American Journal of Epidemiology Advance Access originally published online on April 29, 2008
American Journal of Epidemiology 2008 168(1):49-57; doi:10.1093/aje/kwn094
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ORIGINAL CONTRIBUTIONS |
Risk of Breast Cancer and Gynecologic Cancers in a Large Population of Nearly 50,000 Infertile Danish Women
1 Institute of Cancer Epidemiology, Danish Cancer Society, Copenhagen, Denmark
2 The Juliane Marie Center, Copenhagen University Hospital, Copenhagen, Denmark
Correspondence to Dr. Allan Jensen, Institute of Cancer Epidemiology, Danish Cancer Society, Strandboulevarden 49, DK-2100 Copenhagen N, Denmark (e-mail: allan{at}cancer.dk).
Received for publication October 23, 2007. Accepted for publication March 19, 2008.
Infertility is considered to influence the risk of breast cancer and gynecologic cancers. To assess this association, the authors used data from a large cohort of 54,362 women with a diagnosis of infertility who were referred to Danish fertility clinics between 1963 and 1998. Through 2003, 1,975 cancers were identified by linkage to the Danish Cancer Registry. Cancer risk was assessed through standardized incidence ratios (SIRs) and corresponding 95% confidence intervals, using general and parity-specific cancer incidence rates in the general population of Denmark as a reference. After adjustment for parity status, significantly increased SIRs were observed for breast (SIR = 1.08, 95% confidence interval: 1.01, 1.16) and ovarian (SIR = 1.46, 95% confidence interval: 1.24, 1.71) cancer. The risk of breast cancer increased with follow-up time. Similar risk patterns were observed for the different histologic types of breast cancer and all nonmucinous types of ovarian cancer, whereas the risk of mucinous ovarian cancers seemed not to be increased. These data thus suggest higher risks of breast and ovarian cancer among infertile women. However, since these results could not distinguish the effects of underlying infertility from the effects of fertility treatment, additional studies are needed to disentangle the effects of these two factors.
breast neoplasms; cohort studies; Denmark; endometrial neoplasms; infertility; ovarian neoplasms; parity; uterine cervical neoplasms
Abbreviations: CI, confidence interval; SIR, standardized incidence ratio