Thyroid cancer represents the second more frequent tumor among those diagnosed during pregnancy. Indeed, during pregnancy thyroid volume increases by 2030% and new nodules can appear, due to the effect of choriogonadotropin which stimulates thyroid growth. Hence, it has been proposed that thyroid cancer diagnosed during pregnancy could harbour a poorer prognosis. Aim of the present study was to compare the clinical outcome in the following 3 groups of patients affected with thyroid cancer: group 1 (Gr.1): 12 women with tumor diagnosed during pregnancy and submitted to thyroidectomy during the second trimester or in the first year after delivery; group 2 (Gr.2): 33 women with diagnosis of tumor at least 1 year after the delivery; group 3 (Gr.3): 49 women with diagnosis and treatment of the tumor before pregnancy or nulliparous. The 3 groups were matched for age, treatment, histology and follow-up. In particular, all patients of group 1 were treated with total thyroidectomy and radiometabolic treatment. Remission or persistence of disease were defined on the bases of basal thyroglobulin (Tg) levels before and after rhTSH, in the absence of anti-Tg antibodies, and of Total Body Scan. No significant differences in tumor size, capsular invasion and local/distant metastases were observed between the 3 groups. As far as the outcome is concerned, patients with the tumor diagnosed during pregnancy showed more frequently persistence or relapse of the disease with respect to the patients of the other groups (Gr. 1 vs Gr. 2: P=0.0035; Gr.1 vs Gr. 3: P=0.0057; Gr1 vs Gr. 2+3, P=0.018; Gr.2 vs Gr.3: P=NS). In particular, 9/12 patients of Group1 showed persistence of disease, with lymph-node metastases in 2 cases, distant metastases in 2 cases and elevated Tg levels in 5 cases.
In conclusion, the present data show that thyroid cancer diagnosed during pregnancy is associated with a poorer prognosis with respect to tumors developed in a non gravidic period, thus suggesting the need for an aggressive treatment by thyroidectomy during the second trimester and radiometabolic therapy soon after delivery.