Verkooijen Helena M, Yap Karen P L, Bhalla Vineta, Chow Khuan Yew, Chia Kee Seng
Centre for Molecular Epidemiology, Faculty of Medicine, National University of Singapore, Singapore.
Breast Cancer Res Treat. 2009 Feb;113(3):553-8. doi: 10.1007/s10549-008-9947-y. Epub 2008 Mar 2.
The relationship between multiparity and premenopausal breast cancer risk is different in Caucasian, African-American and Hispanic women. For Asian women, this relationship has never been well studied.
Within the Singapore Birth Registry, we selected all women who had a first child between 1986 and 2002 (169,936 Chinese, 40,521 Malay, 17,966 Indian). We linked them to the Singapore Cancer Registry data to identify those who developed breast cancer after childbirth (n = 527). We used multivariate Cox analysis to examine the relationship between parity, ethnicity and premenopausal breast cancer risk.
Compared to Chinese, Malay women had increased and Indian women had decreased risks of premenopausal breast cancer (adjusted Hazard Ratios [HRadj] 1.25 [1.0-1.6] and 0.48 [0.3-0.8] respectively). Multiparity did not modify the risk of premenopausal breast cancer in Chinese and Indians. In Malays there was a significant risk reduction with increasing parity (P (trend )0.037). Malay women with one, two and >or=3 children had premenopausal breast cancer risks (HR(adj)) of 1.86 (1.2-3.0), 1.52 (1.1-2.2) and 0.87 (0.6-1.3) respectively compared to their Chinese counterparts.
The impact of multiparity on premenopausal breast cancer risk differs across ethnic groups in Singapore. Increasing parity reduces the risk of premenopausal breast cancer in Malay, but not in Chinese and Indian women. Uniparous Malay women have twice the risk of premenopausal breast cancer compared to uniparous Chinese. This excess risk disappears after giving birth to >or=3 children. Indian women have lower premenopausal breast cancer risks than Chinese, regardless of their parity status.
多产与绝经前乳腺癌风险之间的关系在白种人、非裔美国人和西班牙裔女性中有所不同。对于亚洲女性，这种关系从未得到充分研究。
在新加坡出生登记处，我们选取了1986年至2002年间生育头胎的所有女性（169,936名华人、40,521名马来人、17,966名印度人）。我们将她们与新加坡癌症登记数据相链接，以识别那些产后患乳腺癌的女性（n = 527）。我们使用多变量Cox分析来研究产次、种族与绝经前乳腺癌风险之间的关系。
与华人相比，马来女性绝经前患乳腺癌的风险增加，而印度女性的风险降低（调整后的风险比[HRadj]分别为1.25[1.0 - 1.6]和0.48[0.3 - 0.8]）。多产并未改变华人和印度人绝经前患乳腺癌的风险。在马来人中，随着产次增加，风险显著降低（P（趋势）= 0.037）。与华人相比，生育1个、2个及≥3个孩子的马来女性绝经前患乳腺癌的风险（HR(adj)）分别为1.86（1.2 - 3.0）、1.52（1.1 - 2.2）和0.87（0.6 - 1.3）。
在新加坡，多产对绝经前乳腺癌风险的影响因种族而异。产次增加可降低马来人绝经前患乳腺癌的风险，但对华人和印度女性则不然。未生育的马来女性绝经前患乳腺癌的风险是未生育华人女性的两倍。在生育≥3个孩子后，这种额外风险消失。无论产次状况如何，印度女性绝经前患乳腺癌的风险低于华人。
