‘Cancer during pregnancy can be intense’ | Christianne Lok in NRC

6 Nov 2020 13:56

It’s rare, but some women develop cancer during their pregnancy. Christianne Lok merges the expertise of various physicians, and discussed her work in an interview with NRC Handelsblad.

“Cancer leads to uncertainties,” says gynecologic oncologist Christianne Lok of the Netherlands Cancer Institute in Amsterdam. “You can offer some peace of mind by letting a patient know that there were 20,000 people who came before her, and that research has shown us what the best treatment options are. But this isn’t the case for women who develop cancer during their pregnancy, because there is so much that we don’t know. And they don’t just worry about themselves, but also about their child. It’s all very intense. I want to do my best to give them the best care possible.”

CV New Zealand
Christianne Lok, gynecologic oncologist, has been working at the Netherlands Cancer Institute since 2013. She studied medicine in Amsterdam at the VU, then specialized in gynecology at the Amsterdam UMC and spent a year working in New Zealand. She obtained her PhD at the University of Amsterdam.
Approximately 200 pregnant women in the Netherlands are diagnosed with cancer every year. Breast cancer is the most common type, followed by blood cancer, cervical cancer, and melanomas. Ten years ago, physicians barely treated women during their pregnancies to avoid any impact on the unborn child. Most physicians opted to terminate the pregnancy or induce the labor early.

Nowadays, about three quarters of all pregnant women receive treatment and 90% of babies are born alive. This change in treatment method has been made possible in part by Lok’s research and recommendations. In 2012, she founded The Advisory Board on Cancer in Pregnancy together with 27 other experts, offering advice about the best treatment options to all care providers. Several countries in Europe are currently working into establishing similar advisory boards. Lok intends to set up a European advisory board for rare tumors during pregnancies.

Physicians face difficult decisions.

Christianne Lok Foto Annabel Oosteweeghel
When they’re done with their treatment and show up for a consultation together with their child, completely happy, that’s what I’m doing it for. But I also remember those cases that ended differently
Christianne Lok photo by Annabel Oosteweeghel

How did you come up with this advisory board?
“only one in 1000-2000 women will experience cancer during pregnancy. This does, however, mean that gynecologists and oncologists do not have a lot of experience in treating these patients, and the patients they do encounter present with a wide variety of tumor types, making each individual case even more unique. Physicians face difficult decisions. That’s what initially gave me the idea of the advisory board. I approached several experts who were immediately enthusiastic. We have been around for eight years now. Care providers can submit a case online. We sent the case to all physicians in our group who respond to it from their own expertise. The secretary and I turn all these responses into one recommendation that will be sent to the original submitter within four days.”
Surgery is usually an option, and we recommend chemotherapy with increasing frequency.

What kind of treatments are available to pregnant women?
“That depends on the type of cancer and the stage of the tumor and pregnancy. Late stage cervical cancer can be hard to treat, We try to stick to the the standard treatment as closely as we can, which would mean radiation therapy, and that isn’t an option because it will damage the unborn child. Radiation therapy may be an option for tumors that develop elsewhere in the body, however, We rarely deliver radiation to women in their third trimester because the fetus will be larger and closer to the area receiving the treatment. Surgery is usually an option, and we recommend chemotherapy with increasing frequency. We don’t know much about the effects of immunotherapy so we mostly avoid it for now.”

Can the placenta be a buffer during chemotherapy ?
“Yes. The placenta can form a barrier between the blood of the mother and the blood of the child, and works like some kind of filter. Some chemotherapy will reach the child through the placenta, but the amounts are much smaller. It depends on the exact drugs we used, and we have been learning more about this. We don’t offer chemotherapy to women in the first trimester, by the way, because that’s when the organs are formed. Even a low dose can cause birth defects.”

What are the potential effects of the chemotherapy on the child during the second and third trimester?
“Our research has shown us that these babies can have slightly lower birth weights, although the children tend to catch up quickly. We also know that a premature birth tends to have a larger effect than chemotherapy. Premature babies often face physical and psychological problems later in life.”

Is chemotherapy as effective for pregnant women as it is for non-pregnant women?
“That is one of the questions we are currently researching by measuring the levels of drugs in the blood during therapy. Pregnant women retain more fluids in their bodies, which will dilute the chemotherapy. They will need a higher dose to reach the same concentration of chemotherapy in the blood during pregnancy. We currently do not raise the dose because we have found that the standard treatment proves equally effective for pregnant women and non-pregnant women alike.”
Which trials are currently still running?
“We collaborate with several other countries within the INCIP (International Network on Cancer, Infertility and Pregnancy) to include as many people as possible in our research. We ask women to donate their placentas after birth so we can find out whether the delayed growth is the result of abnormalities in the placenta.”

We suspect that diagnoses are delayed

“Because we want to find out whether cancer behaves the same way in pregnant women, we ask all women to allow us to register them so we can follow the course of their illness. We also want to find out how quicky women receive their diagnosis. We suspect that these diagnoses are often delayed because many symptoms of cancer resemble pregnancy symptoms: light blood loss, fatigue, or swollen breasts. Women and their treatment providers need to stay alert at all times.”

Have there been patients that were particularly memorable?
“Many of them. Even patients I’ve only met on paper: some cases are so intense. But I mostly still think about my own patients. When they’re done with their treatment and show up for a consultation together with their child, completely happy, that’s when I realize that that’s what I’m doing it for. But I also remember those cases that ended differently: when the baby didn’t make it. You really want things to be different for these patients.”

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