CHILDHOOD AND ADOLESCENT CANCER IN SPAIN - MORTALITY TIME TRENDS 1956-1990

Using log-linear Poisson modelling, trends in childhood cancer mortali ty among the population under 20 years of age in Spain are described o ver the 35-year period from 1956 to 1990. Overall cancer mortality and seven specific sites were considered: all leukaemias, Hodgkin's disea se, non-Hodgkin's lymphomas, malignant brain tumours, kidney cancer, m alignant bone neoplasms, and a broad category of ill-defined tumours. An age-period-cohort model was used to analyse the influence of age, p eriod of death and birth cohort. Recent trends were estimated by restr icting analysis to the last three 5-year periods. In general, mortalit y began to decline at the beginning of the 1970s, with reductions of 3 6% in males and 45% in females being registered between 1966-1970 and 1986-1990. The use of age-period-cohort models revealed an initially r ising period effect attributable to diagnostic advances. The decline i n mortality in post-1965 generations and the final downturn in the per iod effect are both most certainly a consequence of the remarkable pro gress achieved in the treatment of such tumours. During the final 15 y ears, there was a relative decline in mortality of approximately 20% e very 5 years. However, in the case of malignant renal tumours in males and malignant bone tumours and non-Hodgkin's lymphomas in both sexes the situation remained stable.