Effect of time to treatment initiation in MCL: A SEER analysis from 2000-2022.

e23069 Background: Mantle Cell Lymphoma (MCL) is a rare subtype of Non-Hodgkin Lymphoma (NHL) with a heterogeneous clinical course that can present as aggressive or indolent. The impact of delayed time to treatment initiation (TTI) remains understudied in MCL patients. Prior analysis from Canadian data found that patients who deferred treatment for greater than 3 months from diagnosis had a similar overall survival (OS) compared to patients treated immediately. Here, we expand on that data with the Surveillance, Epidemiology and End Results (SEER) database to determine if delayed TTI impacts OS. Methods: We conducted a retrospective study using the SEER database. Only patients with a single primary malignancy were included. OS was determined using Kaplan–Meier survival curves with logrank tests to determine significance. Further analysis was performed with multivariate Cox proportional hazards regression model testing. Hazard ratios were calculated for each parameter with p-values to assess significance. Covariates included age, sex, race, and stage. Results: We identified a total of 15,892 MCL patients diagnosed between 2000 to 2022 in SEER. In our survival analysis, we found one-year OS of 80.2% and five-year OS of 51.6%. Female patients had improved OS with a median OS of 67 months compared to male patients with a median OS of 58 months (p<0.003). After multivariate Cox regression model analysis, female patients continued to have a superior OS with HR of 0.8872 (95% CI 0.8226-0.9562; p<0.0017). Age was categorized as patients < 65 years old and > 65 years old. Patients < 65 years old had superior OS after controlling for sex, stage, and race (HR of 0.4272, 95% CI 0.3969-0.4596; p<0.0001). Next, we performed analysis of TTI in days from date of diagnosis. Patients without treatment date information were excluded from this analysis. First, we analyzed TTI by year of diagnosis and found increasing TTI over time: 15 (2005-2009) to 21 (2010-2014) to 27 (2015-2019) to 32 (2020-2022). Median TTI did not significantly vary between male and female patients. Delayed TTI was associated with improved OS. In comparison to TTI < 30 days, TTI of 30 – 89 days (HR of 0.7674, 95% CI 0.7102-0.8288; p<0.0001) and TTI of > 90 days (HR of 0.7202, 95% CI 0.6119-0.8424; p<0.0001) showed statistically significantly improved survival. Conclusions: In our large national cohort of patients, we found that female MCL patients maintain superior survival outcomes. This supports prior analysis from the National Cancer Database that also reported superior survival outcomes in female MCL patients. We also found that delayed TTI was paradoxically associated with improved survival outcomes concordant with prior data. These findings suggest that the aggressive disease biology may be driving the poor survival outcomes of early treatment initiation patients. Future studies should incorporate real-world data to further define aggressive disease biology in MCL patients.