Abortion history and breast cancer risk: results from the Shanghai Breast Cancer Study.
Studies of the association between induced abortion and breast cancer risk have been inconsistent, perhaps due to underreporting of abortions. Induced abortion is a well-accepted family planning procedure in China, and women who have several induced abortions do not feel stigmatized. The authors used data from a population-based case-control study of breast cancer among women age 25-64 conducted between 1996 and 1998 in urban Shanghai to assess whether a history of and the number of induced abortions were related to breast cancer risk. In-person interviews were completed with 1,459 incident breast cancer cases ascertained through a population-based cancer registry, and 1,556 controls randomly selected from the general population in Shanghai (with respective response rates of 91% and 90%). After adjusting for confounding, there was no relation between ever having had an induced abortion and breast cancer (odds ratio [OR] = 0.9, 95% confidence interval [CI] 0.7-1.2). Women who had 3 or more induced abortions were not at increased risk of premenopausal breast cancer (OR = 0.9, 95% CI 0.6-1.4) or postmenopausal breast cancer (OR = 1.3, 95% CI 0.8-2.3). These results suggest that a history of several induced abortions has little influence on breast cancer risk in Chinese women.
Sanderson
M
M
Department of Epidemiology and Biostatistics, University of South Carolina and South Carolina Cancer Center, Columbia, SC, USA. msanderson@sph.sc.edu
Shu
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Jin
F
F
Dai
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Q
Wen
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W
Hua
Y
Y
Gao
Y T
YT
Zheng
W
W
D000028:Abortion, Induced / Q000009:adverse effects*; D000022:Abortion, Spontaneous; D000328:Adult; D000367:Age Factors; D001943:Breast Neoplasms / Q000209:etiology*; D002681:China; D005260:Female; D006801:Humans; D007774:Lactation; D008593:Menopause; D008875:Middle Aged; D016017:Odds Ratio; D012307:Risk Factors