Clinical Characteristics, Progression of Disease Within 24 Months (POD24), and Real-World Outcomes of Follicular Lymphoma in Saudi Arabia: A Two-Centre Retrospective Analysis

Background: Real-world evidence describing the presentation, management, and outcomes of follicular lymphoma (FL) in Saudi Arabia remains limited, and the frequency and prognostic weight of progression of disease within 24 months of first-line therapy (POD24) have not been reported in this population. This study evaluated the clinicopathological characteristics, treatment patterns, POD24 incidence, and survival outcomes of patients with FL treated at two Saudi tertiary centres. Methods: This two-centre retrospective chart review included adults with histologically confirmed FL diagnosed between November 1999 and May 2025. Overall survival (OS) and first-line progression-free survival (PFS) were measured from the initiation of first-line treatment and estimated using the Kaplan–Meier method. POD24 was defined as progression, relapse, or death from any cause within 24 months of first-line initiation among patients evaluable for that endpoint. Outcomes were additionally examined by calendar era of diagnosis. All group comparisons were unadjusted and exploratory. Results: A total of 139 patients were included. The mean age at diagnosis was 54.7 years (range, 18–91), 61.9% were male, 79.1% had Ann Arbor stage III–IV disease, and 51.1% had an FLIPI score ≥ 3. Bendamustine plus rituximab was the most frequent first-line regimen (43.9%), followed by R-CHOP (30.2%). The overall response rate was 77.0% in the whole cohort and 82.4% among the 125 patients who received response-evaluable systemic first-line therapy. After a median follow-up of 71.0 months, 5-year OS was 92.5% (95% CI, 84.8–96.4) and 5-year PFS was 66.1% (95% CI, 54.9–75.0); the corresponding medians were 210.0 and 114.6 months but were estimated with few patients at risk and should be interpreted cautiously. Among 97 patients evaluable for POD24, the event occurred in 24 (24.7%; 95% CI, 17.2–34.2), and the incidence was stable across calendar eras (23.4% before 2018 versus 24.5% thereafter; p = 1.000). Primary refractory disease accounted for 14 of the 24 events (58.3%). POD24 was associated with poorer ECOG performance status (odds ratio [OR] 11.08; 95% CI, 3.85–31.86), older age (OR 5.27; 95% CI, 2.00–13.89), and higher FLIPI score (OR 3.09; 95% CI, 1.13–8.42). In the 24-month landmark analysis, OS was significantly shorter after POD24 (log-rank p = 0.008), and both documented histological transformations occurred in the POD24 group. Conclusions: Patients with FL in this two-centre Saudi cohort frequently presented with advanced-stage and high-risk disease, yet contemporary anti-CD20-based treatment was associated with favourable long-term survival. Approximately one quarter of evaluable patients experienced POD24, predominantly as primary refractory disease, and this event identified a subgroup with materially inferior subsequent survival. POD24 may help identify patients who warrant closer surveillance and consideration for clinical trials or novel therapies.