Use of folic acid-containing supplements after a diagnosis of colorectal cancer in the Colon Cancer Family Registry.
BACKGROUND
Supplement use among cancer patients is high, and folic acid intake in particular may adversely affect the progression of colorectal cancer. Few studies have evaluated the use of folic acid-containing supplements (FAS) and its predictors in colorectal cancer patients.


OBJECTIVE
To assess the use of FAS, change in use, and its predictors after colorectal cancer diagnosis.


METHODS
We used logistic regression models to investigate predictors of FAS use and its initiation after colorectal cancer diagnosis in 1,092 patients recruited through the Colon Cancer Family Registry.


RESULTS
The prevalence of FAS use was 35.4% before and 55.1% after colorectal cancer diagnosis (P = 0.004). Women were more likely than men to use FAS after diagnosis [odds ratio (OR), 1.47; 95% confidence interval (95% CI), 1.14-1.89], as were those consuming more fruit (P(trend) < 0.0001) or vegetables (P(trend) = 0.001), and U.S. residents (P < 0.0001). Less likely to use FAS after diagnosis were nonwhite patients (OR, 0.66; 95% CI, 0.45-0.97), current smokers (OR, 0.67; 95% CI, 0.46-0.96), and those with higher meat intake (P(trend) = 0.03). Predictors of FAS initiation after diagnosis were generally similar to those of FAS use after diagnosis, although associations with race and vegetable intake were weaker and those with exercise stronger.


CONCLUSIONS
Our analysis showed substantial increases in the use of FAS after diagnosis with colorectal cancer, with use or initiation more likely among women, Caucasians, U.S. residents, and those with a health-promoting life-style.


CONCLUSIONS
Studies of cancer prognosis that rely on prediagnostic exposure information may result in substantial misclassification.
Holmes
Rebecca S
RS
National Center for Tumor Diseases Heidelberg, Division of Preventive Oncology, German Cancer Research Center, Im Neuenheimer Feld 581, Heidelberg, Germany.
Zheng
Yingye
Y
Baron
John A
JA
Li
Lin
L
McKeown-Eyssen
Gail
G
Newcomb
Polly A
PA
Stern
Mariana C
MC
Haile
Robert W
RW
Grady
William M
WM
Potter
John D
JD
Le Marchand
Loic
L
Campbell
Peter T
PT
Figueiredo
Jane C
JC
Limburg
Paul J
PJ
Jenkins
Mark A
MA
Hopper
John L
JL
Ulrich
Cornelia M
CM
D000970:Antineoplastic Agents / Q000008:administration & dosage*; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000188:drug therapy*; D019587:Dietary Supplements / Q000706:statistics & numerical data*; D005192:Family Health; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage*; D005500:Follow-Up Studies; D015438:Health Behavior; D006801:Humans; D008297:Male; D008875:Middle Aged; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data*; D011379:Prognosis; D012042:Registries; D012737:Sex Factors; D011795:Surveys and Questionnaires
D000970:Antineoplastic Agents; D005492:Folic Acid