US Presidents Do Not Die From Cancer...Are They Concealing A Cure?

With all of the medical advancements that have been made, why is it that we have not seen a cure for cancer?  I was wondering if we really have not made that discovery yet OR has it been kept secret for the power players of the world.  Looking back at the deaths of every US president I found that only one had died from the disease and that was in 1885.  The 19th president Ulysses S. Grant succumbed to carcinoma of the tongue and tonsils eight years after his presidency. 

Seeing that everyone seems to have had a family member, friend, or acquaintance pass due to cancer my mind wanders to the possibility of government withholding a cure.  The population is being sustained at this time in the United States with areas of severe poverty.  Is the government allowing the massive numbers of deaths due to cancer to continue as a form of population control?  Not much aid comes from the US government to abolish poverty in their country.  Allowing one disease with high mortality rates to continue maybe keeps the budget and population down for a country known for not taking care of their own first.  War, oil, and charity in other countries appear to be a larger concern than their own backyard.

Or, maybe we are not there yet with fighting cancer.  I am lead to believe there is no cure for cancer.  However, believing and knowing are two completely different things.