Tuesday, May 24, 2011

Go FISH



Tomorrow I receive the results of my FISH test. It is the first test to see if I am in remission. So when I say, "Go fish," I don't actually mean "Grab a pole and some bait," although that's exactly what I intend to do the first chance I get. What I mean is: "Go FISH Go! Be negative for the cancerous cells."

At this stage, a few cancerous cells in my blood is okay. The purpose of Phase Two of treatment is to wipe out any bone marrow cells still producing cancerous descendants that the first round of chemo missed. A lot of cancerous cells, which would be evident in the FISH test, would be a bad thing. Last Friday, the oncologist explained the next steps if I am not in remission. Hearing it once was enough. There's no point in thinking about it today because it's not going to happen.

I am approaching the test result as simply getting proof that I am in remission, instead of viewing it as a diagnostic tool with two possible outcomes.

That said, am I nervous? Yes. Why else last night would I have eaten seven of Jackie's oatmeal chocolate chip cookies, each the size of my palm. (They are delicious, but normally I would have stopped at four.)

I am comforted by the oncologist's prediction last Friday. He said that my blood test numbers at the time of diagnosis placed me in the Low Risk category of the three risk categories for AML APL (M3) Leukemia, and APL has the highest cure rate (9 out of 10) for those who survive the first month out of all the types of leukemia. He has had a very high success rate with his patients. Given my risk category, blood counts now, and that I survived the hardest period- that first month- he's confident this first test should show I'm in remission. I'm putting my money on the professional's opinion.

Once I get my favorable test result, I'll be on track for Phase Two of the treatment to begin June 6th. Going forward, I will periodically be tested to see if I'm still in remission with a PCR test. This is a more accurate test, for which the result needs to show ZERO cancerous cells (a single cancerous cell could multiply into a problem). Each of these tests will be one step closer to reaching "Cured" status.

If any of the tests, including this first one, come back with a positive result, I will have to have another bone marrow biopsy to confirm the presence of the bad bone marrow cells. This was my least favorite experience during my hospital stay. On the bright side, I made the four doctors/residents in the room laugh during it. I don't want to make the squeamish squirm, so won't give detail, but the procedure hurt, and the sound of the instrument made it worse. I was holding Ryan's hand and trying to maintain a controlled breathing pattern. To do so, I asked Ryan to begin counting for me. He began with one, and instead of  starting back at one when he reached ten or twenty, he kept going. As the doctor worked, I heard him mention needing a third sample. Meanwhile, Ryan had reached 63. I snapped, "Ryan, we do not need to know how LONG this is taking. Count to ten and repeat." The doctors laughed at this. Normally, I would feel proud of myself for making the room laugh. Instead, I worried the distraction would add a few seconds to the length of the procedure.

As silly as this sounds, I want the FISH test and the periodic PCR tests to show I am in remission as much so I can avoid another bone marrow biopsy as for the remission status itself. It is easier to allow myself to fear something small than to fear something big.

In Conclusion, Go FISH Go!
Praying for a good result tomorrow.


*** Below is a side note, and an opportunity for me to throw around some big words. Also a good time for anyone not interested in science to surf on over to http://www.espn.com/ or http://www.perezhilton.com/.

 - How APL develops: Chromosomes 15 and 17 swap material in a developing marrow cell.



The abnormal marrow cell produces a leukemic cell, which multiplies into 11 billion more cells.  These cells, called "leukemic blasts," do not function normally. They grow and survive better than normal cells and block the production of normal cells. Thus, given that one cancerous cell can multiple into 11 billion more, all of my PCR tests in the future need to show zero leukemic cells in order for me to be considered in complete molecular remission.

Since the leukemic blood cells originated from the abnormal marrow cell, they also have the swapped 15 and 17 chromosome material. Thus the two test described below can detect the abnormality from a blood sample.

- FISH stands for "fluorescent in situ hybridization." In the test, DNA probes tagged with flourescent molecules that emit light of different wavelengths (and different colors) are bound to the targeted chromosomes within the blood cells. The chromosomes thus flouresce in color. By using different colors, the scientist can tell if the two chromosomes (15 &17) have traded genetic material. Basically, if the scientist use a green marker for chromosome 15 green and and a red marker for chromosome 17, there should be no red on chromosome 15 and no green on chromosome 17. Swapped material in the blood cells indicates the presence of marrow cells with the swapped material that are continuing to produce those cancerous blood cells identified in the test. There is a 3-4% chance for a false positive with this test.


The picture above shows how the the pairs of chromosomes 15 and 17, within their cells, would look under the microscope once they've been tagged. If green and red are next to each other (meaning there was a swap/translocation), then the probe creates a yellow flourescent overlap. The genetist looks for the presence of yellow, which in the picture appears in the two bracketed cells. Yellow is now my least favorite color.
 
- PCR stands for "polymerase chain reacton." The technique makes multiple copies of trace amounts of DNA or RNA so that the specific DNA or RNA within the chromosomes can be studied. This makes it possible for the scientists to use engineered probes to find the targeted marker that exists on any abornmal blood cells (which would indicate there are still marrow cells with genetic material on chromosomes 15 and 17 swapped, producing cancerous blood cells). The test can detect the presence of one blood cancer cell among 500,000 to 1 million blood cells. (It is more accurate than FISH, but given I likely still have some cancerous cells pre Phase Two treatment, it would be pointless to do this test now.)

Sources:
- My mother, who is an Advanced Placement Biology teacher
- "Acute Myeloid Leukemia," published by The Leukemia and Lymphoma Society. The explanations of the medical terms have been very helpful, and there are some direct references to my subtype, APL (M3).
http://www.lls.org/content/nationalcontent/resourcecenter/freeeducationmaterials/leukemia/pdf/aml