Predicting the survival of cancer patients recently diagnosed in Sweden and an evaluation of predictions published in 2004.

BACKGROUND: Estimates of cancer patient survival from traditional cohort-based methods may be heavily influenced by the survival experience of patients diagnosed many years ago and may not therefore be relevant to recently diagnosed patients. Period-based analysis provides better predictions of survival for recently diagnosed patients than cohort analysis. The first aim of this study is to provide predictions of the long-term survival of patients diagnosed in 2005-2009 using period analysis and to compare these estimates to the latest available cohort estimates. The second aim is to evaluate predictions published in 2004 regarding the future survival of patients diagnosed 2000-2002.
MATERIAL AND METHODS: We studied survival among patients diagnosed 1985-2009 reported to the nationwide, population-based Swedish Cancer Registry. Predictions of the future relative survival for recently diagnosed patients were made using period analysis with a window of 2005-2009.
RESULTS: The predictions made using period analysis and published in 2004 agreed well with the subsequently observed survival, with common sites showing a better agreement than less common sites. Updated predictions suggest that patients diagnosed today can expect improved survival for many forms of cancer.
CONCLUSIONS: Period, rather than cohort, survival analysis should be used if the primary aim is to predict the future survival of recently diagnosed patients. Recently diagnosed cancer patients can, for many forms of cancer, expect an improved survival compared to patients diagnosed only a few years earlier.