[Broken_Hippo]

We do develop "cancer" drugs to a point. That HPV vaccine is preventing an entire group of cancers!

But cancer itself is... complicated. There are many different types with many different causes that are complicated by many different things. Breast cancer is not the same as skin cancer, and neither of these are lung cancer.

But we do, to an extent, know how to treat things to a point. Sometimes, our best efforts have only resulted in giving folks 3-6 months.

And we do cure or prevent some infectious disease. The plague and leprosy, for example, is curable. We have taken leaps and bounds with HIV/Aids - while we can't really cure it, we can give drugs to folks to stop it from being so infectious. But like cancer, "infectious disease" comes in many forms, some being vastly more complicated to "cure" than others. This is why some things, like the common cold and common influenza do not have cures. These are hard problems. And for lack of better words, we've simply not "unlocked" the secret in ways that would be good year after year.