Lifetime risk is the probability, usually expressed as a percentage (e.g. 33%) or using odds (e.g. 1 in 3), of developing a condition such as cancer over the course of a lifetime. It is an estimation that is based upon current incidence and mortality rates and therefore is calculated under the assumption that the current rates (at all ages) will remain constant during the life of the new born child. There are two methods used to calculate lifetime risk on this site: "Current Probability" and the AMP method.
"Current Probability" is a method developed to calculate lifetime risk by Goldberg et al in 1956 and termed "Current Probability" by Esteve et al in 1994. It was an improvement over older methods because it uses a life table approach to calculating lifetime risk in order to take into account that people die from other causes (also known as competing risks).
The AMP method (Lifetime Risk Adjusted for Multiple Primaries), developed by Sasieni et al in 2011, is similar to the "Current Probability" method but takes into account that for some cancers (e.g. breast cancer) it is possible to have more than one diagnosis over the course of a lifetime. Not adjusting for this can over-estimate the risk in some cancer types.