Individual cancer risk as a function of current age and risk profile.

Behavioural changes are an important partner in the fight against cancer (primary prevention or the choice to participate in secondary prevention). To make such behavioural changes, people need to have a correct assessment of their own risk, which is often underestimated or overestimated. These risk estimates depend, among others, on the calculation method that is used. Currently, the method that is used most often is 'indirect cumulative risk' (ICR). We discuss several drawbacks of using ICR in individual counselling and therefore use an alternative method. In this alternative (life table method) we calculated 10-year risks for a whole range of cancers as a function of the current age and risk profile, while taking into account other causes of death. These estimates can easily be used to give an individualized assessment of the risk of cancer. Regardless of the risk estimation method used, the risk needs to be broken down for 'risk factors'. If only the risk for an average person of the population is given, this means a small overestimation for the non-risk group, but a significant underestimation for the at-risk group. When we compare the life table risk as a function of risk factors to the more commonly used ICR, large differences are found, especially in prostate, breast and lung carcinomas. The life table method, although it has certain limitations, has advantages over the ICR method for individual counselling. To our knowledge this is the first overview in which 10-year risks as a function of the current risk profile are given for multiple cancers. The calculated risks are primarily intended to better inform people who are considering preventive measures. For example, for a 40-year-old woman without familial risk who is considering the pros and cons of breast cancer mammographic screening, it is more interesting to know that she has a 0.7% chance of getting breast cancer in the next 5 years, rather than being told that 11% of women get breast cancer during their lives (ICR 0-74). Current smokers can now be given absolute risk reduction estimates of smoking cessation. To keep the life table risk estimates up to date, they must be repeated every couple of years, using up-to-date incidence and mortality data.