Clinical characteristics and prognosis of acute myeloid leukemia and plasma cell neoplasms with bidirectional occurrence: a retrospective population-based study.

The bidirectional occurrence of acute myeloid leukemia (AML) and plasma cell neoplasms (PCN) is rare, and clinical characteristics and survival outcomes remain poorly defined. We conducted a retrospective population-based study using the Surveillance, Epidemiology, and End Results (SEER) database (2000-2022). Patients diagnosed with both AML and PCN were identified and categorized based on diagnostic sequence. Overall survival (OS) and cancer-specific survival (CSS) were analyzed using Kaplan-Meier methods and Cox proportional hazards models adjusting for demographic and clinical variables. The research cohort consisted mainly of elderly individuals (≥65 years old, 76.2%) and males (66.3%). The median survival time was 4.0 months (IQR: 1.0-13.0). Multivariable Cox regression analysis demonstrated that chemotherapy was associated with a significant survival benefit across all models of OS (Model III: HR = 0.54, 95% CI: 0.37-0.78, p = 0.001) and CSS (Model III: HR = 0.55, 95% CI: 0.35-0.85, p = 0.008). In contrast, radiotherapy showed no significant association with survival (all p>0.5). Kaplan-Meier analysis confirmed a significant survival advantage for patients receiving chemotherapy (log-rank p < 0.0001) but not for radiotherapy (log-rank p = 0.35). Subgroup analyses revealed that the protective effect of chemotherapy was consistent (all p for interaction > 0.5).In this population-based cohort, chemotherapy receipt was associated with improved survival among patients diagnosed with both AML and PCN. Given the observational nature of the study and limitations inherent to registry-based treatment ascertainment, these findings should be interpreted cautiously and warrant confirmation in studies designed to account for treatment timing and confounding.