Cancer Diagnosed During Pregnancy: — Can Targeted Therapy Be Used?

Most targeted agents — including tyrosine kinase inhibitors and many monoclonal antibodies — can cross the placenta and reach the developing baby. The first trimester is when the baby's organs and systems are forming, and interference with the signalling pathways these drugs target can disrupt that process. The result can range from growth restriction to structural malformation. In the second and third trimester the risk of structural malformation is lower, but drugs can still affect fetal growth, kidney development, and how the baby manages its own blood supply near birth. The honest answer is that safety data for most targeted agents in pregnancy is very limited, because clinical trials exclude pregnant people. What exists comes from case reports and registries, not controlled studies.

For some cancers, yes — and this is the first question your oncologist should answer clearly. Slow-growing tumours diagnosed near the end of pregnancy are sometimes managed by bringing birth forward slightly and starting treatment afterwards. Aggressive cancers, or those diagnosed early in pregnancy, are less likely to allow a safe delay. The decision is based on your tumour biology, not on a general rule about cancer in pregnancy. Ask your team how long a delay is clinically acceptable for your specific cancer, what would change if you waited, and how they would monitor the cancer during that time. That conversation should give you a specific answer, not a vague one.

The washout period is how long a targeted drug needs to clear from your body to a level considered safe — for conception, or for the baby near delivery. It is calculated from the drug's half-life: the time it takes the body to reduce the drug's concentration by half. Most guidelines recommend waiting for several half-lives to pass after stopping a targeted agent, and depending on the specific drug that can mean anywhere from a few weeks to several months. ESMO guidance advises discussing the washout period per drug with the prescribing oncologist, because no single number applies to all agents. Why it matters near birth: if targeted therapy is still being taken close to delivery, the drug concentration in the baby at birth can be significant, affecting feeding, breathing, and temperature regulation in the first days of life.

It can, depending on what treatment comes next and whether fertility preservation was possible before treatment started. If your treatment plan involves drugs or radiation that may affect the ovaries, this needs to be planned for before treatment begins — not assumed to be someone else's concern later. Egg or embryo freezing before starting treatment is the most established route. It typically takes approximately 2 weeks from the start of hormonal stimulation to egg collection. Whether that window fits your treatment timeline is a clinical question your oncologist and a fertility specialist should answer together. Do not assume the question will be raised for you — ask it yourself at the first opportunity.

This is one of the most frightening questions in this situation. The honest answer is: it depends on the drug, the dose, and when in the pregnancy exposure happened. Very early exposure — before implantation — often follows an all-or-nothing pattern: either the pregnancy does not continue, or it does and the most affected cells have been replaced. Exposure during organogenesis, roughly weeks four to ten, is when the risk of structural harm is highest. Tell your oncologist immediately and ask for a referral to a maternal-fetal medicine specialist. They can assess the specific drug and timing and will likely arrange detailed fetal imaging. Do not assume the worst and do not assume everything is fine — get the assessment done.

Yes. CION's oncologists work with referring obstetricians and maternal-fetal medicine specialists to coordinate care for pregnancy-associated cancer across its centres. Treatment decisions — including any systemic therapy, response assessment, or staging imaging — are made with the pregnancy in mind. Imaging such as PET-CT is arranged through partner imaging centres with appropriate precautions, or deferred where it is safe to do so. CION does not provide fertility preservation procedures directly; if egg or embryo freezing is needed, referral to a fertility specialist is coordinated as part of the treatment planning conversation.