UC Irvine

Introduction/Background: Hispanic subgroups are often grouped under the combined Hispanic global term, preventing us from identifying any differences or disparities within that group that might exist. As California currently has the largest collectively identified Hispanic population in the US at 39%, data maintained for California has an adequate sample for the study of subgroups within this population for differences in health and illness. This paper will examine cancer-related survival involving the eight major cancer sites: colon, rectum, stomach, liver, female breast, prostate, ovary, and cervix. This study aims to discern whether there are differences in cancer-related survival in the following Hispanic subgroups: Mexican, Puerto Rican, Cuban, Southern or Central American, and other Spanish/Hispanic origin.

Methods: Data was gathered from the California Cancer Registry (CCR) using 2004-2017 to conduct a retrospective longitudinal population-based cohort study. The following patient characteristics were obtained: race/ethnicity, age at diagnosis, year of diagnosis, gender, insurance type, socioeconomic status (SES), marital status, type of hospital where treatment was received, adherence to treatment status, tumor stage, and tumor grade. Cancer types included both male and female cancers: colon, rectum, stomach, liver, prostate, female breast, ovary, and cervix. A multivariate proportional hazards model was used to perform a cancer-specific survival analysis while controlling for numerous potential confounders. Non-Hispanic white (NHW) cases were used as the comparison group for each Hispanic subgroup. There were no comparisons between Hispanic subgroups themselves.

Results: Between 2004-2017, 420,671 cases of cancer were identified. Of these, 306,262 (72.8%) were NHW, 34,897 (8.3%) were Mexican, 647 (0.2%) were Puerto Rican, 698 (0.2%) were Cuban, 9,638 (2.3%) were South or Central American, and 68,528 (16.3%) were other Spanish/Hispanic origins. Compared to NHW cases, Mexican race/ethnicity was associated with better survival for colon (HR 0.89, 95% CI 0.84-0.96, p=0.0008) and liver cancer (HR 0.88, 95% CI 0.82-0.95, p=0.0006), but Mexican race/ethnicity was associated with worse survival for stomach cancer (HR 1.19, 95% CI 1.10-1.27, p<0.0001). South or Central American was associated with better survival for colon (HR 0.74, 95% CI 0.65-0.83, p<0.0001), liver (HR 0.69, 95% CI 0.60-0.80, p<0.0001), breast (HR 0.88, 95% CI 0.78-0.99, p=0.0303), and cervix (HR 0.70, 95% CI 0.58-0.85, p=0.0003). Most Hispanic subgroups had no difference in survival rates over a 5-year period compared to NHWs or were associated with better survival rates than NHWs. Only among Mexicans with stomach cancer were the survival rates worse than NHWs.

Conclusion: Compared to NHW cases, Mexicans were the only Hispanic subgroup associated with worse survival rates; this was found only among stomach cancer patients. For the rest of our results, Hispanic subgroups were associated with better or similar survival rates than NHWs. These results reinforce previous studies highlighting the Hispanic paradox. Hispanics have better cancer survival outcomes than NHWs despite health disparities such as lower SES and less healthcare access. Nonetheless, we do see worse survival, at least in one subgroup, which should encourage us to report Hispanics as disaggregate groups to identify differences when they exist. We also saw a large portion of unknown Hispanic data, which highlights the need for better practices in race/ethnic identification in data collection. Such practices will then enable us to develop targeted interventions and policies that will improve the health of this fast-growing ethnic population.