Background

• Myelodysplastic syndromes (MDS) are clonal hematopoietic disorders that carry a variable risk of

transformation to acute myeloid leukemia (AML) — the primary driver of disease-related mortality.

• Whether the incidence, age at transformation, and temporal latency of leukemic progression differ

systematically by race and ethnicity remains poorly characterized.

• Current risk-stratification tools are race-agnostic, and may therefore underestimate transformation

risk in minority populations who progress earlier in life.

• Characterizing these disparities is a prerequisite for equitable, biologically informed surveillance

and treatment planning.

Methods

• Retrospective population-based cohort study using the SEER 18 database (2000–2023), including all

patients aged ≥20 years with a confirmed diagnosis of MDS.

• Leukemic transformation was defined as a subsequent AML diagnosis per HAEMARC multiple-primary

rules.

• Race/ethnicity was classified into five groups: Non-Hispanic White (NHW), Non-Hispanic Black (NHB),

Hispanic, Asian/Pacific Islander (API), and American Indian/Alaska Native (AI/AN).

• We examined mean age at transformation, the young-onset (<50 years) subgroup, and progression

latency across nine pre-specified intervals (0 to 120+ months).

• Group differences in age at transformation were compared statistically, and NHW latency phases were

characterized to describe the temporal course of progression.

Results

• Mean age at transformation was significantly younger in minority groups: NHB 68.4 y, Hispanic 67.7 y,

and AI/AN 68.9 y vs NHW 72.2 y (all p<0.001).

• In the young-onset (<50 y) subgroup, Hispanic patients contributed 19.0% of events despite being

8.2% of the cohort — a 2.4-fold enrichment; NHB contributed 13.8% vs 8.1% overall.

Triphasic Latency Pattern (NHW)

• Rapid phase (0–5 months): 23.8% of transformations occur within the first half-year after

MDS diagnosis.

• Subacute phase (6–47 months): 53.8% of events — the dominant window, peaking at 12–

47 months (39.0%).

• Late phase (48+ months): 22.4% of events, including a clinically underrecognized long-tail

group transforming at ≥120 months (4.6%).

• This triphasic structure argues against a fixed surveillance horizon: risk persists well

beyond the early post-diagnosis period and extends years into follow-up.

Conclusions

• Hispanic and NHB MDS patients transform at substantially younger ages, carrying a

disproportionate mid-life disease burden that race-agnostic tools miss.

• NHW transformation follows a distinct triphasic pattern with a clinically underrecognized

late-transformation tail beyond ≥120 months.

• Findings support race-stratified risk models and latency-informed surveillance protocols

accounting for earlier onset and sustained late risk.