Waldenström Macroglobulinemia: A Retrospective Survival Analysis Study from SEER Database

Background: Waldenstrom Macroglobulinemia (WM), also referred as IgM monoclonal gammopathy, is an uncommon hematologic malignancy and a subtype of lymphoplasmacytic lymphoma, characterized by increased lymphocytes and IgM immunoglobulin in blood or bone marrow. Symptoms stem from serum hyperviscosity caused by the pentameric IgM structure, including visual disturbance, headache, or stroke/TIA. B-symptoms, amyloidosis, bleeding abnormalities, hepatosplenomegaly and lymphadenopathy can also be observed. The annual incidence of Waldenstrom macroglobulinemia is about 3 cases per million people, and around 1,000-1,500 people are diagnosed every year in the US1. There are various treatment options including chemotherapy, immunotherapy, enzyme inhibitors, plasmapheresis and watchful waiting. The purpose of this study is to determine epidemiology and prognosticators for WM, identified in SEER Database in the last two decades . Method: We extracted Waldenstrom macroglobulinemia cases in adults, diagnosed after the age of 18, using the ICD Code 9761/3, from Surveillance, Epidemiology and End Result (SEER) database Research Plus Data, 17 Registries, Nov 2023 Sub (2000-2021). The analysis was stratified on the basis of age, gender, race, primary site labelled, median household income inflation adjusted to 2022, and treatment options utilized. Further, survival curves were compared using the Log-Rank test (GraphPad Prism). Results: Between 2000 and 2021, 7684 cases of Waldenstrom macroglobulinemia were identified. The median age of diagnosis was 72 years. <5% of the cases were diagnosed before the age of 50 years and only 43.78% underwent chemotherapy. 60.9% were males and 39.1% were females. Distribution based on race in a descending order was observed as: Caucasians 84.83%, Hispanics 5.67%, Asian/Pacific Islanders 4.7%, Blacks 3.87%, non-Hispanics of unknown race 0.68%, and <1% were American Indians/Alaskan natives 0.26%. The median of survival (MoS) was higher for earlier age groups, whereas survival declined with advancing age (p value <0.0001). MoS calculated for males was 105 and females 120 (p value <0.0001). Comparison of survival curves based on race was significant for White (110), followed by Asian/PI (109), Black and Alaskan/Native Americans (105), Hispanic (101), and undefined MoS for unknown race (p 0.0002). On the basis of primary site involved, survival analysis revealed 126 months for disease confined to bone marrow, 115.5 for lymph node involvement and 108 for blood borne disease (p 0.0155). MoS improved in parallel to increasing income, <70,000 (98), 70K-100K (113), and >100K (118) (0.0004). Results were significant for the use of chemotherapy (104) vs no chemotherapy (116) (p 0.0023), while radiation therapy had no influence on survival outcomes. Conclusion: Waldenstrom macroglobulinemia is a rarely encountered malignancy, and favours advanced age, male gender, and Caucasian race. Alaskan and native Americans were least affected. Our study revealed superior survival outcomes with younger age, female gender, Caucasian race, and disease confined to bone marrow. This is the first study to our knowledge to establish association of WM to income, showing higher survival with increasing median household income. Lower survival with chemotherapy, on the other hand, could be secondary to its use at comparatively advanced stages of disease. Reference: Key Statistics About Waldenstrom Macroglobulinemia | American Cancer Society