Risk factors for breast cancer in postmenopausal Caucasian and Chinese-Canadian women.
BACKGROUND
Striking differences exist between countries in the incidence of breast cancer. The causes of these differences are unknown, but because incidence rates change in migrants, they are thought to be due to lifestyle rather than genetic differences. The goal of this cross-sectional study was to examine breast cancer risk factors in populations with different risks for breast cancer.


METHODS
We compared breast cancer risk factors among three groups of postmenopausal Canadian women at substantially different risk of developing breast cancer - Caucasians (N = 413), Chinese women born in the West or who migrated to the West before age 21 (N = 216), and recent Chinese migrants (N = 421). Information on risk factors and dietary acculturation were collected by telephone interviews using questionnaires, and anthropometric measurements were taken at a home visit.


RESULTS
Compared to Caucasians, recent Chinese migrants weighed on average 14 kg less, were 6 cm shorter, had menarche a year later, were more often parous, less often had a family history of breast cancer or a benign breast biopsy, a higher Chinese dietary score, and a lower Western dietary score. For most of these variables, Western born Chinese and early Chinese migrants had values intermediate between those of Caucasians and recent Chinese migrants. We estimated five-year absolute risks for breast cancer using the Gail Model and found that risk estimates in Caucasians would be reduced by only 11% if they had the risk factor profile of recent Chinese migrants for the risk factors in the Gail Model.


CONCLUSIONS
Our results suggest that in addition to the risk factors in the Gail Model, there likely are other factors that also contribute to the large difference in breast cancer risk between Canada and China.
Tam
Carolyn Y
CY
Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, 610 University Avenue, Toronto, Ontario M5G 2K9, Canada.
Martin
Lisa J
LJ
Hislop
Gregory
G
Hanley
Anthony J
AJ
Minkin
Salomon
S
Boyd
Norman F
NF
D000368:Aged; D044466:Asian People; D049628:Body Size; D001943:Breast Neoplasms / Q000208:ethnology* / Q000209:etiology*; D002170:Canada; D003430:Cross-Sectional Studies; D005247:Feeding Behavior; D005260:Female; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D012307:Risk Factors; D014171:Transients and Migrants; D044465:White People