I agree. Rates of cancer and diabetes are up. We might have better treatments than in the past, but I though I even saw graphs showing that overall cancer fatalities rates are flat - a lower percentage of people die from it, but the increase in cases mostly offsets that (depends on the specific type).
One angle is that as we find cures for other diseases, cancer rates go up because we live long enough to get cancer.
The sum of all causes of death will very likely continue to be 100%...