The cause of breast cancer remains an enigma, but the risk of it occurring is definitely associated with female reproductive history.  The fact that  the development of breast cancer is linked to repeated or sustained exposure to high blood estrogen levels has raised obvious concern that fertility drugs, by increasing ovarian estrogen output (albeit for a relatively short period of time), might increase the risk of its occurrence.

While available published data does not suggest a higher overall risk of breast cancer in women who receive fertility treatment, the question regarding IVF versus non-IVF fertility treatment has not been adequately evaluated. Now, a recent report on a large Western Australian study, comprising data from 21,025 women and spanning 20 years suggests that  that while overall, IVF treatment itself does not increase the risk of  breast cancer in older women, younger women undergoing their 1^st IVF attempt could well be at increased risk.. This study revealed that women who initiated their 1^st IVF attempt in their mid-twenties were approximately one-and-a-half times more likely to develop breast cancer than were controls (of the same age), who underwent other (non-IVF) forms of fertility treatment, while women who first underwent IVF after the age of 40 years were not at increased risk.

Presently, the general consensus is that overall, IVF is not associated with an increased risk for development of breast cancer. However, all women (even younger women) with predisposing risk factors should undergo breast cancer screening  prior to initiating IVF.  In addition, women should be made aware of the fact that the risk of breast cancer increases incrementally along with the age at which a women gives birth to her 1^st child.

*The AmericanCollegeof Obstetricians and Gynecologists recommends that women be offered annual screening for breast cancer starting at age 40; the American Cancer Society endorses mammograms starting at the same age. However, women who have risk factors that increase the chance of breast cancer should undergo earlier screening, especially if they are planning to undergo fertility treatment.