A Multidisciplinary Approach for a Patient With Synchronous Lip and Thyroid Cancer Involving Radiotherapy

Synchronous cancers, defined as malignancies diagnosed concurrently or within 2 months of each other, are rare, with an incidence of 1%-6%. Environmental factors such as tobacco smoking play a significant role in their development. Patients with head and neck squamous cell carcinoma (SCC) are at increased risk of second malignancies, complicating treatment strategies and prognosis. This report presents a rare case of synchronous SCC of the lower lip and papillary thyroid carcinoma (PTC).

A 61-year-old male with a history of smoking presented with a 2.5 cm exophytic lesion of the lower lip, diagnosed as keratinizing SCC. A suspicious cervical lymph node was revealed, which intraoperatively demonstrated metastatic PTC. Following partial lip resection and neck dissection, total thyroidectomy was performed, confirming a 1.5 mm PTC focus with micrometastases. The patient underwent adjuvant conventional radiotherapy (RTH) for SCC (66 Gy in 33 fractions) and radioiodine therapy (131-I) for PTC. Post-therapeutic scintigraphy identified suspected micrometastases in the iliac bone, prompting further 131-I treatment. Following completion of therapy, the patient achieved a complete response, with no radiologic or clinical evidence of residual disease from both malignancies.

Synchronous SCC of the lip and PTC are exceedingly rare, lacking standardized treatment guidelines. This case highlights the necessity of a multidisciplinary approach, integrating surgery, RTH, and systemic therapy. Careful postoperative histopathological assessment of lymph nodes may reveal unexpected findings that necessitate further diagnostic work-up and a multidisciplinary approach, as this can significantly influence staging, treatment decisions, and patient prognosis, representing an important key learning point.