Ki-67, p53 and epidermal growth factor receptor expression in early glottic cancer involving the anterior commissure treated with radiotherapy.

OBJECTIVE: TNM staging system is not a sufficiently accurate method for predicting the response of an individual patient to a course of radiotherapy. After irradiation, it can become very difficult to assess data obtained by imaging and endoscopy for the diagnosis of both minimal persistent disease and early recurrence. The search for biological parameters that could be used to identify patients who will respond to radiotherapy is crucial. At this study we aimed at evaluating the prognostic significance of immunohistochemical expression of Ki-67, p53 and epidermal growth factor receptor (EGFR) in laryngeal glottic cancer involving the anterior commissure and treated with radiotherapy.
METHODS: From January 1995 to August 2005, 24 patients with glottic cancer involving the anterior commissure were primary treated with radiotherapy. Six patients presented with T1a, 12 patients with T1b and 6 patients with T2. Biopsies were taken before the radiotherapy treatment started. Radiotherapy was done with the same technique for all patients using a linear accelerator device with beam energy of 4-MV photons. Immunohistochemical staining was performed using avidine-biotin-peroxidase technique with antibodies to Ki-67, p53 and EGFR.
RESULTS: p53 and EGFR positive expression values and labeling indices were greater in radioresistant than in radiosensitive tumors but without significant differences. On the other hand, Ki-67 was expressed in all radiosensitive tumors and Ki-67 labeling indices were significantly higher in radiosensitive tumors than radioresistant tumors (p=0.01).
CONCLUSION: We identified overexpression of Ki-67 as predictive marker of radiosensitivity in glottic cancer involving the anterior commissure, with the results showing significant difference between radiosensitive and radioresistant tumors.