I wanted to share with you a blog post I recently came across. Being a practitioner who sees mainly patients going through fertility treatments, the concern that fertility drugs increase the risk of breast cancer is a big one to me and to my patients. This post, published by the Northwestern University Oncofertility group addresses the recent research highlighting breast cancer and fertility drugs.

Here's the post in its entirety.

Giuliana Rancic, Infertility Treatments, and Breast Cancer
Posted by Kate Waimey Timmerman, Ph.D.
December 21, 2011

A few days ago, we posted a blog about Giuliana Rancic’s personal experiences this year, first with infertility treatments, and then with a breast cancer diagnosis. Her story caused people to ask if her infertility treatments were related to her breast cancer diagnosis. Simultaneously, this fall, a scientific article was published that asked a similar question about any potential link between infertility treatments, such as in vitro fertilization (IVF), and breast cancer.

IVF is the process by which a woman’s eggs are combined with sperm in a laboratory setting to produce an embryo. For this procedure, a woman undergoes hormonal stimulation to cause the release of multiple eggs from her ovaries, which are then surgically retrieved. While some studies have previously found that there may be an increased risk for breast cancer in some patients who participate in infertility treatment, no cause-and-effect relationship has been identified. Dr. Jacqueline Jeruss and colleagues recently examined whether exposure to hormones during infertility treatment may cause the development of cancerous breast cells or affect the proliferation of cancer cells. They investigated this question with the use of breast cancer cell lines in a laboratory setting.

In the journal, Human Reproduction, the researchers communicated the effects of estrogen, progesterone and human chorionic gonadotropin (hCG), which are all hormones that are elevated during infertility treatment or early pregnancy, on breast cancer cell lines. In addition, they examined how these cells may be affected by clomiphen citrate, also known as Clomid, a drug frequently used to increase egg production in women prior to egg retrieval. The authors found that Clomid, progesterone, and hCG were all found to either have no effect on breast cancer cells or reduce their division and growth. As hCG is elevated in early pregnancy, this study raises the possibility that pregnancy may actually have protective effects on reducing breast cancer risk.

In the same article, “Effect of infertility treatment and pregnancy-related hormones on breast cell proliferation in vitro,” one type of breast cancer cell line, derived from breast cancer cells that contain estrogen receptors (ER positive), responded to the estrogen treatment with increased cell division and growth. About 70% of breast cancers are ER positive, so women with a predisposition to these cancers, such as those with a BRCA2 mutation, may want to discuss breast cancer risks of infertility treatment with their doctors. However, women with mutations in the BRCA1 gene are more likely to have ER negative tumors, especially those who are diagnosed under age 40. In the study by Cooley et al., BRCA1 breast cancer cells responded to Clomid and progesterone with a decrease in cell division, indicating that BRCA1 women may not be at increased risk for breast cancer after infertility treatments. This information may help women who are at high risk for breast cancer to better understand their risk of breast cancer after infertility or oncofertility treatments.