The association of diabetes with colorectal cancer risk: the Multiethnic Cohort.
BACKGROUND
Diabetics have been found to have a greater risk of colorectal cancer than non-diabetics.


METHODS
We examined whether this relationship differed by ethnic group, cancer site or tumour stage in a population-based prospective cohort, including 3549 incident colorectal cancer cases identified over a 13-year period (1993-2006) among 199 143 European American, African American, Native Hawaiian, Japanese American and Latino men and women in the Multiethnic Cohort.


RESULTS
Diabetics overall had a significantly greater risk of colorectal cancer than did non-diabetics (relative risk (RR)=1.19, 95% confidence interval (CI)=1.09-1.29, P-value (P)<0.001). Positive associations were observed for colon cancer, cancers of both the right and left colon, and cancers diagnosed at a localised and regional/distant stage. The association with colorectal cancer risk was significantly modified by smoking status (P(Interaction)=0.0044), with the RR being higher in never smokers (RR=1.32, 95% CI=1.15-1.53, P<0.001) than past (RR=1.19, 95% CI=1.05-1.34, P=0.007) and current smokers (RR=0.90, 95% CI=0.70-1.15, P=0.40).


CONCLUSIONS
These findings provide strong support for the hypothesis that diabetes is a risk factor for colorectal cancer.
He
J
J
Department of Preventive Medicine, Keck School of Medicine, University of Southern California/Norris Comprehensive Cancer Center, Los Angeles, CA, USA.
Stram
D O
DO
Kolonel
L N
LN
Henderson
B E
BE
Le Marchand
L
L
Haiman
C A
CA
D001741:Black or African American; D000368:Aged; D044466:Asian People; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000208:ethnology / Q000209:etiology*; D048909:Diabetes Complications / Q000208:ethnology / Q000209:etiology*; D005260:Female; D006254:Hawaii; D006630:Hispanic or Latino; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011446:Prospective Studies; D012307:Risk Factors; D044465:White People