While earlier detection has been beneficial, there's such a thing as too much. Really, there's balance to be struck. For instance the detection procedures themselves (even things like non-invasive imaging) aren't risk free themselves, false positives can set off a chain of events that carry their own harm, and even it's not at all uncommon to develop cancers you "die with" instead of "die from" but once they're detected you have to assume the worst - and treatment itself causes its own form of harm.