Considerations in radiation therapy for pregnant women with malignancy

Treatment of pregnant women with cancer with radiation presents medical, technical, and ethical challenges. Cancer during pregnancy occurs in 1 out of 1000 cases. The most common cancers are those that are common in females of childbearing age, including breast cancer, cervical cancer, melanoma, Hodgkin lymphoma, and leukemia. The in utero radiation exposure of a developing fetus through diagnostic radiology/nuclear medicine and radiation therapy is always a concern for healthcare providers and parents. Radiation exposure to the fetus seems to be associated with increased incidences of childhood cancer at any fetal dose. However, there also seem to be threshold doses for non-cancer adverse outcomes such as intellectual disability, organ malformation, and fetal death. The fetal radiation exposure from diagnostic radiology and nuclear medicine studies is far smaller than these threshold levels. On the other hand, fetal doses from radiation therapy for treatment of maternal cancers depend largely on gestational age and distance of fetus from the treatment field. Treatment of cancers in head and neck or extremities is relatively safe, while that of pelvic organs, such as cervical cancer, is not compatible with pregnancy. It is important to note that the “threshold” doses were calculated based on observational data and therefore should be used with careful considerations in individual clinical scenarios. Ultimately, it is the frank discussion between the pregnant mother and her family with the entire medical team, including her oncologist, the obstetrician, the neonatologist, the psychologist, and the social worker, that will lead to the best individualized management plan.