BACKGROUND: HPV-related cancer is highly preventable through HPV vaccination and cancer screening, but people experiencing homelessness or housing instability (PEH) may not engage in these behaviors due to conflicting priorities. This systematic review synthesized and estimated HPV-related cancer prevention behaviors among PEH. METHODS: Using PRISMA guidelines, articles published before 2023 were located via PubMed, Ovid/Medline, CINAHL, and Embase. Full-text, peer-reviewed studies that measured HPV-related cancer prevention in any sample of people experiencing homelessness were included. Two researchers abstracted data independently, with high interrater reliability (>
90%). Results were narratively summarized with consensus, and proportions were compared using preventive behavior. RESULTS: After reviewing 405 articles, we included 18 articles from the U.S. from 1998-2022. There were 6,674 people (e.g., women, youth, men who have sex with men) experiencing homelessness assessed for HPV-related cancer prevention behaviors. Pooled prevalence was approximately 59.8% (±6%) for cervical cancer screening in the last 3 years and 42.9% (±4.7%) for HPV vaccination initiation. Other factors related to housing instability and HPV-related cancer prevention included gender, sexual trauma, and procedural pain, with mixed results for housing status and HPV knowledge. CONCLUSIONS: Findings demonstrate the varied adherence to HPV-related cancer prevention, with rates consistently below recommended World Health Organization guidelines. Future studies should adjust for specific risk factors in modeling that may be associated with or modified by the effects of homelessness and evaluate upstream prevention (e.g., vaccination) and other types of HPV-related cancer (e.g., anal cancer).