Objective  To analyze the clinical and pathological features of multiple primary malignancies involving thyroid cancer.

  Methods  A retrospective study of 4, 861 thyroid cancer cases was performed. All patients were diagnosed at Yunnan Cancer Hospital between October 2007 and March 2017; among them, 290 patients harbored multiple primary malignancies involving thyroid cancer.Their clinical and pathological features were analyzed.

  Results  Among the 290 patients with multiple primary malignancies involving thyroid cancer, 7 (2.4%) had three malignancies and 283 (97.6%) had two malignancies. Eighty-three cases (28.6%) were synchronous multiple primary malignancies, and 207 cases (71.4%) were metachronous ones. Two hundred and forty-eight patients (85.5%) were primarily diagnosed with non-thyroid primary malignancies, and 42 patients (14.5%) had thyroid cancer as their primary diagnosis. Among 290 patients with multiple primary malignancies involving thyroid cancer, women (256, 88.3%), age ≥45 years (191, 65.9%), and presence of papillary thyroid carcinoma (281, 96.9%) were more common characteristics. Breast cancer was the most frequent accompanying disease (129, 44.5%), followed by cervical cancer (47, 16.2%), lung cancer (28, 9.7%), and colon cancer (17, 5.9%).

  Conclusions  Female cancer patients aged ≥45 years, especially those with breast cancer, should undergo thyroid disease screening during their follow-up period.