Type of publication:
Conference abstract
Author(s):
Backer G.; *Arunachalam J.
Citation:
HemaSphere. Conference: 30th Congress of theEuropean Hematology Association Annual Congress, EHA2025. Milan Italy. 9(Supplement 1) (pp 1214-1215), 2025. Date of Publication: 01 Jun 2025.
Abstract:
Background Primary malignant lymphomas of the parotid glands are rare, estimated to account for just 0.6% to 5% of all tumors of the parotid gland. Primary Parotid Follicular Lymphoma (PPFL) is a rare subtype of non-Hodgkin lymphoma (NHL) originating in the parotid gland, often associated with autoimmune disorders such as Sjogren's syndrome. Due to its low incidence, comprehensive population-based studies are scarce, limiting our understanding of epidemiological factors associated with PPFL and how they impact survival outcomes. Aims Using a large, population-based cancer registry, we aimed to evaluate the incidence trends and survival patterns of PPFL for the past 20 years in the US. Methods We conducted a retrospective population-based study utilizing data between 2000-2021 from the SEER (Surveillance, Epidemiology, and End Results) database. SEER is a program of the National Cancer Institute that collects epidemiological and survival data from cancer registries across the United States. We identified and extracted data from patients diagnosed with PPFL using ICD codes specific for primary tumors of the parotid gland (C07.9) and for follicular lymphoma (ICD codes 9690, 9691, 9695, 9698). Demographic data collected included year of diagnosis, age, sex, race, and area of residence. Incidence rates (IR) were calculated per 100,000 population and were age adjusted to the US standard population using SEER*stat 8.4.4. Using GraphPad Prism software, Kaplan-Meier survival analysis was done to calculate overall survival (OS) and cancer specific survival (CSS). Log rank (Mantel-Cox) test was used to compare survival outcomes between different groups. Results 793 patients with primary parotid follicular lymphoma were identified. 52% were male. 56% were older than 65 years at the time of diagnosis. 79% of patients were white, 10% were Hispanic, and 5% were black. 18% of patients had metastatic disease at initial presentation. IR was 0.050 (SE 0.002, 95% CI 0.045-0.055) for the years 2000-2010 and 0.036 (SE 0.002, 95% CI 0.032-0.040) from 2011 to 2021. Incidence was 29.7% higher in males compared to females with p = 0.0001(IR 0.048 vs 0.037, respectively). IR was 0.049 amongst white patients (SE 0.002, 95% CI 0.046 – 0.054), 0.021 amongst black patients (SE 0.003, 95% CI 0.015 – 0.029), and 0.031 amongst hispanic patients (SE 0.004, 95% CI 0.024-0.038). Patients between the ages of 75-79 years had the highest IR of 0.241 (SE 0.024, 95% CI 0.197- 0.293). Median overall survival (mOS) was 174 months. 5-year and 10-year CSS was 90% and 84%, respectively. mOS was 180 months in patients who received chemotherapy. mOS was 106 months in adults older than 65 years, compared to those younger (p<0.0001). White patients had the poorest mOS of 161 months (p=0.0042). There was no statistically significant difference in survival outcome based on gender. mOS was 109 months in patients residing in non metropolitan counties compared to mOS of 187 months in patients residing in metropolitan counties (p=0.0005). Summary/Conclusion PPFL primarily affects older adults, with high incidences in males and white patients. Though CSS rates are generally favorable, overall survival was found to be worse in white patients, adults aged > 65, and people residing in non metropolitan counties. These differences highlight potential disparities in disease outcomes and suggest the need for future research into factors influencing survival and access to care for patients with PPFL.
DOI: 10.1002/hem3.70152
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