Epidermal Growth Factor Receptor Expression in Spindle Cell Carcinomas of the Head and Neck.

Abstract

Spindle cell carcinoma (SpCC) is an uncommon head and neck squamous cell carcinoma (SCC) variant consisting of spindled and/or pleomorphic cells with epithelial differentiation. Epidermal growth factor receptor (EGFR) is expressed by >90 % of conventional SCC, and high level expression is associated with a poorer prognosis. Anti-EGFR therapies are commonly used to treat head and neck SCC. However, no studies have evaluated EGFR expression in SpCC. Cases of SpCC were retrieved from department files. The diagnosis required either a biphasic lesion with a squamous neoplastic component, or a purely spindle cell or pleomorphic tumor with immunohistochemical positivity for epithelial markers. EGFR immunohistochemistry was performed and was quantified in quartiles. Medical records were reviewed for clinical follow up information. EGFR was expressed in 21/30 (70 %) cases, including in the squamous component in 18/19 (95 %) and the spindle cell component in only 12/30 (40 %). Where the spindle cell component was positive, the intensity and distribution were lower than for the squamous component. Recurrent tumors were predominantly (80-90 %) of the spindle cell component, and had low (or absent) EGFR expression. Kaplan-Meier survival analysis showed no statistically significant differences in overall or disease free survival between the EGFR expressing and non-expressing groups (p = 0.414 and 0.19, respectively). SpCCs of the head and neck have a poor prognosis, and markedly reduced EGFR expression. EGFR-specific therapies may not be ideal for SpCC patients, which may lack EGFR expression, but further studies are needed.