I first heard about "minimal residual disease" from a special on cancer research on TV sometime in 1998. At St. Judes, children with leukemia were being tested to see if they had any leukemia at all left in their bodies, and if they did, treatment continued. If they did not, treatment was discontinued. Wow! At the time, my own son was in the middle of his intense leukemia protocol. How I'd like to pull him off therapy if no more was needed! How I'd like to know at the end of planned treatment whether or not there were any leukemia cells left, to know if his treatment should be continued!
The TV program made it look like an easy test. The researchers were shown looking at large photographic sheets and supposedly could just read from these whether or not the children still had cancer. Now, I have a background in molecular biological techniques, and I had the feeling that it wasn't quite as easy as it looked. My husband was urging me: "get this test done on our son!" and I'm sitting back, hemming and hawing. I knew that I had to look deeply into the techniques before I could make a judgement of whether or not I wanted to pursue a minimal residual disease test.
Over a year later, I finally have studied minimal residual disease testing. What have I found? That it is much more complex than I ever guessed. Will I have my son tested? I'll save my own decision until the end, so that you can read what I have learned and make your own decision.*
My aim in writing these web pages is to explain to parents both the methodology behind MRD testing and the results obtained so far of studies of medium to large groups of children in treatment. I have tried to write in terms that parents from all walks of life can understand. I myself walk the road of Biochemistry, with an MS from CU Boulder. Many of the techniques in the MRD studies I have done myself: electrophoresis gels, isolation of DNA from tumor cells, studies of transcription complexes, restriction enzyme digests, DNA sequencing and synthesis, among others. However, I have been out of this particular field for over 15 years, as I now supervise teaching labs in organic chemistry. Southern gels were around back then, but PCR was not. DNA synthesis and sequencing were not yet fully automated back then, and the zippy ways these are done now were just dreams then. This in turn makes schemes only dreamed of then possible today. (I know: I was in the lab that was developing one of the first automatic DNA synthesizers - another story in itself!)
I found the whole MRD subject fascinating reading. I hope that my explanations make sense to parents, if I sometimes get too technical or throw out a term without a good definition, please e-mail me and ask questions. Note: the discussion is written in the context of B-cell leukemias, however, the same principles - but not specifics - apply for T-cell leukemias.
Editor, Ped-Onc Resource Center
(page created September 22, 1999)
*We decided not to have my son tested for MRD. By 1999, he had been on treatment for two years, and MRD should be done at specific times during the first part of treatment to get meaningful results. I'm not sure they had a sample from the start of treatment to have a good primer, so a negative result two years into treatment might mean he had no MRD, but then again, it might not. Even a positive result at the end of treatment might or might not predict relapse.
These pages are intended for informational purposes only and are not intended to render medical advice. The information provided on Ped Onc Resource Center should not be used for diagnosing or treating a health problem or a disease. It is not a substitute for professional care. If you suspect your child has a health problem, you should consult your health care provider.