OI Ljubljana

New method for estimating life-years gained in population-based cancer screening programmes (S-LYG)

New method for estimating life-years gained in population-based cancer screening programmes (S-LYG)

ARRS code: J3-2537
Title: New method for estimating life-years gained in population-based cancer screening programmes (S-LYG)
Duration: 09.2020- 08.2023
Applicant research organisation: 302 INSTITUTE OF ONCOLOGY LJUBLJANA
Participating research organisations: 381 University of Ljubljana, Medical faculty and 3333 Nacional institute of public health
Project leader: 23050 VesnaZadnik
Financing: Slovenian Research Agency



Within population-based screening programmes we screen a large number of apparently healthy people through screening tests in order to detect and treat precancerous or early-stage cancerous lesions. At the population level, the benefits of screening are reflected in reduced incidence and mortality. Though we have most of the necessary information to monitor the effectiveness of screening programmes, the effectiveness measures that are currently in place are insufficient. Classical indicators are available too late (mortality) or else their calculations are subject to biases that limit their usability (survival).


The aim of the project is to contribute to further reducing the burden of cervical, breast, colon and rectal cancers both in Slovenia and abroad by developing a new method that will enable organised screening programmes to more strategically and quickly adapt screening policy to the real-world situation.

Project goals:

  1. Develop a new S-LYG method that will allow faster monitoring of the screening programme effectiveness without the common biases not corrected for within existing methods. This will allow for better management of the programme and faster introduction of changes to the screening policy - either when establishing new organised screening programmes or when changing the screening policies of existing programmes.
  2. Test the new method via linking data from all three cancer screening registries and the National Cancer Registry.
  3. Reduce the complexity of calculating the new indicator and set a minimum data set so as to increase the usability of the method in everyday practice.


As part of the proposed project, we will develop a new S-LYG method based on the calculation of the life years gained in persons who responded to screening invitation compared with those who did not. We will overcome lead time and length time biases by appropriately defining the start of follow-up and the (observed) outcome.

Within the framework of the project, the S-LYG method will be tested using real data from all three of Slovenia's national cancer screening programmes: ZORA (cervical cancer), DORA (breast cancer), and Svit (colorectal cancer). These will be linked to the population-based cancer registry. The test example will be very demanding to perform due to differences between screening programmes in target groups, invitation practices and effects, and will promptly reveal potential shortcomings of the method that will need to be corrected/eliminated.

Furthermore, we will adapt the S-LYG method to use on a minimum set of routinely collected data (aS-LYG) from population registers, mortality tables and already established periodic screening programme indicators, such as the number invited and participation rates by gender, age and calendar year. We will pay particular attention to the feasibility of introducing the adjusted aS-LYG as a new indicator for the effectiveness of screening programmes, which could then be included in regular reporting.


The new S-LYG/aS-LYG method will allow for an unbiased and up-to-date calculation of the number of life years gained among persons who responded to the screening invitation. S-LYG will be useful in the management of screening programmes, their promotion and in evaluation of the effects of changes in screening policies, while it may also be used in decision making regarding the introduction of new screening programmes.


The research team of the proposed project includes heads from the ZORA, DORA and Svit screening registries as well as from the population-based Cancer Registry, who are experts in cancer epidemiology and cancer screening as well as the internationally recognised team of medical biostatistics experts at the Institute for Biostatistics and Medical Informatics of the University of Ljubljana, for whom survival analysis is a core topic of methodological research.



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