Clinicopathological and Molecular Features of Secondary Cancer (Metastasis) to the Thyroid and Advances in Management

Abstract

Secondary tumours to the thyroid gland are uncommon and often incidentally discovered on imaging. Symptomatic patients often present with a neck mass. Collision tumours of secondary tumours and primary thyroid neoplasms do occur. Ultrasound-guided fine-needle aspiration, core-needle biopsy, and surgical resection with histological and immunohistochemical analysis are employed to confirm diagnosis as well as for applying molecular studies to identify candidates for targeted therapy. Biopsy at the metastatic site can identify mutations (such as EGFR, K-Ras, VHL) and translocations (such as EML4-ALK fusion) important in planning target therapies. Patients with advanced-stage primary cancers, widespread dissemination, or unknown primary origin often have a poor prognosis. Those with isolated metastasis to the thyroid have better survival outcomes and are more likely to undergo thyroid resection. Systemic therapies, such as chemotherapy and hormonal therapy, are often used as adjuvant treatment post-operatively or in patients with disseminated disease. New targeted therapies, such as tyrosine kinase inhibitors and immune checkpoint inhibitors, have shown success in reported cases. A tailored treatment plan based on primary tumour features, overall cancer burden, and co-morbidities is imperative. To conclude, secondary cancer to the thyroid is uncommon, and awareness of the updates on diagnosis and management is needed.

Investigation of pre‐operative demographic, biochemical, sonographic and cytopathological findings in low‐risk thyroid neoplasms

“…TNM staging, which illustrates an association between mortality and nodal spread, is widely assessed to classify disease stage 19 . In thyroid staging, TNM also considers patient age 20 .…”

“…17,18 TNM staging, which illustrates an association between mortality and nodal spread, is widely assessed to classify disease stage. 19 In thyroid staging, TNM also considers patient age. 20 Another system that endocrinologists widely prefer is the MACIS evaluation system, 21 described by the Mayo Clinic.…”

Neuroendocrine neoplasm with metastasis to the thyroid: a case report and literature review

“…Fine-needle aspiration cytology (FNAC) is the first choice for patients with suspected metastatic thyroid cancer. FNAC is simple and easy to perform, and it is the best method for preoperative diagnosis (9). A multi-institution study report on FNAC showed that 87% of TM patients could be diagnosed with thyroid malignancy by FNAC, and 93% of them could be specifically diagnosed with TM (14).…”

Metastatic renal cell carcinoma to the thyroid with cervicothoracic venous tumor thrombosis

“…The majority of patients with metastatic RCC to the thyroid have widely metastatic disease at time of detection, but a small percentage have oligometastatic spread to the thyroid alone. 5 In this subset of patients with RCC confined to the thyroid gland, thyroidectomy offers improved outcomes. Prior studies have demonstrated that thyroidectomy improves 1-year survival rates from 35% to 55% and increases overall survival from 12 to 36 months.…”

“…Generally, metastatic disease portends a poor prognosis in RCC. The majority of patients with metastatic RCC to the thyroid have widely metastatic disease at time of detection, but a small percentage have oligometastatic spread to the thyroid alone 5 . In this subset of patients with RCC confined to the thyroid gland, thyroidectomy offers improved outcomes.…”