Outcome of differentiated thyroid cancer diagnosed in pregnant women.

The clinical features and outcome of thyroid cancer in 61 pregnant women (mean age, 26.0 +/- 5.9 SD yr) and in 528 female, age-matched controls who were not pregnant (mean age, 26.3 +/- 5.9 SD yr) were compared. Median follow-up was 22.4 and 19.5 yr [P = not significant (NS)] in the two groups, respectively. The thyroid nodule was asymptomatic and discovered on routine examination more often in the pregnant women (74%) than in controls (43%, P < 0.001); other clinical and tumor features were similar in the two groups. Most of the pregnant women underwent thyroidectomy after delivery (77%) or during the second trimester of pregnancy (20%). Near-total thyroidectomy was done in 43 (73%) of the pregnant women and 265 (59%) of the controls (P = NS), and nearly the same proportion of both groups (30% and 25%, respectively) were treated with 131I postoperatively. Outcome in the pregnant women and controls, respectively, was: cancer recurrence 9 (15%) and 107 (23%, P = NS); distant recurrences 1 (2%) and 12 (3%, P = NS), and cancer deaths 0 and 6 (1.2%, P = NS). Outcomes were similar when surgery was done during or after pregnancy, despite a longer delay in treatment of the latter (1.1 +/- 1.0 vs. 16.1 +/- 19.7 months, P < 0.001). This study suggests that the prognosis of differentiated thyroid cancer is the same in pregnant women and nonpregnant women of the same age, and that the diagnosis and treatment of thyroid cancer occurring during pregnancy can be delayed until after delivery in most patients.