NEW YORK - Mayor Rudolph Giuliani disclosed Thursday that he has prostate cancer and acknowledged that while the disease was caught early, it could spell the end of his Senate run against Hillary Rodham Clinton.
Appearing upbeat and energetic at a City Hall news conference, Giuliani, 55, confirmed speculation that started Wednesday evening when he was seen entering a hospital and leaving three hours later.
''I was diagnosed yesterday,'' Giuliani said. ''It's a treatable form of prostate cancer. It was diagnosed at an early stage.''
The Republican mayor said he would continue his Senate run for now but would make a more definitive statement in two to three weeks after he decides on a course of treatment. He still plans campaign appearances in Saratoga and Buffalo on Friday and Saturday.
''I really need to know what the course of treatment is going to be before I can evaluate,'' he said. ''And then, after I determine that, then I will figure out does it make sense this year or doesn't it or whatever.''
Treatment of the cancer would almost certainly require as much as several weeks away from City Hall and off the campaign trail.
The first lady, who was campaigning in the upstate village of Penn Yan, spoke briefly by telephone with the mayor and wished him ''a speedy and complete recovery,'' said Clinton spokeswoman Karen Dunn.
Clinton did not even obliquely criticize Giuliani, as she has done at many of her recent campaign appearances. Aides said that given the news of the mayor's health, even a veiled political attack would have been inappropriate.
Rep. Rick Lazio, who has considered challenging Giuliani for the GOP Senate nomination, issued a statement offering his prayers and support, adding that health issues transcend politics. Through his spokesman, Lazio declined to say whether he would enter the race if Giuliani dropped out. The Senate primary is in September.
Cancer of the prostate, a gland involved in semen production, is the second most common type of cancer in American men, but early detection greatly increases the chance of successful treatment. About 179,300 men were diagnosed with the disease in 1999.
Overall, 92 percent of victims survive at least five years. According to the American Cancer Society, two-thirds of men diagnosed with the disease survive at least 10 years and half live at least 15 years.
Among those who have survived prostate cancer are former Sen. Bob Dole and New York Yankees manager Joe Torre.
Treatments include radical prostatectomy - removal of the prostate - and radiation.
Dr. William Catalona of Barnes-Jewish Hospital in St. Louis, who removed Torre's cancerous prostate last year, said that with surgery, the patient is typically in the hospital for three days.
''They're usually able to return to normal activities within a few weeks,'' he said, ''but they're anemic and it takes six to eight weeks or somewhat longer to build their blood count up.''
Asked whether Giuliani should be able to resume his mayoral schedule after that and also run for Senate, Catalona replied: ''Absolutely.''
Giuliani said he got regular prostate checkups because his father died at 73 of prostate cancer in 1981.
''It brings up very painful memories,'' said the mayor, who rarely speaks about personal matters to the media. ''And, you know, I miss my father every day of my life. And he's a very, very important reason for why I'm standing here as the mayor of New York City.''
Giuliani, who can be testy, also smiled, laughed and joked during his announcement Thursday.
Asked whether he would be nicer, he replied, ''No way.''