“Does IVF cause cancer?”
I see many patients from around the world with the severest forms of male infertility who as a couple need in vitro fertilization (IVF) to conceive and I am asked this question all the time. It’s an issue that I have been thinking about for 15 years, since I first entered the field. And honestly, I still don’t have a great answer…nor does anyone else.
It was recently reported that IVF produced its 5 millionth baby worldwide since first performed in 1978. In some developed countries, up to 3% of babies are IVF babies. That number stands at around 1-2% in the U.S. The point is, IVF isn’t going away soon.
The Candidate Cancers
The concern about IVF and female cancers is based on the fact that several of them, including ovarian and breast cancer, are known to be hormonally sensitive. And IVF involves lots of hormones and, in many cases, for several treatment cycles. Breast cancer tends to occur earlier in a women’s life than ovarian cancer and is much more common. Ovarian cancer is also a relatively “silent” cancer that is harder to detect early whereas breast cancer has established, validated screening protocols for early detection.
Given the caveats and based on the few good studies that address this issue, my understanding is that there is no increased risk of ovarian cancer after IVF. It is true that women who undergo IVF are more thoroughly “screened” medically than other women, and so the rate of finding non-malignant tumors in IVF women is higher. Not surprisingly, the harder you look, the more you find. But not ovarian cancer.
The Latest on Breast Cancer
The story with breast cancer may be different. IVF involves hormone injections that increase a young woman’s estrogen levels significantly, up to 15 times normal. And breast cancers are very common and are exquisitely hormonally sensitive. This is a real issue, even to the degree that if you are a breast cancer survivor, IVF (and pregnancy) is not recommended after cancer treatment. Witness the recent family building efforts of the popular TV show host Guiliania Rancic who, as a breast cancer survivor, is having another women carry her child to term (gestational surrogacy).
To date the link between later breast cancer and IVF has been unclear. However, two very recent studies shed more light on this link. One from Australia followed 21,000 women over 16 years after taking fertility drugs and compared breast cancer rates in those who had taken drugs with or without IVF over the same period. A powerful study design, it showed that breast cancer rates did not differ among women who received fertility drugs either with (2%) or without (1.7%) IVF. However, there was a 56% increase in breast cancer rates in women who had IVF treatments before the age of 30 years compared to controls. So, exposing younger women to high estrogen levels through IVF treatments may lead to an increased risk of breast cancer.
Another study from the U.S. examined the history of fertility treatments in 3091 sister-paired women, one of whom had breast cancer before age 50 years. Notably, the study did not find an increase in breast cancer rates in women who had used fertility drugs in the past. Realize, though that this study design is smaller and weaker than the longitudinal study from Australia. Because of this, it doesn’t address the question as directly and precisely as the Australian study.
So what’s a couple to do? First, understand that the jury is still out on the link between breast cancer and IVF. Second, it’s safest to assume that there is an increased risk of breast cancer after IVF. This risk may not be strong enough to be considered a cancer “risk factor,” like for example, having a family history is, but think of it as being “on the table” as you examine the risk-reward ratio of pursuing IVF. Life is a path and we all make decisions daily that involve risk. As Horace once said: “Remember when life’s path is steep to keep your mind even.” Knowing this risk can help make the path a less strenuous one.