Timing of multiple primary malignancies does not affect overall survival in lymphoma patients: a comparative study of 167 synchronous vs. metachronous cases.

In recent years, growing attention has been paid to the clinical management and prognosis of lymphoma patients with multiple primary malignancies (MPMs). This study aimed to determine whether the timing of MPM diagnosis affects the clinical characteristics and prognosis of these patients. A total of 167 patients with lymphoma complicated by MPMs were retrospectively analyzed. Patients were divided into a synchronous cancer group (SC, interval ≤6 months between diagnoses) and a metachronous cancer group (MC, interval >6 months) based on the interval between the diagnoses of lymphoma and the second malignancy. Clinical characteristics were recorded and compared between the two groups. Overall survival (OS) was estimated using the Kaplan-Meier method, and independent prognostic factors were identified through a multivariate Cox proportional hazards regression analysis. No significant differences were observed in baseline clinical characteristics between the SC and MC groups. The 1-, 3-, and 5-year OS rates for the entire cohort were 94.01%, 74.25%, and 72.46%, respectively. Multivariate analysis revealed that aggressive lymphoma (hazard ratio [HR]=2.618; 95% confidence interval [CI], 1.169-5.863; P=0.026) and Ann Arbor stages III-IV (HR=5.793; 95% CI, 2.658-12.625; P<0.005) were independent predictors of poor prognosis. The temporal sequence of MPMs was not identified as a significant factor influencing OS. Overall, prognosis in patients with lymphoma with MPMs is determined primarily based on the biological behavior and treatment response of lymphoma, whereas the diagnostic interval and sequence of MPM occurrence do not appear to significantly affect long-term survival. These results highlight the importance of focusing on lymphoma-specific features and treatment response in prognostic evaluation of patients with lymphoma with MPMs.