Abstract: EP744

Type: e-Poster

Presentation during EHA25: All e-Poster presentations will be made available on the on-demand Virtual Congress platform as of Friday, June 12 at 08:30 CEST and will be accessible until October 15, 2020.

Background

Chronic myeloid leukemia (CML) treatment was revolutionized with the advent of the first tyrosine kinase inhibitor (TKI) imatinib in 2001 and subsequent generations of TKI as from 2009. The improved longevity of CML patients in the TKI era necessitates research on the likelihood of surviving at a given time point after diagnosis; that is, conditional survival (CS). However, statistics on CS in CML are scarce.

Aims

This nationwide, population-based study aimed to assess 5-year relative survival (RS) at diagnosis and for each additional year survived among CML patients diagnosed in the TKI era.

Methods

We selected all adult CML patients diagnosed between 2001-2017 from the nationwide Netherlands Cancer Registry, with survival follow-up until 2019. Five-year RS was calculated from diagnosis and for each additional year survived up to 5 years post-diagnosis. RS is the ratio of the patients’ overall survival to the expected survival of an age-, sex-, and period-matched group from the general population. Excess mortality is considered low and minimal when 5-year RS ranges between 90%>95% and exceeds 95%, respectively. All analyses were performed for the overall cohort and stratified by sex, calendar period of diagnosis (2001-2008 and 2009-2017), and age at diagnosis (18-44, 45-54, 55-64, and ≥65 years). The first calendar period represents the era in which imatinib was introduced in daily practice, whereas the second calendar period represents the era in which subsequent generations of TKI were introduced for application in daily practice.

Results

A total of 2,751 adult CML patients were included in the study (54% males; 44% diagnosed in 2001-2008; 41% aged ≥65 years; and median age 60 years). Overall, 5-year RS from diagnosis was 80% and increased with each additional year survived up to 91% at 5 years post-diagnosis (Fig A). There were no sex-related differences in RS over time (Fig B). Five-year RS from diagnosis improved between the first and last calendar period (Fig C). An improvement in 5-year conditional RS (CRS) was objectivated for both calendar periods, which was most pronounced for the first calendar period. The difference in 5-year RS between the calendar periods started to diminish after 3 years post-diagnosis. For patients up to age 65 5-year RS from diagnosis was comparatively high (Fig D). For these patients 5-year CRS gradually increased with each year survived up to almost 100% after 5 years post-diagnosis for those aged 18-54 years, while it was close to 95% for those aged 55-64 years. Lastly, 5-year RS from diagnosis among patients aged ≥65 years was considerably lower than their younger counterparts and remained unchanged over time (Fig D).

Conclusion
In this study covering the TKI era, the overall 5-year CRS gradually increased over time and exceeded 90% by 5 years after diagnosis, suggesting lower excess mortality in the next 5 years post-diagnosis compared to the life expectancy at diagnosis. Encouragingly enough, at 2 to 3 years post-diagnosis, patients up to age 65 had survival expectations similar to a comparable group from the general population. In contrast, CRS among patients aged ≥65 years remains poor, indicating continuing excess mortality in a modern TKI era. Whether this can be explained by comorbidity, side effects or frailty of the patient and/or reluctancy of the physician in prescribing TKIs should be of focus in future research, in order to also improve their outcomes. Age-specific information on CRS can aid in dynamic decisions regarding management and follow-up activities.

Session topic: 08. Chronic myeloid leukemia - Clinical

Keyword(s): Chronic myeloid leukemia, Survival