TY - JOUR
T1 - Red blood cell folate and plasma folate are not associated with risk of incident colorectal cancer in the Women's Health Initiative observational study
AU - Neuhouser, Marian L.
AU - Cheng, Ting Yuan David
AU - Beresford, Shirley A.A.
AU - Brown, Elissa
AU - Song, Xiaoling
AU - Miller, Joshua W.
AU - Zheng, Yingye
AU - Thomson, Cynthia A.
AU - Shikany, James M.
AU - Vitolins, Mara Z.
AU - Rohan, Thomas
AU - Green, Ralph
AU - Ulrich, Cornelia M.
N1 - Publisher Copyright:
© 2015 UICC.
PY - 2015/8/15
Y1 - 2015/8/15
N2 - The relationship between folate and colorectal cancer (CRC) risk is unclear. We investigated the association of two biomarkers of folate status, plasma folate and red blood cell (RBC) folate, with CRC risk using a nested case-control design in the Women's Health Initiative Observational Study. Postmenopausal women (n = 93,676) aged 50-79 years were enrolled in the Women's Health Initiative Observational Study (1993-1998). A fasting blood draw and extensive health, dietary and lifestyle data were collected upon enrollment. Through 2008, 988 incident CRC cases were reported and confirmed with medical records adjudication. Cases and controls were matched on age (±3 years), enrollment date (±1 year), race/ethnicity, blood draw date (±6 months) and hysterectomy status. Plasma and RBC folate were determined by radio assay. Folate biomarker values were divided into quartiles, and conditional logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CI) for the associations of folate with total CRC, by tumor site and by stage at diagnosis. Additional analyses examined whether risks varied across time periods corresponding to the United States folic acid fortification policy: prefortification (1994-1995), perifortification (1996-1997) and postfortification (1998). ORs for overall CRC risk comparing Q4 vs. Q1 were 0.91 (95% CI 0.67-1.24) and 0.91 (95% CI 0.67-1.23) for RBC and plasma folate, respectively. There were no changes in risk attributable to food supply fortification. These results do not support an overall association of folate with CRC risk and suggest that folic acid fortification of the US food supply did not alter the associations in these postmenopausal women. What's new? Poor intake of the B-vitamin folate has been associated with increased risk of colorectal cancer (CRC). However, some studies suggest that very high intakes of folate may increase CRC risk. Given that certain foods are now fortified with folic acid in the U.S., it's important to ascertain whether fortification might increase CRC risk in the general population. In this large study of folate status, the authors found no evidence that folate fortification increases the risk of CRC.
AB - The relationship between folate and colorectal cancer (CRC) risk is unclear. We investigated the association of two biomarkers of folate status, plasma folate and red blood cell (RBC) folate, with CRC risk using a nested case-control design in the Women's Health Initiative Observational Study. Postmenopausal women (n = 93,676) aged 50-79 years were enrolled in the Women's Health Initiative Observational Study (1993-1998). A fasting blood draw and extensive health, dietary and lifestyle data were collected upon enrollment. Through 2008, 988 incident CRC cases were reported and confirmed with medical records adjudication. Cases and controls were matched on age (±3 years), enrollment date (±1 year), race/ethnicity, blood draw date (±6 months) and hysterectomy status. Plasma and RBC folate were determined by radio assay. Folate biomarker values were divided into quartiles, and conditional logistic regression estimated odds ratios (ORs) and 95% confidence intervals (CI) for the associations of folate with total CRC, by tumor site and by stage at diagnosis. Additional analyses examined whether risks varied across time periods corresponding to the United States folic acid fortification policy: prefortification (1994-1995), perifortification (1996-1997) and postfortification (1998). ORs for overall CRC risk comparing Q4 vs. Q1 were 0.91 (95% CI 0.67-1.24) and 0.91 (95% CI 0.67-1.23) for RBC and plasma folate, respectively. There were no changes in risk attributable to food supply fortification. These results do not support an overall association of folate with CRC risk and suggest that folic acid fortification of the US food supply did not alter the associations in these postmenopausal women. What's new? Poor intake of the B-vitamin folate has been associated with increased risk of colorectal cancer (CRC). However, some studies suggest that very high intakes of folate may increase CRC risk. Given that certain foods are now fortified with folic acid in the U.S., it's important to ascertain whether fortification might increase CRC risk in the general population. In this large study of folate status, the authors found no evidence that folate fortification increases the risk of CRC.
KW - colorectal cancer
KW - folate
KW - observational studies
KW - postmenopausal women
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U2 - 10.1002/ijc.29453
DO - 10.1002/ijc.29453
M3 - Article
C2 - 25643945
AN - SCOPUS:84931564612
SN - 0020-7136
VL - 137
SP - 930
EP - 939
JO - International Journal of Cancer
JF - International Journal of Cancer
IS - 4
ER -