Hi Nigel.... this is the result you need at this point in you journey... and translates into a 60% decrease of PH+ cells. The 'log reduction' is when you describe the drop by decimal points rather than percentage drops.
Here is my rather simplistic example:
If you start at 100% PH+ -this means that more or less all of the white cells in the particular blood sample taken have the PH chromosome.
Therapy is started and in your case the next result shows that 35% of the white cells in the blood sample taken are Ph+ cells...this is a percentage drop (rather than a log reduction) of 60% PH+ cell.
This is a major cytogenetic response (MCyR) and at 3 months is a good response.
For arguments sake, say the next result shows PH+ cells at around 1.5 %. This would be a drop of virtually all the PH+ cells in the blood sample tested.
Then although this is a very low level it is know that there is still a sizable population of PH+ cells existing in the marrow, but at these low levels they are harder to detect and quantify by standard cytogenetics/FISH testing. However, at this level of 1.5% you would have had a complete cytogenetic response (CCyR) but you would still be looking to reduce the PH+ cell further.
So the PCR test results then takes precedence and is used to calculate the presence of the residual population of PH+ cells by measuring the level of bcr/abl- the oncogene that gives rise to the PH+ cell.
Once the PH+ cell population is reduced to such low levels.... i.e. below zero, we enter the realms of the molecular- so any further tests that shows bcr/abl at below 0% is described as a log reduction and each move of the decimal point represents a log.
0.1...% then that would be described as a reduction of 1 log.
0.01....% would be 2 log
0.001....% would be 3 log
0.0001....% would be 4 log and on down to undetectable by current pcr sensitivity.
As you are now at 35% you are still PH positive so will not be described as having a 'log reduction'... you have to wait until you reach 1.5%, or below, for that.
I hope this explanation helps......... it is my own understanding as a lay person and may be subject to correction from others who are more adept at maths etc.
Best wishes,
Sandy
