Substantial annual variation in gastrointestinal cancer incidence and mortality among American Indians & Alaskan Natives - 1995-2004

INTRODUCTION:

Substantial disparities involving American Indians and Alaskan Natives (AIANs) exist in incidence and mortality of gastrointestinal cancers (GIC) which includes cancers of esophagus, stomach, and the intestines. Health status of AIANs is generally poorer, with associated problems in accessing healthcare.

OBJECTIVE:

To assess the elements of incidence and mortality rate disparities among AIANs compared to other race/ethnic groups in order to understand year to year variations and review the associated literature.

METHODS:

We obtained SEER data (1995-2004) including age-and delay-adjusted incidence, mortality by gender, geographical distribution for states, and stage of diagnosis and lifetime risk for being diagnosed with GICs. All adjustments used the 2000 US population as the reference standard. We compared GIC age adjusted incidence, and mortality rates across gender and race/ethnic categories using SEER-stat program. We tested for a trend in annual percent changes in frequency count, incidence rate, and mortality (weighted least squares and one-year end points) using SEER-stat.

RESULTS:

We compared age-adjusted colorectal cancer incidence and mortality rates for AIANs to other race/ethnic groups, for year-year variations were substantially higher for AIANs compared to others. The numbers of GIC cases were similar for other races which had more stable rates over time. Results were similar for esophageal and gastric cancer and GIC taken together. Literature provided insights into errors resulting in inaccurate ascertainment of race for AIANs throughout their life-span.

CONCLUSIONS:

Year-year variation in GIC rates for AIANs were substantially greater than other race/ethnic groups and may occur due to errors in race/ethnicity ascertainment.