Lymphoid neoplasm incidence by WHO subtype in Australia 1982-2006

There are limited data characterizing the subtype-specific incidence of lymphoid neoplasms in the World Health Organization (WHO) Classification era. Data were obtained on all incident lymphoid neoplasms registered in Australia during 1982-2006. Subtypes were grouped using the InterLymph nested hierarchical classification, based on the 2008 WHO Classification. Temporal trends were examined using Joinpoint regression; average annual percentage change in incidence was computed. Multiple Poisson regression was used to compare incidence by sex and age. The incidence of all non-Hodgkin lymphoma (NHL) increased by 2.5%/year during 1982-1996 and was stable thereafter. During 1997-2006, several mature B- and natural killer (NK)-/T-cell NHL subtypes increased in incidence, including diffuse large B-cell (1.3%/year), follicular (2.5%/year), Burkitt (6.8%/year), marginal zone (13.2%/year), mantle cell (4.2%/year), peripheral T-cell lymphoma (4.7%/year) and plasmacytoma (7.1%/year). While chronic lymphocytic leukemia incidence was stable, small lymphocytic lymphoma incidence declined (8.1%/year). Hodgkin lymphoma (HL) incidence increased during 1997-2006 (2.2%/year), both classical (4.3%/year) and nodular lymphocyte predominant (12.1%/year) HL. Diagnostic artifact, evidenced by a sustained decline in the incidence of NHL not otherwise specified (NOS; 5.8%/year) and lymphoid neoplasms NOS (5.6%/year), limits the interpretation of temporal trends for some subtypes. A marked male predominance was observed for almost all subtypes. Incidence of mature B- and NK-/T-cell NHL subtypes increased sharply with age, except for Burkitt lymphoma/leukemia. For HL subtypes, a bimodal age distribution was only evident for nodular sclerosis HL. Variation in incidence patterns over time and by sex and age supports etiological differences between lymphoid neoplasm subtypes.