Cancer Incidence and Survival Among Ever-Incarcerated Patients in California and Massachusetts

Importance Cancer is the leading cause of death in US prisons. Few studies have compared cancer incidence and survival for currently and formerly incarcerated populations with those for the general population. Objective To ascertain the association of prison incarceration with cancer outcomes, and to inform potential public health interventions. Design, Setting, and Participants This cohort study used state cancer registry data on patients with cancer diagnosed in California and Massachusetts between January 1, 2010, and December 31, 2019. Identifiers of persons incarcerated in California and Massachusetts state prisons during this study period were linked to cancer registry data to identify incarceration status at diagnosis. Data analysis was performed between March 2023 and August 2025. Exposures Current, former, or never incarceration status at diagnosis. Main Outcomes and Measures Cancer incidence, which was calculated as standardized incidence ratios (SIRs) relative to never-incarcerated patients. Stage at diagnosis and survival outcomes were characterized. The association between incarceration status and diagnosis stage and survival were assessed using regression models adjusted for demographic characteristics, year of diagnosis, cancer type, and state of residence. Results The study included 2 171 336 cancers, among which 2 165 540 (99.7%) were diagnosed in never-incarcerated, 3305 (0.2%) in currently incarcerated, and 2491 (0.1%) in formerly incarcerated patients. The median (IQR) age at diagnosis was 66 (56-75) years, 57 (49-64) years, and 55 (46-62) years, respectively. Overall, patients included 1 141 745 males (52.6%). Compared with never-incarcerated patients, currently incarcerated patients were more likely to have cervical (SIR, 3.57; 95% CI, 2.26-5.35) and liver cancers (SIR, 3.10; 95% CI, 2.79-3.43). In Massachusetts, currently incarcerated patients (odds ratio [OR], 1.62; 95% CI, 1.07-2.46) and all formerly incarcerated patients (OR, 1.19; 95% CI, 1.02-1.38) had a higher likelihood of advanced-stage diagnoses of screen-detectable cancers. Five-year survival was 62.4% for all never-incarcerated patients, 54.4% for currently incarcerated patients in California, 36.4% for currently incarcerated patients in Massachusetts, and 51.8% for all formerly incarcerated patients. Compared with never-incarcerated patients, formerly incarcerated patients had worse adjusted survival (hazard ratio [HR], 1.71; 95% CI, 1.61-1.82), while currently incarcerated patients had worse survival that varied by state (California: HR, 1.41 [95% CI, 1.33-1.49]; Massachusetts: HR, 2.18 [95% CI, 1.85-2.56]). Conclusions and Relevance In this cohort study of Massachusetts and California cancer registry data, currently and formerly incarcerated patients with cancer had inferior survival. The distinctive epidemiologic pattern of cancer incidence and mortality in incarcerated populations identifies strategic targets for cancer control.