Thanks gnawkz for post# 11746 link to the paper about various methods for measuring tumor response. Thanks Astavakra for spoon feeding me the key statement. That is gold! Good stuff.
They could simplify things by simply using the change in the number of tumor cells as the criteria. It seems they are dancing around that, very awkwardly, instead of stating that. You set different thresholds as critical thresholds. This fans out into different methods to estimate the number of cells.
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"
Choi criteria
A response is a 10% decrease in tumor size or a 15% decrease in tumor density on contrast-enhanced computed tomography scan."
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That is just horrible as a description of a criterion. Does anybody else see this? This is silly. I hope this is not really the official "Choi criteria". What matters is the number of cells. A meaningful criteria has to involve the size and the density, not one or the other, as it does here. Or you just skip talking about those things in the criteria and talk about the number of cells.
And when they say (above) "10% change in tumor size" is that length, or volume? That matters! A great deal. How you could they manage to be ambiguous in something so simple, that clearly needs to be unambiguous. That's goofy.