Identifying barriers to cancer screening among people experiencing homelessness: a systematic review

People experiencing homelessness (PEH) face significant health disparities including higher morbidity from chronic diseases such as cancer. Despite the availability of screening programs for breast, colorectal, lung, and cervical cancers, screening availability and participation among PEH remains low. The impact of cancer screening is profound, with the ability of early detection to improve treatment prognoses, reducing the burden of cancer-related complications. Our review aims to assess current screening rates for PEH globally and identify barriers impacting their uptake. A literature search was conducted using Medline, Embase, and Scopus databases to search terms related to homelessness and cancer screening. Records were managed in Covidence and screened independently by two reviewers at both the title/abstract and full text stages. Inclusion criteria was as follows: studies must focus on PEH at the time of data collection or clinical encounter and discuss at least one of the cancer screening programs of interest (lung, colorectal, cervical, or breast). Each eligible study was independently extracted by two reviewers using a standardized data extraction template. Risk of bias was assessed using the appropriate Joanna Briggs Institute critical appraisal tool. Due to heterogeneity in study designs and outcomes, findings were summarized using a narrative synthesis. Our findings, across 36 papers, indicated cancer screening rates for PEH were typically below 60%, other than three outliers which reported higher rates of cervical cancer screening uptake. We identified multiple intersecting barriers that impacted screening utilization. Patient level barriers included: competing priorities, fear/anxiety about diagnosis, and transportation. Provider level barriers encompassed: communication gaps and poor patient-provider relationships. Finally, system level barriers were identified which related to health literacy, access to services, and healthcare system navigation. Cancer screening disparities among PEH are shaped by interacting patient, provider, and system level barriers. These findings suggest that improving screening uptake requires more than making screening available; interventions must also address the practical, relational and structural barriers that prevent PEH from accessing preventative care.