Prognostic significance of Ki-67 (MIB1), PCNA and p53 in cancer of the oropharynx and oral cavity

Abstract Up to now results concerning the prognostic value of tumor proliferation markers in squamous cell head and neck carcinoma have been equivocal. Beside biological reasons, different treatment modalities are hypothetically responsible for contradictory findings. The aim of this study was to investigate the relationship between proliferative capacity, represented by the immunohistochemical labeling index of proliferation markers Ki-67, PCNA and p53 status, and treatment failure in a matched-pair study design of recurrent and non-recurrent carcinoma initially treated with primary surgery combined with curative post-operative radiation. From a group of 239 patients with T1–T3 carcinoma of the oropharynx or oral cavity, 28 patients with recurrent disease were selected and matched with 28 patients with non-recurrent disease regarding stage and location of tumor as well as age and therapy. All patients received primary surgery combined with post-operative radiation. Immunohistochemistry determined the p53 status and the PCNA and MIB1 (Ki-67) labeling index. The Ki-67 labeling index was significantly ( p =0.032) higher in tumors from patients suffering from treatment failure (mean=59.1%) than in non-failures (mean=50.5%). Carcinoma with a Ki-67 (MIB1) labeling index above the median (53.7%) of the general study population showed a mean time to relapse of 45 months ( n =25), whereas mean time-to-relapse was 61.7 months for those cases ( n =31) below the median of the general study population ( p =0.029). The PCNA labeling index did not correlate significantly with tumor recurrence (mean=50.2% for treatment failures, 45% for non-failures, p =0.31), nor with time-to-relapse ( p =0.26). Forty-six percent of tumors showed p53 over-expression. However, there was no significant correlation between p53 over-expression and tumor recurrence or time-to-relapse. We present the largest series of oropharyngeal and oral cavity carcinoma investigated by immunohistochemistry in a controlled study. We conclude that a high Ki-67 labeling index is an indicator for treatment failure in these patients. Like other investigations for different head and neck subsites, we found no relationship between p53 or PCNA status and tumor prognosis. Our data, obtained from a group of patients treated with a combination of surgery and post-operative irradiation, show that for squamous cell carcinoma of the oropharynx and oral cavity the detection of Ki-67 is an unfavorable prognostic factor.