Abstract B73: Disparities in colorectal cancer incidence and survival among Hispanics in California.
Authors: Stern Mariana C. , Zhang JuanJuan , Lewinger Juan Pablo , Deapen Dennis , Liu Lihua 
Published: August 2014

In California, colorectal cancer (CRC) is the second most common cancer in Latino men and women with incidence rates that are 12% and 23% lower than those for non-Hispanic white (NHW) men and women, respectively. Given the heterogeneity among US Hispanics, analyses of cancer incidence and clinical characteristics among the major Hispanic subgroups are warranted. However, for a considerable proportion of US Hispanics the specific country of origin of the patient, or their parents if US-born, is unknown. Therefore, estimated Hispanic subgroup specific cancer incidence rates will tend to underestimate the true incidence rates for those subgroups.

Using data from the California Cancer Registry (CCR), we investigated the CRC incidence and survival rates of Latinos living in California for 1995-2005 by demographic and clinical characteristics of CRC patients. We identified 20,236 CRC cases diagnosed during 1995-2005 and defined as Hispanic according to the NAACCR Hispanic Identification Algorithm (NHIA). We also used information in the Death Certificates and identified additional 6,369 CRC cases of Hispanic origin for a total of 26,605 CRC cases. Based on the NHIA definition and information on birthplace, we further grouped these cases by country of origin: Mexico, Puerto Rico, Cuba, Central America, and South America. To overcome the large proportion of cases with unspecified information on country of origin, we allocated these cases into specific Hispanic subgroups using different approaches. Annual and age-adjusted incidence rates (AAIR) and survival by Hispanic subgroup were calculated.

Hispanics showed lower proportion of carcinoma in situ and stages I and II tumors than NHW, with Latinos of Puerto Rican or South American origin having the highest proportions of Stage IV tumors. The AAIR for all Hispanics combined when using data from the CCR only were 16.6% and 21.4% lower than rates for NHW, with Hispanics of Mexican origin having the lowest AAIRs, and Hispanics of South American origin the highest. Inclusion of cases detected through Death Records showed an AAIR for all Latinos combined (72.2/100,000 in men and 49.9/100,000 in women) that was slightly higher than NHW, with Mexicans and Central Americans showing the lowest AAIRs and Cubans and Puerto Ricans showing the highest. Allocation of ‘Other Hispanics’ using both methods elevated all subgroup-specific AAIRs, but did not significantly change the disparities observed across subgroups. Hazard ratios from Cox regression models adjusted for SES, immigration status, demographics, stage, and type of treatment received showed that being of Cuban or Puerto Rican origin is associated with greater risk of cancer death compared to being Mexican. Being from South American, Central American, or from ‘other’ Hispanic origin was associated with reduced risk of cancer death when compared to being of Mexican origin.

Our findings highlight the importance of taking into account the heterogeneity within the Hispanic population when studying cancer incidence patterns, as this may help understand the true cancer risk and cancer determinants in this minority population.

Citation Format: Mariana C. Stern, JuanJuan Zhang, Juan Pablo Lewinger, Dennis Deapen, Lihua Liu. Disparities in colorectal cancer incidence and survival among Hispanics in California. [abstract]. In: Proceedings of the Fifth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2012 Oct 27-30; San Diego, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(10 Suppl):Abstract nr B73.