Approach to the pregnant patient with thyroid cancer.

Thyroid cancer, the most common endocrine malignancy, increased progressively from 1972 through 2002 largely as the result of an increasing incidence of small papillary thyroid cancers, the majority of which are less than 2 cm and which increased almost 3-fold during the 30-yr study. During this time, thyroid cancer was found to affect women more often than men by a ratio of almost 3 to 1. Moreover, papillary thyroid cancer was found to be the most common form of differentiated thyroid cancer among women of childbearing age, 10% of whom were either pregnant or in the early postpartum period when thyroid cancer was diagnosed. Although the prevalence of thyroid cancer in pregnant women remains high, most are first identified after delivery. Nonetheless, the management of thyroid cancer during pregnancy poses serious diagnostic and therapeutic challenges to both the patient and fetus. The thyroid gland may secrete more thyroid hormone than usual during early pregnancy, which may not only be the cause of this problem but also may be responsible for the higher rate of differentiated thyroid cancer during pregnancy. There is concern about therapy for thyroid cancer during this period, including the timing of surgery, the use of levothyroxine, and the assessment of follow-up during gestation.