Epidemiologic and Clinical Patterns of Malignant Lymphoma in Qatar 2013-2017: A Population-Based Cohort Study

Introduction: Lymphoma, encompassing common non-Hodgkin lymphoma (NHL) and less common Hodgkin lymphoma (HL), represents significant hematological malignancies. Advancements in treatment modalities have reshaped survival rates, particularly in NHL. This complexity results in varying outcomes, some requiring extended observation periods and multiple chemotherapy treatments. The primary objective was to explore and compare the overall survival (OS) of HL and NHL at 1, 3, and 5-year follow-ups among adult lymphoma patients in Qatar during January 2013-December 2017. Further objectives encompass comparing the most prevalent histological types, clinical and epidemiological traits of HL and NHL, as well as secondary aims of assessing clinical features, treatment, response, disease-free survival, and OS. Methods: A retrospective, descriptive study of consecutive cases was conducted at Qatar's NCCCR between 2013 and 2017. Inclusion criteria involved patients >= 18 years old, of any gender and clinical stage at diagnosis, who received chemotherapy and had known outcomes. Descriptive statistics were applied, and survival analysis utilized Kaplan-Meier curves. STATA version 13.0 facilitated data analysis. Results: Between 2013 and 2017, 414 individuals in Qatar were diagnosed with lymphoma. The median age at diagnosis was 49 years (IQR 36-95 years; p < 0.001) across all patients. Males exhibited a higher likelihood of developing HL and NHL, comprising 74% and 70% of cases, respectively, though this difference was statistically insignificant (p = 0.45). Among NHL-B subtypes, mature B-cell neoplasms (60%) predominated, while lymphocyte-rich subtype (49%) was prominent in HL cases. With a median follow-up of 17.3 months, OS rates at 1, 3, and 5 years were 99%, 82%, and 64%, respectively for all lymphoma patients. Subtype stratification revealed trends in 3-year follow-up OS (94 vs. 82%) for HL and NHL, with 5-year OS of 67% and 60%, respectively. HL demonstrated higher OS throughout the study period compared to NHL (p < 0.001), though median OS remained unreached. Conclusions: Diffuse large B-cell lymphoma emerged as the most prevalent subtype among lymphomas in Qatar. Generally, HL exhibited superior survival rates, at 67% compared to 60% for NHL. Minor deflation in survival rates, particularly for HL, might be attributed to Qatar's immigration patterns.