IVF May Not Increase Breast Cancer Risk

A new study’s findings contradict previous assumptions about IVF and breast cancer risk.

A recent study found no association between in vitro fertilization (IVF) and an increased risk of breast cancer.

Since IVF increases estradiol and progesterone temporarily, it was thought that IVF could potentially increase the risk of breast cancer, but there have been no long-term studies to examine this relationship. Researchers in the current study published by JAMA, conducted a long-term study with a median follow-up for 21 years.

The examined the risk of breast cancer in 19,158 women who underwent IVF between 1983 and 1995. They also included 5950 women who underwent other fertility treatments between 1980 and 1995.

Researchers found 839 cases of invasive breast cancer and 109 cases of in situ breast cancer. They discovered that the incidences of cancer were 3% for women who underwent IVF, and 2.9% for women who underwent other treatments.

They did not find that the risk was effected by the type of fertility drugs or diagnosis; however, women with 7 or more IVF cycles had a decreased risk compared with women who only had 1 or 2 cycles.

A decreased risk was also seen among women who had a poor response to the initial IVF treatment.

"These findings are consistent with the absence of a significant increase in the long-term risk of breast cancer among women treated with these IVF regimens," the authors concluded.