This study delves into the occurrence, clinical evolution, diagnosis, and treatment outcomes of secondary thyroid tumors, which constitute about 1% of malignant thyroid nodules and often signify a challenging prognosis.

Data from 2527 patients, admitted between October 2013 and May 2023, with suspected or confirmed malignant thyroid cancer, formed the basis of our analysis.

Among all malignant tumors, 1.11%(28 patients) were identified as secondary cancers, originating from diverse sites such as RCC(5), SCC of the head and neck(5) or esophagus(3), lung(3), breast(2) and others: mucoepidermal carcinoma, HCC, cervix carcinoma, squamous NUT carcinoma, MPNST(2), fibrosarcoma from the scapula, uterine sarcoma, osteosarcoma of the larynx and occult mucosal adenocarcinoma. The occurrences were evenly distributed across genders, with an average age of 62.0 years. Metachronic changes were noted in 10 patients and synchronous tumors in 18. Lymph node involvement was observed in 12 patients, and multi-organ metastases in 10. Diagnosis methods included preoperative neck tumor examination or postoperative histopathological evaluation. Non-radical surgery was performed on 12 patients, with adjuvant chemotherapy in 7, and the rest underwent conservative treatment. Sixteen patients succumbed during the follow-up, with an average survival of 0.52years after thyroid changes diagnosis. One patient survived for 9.13years, the average survival for others was 1.68years.

Considering metastatic tumors in the differential diagnosis of thyroid nodules is crucial, especially for patients with a cancer history. Surgical treatment may be suitable for isolated metastasis, while palliative measures are recommended for dissemination. Surgical intervention is essential to maintain airway and gastrointestinal patency and carotid continuity.