Chronic myeloid leukemia treatment guidelines: Brazilian Association of Hematology, Hemotherapy and Cell Therapy. Brazilian Medical Association Guidelines Project – 2012 mortality by 36% (NNH: 3) and reduces the mean overall survival of CML patients submitted to stem cell transplantation(25)(B). CML-related disease-free and overall survival at 5 years is different in patients with cytogenetic changes compared to those without. The presence of major cytogenetic aberrations (major route abnormalities) (such as a second Philadelphia chromosome, trisomy 8, isochromosome 17q, or trisomy 19) reduces disease-free and overall survival at 5 years by 40%(26)(B). Recommendation: The presence of additional chromosomal aberrations at diagnosis (major route abnormalities) reduces the overall and disease-free survival and increases mortality by 36% to 40%. Are the criteria of the World Health Organization comparable to other criteria to classify CML phases (chronic, accelerated and blast crisis phases)? The use of the World Health Organization (WHO) classification of CML stratifies patients into chronic, accelerated and blast crisis phases at approximate rates of 77.8%, 15.5% and 6.7%, respectively(27)(C). The appropriate classification allows the establishment of adequate estimates of response(28)(D). In the treatment of CML patients with imatinib, there is no difference in the overall classification of patients in the chronic, accelerated and blast crisis phases between the standard method and the WHO criteria. The distribution of patients according to the standard classification is about 60% in the chronic phase, 28% in the accelerated phase and 12% as blast crisis. Although there is no significant difference between the two classifications, 6% of patients classified in the chronic phase by the standard classification were reclassified in the accelerated phase (WHO). Similarly, 9% of patients classified in the accelerated phase were reclassified as blast crisis (WHO), and 7% in the chronic phase(29)(B). There are differences between the M. D. Anderson Cancer Center (MDACC), International Bone Marrow Transplant Registry (IBMTR) and WHO classifications and definitions of the accelerated phase of CML particularly in respect to the percentages of blasts and platelets (Table 1)(30)(D): Table 1 - A comparison between the M. D. Anderson Cancer Center, International Bone Marrow Transplant Registry and World Health Organization classifications and definitions of the accelerated phase of CML Characteristic Blasts (%) Platelets MDACC > 15 < 100 IBMTR > 10 No response WHO 10 – 19 < 100 or > 1000 MDACC: M. D. Anderson Cancer Center; IBMTR: International Bone Marrow Transplant Registry; WHO: World Health Organization (main differences) Recommendation: The WHO classification for the chronic, accelerated and blast crisis phases of CML are similar to the IBMTR and MDACC classifications. Is it important to define risk in CML patients using the Sokal and Hasford scores? The Sokal score can be determined using an online calculator (www.pharmacoepi.de). The score takes into account the size of the spleen (in centimeters) palpable below the left costal border, the platelet count, the percentage of blasts and the age, where a result < 0.8 corresponds to low risk, from 0.8 to 1.2 intermediate risk and > 1.2 high risk. The Sokal score has a predictive value in CML patients treated with imatinib, where molecular and cytogenetic responses are higher in low-risk patients. High-risk, intermediate-risk and low-risk patients who achieve cytogenetic response within 12 months have probabilities of survival of 90%, 94% and 97%, respectively. The Hasford score considers the age, the percentage of eosinophils and basophils, platelet count, spleen size in centimeters and percentage of blasts; the patient has low risk when the result is ≤ 780, intermediate risk between 780 and 1480 and high risk ≥ 1480. The 5-year survival rate corresponding to each risk group is 76%, 55% and 25%, respectively(31)(D)(32)(B). The Sokal score predicts treatment response of CML patients on interferon alpha therapy. The high-risk, intermediate-risk and low-risk groups include 48%, 29% and 23% of the cases with mean survival rates of 45, 76 and 105 months, respectively. The 10-year survival is 8%, 28% and 34%, respectively(33)(B). After the introduction of imatinib treatment, the Sokal score identified an increase in the 5-year survival rate of low-risk CML patients of 11%, intermediate-risk patients of 40% and of high- risk patients of 38%(34)(B). Moreover, it is known that high-risk patients are more likely to evolve to the accelerated or blast crisis phases even on imatinib therapy(35)(A). The Sokal score is also inversely related to cytogenetic response in high-risk patients(36) (B), as, for high-risk patients, there is a 30.4% reduction in cytogenetic response(37)(B). The Hasford score identifies patients at low risk, with probability of survival at 9 years of 41%, intermediate risk, with probability of 0.16%, and high-risk, with a probability zero at 9 years. The Sokal and Hasford scores classify 23% and 9% of all patients as high-risk, respectively. Patients with low or intermediate risk who achieve complete hematological response, have probabilities of survival of 51% and 23%, respectively; those without complete hematologic response have probabilities of 26% and 12%, respectively. High-risk patients who achieve cytogenetic response have prognoses similar to those with low risk(38)(B). Of the different groups as classified by Hasford, 57% of low-risk patients present complete cytogenetic response and 27% of intermediate-risk and high-risk patients achieve complete cytogenetic responses(39)(B). The Hasford and Sokal scores predict complete hematological responses mainly in low-risk patients(40)(B). Recommendation: The Sokal and Hasford scores are prognostic predictors of CML patients. Rev Bras Hematol Hemoter. 2012;34(5):367-82 369