Abstract PR04: Low-income minorities and immigrants are priority targets in late stage hepatocellular carcinoma hotspots
Authors: Zhou Kali , Thompson Laura , Terrault Norah A. , Cockburn Myles G. 
Published: December 2020

Abstract
Background: Survival for hepatocellular carcinoma (HCC) is highly contingent on stage at diagnosis. Identifying high-risk population groups is crucial for efficient delivery of limited resources. We present a population-based geospatial approach to identifying priority targets for early detection interventions in a defined area with high rates of late stage HCC. Methods: We utilized a high-quality population-based cancer registry for cohort identification. Inclusion criteria were: 1) incident HCC (C22.0, 8170-8175), 2) diagnosis between 2008-2017, and 3) residence within boundaries of a single large metropolitan county (Los Angeles). Late stage included AJCC 7th Edition stages III-VI and unstaged cases. We mapped “hotspots” or areas with high density of late stage disease using address coordinates and kernel density estimation in ArcMap 10.3.1. We selected a hotspot density threshold that best optimized number of hotspots, number of cases, and proportion of late stage cases within hotspots. Individual-level factors associated with residence in a hotspot were identified with univariate logistic regression. Age-adjusted incidence rate (AAIR) and population attributable risk (PAR) of late stage disease if residence in a hotspot were calculated. Results: In Los Angeles County, 3894 (51.8%) of 7519 incident cases of HCC were late stage. We identified 23 discrete hotspots that encompassed 26.7% of all cases and 30.0% of late stage cases. Hotspots had 10% more late stage disease (59.1% within vs 49.1% outside hotspots, p&lt;0.01). The composition of hotspots heavily favored racial/ethnic minorities (86.3% vs 69.5%, p&lt;0.01) and nearly half of hotspot residents were foreign-born (48.6% vs 36.9%, p&lt;0.01; &gt;25% with unknown birthplace). 45.4% of residents within hotspots were in the lowest socioeconomic status (SES) quintile compared to only 19.1% outside hotspots. Factors associated with residence in a hotspot included non-White race/ethnicity (OR 2.6, 2.7, and 3.1 for Black, Hispanic, and Asian, respectively, compared to White), foreign-born (OR 1.3 vs US-born), and Medicaid insurance (OR 1.7 vs non-Medicaid) (all p&lt;0.05). Likelihood of residence in a hotspot sequentially increased with each quintile decrease in SES (OR 3.3 for highest-middle to OR 33.2 for lowest vs highest quintile, p&lt;0.01). The AAIR of late stage HCC was twice as high within compared to outside hotspots (6.85 vs 3.38) and 43% of late stage HCC at diagnosis was attributable to residence in a hotspot (PAR=0.43). Conclusion: Late stage HCC hotspots in Los Angeles County are disproportionately comprised of low-income minority and immigrant populations. Early detection interventions that modify risk in these priority groups have potential to reduce late stage burden by nearly 40%. Our strategy can be replicated in any population-based cancer registry for individualized area-specific targets.
Citation Format: Kali Zhou, Laura Thompson, Norah A. Terrault, Myles G. Cockburn. Low-income minorities and immigrants are priority targets in late stage hepatocellular carcinoma hotspots [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr PR04.