At ECR 2026, the session Cancer imaging during pregnancy: sharing our experience examined how radiology supports diagnosis, staging and treatment assessment when cancer and pregnancy intersect. Across lymphoma, breast, colorectal and gynaecological malignancies, the speakers returned to the same core challenge: balancing maternal care with fetal safety, while avoiding delays that can worsen outcomes. Imaging choices were presented not as fixed rules, but as careful decisions shaped by tumour type, pregnancy stage and the need for multidisciplinary care.
Balancing Diagnostic Accuracy and Fetal Safety
Doris Leithner began with lymphoma, noting that in non-pregnant patients CT and especially PET/CT remain central, because many common lymphoma subtypes are FDG-avid and PET/CT directly influences treatment decisions. During pregnancy, however, the picture changes. She stressed that “ultrasound and MRI are not associated with risks and are the imaging techniques of choice”, while also warning that “gadolinium contrast should be definitely limited” and that in lymphoma “we do not need gadolinium”. For her, whole-body MRI with diffusion-weighted imaging has a particularly important role, since diffusion substantially improves sensitivity and can also support response evaluation. She also underlined that PET is not excluded absolutely, but remains a cautious choice: “the fetal radiation dose from PET is low”, yet it is “still not considered risk free”.
Alexandra Athanasiou then turned to breast cancer during pregnancy and lactation, where delayed diagnosis remains a major concern. She repeatedly returned to the clinical tendency to dismiss symptoms as pregnancy-related, even though “every lesion persisting more than two weeks should be investigated”. Her central message was clear: “we shouldn’t delay the diagnosis”, and women should not be undertreated simply because they are pregnant. Ultrasound, she said, is “our modality of choice”, while mammography can be used in selected cases with a high pre-test probability of malignancy. She insisted that radiologists have an important role in discussing radiation fears, describing mammography in pregnancy as a “very, very, very low dose” examination that is “completely safe” when indicated. MRI, in contrast, is reserved more selectively during pregnancy, particularly because of contrast concerns, but remains useful after delivery for staging and response assessment.
When MRI Becomes the Backbone of Care
Vincent Vandecaveye described colorectal cancer in pregnancy as both rare and difficult, partly because symptoms are often attributed to physiological changes and many patients present late. He called it “a very rare tumor during pregnancy”, but also one in which “most patients present with late diagnosis” and often already have stage III or IV disease. That reality shapes imaging strategy. In his view, MRI becomes the backbone of care because it is a “no dose modality” and particularly valuable when repeated imaging is needed during pregnancy. He cautioned not only against single-exam exposure, but against accumulation over time: “you’re at danger of cumulative doses and really keep aware of that”. For colorectal cancer, he favoured either full abdominal MRI with diffusion-weighted and T2-weighted imaging, plus chest CT when needed, or whole-body MRI in expert centres. He also argued strongly against unnecessary contrast exposure, stating that his institution follows a “strictly no gadolinium policy”. Even when CT is used, it is chosen selectively and only after weighing diagnostic benefit against fetal risk.
His cases illustrated how imaging strategy changes with timing. In one patient, whole-body MRI during pregnancy allowed staging and follow-up until delivery, after which pelvic MRI and PET/CT were used according to standard post-pregnancy practice. In another, MRI identified both the primary tumour and a small liver metastasis, helping guide the decision to bring delivery forward so that surgery and subsequent treatment could proceed without exposing the fetus to chemotherapy. Imaging, in this account, was not simply diagnostic. It directly shaped the sequence of treatment, delivery and reassessment.
Tailored Imaging for Complex Pelvic Malignancies
Charis Bourgioti addressed gynaecological cancers, reminding the audience that pregnancy-associated cancer includes any cancer diagnosed from conception to one year postpartum. She noted that these cancers remain rare, but incidence appears to be rising, possibly alongside advanced maternal age. In this setting, ultrasound is the initial step, but as pregnancy progresses its limitations become more apparent. For that reason, she described MRI as “the reliable alternative” and “the imaging modality of choice for diagnosis and stage in gynecological cancer during pregnancy”. She emphasised that no single universal protocol fits every case. Instead, imaging should be built around the question being asked, with attention to fetal safety, maternal comfort and scan time. Her protocol relied on T2-weighted imaging, T1 sequences for haemorrhage or fat, and diffusion-weighted imaging as part of the basic examination, while intravenous contrast was reserved only for exceptional situations in which the information would be critical for decision-making.
In cervical cancer, she pointed out that MRI is especially valuable once disease is pathologically confirmed and macroscopic tumour or metastatic suspicion is present. Pregnancy-related oedema can make small lesions harder to define on T2-weighted images, which is why diffusion-weighted imaging becomes so useful to “better delineate tumor borders”. She also stressed the importance of defining the distance from the internal cervical os, since selected patients may be candidates for radical trachelectomy. In ovarian masses, MRI helps when ultrasound is indeterminate, when lesions are too large for full sonographic assessment, or when there is concern for spread beyond the pelvis. Yet she also highlighted the many mimics that can complicate interpretation during pregnancy. Her closing message was not only technical but human: “management of malignant tumors during pregnancy is challenging”, “careful counseling is advised”, and imaging remains “the important part of the diagnosis, staging and follow up”.
Conclusion
In the end, the session did not present one universal pathway for cancer imaging during pregnancy. It showed instead that good practice depends on choosing the safest effective modality for each clinical situation, avoiding unnecessary delay, and integrating radiology into multidisciplinary decision-making. MRI emerged as the common thread across tumour types, valued for its breadth, reproducibility and lack of ionising radiation, while CT and PET retained a role when clinically justified. The message across all four talks was consistent: imaging must protect fetal safety without compromising the mother’s chance of timely, appropriate cancer care.
