Abstract B39: Trends in 5-year and 10-year crude survival rates among American Indians and Alaskan Natives diagnosed with cancer, 1997-2012
Authors: Emerson Marc A. , Banegas Matthew P. , Chawla Neetu , Achacoso Ninah , Adams Alyce , Habel Laurel A. 
Published: October 2015

Background: Cancer is the second leading cause of death among American Indians and Alaskan Natives (AIANs) in the United States. However, information on cancer survival among AIANs, especially those living in urban areas, is limited. California is home to the largest AIAN population, comprised of over 700,000 individuals. To address this gap, we present data on cancer diagnoses and survival after cancer diagnoses among AIANs and non-Hispanic whites (NHWs) from the Kaiser Permanente Northern California (KPNC) tumor registry.

Purpose: To examine cancer diagnoses and overall survival rates among AIAN individuals diagnosed with primary invasive cancer and compare to NHWs.

Methods: This prospective cohort study uses data on 1,022 AIANs and 139,725 NHWs diagnosed with primary invasive cancer between 1997 and 2012, from the KPNC tumor registry and other electronic health records. Information on race, cancer site, tumor size, tumor grade, stage, year and age at diagnosis, type of treatment (e.g. surgery, radiation, chemotherapy, and hormone), comorbidities, follow-up time and sociodemographics were extracted. Follow-up time was defined as number of days from date of diagnosis through either death from any cause, disenrollment or end of study period (March 31, 2014), whichever came first. Descriptive statistics were calculated for tumor, and clinical characteristics. Sociodemographic characteristics, including race, were extracted from the electronic health record. We identified the top 5 cancer sites, by sex, and estimated 5- and 10-year Kaplan-Meier survival rates for AIANs and NHWs. Charlson comorbidity scores and top 5 comorbidities were also compared between these populations.

Results: Among AIANs, the 5 most common cancers diagnosed were prostate (16.4%), breast (16.4%), lung (13.3%), colorectal (12.5%), and non-Hodgkin lymphoma (4.0%). Among NHWs, the most commonly diagnosed cancer was prostate (17.3%), followed by breast (16.8%), lung (11.7%), colorectal (9.3%) and melanoma (6.6%) cancers, respectively. Overall 5- and 10-year survival estimates among AIANs with any cancer were statistically significantly lower than for NHWs (51.9 vs. 58.2, p&lt;0.001 and 37.4 vs. 43.8, p&lt;0.001, respectively). When examining the most common individual cancer sites, 5- and 10-year overall survival estimates were consistently lower among AIANs compared to NHWs, although only the 5-year survival following breast cancer was statistically significant. AIANs with any cancer had a significantly higher rate of comorbidity compared to NHWs (p&lt;0.003). The most common non-malignancy comorbidities among AIANs were chronic pulmonary disease (25.5%), diabetes (with and without end-organ damage), (18.7%), and congestive heart disease (7.0%); the most common for NHWs were chronic pulmonary disease (21.4%), diabetes (14.3%) and congestive heart (6.0%).

Conclusions: This study adds valuable information to the literature, identifying the most commonly diagnosed cancers and overall survival among AIANs outside of the Indian Health Service (IHS). Despite equal access to health care in the study population, our results show a lower survival for AIANs than NHWs, following invasive cancer, and a greater proportion of AIAN cancer patients with multiple comorbid conditions. Given that over two-thirds of AIANs live in urban settings, research efforts to identify potentially unique drivers of cancer health disparities are warranted to improve outcomes for urban dwelling AIANs within non-IHS health care systems.

Citation Format: Marc A. Emerson, Matthew P. Banegas, Neetu Chawla, Ninah Achacoso, Alyce Adams, Laurel A. Habel. Trends in 5-year and 10-year crude survival rates among American Indians and Alaskan Natives diagnosed with cancer, 1997-2012. [abstract]. In: Proceedings of the Seventh AACR Conference on The Science of Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; Nov 9-12, 2014; San Antonio, TX. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2015;24(10 Suppl):Abstract nr B39.