A Healthy Pregnancy with Breast Cancer

Sibylle Loibl, MD, PhD

Sibylle Loibl, MD, PhD

It is possible to have a healthy pregnancy amidst a breast cancer diagnosis, though there are some treatment concerns that must be considered, said Sibylle Loibl, co-chair of the German Breast Cancer Group and Associate Professor at the University of Frankfurt, Germany.

In a recent interview at the 2016 San Antonio Breast Cancer Symposium (SABCS), Loibl discussed some of the challenges and misconceptions about breast cancer treatment for pregnant women.

Can you explain the biological findings about being pregnant with breast cancer?

From our data and from our registry, since 2003, we are collecting patients who have been diagnosed with breast cancer during pregnancy because we found that it a very important topic with very little research. We also collected tissue and we want to investigate if those patients diagnosed with breast cancer during pregnancy have another biology, meaning if there is another expression of certain proteins, like hormone receptor status, HER2 status or if there is another proliferation status.

We also wanted to look with modern techniques like sequencing techniques if the mutation pattern is different. We know the main mutation in breast cancer is TP53, which is a so-called tumor suppressor gene. And if that is mutant, then of course the tumor cannot be suppressed and is growing. Then a very important gene is the Pf3 kinase gene, which is also mutated quite often. The main difference is that the Pf3 kinase is more mutant in hormone-receptive positive breast cancer, whereas the TP53 is more often mutated in the triple-negative breast cancer. This we have seen.

Here we have an increase in the higher-risk mutant genes, the tumor suppressor genes, and have less Pf3 kinase mutations in our cohort, indicating that these cancers might have slightly more aggressive biology, but we also saw that they are less hormone receptor-positive compared to another data set, which we took from what was publicly available.

You mentioned that there's a lack of research in this area. So for a patient who is pregnant and has just been diagnosed with breast cancer, what advice would you give her?

I hope you cannot find any horror stories by Googling that. Since a couple of years ago, we've really motivated the patients to keep the pregnancy, to look forward to being a happy and healthy mother. Go and get treated, because only if you go and get treated can you be a healthy mother, as well. This is very important.

It took some time to convince the physicians and the oncologists that they can give chemotherapy during pregnancy, which, of course, is important because the pregnancy takes some time to end by nature and it's too late if you wait too long. So we can give almost all chemotherapies, but we have to be careful with Herceptin (trastuzumab), and we have to be careful with endocrine treatments. Otherwise, we can naturally start these treatments after chemotherapy so there is no need to not treat our patients according to the current standard, and this is very important.

How, if at all, is Herceptin and endocrine therapy given during pregnancy?

Endocrine treatment should definitely not be given during pregnancy. We know from all the data that they could cause mutilations, so they should be given after chemotherapy. That's what we normally do in non-pregnant women.

And with Herceptin, we have to be very careful. We have seen that the amniotic fluid is decreasing, even completely going away. For that reason, if you have a high-risk patient and you want to treat them with Herceptin during pregnancy, you have to really closely monitor them. As soon as the amniotic fluid is decreasing, then you have to stop the treatment and it might be safely delivered. Personally, I have never done that, but I know that colleagues in high-risk situations have done that, and the case reports are not all fatal. There are some case reports where patients were managed with Herceptin during pregnancy.

Are there any kind of lifestyle changes that pregnant women with breast cancer should make?

In general, or not, the advice we give to all the other cancer patients is that they should be careful of not getting infections. They should go out and be physically active because this can reduce neutropenia. Anemia is also a problem because pregnant patients are anemic by their status themselves, and the chemotherapy might make them even more anemic. So this might be a situation where we have to be careful, but usually pregnant patients get iron and I will do that definitely and watch closely.

But otherwise, be a healthy, happy mother.