Impact of postal correspondence letters on participation in cancer screening: a rapid review

The purpose of this rapid review was to identify and synthesize evidence on the impact of postal correspondence letters on participation in cancer screening and to determine whether impact varied by cancer site or inclusion of the participant's physician's name within the letter (i.e., physician-linked). PubMed and the Cochrane Database of Systematic Reviews were searched for English-language systematic reviews and randomized controlled trials (RCTs) published up until October 2019. One reviewer completed citation screening and data extraction with 30% verification by a second reviewer. Systematic reviews and RCTs were appraised using A MeaSurement Tool to Assess systematic Reviews (AMSTAR) 2 and Cochrane Risk of Bias 2.0 tools, respectively, by one reviewer with complete verification by a second reviewer. Findings from systematic reviews and RCTs were examined separately and presented narratively. Six systematic reviews and 18 RCTs of generally low quality were included. Evidence generally demonstrated a positive impact of a letter as compared to no letter or usual practice on screening participation. This finding was consistent for breast cancer and cervical screening participation but inconsistent for colorectal cancer screening participation. Studies comparing physician-linked letters to no letters or usual practice reported similar effect estimates as those examining letters in general. Limited and inconsistent evidence was identified on the impact of physician-linked letters as compared to non-physician-linked letters on screening participation. Evidence identified in this rapid review, and other contextual and implementation considerations, may be useful for jurisdictions considering how to promote cancer screening participation.