P1676: risk of dementia in older patients treated with chemotherapy for lymphoma: a danish nationwide cohort study

Topic: 35. Quality of life and palliative care Background: Dementia is a common cause of memory problems, and it affects more than 7% of the world’s population above the age of 65 years. Cancer patients can experience memory difficulties due to a variety of causes such as dementia, stress, depression, anxiety, or chemotherapy-related cognitive impairment (CRCI) resulting in reduced memory, executive functions, and cognition. These symptoms can persist years after treatment, mimicking the symptoms of dementia. Cancer and dementia have been shown to have an inverse relationship with a reduced risk of dementia after cancer in general. As an increasing number of older patients are treated for lymphoma, the group of survivors is growing, thus increasing the need for understanding the long-term complications for older patients. Aims: The aim of this study was to investigate the risk of dementia in older patients treated with chemotherapy for lymphoma compared with matched comparators. Methods: Patients with lymphoma were identified in the Danish National Lymphoma Registry (LYFO). All patients diagnosed with a non-central nervous system lymphoma of any type at age ≥65 years were included. Patients should be diagnosed, treated with chemotherapy, and achieved complete remission (CR)/complete remission unconfirmed (CRu) between January 1, 2000, and December 31, 2018. Patients with dementia before inclusion were excluded. Dementia was defined as either having an ICD-10 code for dementia in the Danish National Patient Registry or the Danish Psychiatric Central Research Register or a redeemed prescription for dementia-specific treatments in the National Prescription Registry. Patients were followed from CR/CRu. All patients were matched with five random comparators from the general population on sex, year of birth, and Charlson Comorbidity Index. Patients and matched comparators were followed until a diagnosis of dementia, death, or censoring (emigration or December 31, 2018). The cumulative risk of dementia was calculated using the Aalen-Johansen estimator with death as competing risk. 5-year risk differences (RD) were calculated using a pseudo-observations approach. Crude cause-specific hazard ratios (HR) were calculated by Cox regression. Results: The study included 3,845 older patients with lymphoma and 19,225 matched comparators. The majority were men (53.7%), and the median age was 72 years. Most patients were diagnosed with Diffuse Large B-cell lymphoma (58.4%) and treated with CHOP-like regimens (69.2%). Median follow-up for patients was 6.3 years. The cumulative incidence of dementia over the entire study period was significantly lower for patients with lymphoma compared with the matched comparators (p<0.001). The overall crude cause-specific HR was 0.79 (95% Confidence Interval (CI): 0.67;0.93). Figure 1 shows the 5-year RD in subgroups of patients with lymphoma compared with matched comparators. The risk of dementia was significantly lower for patients with lymphoma in all subgroups except for Hodgkin lymphoma and the youngest patients (age group ≤69 years). The 5-year risk was significantly lower among patients in all time periods (2000-2004, 2005-2009, 2010-2014), but with a trend towards lower RD in the most recent years. Summary/Conclusion: The overall risk of dementia for older patients with lymphoma treated with chemotherapy was significantly lower compared with age, sex, and comorbidity-matched comparators from the general Danish population. Stratified by age the risk was significantly lower in all age groups except in the youngest patients ≤69 years.Figure 1: 5-year absolute crude risk differences of dementia in subgroups between patients with lymphoma and comparators. Abbreviations: RD, risk differences; CI, confidence interval; ECOG PS, ECOG Performance Status. Keywords: Lymphoma, Elderly, Late complications and outcome