Scott Alexander in Slate Star Codex:
Official statistics say we are winning the War on Cancer. Cancer incidence rates, mortality rates, and five-year-survival rates have generally been moving in the right direction over the past few decades.
More skeptical people offer an alternate narrative. Cancer incidence and mortality rates are increasing for some cancers. They are decreasing for others, but the credit goes to social factors like smoking cessation and not to medical advances. Survival rates are increasing only because cancers are getting detected earlier. Suppose a certain cancer is untreatable and will kill you in ten years. If it’s always discovered after seven years, five-year-survival-rate will be 0%. If it’s always discovered after two years, five-year-survival-rate will be 100%. Better screening can shift the percent of cases discovered after seven years vs. two years, and so shift the five-year-survival rate, but the same number of people will be dying of cancer as ever.
This post tries to figure out which narrative is more accurate.
More here.