How many cancers are cured?

One can often read in the lay press that 50% of cancers can be cured. Knowing the frequency and the relative 5-year survival rate for each cancer site, one can estimate the probability of cure. This estimation is presented for cancers diagnosed in 1975, using 5-year survival rates for cancers diagnosed in the period 1978-1985. The 5-year survival probability after a diagnosis of cancer is 37%. The statement that 50% of cancers are cured is too optimistic, and is not based on reliable data. One can nevertheless hope to achieve a 50% cure rate in the beginning of the xxi-st century.