Thyroid Papillary Microcarcinoma Might Progress During Pregnancy

Background: Papillary thyroid cancer occasionally occurs in women of childbearing age. As papillary microcarcinoma (PMC) rarely grows or becomes clinically apparent, observation without surgery is an appropriate strategy for patients with low-risk PMC. Human chorionic gonadotropin possesses weak thyroid-stimulating activity. The aim of this study was to assess the effect of pregnancy on PMC. Methods: We studied 9 patients with PMC who became pregnant between 2005 and 2011. Twenty-seven agematched nonpregnant female PMC patients from a database we used in our previous report served as controls. Tumor enlargement was defined as an increase in the diameter of the tumor of 3 mm or more. Results: PMC enlargement occurred in 44.4% (4/9 patients) of the pregnant subjects, whereas it occurred only in 11.1% (3/27 patients) of the controls ( p= 0.0497). Three of the pregnant patients who exhibited tumor enlargement underwent surgery after delivery. No relationship was detected between the changes in the serum thyroglobulin level, the serum thyrotropin level, and tumor size during pregnancy. Immunohistochemical examinations did not detect the estrogen receptor in the tumors of the three patients who underwent surgery. Conclusions: This study is an initial report indicating that the risk of PMC enlargement might increase during pregnancy. PMC should be carefully followed-up for possible disease aggravation during pregnancy. Even if a PMC enlarges during pregnancy, the patient’s prognosis will probably not worsen.