An attribute unique to cancer is manifested in every survival curve
and absent in other chronic diseases While cancer survival is concave upward,
non cancer survival is concave downward.

Since Upward concavity is associated with a hazard rate decline, each
cancer survival curve has two unique attributes:
Upward concavity .and declining hazard rate.
An observed survival curve is composed of two hazard rates:

1. Hazard caused by cancer, h[cancer]
2. Hazard caused by coexisting diseases in the patient, h[co-morbidity]

h[observed] = h[cancer] + h[co-morbidity]

Since h[co-morbidity] rises and h[observed] declines h [cancer] declines

A simple rule distinguishes between cancer and non cancer survival:
If [h’[t] < 0] it is cancer
If [h’[t] > 0] it is not a cancer
h’[t] is hazard rate derivative.
Cancer is more than just a tumor. It is an interaction between organism and tumor.