The Epidemiology of Cancer Among Homeless Adults in Metropolitan Detroit

Background: Homeless individuals suffer and die disproportionately from chronic diseases and disorders. We describe the epidemiology of cancer among homeless persons in metropolitan Detroit. Methods: A retrospective cohort study was performed using 1973-2014 data from the Metropolitan Detroit Cancer Surveillance System, a population-based cancer registry and member of the National Institutes of Health-National Cancer Institute's Surveillance, Epidemiology, and End Results program. Homeless adults were identified through address at diagnosis listed as a homeless shelter, hospital, or supplemental field indicating homelessness. Age-adjusted, sex-specific proportional incidence ratios (PIR) compared cancer incidence proportions by primary tumor site of homeless patients to the non-homeless referent population. Kaplan-Meier curves depicted unadjusted survival differences in a propensity score matched sample. Differences in 10-year survival were assessed using the score test with a sandwich estimator accounting for matched cluster effects. Statistical tests were two-sided. Results: A total of 388 individuals experienced homelessness at first primary invasive cancer diagnosis. Statistically significantly higher proportions of respiratory system (PIR = 1.51; 95% confidence interval = 1.28 to 1.79) and female genital system (PIR = 1.83; 95% confidence interval = 1.31 to 2.55) cancers were observed among homeless men and women, respectively. Homeless persons had poorer overall and cancer-reported survival compared with a propensity score matched referent population (median: overall survival, 20.0 vs 38.0 months, respectively, P<.001; cancer-reported survival, 38.0 vs 64.0 months, respectively, P <.001). Conclusion: Disparities in disease burden exist between adults who are experiencing homelessness compared with the nonhomeless population at cancer diagnosis. These findings provide clinically relevant information to understand the cancer burden in this medically underserved population and suggest an urgent need to develop cancer prevention and intervention programs to reduce disparities and improve the health of homeless persons.