Comparison of fecal occult blood tests for colorectal cancer screening in an Alaska Native population with high prevalence of Helicobacter pylori infection, 2008-2012.
BACKGROUND
Alaska Native colorectal cancer (CRC) incidence and mortality rates are the highest of any ethnic/racial group in the United States. CRC screening using guaiac-based fecal occult blood tests (gFOBT) are not recommended for Alaska Native people because of false-positive results associated with a high prevalence of Helicobacter pylori-associated hemorrhagic gastritis. This study evaluated whether the newer immunochemical FOBT (iFOBT) resulted in a lower false-positive rate and higher specificity for detecting advanced colorectal neoplasia than gFOBT in a population with elevated prevalence of H. pylori infection.


METHODS
We used a population-based sample of 304 asymptomatic Alaska Native adults aged 40 years or older undergoing screening or surveillance colonoscopy (April 2008-January 2012).


RESULTS
Specificity differed significantly (P < .001) between gFOBT (76%; 95% CI, 71%-81%) and iFOBT (92%; 95% CI, 89%-96%). Among H. pylori-positive participants (54%), specificity of iFOBT was even higher (93% vs 69%). Overall, sensitivity did not differ significantly (P = .73) between gFOBT (29%) and iFOBT (36%). Positive predictive value was 11% for gFOBT and 32% for iFOBT.


CONCLUSIONS
The iFOBT had a significantly higher specificity than gFOBT, especially in participants with current H. pylori infection. The iFOBT represents a potential strategy for expanding CRC screening among Alaska Native and other populations with elevated prevalence of H. pylori, especially where access to screening endoscopy is limited.
4000 Ambassador Dr, C-DCHS, Anchorage, AK 99508. Telephone 907-729-3959. E-mail: dredwood@anthc.org.
Diana
D
Redwood
Alaska Native Tribal Health Consortium, Anchorage, Alaska.
Ellen
E
Provost
Alaska Native Tribal Health Consortium, Anchorage, Alaska.
Elvin
E
Asay
Centers for Disease Control and Prevention, Albuquerque, New Mexico.
Diana
D
Roberts
Centers for Disease Control and Prevention, Albuquerque, New Mexico.
Donald
D
Haverkamp
American Indian Cancer Foundation and Minnesota Gastroenterology PA, Minneapolis, Minnesota.
David
D
Perdue
Centers for Disease Control and Prevention, Anchorage, Alaska.
Michael G
MG
Bruce
Alaska Native Tribal Health Consortium, Anchorage, Alaska.
Frank
F
Sacco
Centers for Disease Control and Prevention, Albuquerque, New Mexico.
David
D
Espey
D000328:Adult; D000413:Alaska; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D055088:Early Detection of Cancer / Q000379:methods; D005243:Feces / Q000737:chemistry*; D005260:Female; D016481:Helicobacter Infections / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D016480:Helicobacter pylori; D006801:Humans; D007198:Indians, North American; D008297:Male; D008875:Middle Aged; D009780:Occult Blood