Recent diet and breast cancer risk: the California Teachers Study (USA).
OBJECTIVE
The impact, if any, on breast cancer risk of modifying adult dietary intake is an area of much interest. We take the opportunity to address the relationship between recent adult diet and breast cancer risk during the first two years of follow-up of the large California Teachers Study cohort.


METHODS
Of the 111.526 at-risk cohort members who resided in California and completed a baseline dietary assessment, 711 were diagnosed with invasive breast cancer after joining the cohort and before January 1998. Average daily nutrient intake was computed based on a food-frequency questionnaire assessing usual dietary intake and portion size during the year prior to joining the cohort. Incident breast cancers were identified through the California Cancer Registry and follow-up for death and confirmation of continued California residence utilized a variety of data sources. Cox proportional hazards models were used to calculate relative hazards.


RESULTS
The following components of recent dietary intake were not associated with breast cancer risk: energy, fat, fiber, antioxidant vitamins, and phytoestrogens. Only recent average alcohol consumption of 20 or more grams per day (approximately two or more glasses of wine) was associated with increased risk (RR= 1.5, 95% CI: 1.2-2.0 compared to non-drinkers; P(trend) = 0.01 across quintiles).


CONCLUSIONS
With the exception of alcohol consumption, this study provides no evidence that recent macro- or micronutrient composition of adult diet is likely to have a direct effect on breast cancer risk. Some reduction of alcohol consumption among those consuming more than one drink per day may be beneficial.
Horn-Ross
Pamela L
PL
Northern California Cancer Center, Union City 94587, USA. phornros@nccc.org
Hoggatt
K J
KJ
West
Dee W
DW
Krone
Melissa R
MR
Stewart
Susan L
SL
Anton
Hoda
H
Bernstei
Culver Leslie
CL
Deapen
Dennis
D
Peel
David
D
Pinder
Richard
R
Reynolds
Peggy
P
Ross
Ronald K
RK
Wright
William
W
Ziogas
Al
A
D000328:Adult; D000368:Aged; D000428:Alcohol Drinking; D001943:Breast Neoplasms / Q000453:epidemiology* / Q000209:etiology* / Q000517:prevention & control; D002140:California / Q000453:epidemiology; D015331:Cohort Studies; D004032:Diet; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D009752:Nutritional Status; D012042:Registries / Q000706:statistics & numerical data*