International Classification of Diseases for Oncology (ICD-O)

Sorry for the naïve question, but I am having trouble understanding where to draw the line of where things go.

For cardiology, we have heart failure under condition, but the ejection fraction, which quantifies the heart failure, is in measurement.

For ID, we have infection under condition, and often the organism, but only rarely the sensitivity (other than methicillin resistant, etc.). Sensitivity usually goes with the micro data.

If the histology worsens over time, or if the metastatic location grows over time, is that analogous to ejection fraction?

George