EPID-11. Educational and regional differences in population-based incidence and survival of primary CNS lymphoma in Finland

Abstract INTRODUCTION Primary central nervous system lymphoma (PCNSL) is a rare disease with increasing incidence worldwide, especially in Western countries. Finland has the highest reported age-adjusted incidence globally (0.68/100,000 person-years from 2007-2017). The median incidence globally is approximately 0.4/100,000 person-years. There are no previous studies comparing Finland’s incidence and survival between regional levels and various socioeconomic groups. In previous study in Finland 2-year and 5-year age-adjusted relative survival rates were 33% and 26% during 2007-2017. Survival among elderly people was dismal. Aim of this study was to investigate differences and factors explaining the incidence and survival rates. MATERIAL AND METHODS Data were extracted from Finnish Cancer Registry by tumor location for cases with LBCL diagnosed during 2007-2022. RESULTS Data included 623 PCNSL patients (48% women), 27% of whom had higher, 34% secondary and 39% primary/unknown education. Age-adjusted overall incidence was 0.89/100,000 during 2007-2022. Incidence for females was 0.79/100,000 person-years and for males 1.0/100,000 person-years. During 2007-2022 the percentage of PCNSL cases of all LBCL cases remained stable, being 6.4%. In 2007-2022 the 2-year and 5-year age-adjusted relative survival rates were 38% (95% Cl 32-43%) and 30% (95% Cl 25-36%) respectively. Concerning five collaborative regions of Finland, incidence rates varied in between 0.80-0.99/100,000 person-years during 2007-2022 (p=0.436). The 2-year and 5-year age-adjusted relative survival rates of collaborative regions varied in between 25-56% and 16-45% (p<0.001). Survival rates did not differ by educational level (p=0.282). CONCLUSIONS While incidence of PCNSL is still increasing in Finland, the proportion among patients with aggressive lymphomas remains stable. There was no significant difference in the incidence rates between educational levels or collaborative regions. Survival was slightly improved compared to previous study with a trend towards better survival among higher education level. Regional survival rates varied significantly. Keywords: pcnsl, primary central nervous system lymphoma, incidence, survival, regional, education level