Many instruments have been proposed to assess residents' knowledge about participation in cancer screening programmes, but their measurement properties are poorly elucidated. This impedes consistent use of instruments, making it challenging to conduct evidence synthesis and meta-analysis about effective interventions and programmes.

In recent years there has been an increased focus on the importance of ensuring that residents make informed choices about participation in population-based cancer screening (Ghanouni et al., 2016). An informed choice is defined as ‘one that is based on relevant knowledge, consistent with the decision-maker's values and behaviourally implemented’ (Marteau et al., 2001). Thus, obtaining relevant knowledge is central for an informed choice.

It is usually expected that residents make the decision about whether or not to participate in cancer screening without consulting health care professionals. Therefore, it is essential to have comprehensible and useful self-administered information materials, which can contribute to knowledge about cancer screening and support individuals to make informed decisions about participation or not (European Colorectal Cancer Screening Guidelines Working Group et al., 2013). Several studies have developed and evaluated interventions, which aim to improve informed choice and residents' knowledge about cancer screening (Gabel et al., 2020a; Gabel et al., 2020b; Hersch et al., 2015; Larsen et al., 2021; Mathieu et al., 2007; Mathieu et al., 2010; Reder and Kolip, 2017; Roberto et al., 2020; Smith et al., 2010; Trevena et al., 2008). However, these studies lack standardized instruments for assessing knowledge related to cancer (Ghanouni et al., 2016). This is problematic in terms of the validity of reported findings. Furthermore, it hampers comparison of results across patient populations making it more difficult to make general recommendation on requirements for informed choice.

It can be difficult and time consuming to choose the most appropriate measurement instrument, and biased inferences may be drawn if the chosen instrument does not measure the construct of interest, or if the instrument used has not been validated in the target population in which the investigation is conducted (Mokkink et al., 2006; Terwee et al., 2007). The best method to assess the validity of instruments is through a systematic review that appraises the instruments´ measurement properties according to key criteria such as the COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) guideline for Patient-Reported Outcome Measures (PROM) (Scholtes et al., 2011; Terwee et al., 2007).

This systematic review aims to identify and critically appraise the measurement properties of instruments measuring knowledge about cancer screening in individuals eligible for population-based screening.