VI. PROGNOSIS/CLINICAL COURSE

At the end of the first month of therapy, he entered a clinical remission. Remission at this point refers to a condition in which a patient likely still has a substantial number of leukemia cells, but they can no longer be found by conventional techniques, the patient has recovered normal marrow function, and has no systemic symptoms. If treatment were to end at this point, he would most likely relapse rapidly.

Consider that a typical patient with ALL may have 100 billion lymphoblasts at diagnosis, and that induction chemotherapy can kill 99% of them. The patient would still be left with a billion lymphoblasts. Some of these are in permanent G0 state, that is they are not dividing, and they cannot re-enter the cell cycle. Most though are still capable of replication.

Later phases of therapy are in place to slowly carve the number of lymphoblasts down and consolidate the patient’s remission.

The speed of entry into remission is prognostically significant for ALL. Patients who are not in remission by the 28th day of induction chemotherapy may let go into remission, but face a much lower likelihood of remaining in remission. Those patients who have emptied their marrow of lymphoblasts and show signs of marrow recovery by day 15 of induction do better than those who do not.