Time-space trends in cancer incidence in The Netherlands in 1989–2003

Incidence of cancer may vary within a country and over time because of previous differences in exposure to risk factors or interventions for early detection (screening). This study describes time-space trends of incidence of common cancer sites across the Netherlands during the period 1989–2003 and speculates on the reasons for the observations. From the Netherlands Cancer Registry, World standardized incidence rates per municipality were smoothed calculating weighted averages for each 2 km by 2 km grid of the population mid-points of neighbouring municipalities and presented as map animations. Spatial relative changes in incidence were estimated by comparing the periods 1989–1994 and 1998–2003. Complete time-space trends can be found as map animations on http://maps.ikcnet.nl. The incidence of cervical and stomach cancer (for both sexes) decreased, being higher in the cities than in the rural areas during all periods and contrasting the trends in colorectal and breast cancer. The relative increase in incidence of lung cancer among females was highest in the rural north, but the incidence remained higher in the cities of the mid-west Netherlands. For males, there was a marked decrease in lung cancer incidence across the country since 1991. Incidence of melanoma increased, rates being twice as high in the coastal area than in the cities. Prostate cancer maps largely replicated the known history of PSA-testing in the Netherlands. Time-space cancer incidence patterns gave insight into effects of changes in exposure to risk determinants and early detection. The maps illustrate marked potential for cancer prevention at the national and regional level