Your understanding as evinced by the comment above leaves me to wonder if you actually get that this is not about individual outcomes but about the overall statistics. Even if more accurate tests would turn up more true positives that still would not necessarily result in increased patient outcomes. That is why absent symptoms testing makes sense for only a very low number of cancers where early detection does improve patient outcomes significantly, typically this is vastly improved if there is knowledge about the genetical make-up of the individuals.

> absent symptoms

A positive blood test is a symptom. One which you'll miss if you don't do the blood test regularly.

And looking for symptoms (other than a blood test) is a form of testing... one with much worse accuracy (both positive and negative) than the blood test, especially in the early stages.

Just so we are using the same definitions for the words we write, here is the definition of 'symptom' in a medical context:

https://www.cancer.gov/publications/dictionaries/cancer-term...

"A physical or mental problem that a person experiences that may indicate a disease or condition. Symptoms cannot be seen and do not show up on medical tests. Some examples of symptoms are headache, fatigue, nausea, and pain."

That still sounds like a subset of medical testing to me, where you're using the patient as your test equipment and ignoring anything the patient cannot sense directly (or fails to report). Perhaps you don't call the results of medical tests "symptoms", but to me this is an insignificant distinction. Either way we're talking about an observable result of some underlying condition; only the means of observation varies. Jargon aside, this approach still means waiting until after the condition has already affected the patient's quality of life, and perhaps beyond the point where it can be treated effectively, when it could have been treated and perhaps even cured before any symptoms manifested.

That's not what symptoms are.