Treatment optimization and prognostic considerations for primary squamous cell carcinoma of the thyroid

Abstract

Background: Primary squamous cell carcinoma of the thyroid (PSCCT) is a rare aggressive malignancy that usually presents in an advanced stage and has a poor prognosis. Our study aimed to investigate the clinical characteristics, treatment, and prognosis of PSCCT.

Methods: We retrospectively reviewed the medical information of patients with PSCCT diagnosed from January 2006 to May 2018 at Xiangya Hospital. Survival analysis was conducted using the Kaplan-Meier method, and Log-Rank tests were performed for statistical testing.

Results: We identified 12 patients with PSCCT (nine males and three females), accounting for only 0.19% of all thyroid cancer diagnosed during this time period. The median age of these patients was 59.5 years old and their symptoms included neck masses (n=5), hoarseness (n=2), dyspnea (n=1), dysphagia (n=1) and neck pain (n=1). Four patients were in stage IVA, five were stage IVB, and three patients were stage IVC. Six patients underwent comprehensive treatment (surgery + radiotherapy or surgery + radiotherapy + chemotherapy) and the remaining patients received radiotherapy and/or chemotherapy. The 6-month survival rate was 66.7%, compared to a 1-year survival rate of 25.0%, with a median overall survival time was 10.5 months. Kaplan-Meier analysis showed that the comprehensive treatment was superior to radiotherapy and/or chemotherapy (P=0.003).

Conclusions: PSCCT is a rare type of thyroid cancer that is highly invasive and has a poor prognosis. We show that a comprehensive treatment plan can significantly improve patient survival.

Keywords: Squamous cell carcinoma; chemotherapy; radiotherapy; thyroid.

Figure 1

Prognosis and Kaplan-Meier analysis. (A) Kaplan-Meier curve for primary squamous cell carcinoma of the thyroid showing disease specific survival; (B) comparison of survival rate between comprehensive treatment and the radiotherapy and/or chemotherapy where a is radiotherapy and/or chemotherapy (n=6) and b is comprehensive treatment (n=6).

Figure 2

Computed tomography scans of a representative patient with PSCCT. A nodule with mixed density is found in the right thyroid gland, across the isthmus to the left thyroid lobe, with a size of approximately 3.3 cm × 3.4 cm. The right bronchus was compressed, displaced and invaded. Image view: (A,B) horizontal; (C) sagittal; (D) coronal. PSCCT, primary squamous cell carcinoma of the thyroid.

Figure 3

Histopathology using hematoxylin and eosin (H&E) staining. (A,B) Typical squamous cell carcinoma findings of strands and irregular fields with intercellular bridges, along with a keratinized cancer pearl (40× magnification).

Figure 4

Immunohistochemical (IHC) features of PSCCT (40× magnification). IHC staining for (A) p63, (B) Ki67, (C) CD5, (D) CK19, (E) thyroglobulin, or (F) TTF-1 (4F). p63 and CK19 was deemed positive and thyroglobulin, CD5, and TTF-1 did not stain (negative). Ki67 proliferation index was 50%. PSCCT, primary squamous cell carcinoma of the thyroid.