Regional differences in colorectal cancer incidence, stage, and subsite among American Indians and Alaska Natives, 1999-2004.
BACKGROUND
Colorectal cancer (CRC) is a leading cause of cancer morbidity and mortality for American Indians and Alaska Natives (AI/ANs), but misclassification of race causes underestimates of disease burden.


METHODS
The authors compared regional differences in CRC incidence, stage at diagnosis, and anatomic distribution between AI/ANs and non-Hispanic whites (NHWs). To reduce misclassification, data from the National Program of Cancer Registries; the Surveillance, Epidemiology, and End Results Program; and the Indian Health Service (IHS) were linked. The analysis was limited to the 56% of AI/AN who live in IHS Contract Health Service Delivery Areas.


RESULTS
From 1999 to 2004, the overall incidence rate (per 100,000 persons per year) of CRC was 9% lower in the AI/AN population (46.3) than in the NHW population (50.8). However, AI/AN CRC incidence rates varied nearly 5-fold regionally, from 21 in the Southwest to 102.6 in Alaska. Compared with NHW rates, AI/AN rates were significantly higher in Alaska (rate ratio [RR], 2.03), the Northern Plains (RR, 1.39), and the Southern Plains (RR, 1.16) but were lower in the Pacific Coast (RR, 0.80), the East (RR, 0.65), and the Southwest (RR, 0.45). AI/ANs were diagnosed more often with advanced CRC than with localized CRC (RR, 1.92) compared with NHWs (RR, 1.48). Females more often had proximal CRC among both the AI/AN population (females, 40.1%; males, 33.5%) and the NHW population (females, 50.1%; males, 40.3%), although AI/ANs had a higher proportion of distal cancers overall.


CONCLUSIONS
CRC incidence rates in AI/AN populations varied dramatically between regions. Efforts are needed to make CRC screening a priority, overcome barriers to endoscopic screening, and to engage AI/AN communities in culturally appropriate ways to participate in prevention and early detection programs.
Perdue
David G
DG
Division of Gastroenterology and Hepatology, Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota, USA. dperdue@mngastro.com
Perkins
Carin
C
Jackson-Thompson
Jeannette
J
Coughlin
Steven S
SS
Ahmed
Faruque
F
Haverkamp
Donald S
DS
Jim
Melissa A
MA
D000230:Adenocarcinoma / Q000208:ethnology / Q000473:pathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000413:Alaska / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D015179:Colorectal Neoplasms / Q000208:ethnology* / Q000473:pathology*; D005260:Female; D005843:Geography; D006801:Humans; D015994:Incidence; D007198:Indians, North American / Q000706:statistics & numerical data*; D007223:Infant; D007231:Infant, Newborn; D004930:Inuit / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D044469:Racial Groups / Q000706:statistics & numerical data; D014481:United States / Q000453:epidemiology