Ki-67 expression predicts radiotherapy failure in early glottic cancer.

Background: Early-stage laryngeal squamous cell carcinoma is managed with radiotherapy or endoscopic surgery. Although cure rates are high, radiation failures often require total laryngectomy for salvage. Biomarkers that can predict tumour radioresistance may be useful in modifying the treatment approach for individual patients. Methods: Retrospective patient chart review yielded 75 patients with T1-T2 glottic squamous cell carcinoma treated with radiation therapy at the London Health Sciences Centre. Pretreatment tumour biopsies were immunostained for B-cell lymphoma 2 (Bcl-2), Ki-67, and epidermal growth factor receptor (EGFR) to correlate biomarker expression with disease-free survival (DFS). Results: Ki-67 expression was strongly associated with recurrence following radiation and independently predicted poor DFS (hazard ratio 4.86, 95% CI 1.58-15.00; p = .006). EGFR and Bcl-2 were not associated with a risk of recurrence. Conclusions: Ki-67 expression identified a subset of patients with increased risk of local recurrence after radiation therapy. Ki-67 expression can potentially guide improved personalized treatments for patients with early-stage glottic squamous cell carcinomas.