CURE?

Linda contends with the cat from hell!

The latest Fred Hutch magazine has an interesting, but not very clarifying, discussion of what the word “cure” means in oncology.  The article infers that it is a statistical concept, but then fails to clarify.  That may be deliberate; real statistics would either drive us away or bore us to death.  I remember asking Linda’s oncologist about the possibility of a complete cure.  He did a verbal version of a soft-shoe Shuffle off to Buffalo dance routine and introduced the concept of “chronic disease” (see http://ljb-quiltcutie.blogspot.com/2016/08/a-new-approach.html).   I was so ignorant that I thought I’d received an answer!

Well, this Fred Hutch article provides a definition of “cure” that seems logical to me.  You are “cured” when your disease has disappeared and you are no more likely to see it flare up again than the general population is to get it in the first place.  That makes sense to me, although in practice it might be very hard to apply.  Here is a glossary of onco-speak from the article:

If the doctor says                                                            He/she means

Stable disease                                                                 Tumor constant in size or severity

Partial remission                                                             Tumor getting smaller and/or less virulent

Complete remission                                                        Tumor gone.  No evidence of disease

Cure                                                                                 No trace of tumor – which won’t come back*

For my money, the best way to judge how far out of the woods you are is to use a Kaplan-Meier curve based on plentiful data.  Such a plot illustrates the probability that someone with a given disease will be alive at various times after diagnosis.  (I wish to hell that I could draw – and post – an example, but I don’t know how. )  Anyway, plot the probability of being alive on the Y-axis and time on the X-axis,  The curve will fall off toward increased time, and (hopefully) flatten out eventually.  For a nasty bastard like pancreatic cancer it drops rapidly, then flattens near zero; for something like prostate cancer it falls off much less precipitously and begins to flatten out at a much higher probability.  Got that?  Well, never mind, just remember this:  if you have a disease and find that you plot on the near-horizontal part of the curve, for all reasonable purposes you can consider yourself cured

You can get the graph you need by going to the following:  

http://seer.cancer.gov/faststats/selections.php?  And fiddling around for awhile.

As an example, pancreatic cancer victims are “cured” by this definition at 12-15 years, but at that time only about 5% of them are alive.  OVCA patients are considerably more lucky.

*Don’t use this definition.  Use the one in the text, above.