Disparities in hepatocellular carcinoma incidence by race/ethnicity and geographic area in California: Implications for prevention

Abstract

Background: The incidence of hepatocellular carcinoma (HCC) has been rising rapidly in the United States. California is an ethnically diverse state with the largest number of incident HCC cases in the country. Characterizing HCC disparities in California may inform priorities for HCC prevention.

Methods: By using data from the Surveillance, Epidemiology, and End Results 18-Registry Database and the California Cancer Registry, age-adjusted HCC incidence in California from 2009 through 2013 was calculated by race/ethnicity and neighborhood ethnic enclave status. A geographic analysis was conducted using Medical Service Study Areas (MSSAs) as the geographic unit, and race/ethnicity-specific standardized incidence ratios (SIRs) were calculated to identify MSSAs with higher-than-expected HCC incidence compared with the statewide average.

Results: During 2009 through 2013, the age-adjusted incidence of HCC in California was the highest in Asians/Pacific Islanders (APIs) and Hispanics (>100% higher than whites), especially those living in more ethnic neighborhoods (20%-30% higher than less ethnic neighborhoods). Of the 542 MSSAs statewide, 42 had elevated HCC incidence (SIR ≥ 1.5; lower bound of 95% confidence interval > 1) for whites, 14 for blacks, 24 for APIs, and 36 for Hispanics. These MSSAs have 24% to 52% higher proportions of individuals below the 100% federal poverty line than other MSSAs.

Conclusions: APIs and Hispanics residing in more ethnic neighborhoods and individuals residing in lower income neighborhoods require more extensive preventive efforts tailored toward their unique risk factor profiles. The current race/ethnicity-specific geographic analysis can be extended to other states to inform priorities for HCC targeted prevention at the subcounty level, eventually reducing HCC burden in the country.

Keywords: cancer registry; geographic analysis; hepatocellular carcinoma; racial disparity; targeted prevention.

Figure 1.

Age-adjusted incidence of hepatocellular carcinoma is illustrated by neighborhood enclave status among Asians and Hispanics in California from 2008 to 2012. Note that higher quartiles indicate higher enclave status (more ethnic neighborhoods).

Figure 2.

Hepatocellular carcinoma (HCC) hot spots in California are illustrated overall and by race/ethnicity for (A) all racial/ ethnic groups combined, (B) non-Hispanic whites, (C) non-Hispanic blacks, (D) non-Hispanic Asians/Pacific Islanders, and (E) Hispanics. Note that the geographic unit in this analysis is the Medical Service Study Area (MSSA); these areas are aggregations of census tracts (typically 20–30) that provide a good basis for needs assessment analysis, health care planning, and health care policy development. Hot spots are MSSAs with at least 50% higher HCC incidence than that expected in the average California population. Each map shows the 58 counties in California, and dark areas indicate MSSA hot spots within counties, with some MSSAs bordering others.

Figure 3.

(A) The mean proportion of individuals below the 100% federal poverty line is illustrated, comparing race/ ethnicity-specific hot spots and other Medical Service Study Areas (MSSAs). (B) The mean proportion of individuals below the 100% federal poverty line is calculated according to the number of race/ethnic groups for which a specific MSSA is a hot spot (range, 0–4 groups). Note that MSSAs are aggregations of census tracts (typically 20–30) that provide a good basis for needs assessment analysis, health care planning, and health care policy development. Hot spots are MSSAs with at least 50% higher hepatocellular carcinoma (HCC) incidence than that expected in the average California population. The analysis evaluated whether each MSSA has elevated HCC incidence for each of the 4 race/ethnic groups, respectively; therefore, an MSSA can be a hot spot for 0 to 4 racial/ethnic groups.