But his statement caused an instant controversy as medical experts disputed his statistics and declared his comparison unfair.
In fact, the numbers are wrong.
According to the National Cancer Institute, the five-year survival rate in the U.S. actually is above 99 percent. In the United Kingdom, it's nearly 75 percent, according to their Office for National Statistics.
Giuliani's campaign defends the numbers it used from City Journal, a quarterly magazine funded by the Manhattan Institute, a conservative think tank in New York.
"The bottom line is, the mayor is illustrating a point that you are essentially better off in the U.S. system than the European system,'' said campaign spokesman Elliott Bundy. "You are better off in a system of competition and choice rather than a government-mandated health care system."
Cancer experts say there are two big problems with the City Journal article. For one thing, the numbers quoted in the story are an extrapolation of statistics from the Commonwealth Fund, a foundation that supports health policy research, and that group says its numbers were misused in the City Journal article.
The Commonwealth Fund issued a statement saying that its study of incidence of cancer and mortality rates should not be used to compute survivability rates.
"The numbers basically aren't right," said fund president Karen Davis.
But a gap still exists in the five-year survival rate between the U.S. and the UK. Even if Giuliani's numbers are wrong, could his point still be right?
No, according to cancer experts.
The difference between the two countries comes down to a matter of medical philosophy, experts said.
U.S. officials believe in aggressive testing to find early cases of prostate cancer, while some cancer experts say that since that many cases of prostate cancer develop late enough in life that patients are likely to die of something else, screening everyone for cancer isn't worth the difficulties those treatments can cause.
U.S. men are more than twice as likely to be diagnosed with prostate cancer as men in the U.K. because they are more likely to be screened for the disease. That artificially inflates the survival rate, since many of the U.S. men treated would never have developed symptoms of disease.
A more accurate comparison would be to look at mortality rates, said prostate cancer epidemiologist Lorelei Mucci, an assistant professor at Harvard Medical School and Harvard School of Public Health. In the U.S., about 15.8 of every 100,000 men die of prostate cancer, while in the U.K., the figure is 17.9 deaths.
"They're essentially quite similar," she said.
The statistics Giuliani uses are wrong. The Giuliani campaign insists that it's making a legitimate point about the merits of health care in the U.S. over Britain, but the statistics that say the chances of surviving prostate is higher in America also say the chances of having it are higher in the U.S., too.
We find his statement false.