[Population ageing effect on number of cancer cases: Italian cancer registries data].

OBJECTIVE: To describe causes of cancer incidence increase. We identified and quantified a population ageing factor, a factor due to incidence trend of cancer sites with early-diagnosis interventions and a remainder factor (concerning all other cancer sites). METHODS: We calculated incidence rates for two calendar period (1993-95 and 2003-05).We used data from Cancer Registries with at least one incidence year available for each period (jointly for males and female). We compared crude and age-adjusted rates by the direct method for prostate cancer, breast cancer, colorectal cancer, melanoma of the skin cancer, thyroid cancer, group of other cancer sites and for all cancer sites (but non-melanoma skin cancer). RESULTS: Since 1993-95 to 2003-05 all cancer crude incidence rates have been increasing 17.9% (from 555.4 cases for 100,000 inhabitants/years to 654.8). If population age structure had remained the same, rates would have increased only 6.6% (from 555.4 to 592.0): almost 2/3 of observed increasing are due to population ageing. The remainder part of the increasing is due to incidence trend of cancer sites with early-diagnosis interventions (that anticipates the diagnosis). CONCLUSIONS: This study helps to quantify the incidence increase due to population ageing and the raise due to trend of cancer sites with early-diagnosis interventions.