Diagnostic Radiology and Radiation Therapy
Chapter 1 - Cancer Treatment during Pregnancy
Radiation doses greater than 100 mGy may result in up to 1% risk of childhood cancer and foetal malformations. However, staging procedures that involve radiation exposure are usually below this dose. Nevertheless, it is preferred to strictly limit their use during pregnancy. Chest x-ray could be performed to rule out pleural or lung pathology, yet with adequate abdominal shielding. Abdominal ultrasound is quite safe and can be used to evaluate the liver and abdominal organs. Computed tomography (CT), bone and fluorodeoxyglucose–positron emission tomography (FDG-PET) scans should be strictly avoided during pregnancy. Magnetic resonance imaging (MRI) without gadolinium could serve as a better alternative in the event that an abdominal ultrasound or chest x-ray shows suspicious or inconclusive findings. Whole-body MRI may be an interesting approach for pregnant cancer patients, as it provides a fast and accurate evaluation of the whole body without exposure to radiation or contrast material. However, experience with this technique is rather limited to only a few centres worldwide.
Radiation therapy is better postponed following delivery. Patients with brain metastases often require immediate palliative radiotherapy, and this can be performed during pregnancy, provided adequate shielding is established. Palliative radiotherapy to the cervical spine, upper thoracic vertebrae and shoulders is also possible as the radiation fields are rather far from the uterus. Radiation to the pelvis and lumbar area should be avoided during the course of gestation. In case there is an urgent need for such treatment, abortion should be considered.