday briefing that he was having the growth removed but shrugged it off as a precautionary measure.

"We have found a small growth in my lower abdomen. Blood tests are negative [for cancer]. PET scans are negative," he said. "But out of an aggressive sense of caution, I'm going to go in for surgery on Monday and have it removed."

Snow underwent surgery to have the growth -- about the size of his pinky fingertip -- removed from his pelvic area, and doctors found that his cancer had metastasized, or spread, to his liver, said Snow's deputy, Dana Perino.

Later Tuesday, President Bush said he had spoken to Snow and told him he was in the first family's prayers. Bush also said he looked forward to Snow returning as White House press secretary. (Watch Bush express optimism that Snow will bounce back )

"He is not going to let this whip him, and he's upbeat," Bush told reporters in the Rose Garden. "My attitude is we need to pray for him."

Bush added, "My message to Tony is, 'Stay strong. A lot of people love you and care for you and will pray for you.' "

News that Snow would undergo surgery came a day after Elizabeth Edwards, wife of 2008 Democratic presidential hopeful John Edwards, announced her breast cancer had returned in an incurable form. (Watch how the candidate's wife got back on the campaign trail )

Snow commended her for her bravery Friday, saying, "When you see an Elizabeth Edwards saying, 'I'm going to embrace life and I'm going to move forward,' that is a wonderful thing." (Full story)

John Edwards said Tuesday that he and Elizabeth were praying for Snow, and he returned Snow's kind words: "Tony has been an incredible example for people living with cancer and cancer survivors." (Watch how cancer and politics have made headlines recently )

Snow mulling treatment options

Snow will consult with his doctors about undergoing chemotherapy, Perino said.

Snow was treated for colon cancer in 2005, at which time his colon was removed.

Dr. Otis Brawley, an oncology professor at Emory University in Atlanta, Georgia, said that Snow may not be able to return to work if the colon cancer has spread to his liver.

The press secretary likely will have to undergo chemotherapy or a debilitating radiation treatment, and though he may be able to return to work during therapy, Brawley said that "this condition frequently is usually fatal."

Brawley said he couldn't speak directly to Snow's situation, but when colon cancer spreads to someone's liver, only about 5 percent to 10 percent of patients "do well."

"We all have to hope that there was just one lesion and the surgeon was able to get the entire lesion out. There are some people who do very well, very well meaning they can actually even be cured if there's one lesion to the liver," he said.

Brawley added, "I would be not telling the truth if I said it's likely, but it's possible to have removal of two and then do well for a very, very long period of time, perhaps years."

Snow's family history is also a concern, Brawley said. The press chief's mother died of colon cancer in 1973 when she was 38. Snow was 17 at the time.

Snow left his job at Fox News to become White House spokesman in April after doctors gave him a clean bill of health.