Bit misleading. Tumour-associated antigens can very easily be detected very early. Problem is, these are only associated with cancer, and provide a very high rate of false positives

They’re better used as a stepping stone for further testing, or just seeing how advanced a cancer is

That is to say, I’m assuming that’s what this is about, as i didnt rwad the article. It’s the first thing I thought of when I heard “cancer in bloodstream”, as the other options tend to be a bit more bleak