IMPAIRED IMMUNE HEALTH IN SURVIVORS OF DIFFUSE LARGE B‐CELL LYMPHOMA (DLBCL): A LARGE POPULATION‐BASED STUDY

PURPOSE Therapeutic advances for diffuse large B-cell lymphoma (DLBCL) have led to an increasing number of survivors. Both DLBCL and its treatments perturb the immune system, yet little is known about immune health during extended survivorship. METHODS In this retrospective cohort study, we compared 21,690 survivors of DLBCL from the California Cancer Registry (CCR) to survivors of breast, prostate, head and neck, and melanoma cancers. We linked their CCR records to a statewide database documenting hospital, emergency room, and ambulatory surgery visits and investigated the incidence of autoimmune conditions, immune deficiencies, and infections 1-10 years after cancer diagnosis. RESULTS We found elevated incidence rate ratios (IRRs) for many immune-related conditions in survivors of DLBCL compared with other cancer survivors, including significantly and consistently elevated IRRs for viral and fungal pneumonias (up to 10.8-fold), meningitis (up to 5.3-fold), as well as humoral deficiency (up to 17.6-fold) and autoimmune cytopenias (up to 12-fold). IRRs for most conditions remained high even in the late survivorship period (5-10 years after cancer diagnosis). The elevated risks could not be explained by exposure to chemotherapy, stem-cell transplantation, or rituximab, except for IRRs for humoral deficiency, which were consistently higher after the incorporation of rituximab into DLBCL treatments. CONCLUSION To our knowledge, this is the largest cohort study with extended follow-up to demonstrate impaired immune health in survivors of DLBCL. The observed persistent, elevated risks for autoimmune diseases, immune deficiencies, and infectious conditions may reflect persistent immune dysregulation caused by lymphoma or treatment and may lead to excess morbidity and mortality during survivorship. Improved understanding of these risks could meaningfully improve long-term care of patients with DLBCL.