From the BBC article, Cancer: Number One Killer listed there, "Cancer currently kills 135,000 people a year" (in an article from 2000). And from Cancer now No. 1 killer illness in United States, "In 2002, the most recent year for which information is available, 476,009 Americans under 85 died of cancer". Since cancer rates and medical interventions vary widely, these two numbers are not enough to give a good estimate about worldwide deaths.
Assuming there are 6 billion people alive now, who will most probably die in 100 years, 60 millon people must die each year. I could think of 100 causes of death among cancer, so I think about 600,000 people might die of cancer each year.
"The American Cancer Society estimates that 1,399,790 men and women (720,280 men and 679,510 women) will be diagnosed with and 564,830 men and women will die of cancer of all sites [meaning, of all cancer types] in 2006." Taken from this website on 14 March 2007.
I suppose one could take information from the US Census Bureau to establish a population base for the United States and extrapolate the American Cancer Society death-by-cancer number of the US to the death-by-cancer number of the planet for the population of the planet.