Changes in period and cohort effects on haematological cancer mortality in Spain, 1952-2006

Roberto Pastor-Barriuso,Gonzalo López-Abente

doi:10.1186/1471-2407-14-250

Abstract

BackgroundIn contrast to other haematological cancers, mortality from non-Hodgkin’s lymphoma and multiple myeloma increased dramatically during the second half of the 20th century in most developed countries. This widespread upward trend remains controversial, as it may be attributable either to progressive improvements in diagnosis and certification or to increasing exposures to little-known but relevant risk factors.MethodsTo assess the relative contribution of these factors, we analysed the independent effects of age, death period, and birth cohort on haematological cancer mortality rates in Spain across the period 1952-2006. Weighted joinpoint regression analyses were performed to detect and estimate changes in period and cohort curvatures.ResultsAlthough mortality rates were consistently higher among men, trends across periods and cohorts were virtually identical in both sexes. There was an early period trend reversal in the 1960s for Hodgkin’s disease and leukaemia, which was delayed to the 1980s for multiple myeloma and the 1990s for non-Hodgkin’s lymphoma. Birth cohort patterns showed a first downturn for generations born in the 1900s and 1910s for all haematological cancers, and a second trend reversal for more recent cohorts born in the 1950s and 1960s for non-Hodgkin’s lymphoma and leukaemia.ConclusionsThe sustained decline in Hodgkin’s disease mortality and the levelling off in leukaemia seem to be driven by an early period effect linked to improvements in disease treatment, whereas the steep upward trends in non-Hodgkin’s lymphoma and multiple myeloma mortality in Spain are more likely explained by a cohort effect linked to better diagnosis and death certification in the elderly. The consistent male excess mortality across all calendar periods and age groups points to the importance of possible sex-related genetic markers of susceptibility in haematological cancers.

Highlights

In contrast to other haematological cancers, mortality from non-Hodgkin’s lymphoma and multiple myeloma increased dramatically during the second half of the 20th century in most developed countries
Morbidity and mortality from haematological cancers in Spain are fairly similar to the European average [2], with age-adjusted incidence and mortality rates of 2.4 cases and 0.3 deaths per 100,000 personyears for Hodgkin’s disease, 10.0 cases and 3.3 deaths for non-Hodgkin’s lymphoma (NHL), 3.5 cases and 2.2 deaths
Time trends Age-adjusted mortality rates of haematological cancers were consistently higher among men than among women over all 5-year periods, with male-to-female rate ratios ranging from 1.65 to 2.17 for Hodgkin’s disease, 1.48 to 2.20 for NHL, 1.22 to 1.43 for multiple myeloma, and 1.27 to 1.75 for leukaemia (Table 1)

Summary

Introduction

In contrast to other haematological cancers, mortality from non-Hodgkin’s lymphoma and multiple myeloma increased dramatically during the second half of the 20th century in most developed countries This widespread upward trend remains controversial, as it may be attributable either to progressive improvements in diagnosis and certification or to increasing exposures to little-known but relevant risk factors. The identification of significant trend changes in period and cohort effects may help explain some features of the observed time trends in haematological cancer mortality and assess the relative contribution of both long-term exposure to risk factors and recent improvements in diagnosis and treatment To this end, the present study sought to analyse changes in period and cohort effects on haematological cancer mortality in Spain across the period 1952-2006

Methods

Results

Discussion

Conclusion