GENERAL COMMENTS

This paper describes a protocol for a systematic review and synthesis of qualitative studies to ascertain benefits and barriers to participation in colorectal cancer screening. The manuscript is well written and clear. The main issue is that the introduction does not offer a compelling reason for this specific review. It contains a good introduction to the topic and then offers a descriptive summary of the current evidence. I think for a research protocol it would be more interesting to get a much clearer sense about how the methods used can be justified. As it stands the aim of the review does not clearly follow the research summary. For example it is not clear why qualitative research could address the questions about benefits and barriers to screening participation. The review also uses a number of interesting methods and it would be useful if there was more information in the introduction about their rationale and potential value. This is particularly true of the framework and the data abstraction and extraction methods.

In the method I did not really follow how aspects of the framework map onto the search strategy (i.e. how did the framework determine eligibility criteria, the mapping of individual components such as population, intervention, outcomes, etc). the meta data analysis seems to be central but is not clearly justified or described in either the introduction or the method section. In the method I struggle to get a clear sense of processes underlying meta- theory i.e. what is meant by a creative dynamic process and more importantly how will this aid interpretation of the available evidence in this area. This relates to another major issue that despite already presenting some descriptive summary of existing literature there is no reference to the current depth and width of the literature. The entire scope of the review relies on sufficient studies falling into the search criteria. Given that the underlying issue is relatively niche (compared to other health behaviours) and novel I am not convinced that there are enough qualitative studies for this approach to be successfully applied. Once again a much clearer justification of the overall aims would be important to highlight the potential value of this paper.