“We’ve never had blood tests that detect pancreatic cancer early, therefore we should never use them because when we used other means to try to detect early, it didn’t lead to better outcomes.”
If you can detect colon, kidney pancreatic or liver cancer early, you might be able to do surgery or develop treatments at the stage 1 stage. Right now we don’t have anything except MRIs and CT scans that are too hard and expensive to do frequently. And if you are diagnose with pancreatic cancer it’s usually so late that you will basically die in weeks.
You’re basically saying “give up. Even if we detect early you all die anyway” which is frankly stupid. You’re discounting the possibility that early detection by means of a blood test adds whole new layers of possibilities to fight those particularly dangerous cancers.