When you talk to your doctor about treatment for chronic myelogenous leukemia (CML), you may hear him say that your goal is to get into remission. If you're like most folks, you've got a general idea of what the term means, but you may be fuzzy on the details. For CML, also called chronic myeloid leukemia, there are some concrete milestones that you need to reach.
"We try to be very, very specific in CML because most patients hear the term 'remission' and they feel the cancer is gone," says Gail J. Roboz, MD, director of the Leukemia Program at Weill Cornell Medical College in New York City. "But actually in CML there are specific categories of remission."
Your doctor will use blood test results to figure out which one you're in. He'll refer to these different groups as "responses."
Complete hematologic response. It means your blood cell count is back to normal and tests don't show any abnormal white blood cells. Also, if your spleen was swollen, it's now at its original size.
Complete cytogenetic response. You've reached this milestone when your blood or bone marrow -- the inside of your bone where blood cells are made -- no longer has any cells with the "Philadelphia" chromosome. That's the one that carries a gene called "BCR-ABL," which plays a role in the process that creates abnormal white blood cells.
Major molecular response. The amount of BCR-ABL gene in your blood is low.
"The most important milestone we've derived with the new treatments is the major molecular response," says Michael J. Mauro, MD, of Memorial Sloan Kettering Cancer Center in New York City. "That's when the leukemia is 1,000 times smaller than when we started. It's a significant enough remission where the odds of the leukemia growing again or transforming into an advanced phase are dramatically lower."
Complete molecular response. Your doctor will say you're in this category when the BCR-ABL gene doesn't show up in your blood.
Mauro says patients generally achieve blood remission in a few weeks and cytogenetic remission in a few months. Doctors look for major molecular remission within the first year or two, and research is under way to see if it's OK to stop treatment after you've been in it for a period of time.