To scuba and others

https://www.cancer.org/cancer/chronic-myeloid-leukemia/treating/is-treat...

CCyR = complete cytogenetic remission.

It means under the microscope, no cells are observed with the Philadelphia chromosome (9;22 translocation).

The test is usually done on peripheral blood for convenience or from bone marrow aspirations using a fluorescence in situ hybridization process (F.I.S.H.) in which the Philadelphia chromosome is made to fluoresce so it becomes visible to the naked eye when looking through the microscope. CML cells are then counted out of 200 cells visible. The ratio of CML cells to cell count (rest being normal cells) is the FISH percentage. It is the single most important indicator of disease status.

Goal of TKI therapy is to reduce FISH to zero (no cells observed). Achieving a FISH level = zero indicates a 95% chance of progression free survival.

When I was first diagnosed my research oncologist only cared about my FISH level.

Once FISH falls to zero, the only way to monitor residual disease is to use PCR which is a molecular test measuring the protein products of the bcr-abl oncogene (philadelphia chromosome). A PCR ~ 1.0% is roughly equivalent to a FISH = zero. Typically anone with a PCR below 1% will not show any positive FISH.

Sandy / David and others may provide additional links with additional information.