Cancer complicating pregnancy is a rare coexistence. The incidence is approximately 1 in 1,000 pregnancies. The most common cancers are those more frequently seen during the reproductive age of a woman. Breast cancer, cervical cancer, Hodgkin's disease, malignant melanoma, and leukemias are the most frequently diagnosed malignancies during gestation.The diagnostic and therapeutic management of the pregnant patient with cancer is especially difficult because it involves two persons, the mother and the fetus.In this paper we review: A) the therapeutic and diagnostic management of these patients; B) the safety of diagnostic and therapeutic procedures; C) the metastatic pattern of the maternal tumors to the placenta and fetus, and D) the potential recommendations for therapeutic abortion.