Cancer prevalence in United States, Nordic Countries, Italy, Australia, and France: an analysis of geographic variability.

BACKGROUND: The objectives of this study were to quantitatively assess the geographic heterogeneity of cancer prevalence in selected Western Countries and to explore the associations between its determinants. METHODS: For 20 cancer sites, 5-year cancer prevalence, incidence, and survival were observed and age standardised for the mid 2000s in the United States, Nordic European Countries, Italy, Australia, and France. RESULTS: In Italy, 5-year crude prevalence for all cancers was 1.9% in men and 1.7% in women, while it was ∼1.5% in all other countries and sexes. After adjustment for the different age distribution of the populations, cancer prevalence in the United States was higher (20% in men and 10% in women) than elsewhere. For all cancers combined, the geographic heterogeneities were limited, though relevant for specific cancers (e.g., prostate, showing >30% higher prevalence in the United States, or lung, showing >50% higher prevalence in USA women than in other countries). For all countries, the correlations between differences of prevalence and differences of incidence were >0.9, while prevalence and survival were less consistently correlated. CONCLUSION: Geographic differences and magnitude of crude cancer prevalence were more strongly associated with incidence rates, influenced by population ageing, than with survival rates. These estimates will be helpful in allocating appropriate resources.

Incidence of thyroid cancer in Italy, 1991-2005: time trends and age-period-cohort effects.

BACKGROUND: In Italy, some of the highest incidence rates (IRs) of thyroid cancer (TC) worldwide have been reported. PATIENTS AND METHODS: TC cases <85 years of age reported to Italian cancer registries during 1991-2005 were included. Age-standardized IRs were computed for all TC and age-period-cohort effects were estimated for papillary TC. RESULTS: IRs of TC were twofold higher in 2001-2005 than in 1991-1995 (18 and 8 per 100,000 women, 6 and 3 per 100,000 men, respectively). Increases were similar in the two sexes and nearly exclusively due to papillary TC. Increases of papillary TC by birth cohort were found in both sexes and among all age groups between 20 and 79 years. Age-period-cohort models showed a strong period effect in both sexes (rate ratio for 2001-2009 versus 1991-1995 = 2.5 in women and 2.3 in men), although IRs peaked at an earlier age in women (45-49 years) than men (65-69 years). CONCLUSION: The strength of the period effect in both sexes and the earlier onset in women than men strongly implicated increased medical surveillance in the upward trends of papillary TC incidence in Italy. The consequences of the current intense search for TC on morbidity and possible overtreatment, especially among young women, should be carefully evaluated.