As a matter of fact Sue's myeloma almost certainly will come back. The Leukemia and Lymphoma Society has an informational article about Myeloma on its Fighting Blood Cancers website. They don't talk about curing myeloma. Rather, they say that "the goals of treatment for myeloma are to: (a) slow the growth of the myeloma cells; (b)help patients who have bone pain, fatigue or other problems from their disease to feel better; and (c) provide long periods of remission (when there are no signs of myeloma and/or the myeloma is not causing health problems).
The LLS website defines "remission" as follows:
Remission. No sign of disease
Complete remission or response. No sign of M protein in the blood and urine. Normal percentage of plasma cells or no sign of myeloma cells in marrow
Partial remission or response. More than a 50 percent decrease in M protein in the blood.
Complete molecular remission or response. No sign of myeloma cells in the marrow using very sensitive tests.
Dr. Wolf put a little perspective on the complete remission diagnosis by saying it really just means there is currently no measurable amount of cancer in Sue (that is to say, it is not measurable with the instruments and techniques currently available). But there is still cancer there. If Sue had a trillion cancer cells before her (now completed) first four courses of chemotherapy, hypothetically she could still have a billion active cancer cells and nonetheless be declared to be in "complete remission."
The point of the stem cell transplant procedure (the super toxic chemotherapy part of it) is to kill as many of those remaining cancer cells as possible. The idea is to extend the time the patient spends in remission before having a relapse. Mathematically speaking, when the cancer cells start multiplying again, you want to start the inevitable exponential multiplication (exponential growth) with the lowest possible number.
Today I mentally equated multiple myeloma cancer to felons (the worst kind of felons, like child molesters, rapists, wanton killers, etc.). Think of a billion Charlie Mansons running around inside your blood. Think of society as the body, and prison as the bone marrow. The felons are recidivists. You know if you let them out they're going to wreak havoc, cause pain and dislocation and death. The last thing you want to do is let them multiply and run loose. You don't want even one paroled into your neighborhood, let alone a whole bunch of them. With apologies to my pacifist Mennonite friends, you know the best thing to do would be to kill them all. Sooner than later.
On a more personal note, we (you and me both) can equate myeloma cancer to sin. Say we had four courses of absolution from our trillion sins and are declared to be in "complete remission" from sin. Still, we know that there's a billion sins left in us, and somewhere down the road we are going to relapse. Then what are we going to do? Give up? Declare ourselves hopelessly immoral? No. We are going back for more absolution. Try to get them sin puppies back in remission.
Reconciling the necessary killing of the felons on the one hand and our own multiple absolution petitions on the other will be a topic for another day. We can only go so far with these analagies. The rotten apple has to be removed from the bushel. The cancer has to be killed.