The impact of pregnancy on differentiated thyroid cancer

Objective To study the impact of pregnancy on differentiated thyroid cancer. Methods Retrospective comparative analysis were made between pregnancy-related thyroid cancer patients ( including nine months before delivery and one year after delivery) and the age-matched non-pregnancy-related thyroid cancer patients treated in the Department of head and neck, Fudan University Shanghai Cancer Center. Results There were 125 cases of pregnancy-related thyroid cancer patients from 1998 to 2008, including 28 cases (22.4%) of neck recurrence and metastasis after the surgery of thyroid cancer, meanwhile there were 691 cases of the agematched non-pregnancy thyroid cancer patients, including 90 cases ( 13% ) of neck recurrence and metastasis after the surgery of thyroid cancer. The rate of neck recurrence and metastasis after the surgery of thyroid cancer in the pregnancy-related group was higher than that in the non-pregnancy related group ( P ＜ 0.05). The maximum diameter of tumor in the pregnancy-related group and the non-pregnancy group is 2. 1 cm and 2.6cm respectively.There were 19 cases of multi-focal cancer ( 19.6% ) in the pregnancy-related group and 58 cases (9. 6% ) in the non-pregnant group, P ＜0.05. There were 23 patients (23.7%) of extrathyroid invasion in the pregnancy-related group and 65 patients ( 10.8% ) in the non-pregnant group, P ＜0.05. There were 67 cases (53.6%) and 35 cases (28%) of the central and lateral cervical lymph node metastasis in the pregnancy-related group respectively and 296 cases (42.8%) and 117 cases (16. 9% )in the non-pregnant group, P ＜0.05. There were 19 cases (15.2%) of extralymph invasion in the pregnancy-related group and 32 cases (4.6%) in the non-pregnant group, P ＜ 0.05. Conclusions The incidence of Extrathyroid invasion, multi-focal cancer, cervieal lymph node metastasis and extralymph invasion of the differentiated thyroid cancer is higher in pregnancy-related patients.Pregnancy may deteriorate the prognosis of thyroid cancer. For patients after the surgery of thyroid cancer, pregnancy may increase the risk of neck recurrence and metastasis. However, pregnancy does not affect the stage of thyroid cancer and the prognosis is still good. Key words: Thyroid cancer; Pregnancy