Dairy products and ovarian cancer: a pooled analysis of 12 cohort studies.
BACKGROUND
Dairy foods and their constituents (lactose and calcium) have been hypothesized to promote ovarian carcinogenesis. Although case-control studies have reported conflicting results for dairy foods and lactose, several cohort studies have shown positive associations between skim milk, lactose, and ovarian cancer.


METHODS
A pooled analysis of the primary data from 12 prospective cohort studies was conducted. The study population consisted of 553,217 women among whom 2,132 epithelial ovarian cases were identified. Study-specific relative risks and 95% confidence intervals were calculated by Cox proportional hazards models and then pooled by a random-effects model.


RESULTS
No statistically significant associations were observed between intakes of milk, cheese, yogurt, ice cream, and dietary and total calcium intake and risk of ovarian cancer. Higher lactose intakes comparing > or = 30 versus <10 g/d were associated with a statistically significant higher risk of ovarian cancer, although the trend was not statistically significant (pooled multivariate relative risk, 1.19; 95% confidence interval, 1.01-1.40; P(trend) = 0.19). Associations for endometrioid, mucinous, and serous ovarian cancer were similar to the overall findings.


CONCLUSIONS
Overall, no associations were observed for intakes of specific dairy foods or calcium and ovarian cancer risk. A modest elevation in the risk of ovarian cancer was seen for lactose intake at the level that was equivalent to three or more servings of milk per day. Because a new dietary guideline recommends two to three servings of dairy products per day, the relation between dairy product consumption and ovarian cancer risk at these consumption levels deserves further examination.
Department of Nutrition, Harvard School of Public Health, Room 339, Building 2, 665 Huntington Avenue, Boston, Massachusetts 02115, USA. pooling@hsphsun2.harvard.edu
Jeanine M
JM
Genkinger
David J
DJ
Hunter
Donna
D
Spiegelman
Kristin E
KE
Anderson
Alan
A
Arslan
W Lawrence
WL
Beeson
Julie E
JE
Buring
Gary E
GE
Fraser
Jo L
JL
Freudenheim
R Alexandra
RA
Goldbohm
Susan E
SE
Hankinson
David R
DR
Jacobs
Anita
A
Koushik
James V
JV
Lacey
Susanna C
SC
Larsson
Michael
M
Leitzmann
Marji L
ML
McCullough
Anthony B
AB
Miller
Carmen
C
Rodriguez
Thomas E
TE
Rohan
Leo J
LJ
Schouten
Roy
R
Shore
Ellen
E
Smit
Alicja
A
Wolk
Shumin M
SM
Zhang
Stephanie A
SA
Smith-Warner
D002136:Calcium, Dietary / Q000009:adverse effects*; D015331:Cohort Studies; D003611:Dairy Products / Q000009:adverse effects* / Q000145:classification; D004034:Diet Surveys; D005260:Female; D006801:Humans; D007785:Lactose / Q000008:administration & dosage / Q000009:adverse effects*; D015999:Multivariate Analysis; D017063:Outcome Assessment, Health Care; D010051:Ovarian Neoplasms / Q000209:etiology*; D016016:Proportional Hazards Models; D014807:Vitamin D / Q000008:administration & dosage / Q000009:adverse effects*
D002136:Calcium, Dietary; D014807:Vitamin D; D007785:Lactose