Like most cancers outcome or prognosis of the patient with chronic myeloid leukemia depends on several factors. Many of these further depend on the person’s ability to respond to therapy.
These prognostic factors are sometimes helpful when choosing treatment modalities and predicting possible outcome.
Factors that are not good and are associated with shorter survival time are called adverse prognostic factors. Similarly some factors are good and predict a good response to therapy and better outcome.
Adverse prognostic factors
These factors usually predict a worse outcome from treatment of CML. These include:-
- Patient in accelerated or blast phase – these phases of CML usually fail to respond adequately to therapy unlike those in chronic phase
- Swollen spleen – an enlarged spleen usually predicts a poor response to therapy
- Increased areas of bone damage by the spread of the leukemia
- Certain cells in blood predict a worse outcome of the disease
- Similarly more than a few changes in the chromosomes on cytogenetic analysis mean a bad prognosis for the patient
- Very high or very low platelet counts in blood are a bad prognostic factor
- Patients over the age of 60 years are also less likely to respond favourably to treatment
The Sokal system
The prognostic factors are taken into account and are scored as per the Sokal system to predict the outlook of the patient.
The Sokal prognostic system takes into account several factors like the age of the person, the percent of blasts, the size of the spleen, the numbers of different kinds of cells etc. in order to predict the possible outcome of the cancer.
Before the Sokal system the Euro score system was used to divide patients into different risk groups. It is not clear if these systems are wholly effective in predicting outcome after the advent of more targeted and effective therapies with drugs like Imatinib.
Rates of survival with chronic myeloid leukemia
The exact survival rates are not known for all cases of CML. However, 90% of those patients who respond favourably to tyrosine kinase inhibitors like Imatinib have been seen to survive without complications for at least 5 years after treatment commencement. Most of these patients had normal white blood cell counts at 5 years.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)