ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression of proliferating cell nuclear antigen (Ki-67) in stage III cervical squamous cell carcinoma (SCC) and its correlation with the effect of chemotherapy on sensitivity to radiotherapy.</p><p><b>METHODS</b>In 50 patients with stage III cervical squamous cell carcinoma (SCC), 25 patients were treated with radiotherapy and 25 patients were treated with chemoradiotherapy. The expression of Ki-67 in the biopsy specimens of cervical SCC was detected by immunohistochemistry at diagnosis and after 10 Gy radiotherapy. The correlation of Ki-67 positive cells percentage and chemotherapy with sensitivity to radiotherapy was analyzed.</p><p><b>RESULTS</b>In 25 patients with more than 48% Ki-67 positive cells at diagnosis, the rate of complete response (CR) was 72.0% (18/25). In 25 patients with less than 48% Ki-67 positive cells at diagnosis, the CR rate was 40.0% (10/25), with a significant difference between them (P = 0.023). In 26 patients with more than 31% decrease of Ki-67 positive cells after 10 Gy radiotherapy, the CR rate was 84.6% (22/26). In 24 patients with less than 31% decrease of Ki-67 positive cells after 10 Gy radiotherapy, the CR rate was 25.0% (6/24), showing a significant difference between the two groups (P < 0.001). In the cases of Ki-67<48%, decrease of Ki-67 positive cells of chemoradiotherapy group after 10 Gy radiotherapy was significantly higher than that of the radiotherapy group (P = 0.023). In the cases of Ki-67 ≥ 48%, no difference in the decease of Ki-67 positive cells between the chemoradiotherapy and radiotherapy groups was found (P = 0.173). For the radiotherapy-sensitive patients with CR recently, the 2-year progression free survival (PFS) rate and overall survival (OS) rate were 85.7% and 92.9%, respectively, both were significantly higher than those of radiotherapy-insensitive patients (18.2% and 40.9%, P < 0.05 for both).</p><p><b>CONCLUSIONS</b>In stage III cervical SCC, the expression of Ki-67 before and after treatment with 10 Gy radiotherapy may be used as a biomarker to predict tumor response to radiation, and guide the choice of therapeutic strategies. Yet, the effect of chemotherapy as a radiosensitizer is unconspicuous.</p>