I was introduced to a concept this week referred to as "Fallacy of misplaced concreteness". According to Wikipedia:
According to Alfred North Whitehead, one commits the fallacy of misplaced concreteness when one mistakes an abstract belief, opinion, or concept about the way things are for a physical or "concrete" reality: "There is an error; but it is merely the accidental error of mistaking the abstract for the concrete. It is an example of what I will call the 'Fallacy of Misplaced Concreteness.'"This has substantial implications in the practice of medicine, especially in terms of diagnostic concepts and diagnostic tools. Let's say a patient has some sort of discrete and observable finding such as a growth on the skin or a subtle finding on an imaging study. These represent concrete findings in that there is something observable. That lesion may undergo biopsy which might reveal some other morphological observations. The lump on the skin may reveal it's structure as being a cyst or a solid mass of cells. A lesion seen on mammography similarly may consist of a cyst or a collection of cells. These are concrete findings.
However, almost invariably, the pathologist who examines the tissue goes beyond simply describing the findings under the microscope and goes on the apply some sort of label. The label represents an abstract concept which implies a host of properties and future behavior (or risk of future behavior). The physical reality is still the lump or cyst which represents the current "concrete" reality. The diagnosis is not a concrete thing but instead is prediction of what future reality might be.
There are times where the current reality is not simply some subtle clinical and microscopic finding and the label used by a pathologist is more concrete. A patient may present with hemoptysis and found to have a large lung mass on chest x-ray. Further evaluation may show multiple nodules of the bone and biopsy shows features diagnostic of lung cancer. The abstract concept of a malignant tumor diagnosed by the pathologist aligns with the concrete current reality of multiple invasive tumors.
I guess my point is cancer is characterized by a concrete functional impact of malignant biological behavior. This can only really be defined by the behavior itself. All other markers are surrogates. We have gradually and falsely substituted morphological observations, many increasingly subtle, as a substitute for biological behavior in defining disease. The problem is we have started using the same terms, previous reserved for something very concrete (disease states previous characterized by concrete illness and morbidity and very high risk of death), but use them to describe states without overt illness. There is nothing concrete about the so-called illnesses of people who by almost all measures are symptom free and whose disease states fail to progress.