ET (“Evil” twin) used “leukemia” as a generic term for a blood/bone marrow cancer. Leukemia is (I guess) a bone marrow cancer causing abnormal production of white blood cells. ET’s bone marrow is producing abnormal red blood cells. Since the repeated tests are not showing a worsening of the problem, her doctor is going to wait 3 months before doing more tests.
So, the waiting continues. Waiting is better than the test results getting worse.