Chronic Myeloid Leukemia in Adolescents and Youngadults: Clinicopathological Variables and Outcomes

Introduction Adolescents and young adults (AYAs) are defined as those diagnosed with cancer at ages 15 through 39. [1] In Qatar we have a large number of patients that fall under the category of AYA, reflecting the fact that most of the population are relatively young working force, where the statistics confirm that the median age of the population of Qatar in 2021 is 32.5 [2].

Objective We conducted this study to find out if AYA age group differ from older age group in clinicopathological variables or outcome, which could indicate a unique disease pathology. We also compared different risk scores to find out which one is more representative of real outcome in AYA.

Methodology We conducted a retrospective analysis of the files of 224 patients being treated in our center for CML. Patients' management and response assessment was done based on ELN 2013 guidelines. The analysis is done based on age at diagnosis: < 40 years (AYA) or ≥ 40 years.

Results Our study included 224 patients of diverse ethnicities.

Baseline characteristics for the study cohort are summarized on the attached table.

Patients in the AYA group had a better prognosis based on Sokal score. Same applies for Euro/Hasfold scores. Whereas EUTOS and ELTS scores showed more comparable risk stratification between age groups (see the attached table).

When comparing the outcome at 1 year, 24 patients (35.8%) from AYA group vs. 10 (14.4%) from the other group failed to achieve optimal response or had disease progression. The patients who achieved CCyR were comparable (AYA group = 21 (31.3%) vs 20 (29.0%) in the other group). With regards to MMR or deeper response the number was 22 (32.9%) in AYA group vs 39 (56.3%) in the other group.

The cumulative MMR was significantly lower in AYA group compared with the older patients' group: 55 (56.7%) vs 69 (73.4%) p=0.016. However, there was no significant difference with regards to DMR: 36 (37.1%) vs 44 (46.8%) p = 0.175 (but still with higher percentage of patients achieving DMR in older age group).

Discussion AYA are an important patient population which is underrepresented in the studies done in CML. Most recommendations for CML management are extracted from studies including patients who are much older with a small fraction qualifying as AYA. Some unique challenges for this population include fertility issues, access to health care, and survivorship concerns. Treatment free remissions are more important and more relevant for this age group.

Our study shows that AYA patients present more aggressively with higher WBC count, lower Hb lever, and bigger spleens. Additionally, more patients in AYA group were diagnosed in blast phase. However, Sokal/Euro risk scores classified more patients in this group as lower risk; whereas EUTOS and ELTS risk scores placed the patients in comparable risk groups; despite that, outcome was worse both at 1 year and at last follow up. This may suggest that this patient population may have different underlying disease biology which may warrant different risk stratification and different approach to management.

In conclusion, AYA present a unique age group, and more studies are needed to clarify the differences in disease biology and possible effect on outcome, as well as possibly formulate a new risk score for this age group.

References 1. Adolescent and Young Adult Oncology Progress Review Group. "Closing the gap: research and care imperatives for adolescents and young adults with cancer." NIH Publication No. 06-6067 (2006).

2. https://www.populationof.net/qatar/

No relevant conflicts of interest to declare.