The Nordic cancer registries have carried out a larger study to calculate the cancer incidence in the Nordic countries up through the year 2020. In this study the number of new cancer cases in Norway is estimated to increase with 42% for males and 36% for females. The escalation in cancer cases is mainly due to the ageing of the population, while a smaller part of the increase are due to an increase in risk.
A small increase in cancer risk
From 1958 to 1997 the cancer risk in Norway has increased with more than 60%. Based on trends in this period, the risk for 24 different cancer sites is estimated up to the year 2020. For males, the overall cancer risk seems to level off. The risk of cancers in the floor of the mouth, prostate and testis is estimated to have the highest increase, while cancers in the lip and stomach is excepted to have the highest decrease. For females, the overall cancer risk is also expected to level off, but only after an increase up to about the year 2005. The increase is partly caused by the initiation of the mammography-screening programme for early detection of breast cancer. In addition to breast cancer, a large increase in the risk of lung cancer among females is expected, due to women’s smoking habits. The risk of multiple myeloma, cervix cancer and Hodgkin’s disease will have the highest decrease.
The effect of ageing
The risk of cancer increases with age. When diagnosed with cancer, two-third of the patients are 65 years or older. Information from Statistic Norway shows that the age group over 65 years will increase from 15% today to 18% in 2020. A longer life expectancy and the ageing of the large birth cohorts following the Second World War will lead to this increase in the oldest age groups the next 20 years. The number of new cancer cases are calculated to increase with 42% for males, of which 4% is due to an increase in risk and 38% is caused by changes in the age structure. Among females the number of new cases are estimated to increase with 36%, of which 9% is due to increased risk and 27% is caused by changes in the age structure in the population.