Comparison of characteristics in patients with both thyroid and breast cancer: Based on order of incidence

Abstract

Purpose : Clinicopathologic characteristics of patients with both thyroid and breast cancer during their lifetime were analyzed to investigate the association between the two malignancies according to the order of incidence.

Methods : A total of 405 patients who underwent surgery for breast and thyroid cancer at Severance Hospital between 1995 and 2014 were retrospectively selected and classified into 3 groups according to the order of incidence of the two cancers: simultaneous cancer (S), thyroid cancer followed by breast cancer (TB), and breast cancer followed by thyroid cancer (BT). Univariate analysis was conducted to compare parameters.

Results : S, TB, and BT groups were 166 (41.0%), 96 (23.7%), and 143 (35.3%) patients, respectively. In TB and BT groups, tumor size and surgical site for secondary cancer were smaller; therefore, adjuvant treatments were less frequently required for secondary cancer. ER positive rate was 77.1% in S, 75% in TB, and 63.7% in BT groups (P=0.027). The ratio of ER negative was higher in the group with BRAF mutation. Survival rate for index tumor was higher in order from TB, and BT, followed by S groups without statistical difference.

Conclusion : It is difficult to find a significant difference according to the order of occurrence except by screening test, and more studies are needed in the future. Establishing an appropriate screening program is important in order to detect secondary breast or thyroid cancer after surgery for thyroid or breast cancer.