The natural development of cancers as well as the measures to fight the disease are often long processes that require decades of follow up. Available information on long-term survival will thus often appear outdated and irrelevant. A few years ago, period-survival analysis was proposed as a means to obtain more up-to-date information on long-term cancer survival. This article assesses period and conventional cohort-based survival analyses on their ability to predict future survival. Based on historical data from the nationwide Swedish Cancer Registry 5-, 10- and 15-year relative survival actually observed for patients diagnosed at one particular point in time are compared to the most recent period and cohort-based survival estimates available at that point in time. The study shows that period analysis can, in most cases, be used to provide more up-to-date long-term estimates of cancer survival. Period analysis reduces the time lag of the survival estimates by some 5-10 years for all cancers combined and especially affects the survival estimates for small intestine carcinoids, meningioma and intracranial neurinoma of the brain, non-seminoma testicular cancer, chronic lymphocytic leukaemia and Hodgkin's lymphoma.