Contributions
Abstract: S811
Type: Oral Presentation
Presentation during EHA23: On Saturday, June 16, 2018 from 12:00 - 12:15
Location: Room A2
Background
The European Treatment and Outcome Study (EUTOS) registry contains data on adult patients with chronic-phase (CP) chronic myeloid leukaemia (CML). In 2,205 imatinib-treated patients, the EUTOS long-term survival score (ELTS) was developed to discriminate three risk groups with different probabilities of dying from CML. Still, many investigators continue to apply the Sokal score for the prognostic discrimination of CML-patients treated with tyrosine kinase inhibitors (TKIs).
Aims
The Sokal score had allocated 23% of patients to the high-risk group, the ELTS score 12%. Long-term outcome of TKIs suggests that allocating >20% CP CML patients into a high-risk group is too pessimistic. The aim of this analysis was to compare risk group allocations and prognosis between the two scoring systems.
Methods
Due to the success of TKIs, the number of deaths from CML has distinctly declined. To optimise power, 2,949 patients from other registry sections were added. Survival was calculated from the date of start of treatment to death and censored at the latest follow-up. Cumulative incidence probabilities (CIPs) of dying of CML were compared with the Gray test and overall survival probabilities (OS) with the log-rank test. Only death after confirmed disease progression was regarded as “death due to CML”. Progression was defined in accordance with the current ELN recommendations (Blood 2013). Level of significance was 0.05.
Results
The 5,154 patients in the combined registry sections had a median observation time of 5.3 years. Six-year OS probability was 90% (95% confidence interval (CI): 89-91%). Of 429 deceased patients, in 175 CML progression prior to death was confirmed (40%). The 6-year CIP of dying of CML was 4% (CI: 4-5%). From low to high risk groups, the Sokal score resulted in 6-year CIPs of 3% (n=1,982 (38% of 5,154), CI: 2-3%), 4% (n=1,975 (38%), CI: 3-5%), and 8% (n=1,197 (23%), CI: 6-10%) and the ELTS score in 6-year CIPs of 2% (n=3,037 (59%), CI: 2-3%), 5% (n=1,449 (28%), CI: 4-7%), and 12% (n=668 (13%), CI: 9-15%). Of the 1,197 patients allocated to high risk by the Sokal score, the ELTS score classified 671 (56%) as non-high-risk. Compared to the 526 high-risk patients according to both scores (6-year CIP of dying: 12%, CI: 9-16%), the CIPs of dying were lower for the non-high risk patients (p=0.0003, 6-year CIP: 5%, CI: 3-7%). The Sokal high but ELTS non-high-risk patients (6-year OS: 88%. CI: 85-91%) showed higher OS than the 526 common high-risk patients (p=0.0036, 6-year OS: 81%, CI: 76-85%). Of the 3,037 patients identified as low risk by the ELTS score, the Sokal score allocated 1,200 (40%) to non-low-risk groups. Without significant CIP differences to the latter group, at 6 years, the CIP of dying was 2% (CI: 1-3%) in the 1,837 low-risk and 2% in the 1,200 non-low-risk patients (CI: 2-4%). OS of the Sokal non-low-risk patients (6-year OS: 92%. CI: 90-94%) was lower than in the cases classified as low-risk by both scores (6-year OS: 95%. CI: 94-96%, p=0.0186).
Conclusion
The Sokal score allocated 13% (n=671) more patients to the high-risk group than the ELTS score. As these patients had significantly and clinically relevant lower CIPs of death and higher OS probabilities, the allocation of the Sokal score was not appropriate. OS probabilities but not the CIPs of 1,200 patients assessed as low-risk by the ELTS and non-low-risk by the Sokal score were different from the probabilities of 1,837 assessed as low-risk patients by both scores. For prediction of long-term survival, the use of the ELTS score is recommended.
