Period Survival

Period Survival is a method which enhances up-to-date monitoring of survival. In contrast to traditional cohort analysis of survival, Period analysis derives long-term survival estimates exclusively from the survival experience of patients within some recent calendar period. Turn Period Survival on or off by marking or clearing the Period Survival box on the Survival Statistic tab.

When Period Survival is used, you may only set annual survival intervals (though calculation and display of intervals will be in terms of months). When you mark or clear the Period Survival box, SEER*Stat will display a warning message explaining this change. It may also attempt to automatically update the intervals listed in the Intervals and Cumulative Summary sections of the Survival Parameters tab, if the number of months per interval was previously set to 1, and if the result would be a valid set of intervals. In either case, switch to the Parameters tab and verify that these settings reflect what you want.

In order for Period Survival tables to be created, various standard survival life tables need to be produced. These tables can be displayed if the Period Contributors (Std Life) box is marked in the Display section of the Survival Parameters tab. Each Period Survival table is created from extracting specific survival interval statistics from each contributing standard survival life table. The Maximum Years of Survival and Years per Survival Cohort controls, in the Intervals section of the Survival Parameters tab, help define how many years of diagnosis to place into each specific contributing standard survival life table, and how far survival is to be monitored.

To produce the required standard survival life tables which contribute to the Period table, a special year of diagnosis table variable is produced for each Period Survival run. Because of this, the year of diagnosis variable cannot be used in the case selection statement nor as a table variable. If they are, SEER*Stat will issue an error message when you try to execute the session.

For a detailed description of the Period Survival analysis, please refer to:

Brenner H, Hakulinen T. Advanced detection of time trends in long-term cancer patient survival: experience from 50 years of cancer registration in Finland. Am J Epidemiol 2002 Sep 15;156(6):566-77.

For brief explanations of several methods of survival analysis, including Period Survival, please refer to:

http://srab.cancer.gov/survival/cohort.html