EMMPRIN expression as a prognostic factor in radiotherapy of cervical cancer

Overexpression of extracellular matrix metalloproteinase inducer (EMMPRIN), a member of the immunoglobulin family and a glycoprotein enriched on the surface of many types of tumor cells, has been reported to be linked to invasion, metastasis, growth, and survival of malignant cells. Cervical cancer, the second most prevalent cancer in women worldwide and the fifth leading cause of cancer deaths, responds to radiotherapy variably, with 30% of cases recurring after therapy. The purpose of this study was to determine whether expression of EMMPRIN affects the response of cervical cancer to radiation therapy, and whether this membrane protein can be used as a prognostic marker for cervical cancer.

The retrospective cohort study included 82 patients with invasive cervical cancer referred to the Department of Gynecologic Oncology at The Cancer Hospital of Fudan University (Shanghai) between 1991 and 2000. These patients were treated with brachytherapy at a dose of 15 Gy at point A before radical hysterectomy. Expression of EMMPRIN in cervical tumor specimens was examined by immunohistochemistry staining before and after brachytherapy and scored for both staining intensity and percentage of tumor cells stained. EMMPRIN immunoreactivity and clinicopathologic data were analyzed with respect to survival end points using univariate and multivariate approaches.

The frequency of EMMPRIN overexpression was 52.4% in primary cervical cancer. After brachytherapy, EMMPRIN overexpression was significantly reduced (13.4%) compared with corresponding tumor before brachytherapy (P = 0.032). EMMPRIN expression was associated with pelvic lymph node metastasis (P = 0.026) and reduction in primary tumor volume following brachytherapy (P = 0.008). Although EMMPRIN expression before or after brachytherapy did not correlate with tumor-specific survival, but increased expression of EMMPRIN following brachytherapy tended to predict poor outcomes by univariate survival analysis (P = 0.0008). In addition, lymph vascular space invasion, deep stromal invasion, and lymph node metastasis were significantly associated with poor prognosis. In multivariate analysis, the independent prognostic factors for tumor-specific survival included the decreased expression of EMMPRIN after brachytherapy (P = 0.002; hazard ratio, 0.339; 95% confidence interval, 0.172-0.672) as well as lymph node metastasis (P = 0.044; hazard ratio, 2.053; 95% confidence interval, 1.020-4.133).

Expression of EMMPRIN was associated with a decrease in the reduction of cervical tumor following brachytherapy, and increased EMMPRIN expression after brachytherapy seemed to be an important predictor of poor survival in this patient cohort. Our study suggests that expression of EMMPRIN confers resistance to radiotherapy. Therefore, EMMPRIN expression in cervical cancer may be regarded both as a prognostic factor and a therapeutic target.