Session topic: 8. Chronic myeloid leukemia - Clinical
Keyword(s): Chronic myeloid leukemia, prognosis, Survival
Abstract: S811
Type: Oral Presentation
Presentation during EHA23: On Saturday, June 16, 2018 from 12:00 - 12:15
Location: Room A2
Background
The European Treatment and Outcome Study (EUTOS) registry contains data on adult patients with chronic-phase (CP) chronic myeloid leukaemia (CML). In 2,205 imatinib-treated patients, the EUTOS long-term survival score (ELTS) was developed to discriminate three risk groups with different probabilities of dying from CML. Still, many investigators continue to apply the Sokal score for the prognostic discrimination of CML-patients treated with tyrosine kinase inhibitors (TKIs).
Aims
The Sokal score had allocated 23% of patients to the high-risk group, the ELTS score 12%. Long-term outcome of TKIs suggests that allocating >20% CP CML patients into a high-risk group is too pessimistic. The aim of this analysis was to compare risk group allocations and prognosis between the two scoring systems.
Methods
Due to the success of TKIs, the number of deaths from CML has distinctly declined. To optimise power, 2,949 patients from other registry sections were added. Survival was calculated from the date of start of treatment to death and censored at the latest follow-up. Cumulative incidence probabilities (CIPs) of dying of CML were compared with the Gray test and overall survival probabilities (OS) with the log-rank test. Only death after confirmed disease progression was regarded as “death due to CML”. Progression was defined in accordance with the current ELN recommendations (Blood 2013). Level of significance was 0.05.
Results
The 5,154 patients in the combined registry sections had a median observation time of 5.3 years. Six-year OS probability was 90% (95% confidence interval (CI): 89-91%). Of 429 deceased patients, in 175 CML progression prior to death was confirmed (40%). The 6-year CIP of dying of CML was 4% (CI: 4-5%). From low to high risk groups, the Sokal score resulted in 6-year CIPs of 3% (n=1,982 (38% of 5,154), CI: 2-3%), 4% (n=1,975 (38%), CI: 3-5%), and 8% (n=1,197 (23%), CI: 6-10%) and the ELTS score in 6-year CIPs of 2% (n=3,037 (59%), CI: 2-3%), 5% (n=1,449 (28%), CI: 4-7%), and 12% (n=668 (13%), CI: 9-15%). Of the 1,197 patients allocated to high risk by the Sokal score, the ELTS score classified 671 (56%) as non-high-risk. Compared to the 526 high-risk patients according to both scores (6-year CIP of dying: 12%, CI: 9-16%), the CIPs of dying were lower for the non-high risk patients (p=0.0003, 6-year CIP: 5%, CI: 3-7%). The Sokal high but ELTS non-high-risk patients (6-year OS: 88%. CI: 85-91%) showed higher OS than the 526 common high-risk patients (p=0.0036, 6-year OS: 81%, CI: 76-85%). Of the 3,037 patients identified as low risk by the ELTS score, the Sokal score allocated 1,200 (40%) to non-low-risk groups. Without significant CIP differences to the latter group, at 6 years, the CIP of dying was 2% (CI: 1-3%) in the 1,837 low-risk and 2% in the 1,200 non-low-risk patients (CI: 2-4%). OS of the Sokal non-low-risk patients (6-year OS: 92%. CI: 90-94%) was lower than in the cases classified as low-risk by both scores (6-year OS: 95%. CI: 94-96%, p=0.0186).
Conclusion
The Sokal score allocated 13% (n=671) more patients to the high-risk group than the ELTS score. As these patients had significantly and clinically relevant lower CIPs of death and higher OS probabilities, the allocation of the Sokal score was not appropriate. OS probabilities but not the CIPs of 1,200 patients assessed as low-risk by the ELTS and non-low-risk by the Sokal score were different from the probabilities of 1,837 assessed as low-risk patients by both scores. For prediction of long-term survival, the use of the ELTS score is recommended.
Session topic: 8. Chronic myeloid leukemia - Clinical
Keyword(s): Chronic myeloid leukemia, prognosis, Survival