Objective: to report and analyse time trends in cancer incidence among children (0-14 years of age), adolescents (15-19 years) and young adults (20-24 years) living in the Italian province of Trieste (2003 population, 242,000), between 1972 and 2003.
Design: population-based study of descriptive epidemiology.
Setting and participants: the new cases of cancer diagnosed to the residents of the province of Trieste below 25 years of age were extracted from the database of the Trieste Cancer Registry (period 1972-1994) and from the database of the Friuli-Venezia Giulia Cancer Registry (period 1995-2003), according to the International Classification of Childhood Cancer (3rd edition).
Main outcome measures: age-specific and age-standardized (Italian 1981 census population as standard) incidence rates, by diagnostic group, sex and period of diagnosis. Time trend in incidence was analysed by using a Poisson regression model adjusted for calendar year, sex and 5 year age-group, and was expressed as annual percent change (APC) in rates.
Results: in the period 1972-2003, the new cases of cancer were 168 in the age-group 0-14 years, 79 in the age-group 15-19 years and 111 in the age-group 20-24 years, while the person-years at risk were respectively: 1,050,027; 431,673; 496,450. The APC in the incidence of all cancers combined was 2.3% (IC 95% 0.6%-3.9%) in children, 4.4% (IC 95% 1.8%-7.1%) in adolescents and 5.1% (IC 95% 2.8%-7.5%) in young adults. Hodgkin lymphomas (APC =12.7%; IC 95% 2.6%-23.7%; 7 cases) in the age-group 0-14 years, skin melanomas and carcinomas (APC =8.2%; IC 95% 4.5%-12.0%; 49 cases) and central nervous system tumours (APC = 6.4%; IC 95% 1.5%-11.5%; 25 cases) in the age-group 15-24 years were the malignancies characterised by the highest increase in incidence.
Conclusion: the increase in incidence rates observed in this study can be only partly explained by the small number of ascertained cases, by an improvement in diagnostic techniques and by more efficient registration. However, few environmental and hereditary factors are consistently associated with cancers affecting young people. Therefore, it is imperative to continue to carry out descriptive and analytical studies with primary prevention as the ultimate aim.