Incidence rate and risk factors of second primary neoplasms among older patients with hematological malignancies: Insights from a Chinese single-center experience (1997-2021)

Background: Patients with hematological malignancies face an increased risk of developing second primary neoplasms due to various factors, including immune system compromise and chemotherapy-related effects. However, the incidence and associated risk factors in older patients remain poorly understood. This study aimed to assess the incidence, identify risk factors, and evaluate their impact on survival outcomes among older patients with hematological malignancies. Methods: This retrospective single-center study analyzed data from 163 patients, focusing on the occurrence of second primary neoplasms. Cumulative incidence rates were calculated, and risk factor analysis was conducted using a competing risk model. Results: Among 124 eligible patients with a total follow-up duration of 572.57 person-years, the incidence rate of second primary neoplasms was 15.72/1000 person-years. The standardized incidence ratio (SIR) was 0.81 (95% confidence interval [CI] [0.39-1.48], P = 0.518). History of radiotherapy emerged as a significant risk factor (sub-distribution hazard ratio [SHR] = 21.61 [2.81-166.14], P = 0.003), whereas regular natural killer (NK) cell infusion was associated with reduced risk (SHR = 3.25 e-8 [9.81 e-9-1.08 e-7], P < 0.001). Conclusions: These findings underscore the importance of informing older patients with hematological malignancies about the long-term risks of second primary neoplasms. Healthcare providers should carefully weigh risk factors when formulating treatment strategies. The results are valuable for investigating the fundamental principles underlying the occurrence and progression of second primary neoplasms.