Conjugated linoleic acid intake and breast cancer risk in a prospective cohort of Swedish women.
BACKGROUND
Studies in animals and in vitro suggest that conjugated linoleic acids (CLAs), a group of fatty acids found mainly in dairy products and in the meat of ruminants, have protective effects against mammary carcinogenesis. However, findings from epidemiologic studies on CLA intake in relation to breast cancer risk are sparse and inconsistent.


OBJECTIVE
The objective was to examine prospectively the association between CLA intake and the incidence of invasive breast cancer in the Swedish Mammography Cohort.


METHODS
In 1987-1990, 61,433 cancer-free women completed a food-frequency questionnaire from which we estimated each woman's CLA intake. Cox proportional hazards models were used to estimate relative risks, adjusted for breast cancer risk factors.


RESULTS
During a mean follow-up of 17.4 y, 2952 incident cases of breast cancer were ascertained. In multivariate analyses, no significant association was observed between dietary CLA intake and risk of breast cancer, overall or by estrogen receptor (ER) and progesterone receptor (PR) status. The multivariate relative risks (95% CI) for the highest quintile of CLA intake (> or =155.7 mg/d) compared with the lowest quintile (<78.1 mg/d) were 1.04 (0.92, 1.17) for overall breast cancer, 1.09 (0.90, 1.31) for ER+/PR+ tumors, 1.09 (0.78, 1.53) for ER+/PR- tumors, and 0.84 (0.57, 1.24) for ER-/PR- tumors.


CONCLUSIONS
The results provide no evidence of a protective effect of CLA against breast cancer development in women.
Larsson
Susanna C
SC
The National Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. susanna.larsson@ki.se
Bergkvist
Leif
L
Wolk
Alicja
A
D000328:Adult; D001943:Breast Neoplasms / Q000453:epidemiology / Q000517:prevention & control*; D004034:Diet Surveys; D005260:Female; D006801:Humans; D044243:Linoleic Acids, Conjugated / Q000008:administration & dosage*; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011960:Receptors, Estrogen / Q000032:analysis; D011980:Receptors, Progesterone / Q000032:analysis; D012306:Risk; D013548:Sweden
D044243:Linoleic Acids, Conjugated; D011960:Receptors, Estrogen; D011980:Receptors, Progesterone