Risk of multiple primary malignancies in mantle cell lymphoma: Insights from a SEER-based study (2000–2021).

e19051 Background: With increasing tumor survival rates and advancements in diagnostics, the incidence of multiple primary malignancies (MPMs), particularly in Mantle Cell Lymphoma (MCL), has risen. This study investigates the incidence and risk factors for MPMs in MCL patients. Methods: We analyzed data from the SEER 17 registries (2000–2021), calculating Standardized Incidence Ratios (SIRs) to assess the relative risk of MPMs. Logistic regression identified key risk factors for developing MPMs. Results: Among 10,880 MCL patients, 7,720 (71%) were male, and 8,575 (78.8%) were non-Hispanic White. Of these, 1,309 developed subsequent primary cancers, yielding an SIR of 1.41 (95% CI, 1.34–1.49) and an excess risk of 72.54 per 10,000 person-years. The risk for hematologic malignancies, especially acute myeloid leukemia (AML), was notably higher (SIR, 7.66 [95% CI, 5.90–9.78]; excess risk, 10.58 per 10,000 person-years). Non-hematologic cancers, particularly thyroid cancer, also showed a significant risk increase (SIR, 3.68 [95% CI, 2.59–5.07]; excess risk, 5.12 per 10,000 person-years). Multivariate analysis revealed that female sex (Exp(B) = 1.284, 95% CI: 1.115–1.479, p < 0.001) and longer survival time (Exp(B) = 1.145, 95% CI: 1.131–1.159, p < 0.001) were significant predictors of MPM development. Factors like race, chemotherapy, radiation therapy, and marital status did not show statistically significant associations (p > 0.05). Conclusions: MCL patients face a significantly elevated risk for MPMs, especially hematologic malignancies like AML and non-hematologic cancers such as thyroid cancer. Female sex and prolonged survival are key predictors. These findings underscore the importance of tailored survivorship care and vigilant monitoring for secondary cancers in high-risk MCL patients.