Fertility drugs and young-onset breast cancer: results from the Two Sister Study.

Abstract

BACKGROUND:

Fertility drugs stimulate hyperovulation, which may have implications for breast cancer. We examined the association between use of fertility drugs (clomiphene citrate [CC] and follicle-stimulating hormone [FSH]) and subsequent risk of young-onset (<50 years at diagnosis) breast cancer.

METHODS:

We conducted the Two Sister Study, a sister-matched case-control study, by enrolling 1422 women between September 2008 and December 2010, who were younger than age 50 years at diagnosis with breast cancer and were enrolled within 4 years of diagnosis, and 1669 breast cancer-free control sisters from the Sister Study. Participants reported their use of fertility drugs (CC and FSH) and ever-users reported whether a pregnancy had resulted that lasted 10 or more (10+) weeks. Conditional logistic regression was used to estimate confounder-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for fertility drug use with or without conception of a 10+ week pregnancy.

RESULTS:

A total of 288 participants reported having used ovulation-stimulating drugs (193 CC only, 29 FSH only, and 66 both). Overall, women who had used fertility drugs showed a non-statistically significantly decreased risk of breast cancer, compared with nonusers (OR = 0.82, 95% CI = 0.63 to 1.08). Women who had used fertility drugs but had not conceived a 10+ week pregnancy under treatment showed a statistically significantly decreased risk of breast cancer compared with nonusers (OR = 0.62, 95% CI = 0.43 to 0.89). Women who had used fertility drugs and conceived a 10+ week pregnancy under treatment showed a statistically significantly increased risk of breast cancer compared with unsuccessfully treated women (OR = 1.82, 95% CI = 1.10 to 3.00), although their risk was not increased compared with women who had not used fertility drugs (OR = 1.13, 95% CI = 0.78 to 1.64).

CONCLUSIONS:

In the absence of a 10+ week pregnancy under treatment, exposure to ovulation-stimulating fertility drugs was associated with reduced risk of young-onset breast cancer. This apparent association was absent in women who conceived a 10+ week pregnancy under treatment, for whom risk was higher than that of unsuccessfully treated women, but similar to that of untreated women.

• Authors: Chunyuan Fei, Lisa A Deroo, Dale P Sandler, Clarice R Weinberg
• Journal: Journal of the National Cancer Institute (J Natl Cancer Inst) Vol. 104 Issue 13 Pg. 1021-7 (Jul 03 2012) ISSN: 1460-2105 [Electronic] United States
• PMID: 22773825 (Publication Type: Comparative Study, Journal Article, Research Support, N.I.H., Intramural, Research Support, Non-U.S. Gov't)

Chemical References

• Biomarkers, Tumor
• Estrogen Antagonists
• Fertility Agents
• Receptors, Estrogen
• Clomiphene
• Follicle Stimulating Hormone

Topics

• Adult
• Age of Onset
• Biomarkers, Tumor (analysis)
• Breast Neoplasms (chemically induced)
• Case-Control Studies
• Clomiphene (administration & dosage, adverse effects)
• Estrogen Antagonists (administration & dosage, adverse effects)
• Female
• Fertility Agents (administration & dosage, adverse effects)
• Follicle Stimulating Hormone (administration & dosage, adverse effects)
• Humans
• Logistic Models
• Odds Ratio
• Pregnancy
• Pregnancy Trimester, First
• Pregnancy Trimester, Second
• Receptors, Estrogen (analysis)
• Risk Assessment
• Risk Factors
• Siblings