The diagnosis of cancer complicates approximately 1 in 1000 pregnancies. Once diagnosed, emotional, ethical, diagnostic, and treatment dilemmas confront both the patient and the treating physicians, posing unique challenges. Questions regarding whether or not to terminate the pregnancy, potential maternal risk of delays in cancer treatment, fetal risks of early delivery, and maternal and fetal effects of cancer treatments during gestation are complex and competing factors that make decision making both medically and emotionally challenging. Limited data on the treatment of malignancies during pregnancy and absence of randomized controlled studies in this population contribute to the lack of generalized treatment algorithms. Individualization of treatment planning with a multidisciplinary team is essential. Considerations not only include the risk/benefit assessment of treatment modalities such as chemotherapy, radiation therapy, and surgery during pregnancy, but also include the potential maternal and fetal consequences of diagnostic procedures.
The most common malignancies during pregnancy include those that are most commonly found in women of reproductive age and include cervical and ovarian cancer. The most common nongynecologic malignancies are breast cancer, malignant melanoma, thyroid cancer, and hematologic malignancies.1,2, and 3 Given that the incidence of malignancies increases with increasing age, as more women choose to delay childbearing, it is expected that the incidence of cancer during pregnancy will increase.
The developmental effects of radiation exposure on pregnancy is related both to the dose of radiation as well as the gestational age.
Computed tomography and magnetic resonance imaging, including scans of the pelvis, are associated with negligible fetal risk.
Ionizing radiation is used routinely during imaging for cancer staging or disease surveillance, and radiation therapy is a common component of the treatment of many cancers in the nonpregnant patient. In pregnancy, consideration has to be given not only to the radiation exposure of the mother, but also that of the developing fetus. Much of what we know about the effects of radiation on pregnancy is based on animal studies, accidental or incidental human exposures to diagnostic and therapeutic radiation, and data gathered from victims of radiation exposure after the atomic bombings of Hiroshima and Nagasaki. There are many confounding factors that limit our interpretation of these data, including species differences, potential differential effects of various types of ionizing radiation, lack of certainty regarding the doses of radiation received, potential differential effects of single versus multiple exposures, and the baseline rate of human malformations and other negative outcomes. Given the lack of controlled studies on the issue, patient counseling regarding radiation exposure in pregnancy may be challenging, even as it relates to imaging procedures. The growing importance of this issue is evidenced by a recent review that noted a 107% increase over the past decade in the use of imaging studies using ionizing radiation during pregnancy.4