Multivariate analysis by Cox proportional hazard model on prognosis of patient with epithelial ovarian cancer.

PURPOSE OF INVESTIGATION: To evaluate the influence of various clinicopathological and biochemical factors on the survival of patients with epithelial ovarian cancer (EOC) after radical resection.
METHODS: A retrospective analysis was made for 183 cases of epithelial ovarian cancer treated from January 1997 to January 2001. Six clinicopathological factors, including menopause, histological type, histological grade, lymph node metastasis, FIGO stage and chemotherapy that could possibly influence survival were selected. The expression of COX-2 and VEGF protein as two biochemical factors were detected in EOC tissues using immunohistochemical staining. Independent variables were first analyzed by univariate methods. A multivariate analysis of these variables was performed using the Cox proportional hazard regression model.
RESULTS: The ovarian cumulative survival rate was 48.71% for three years and 30.71% for five years. Univariate analysis of overall survival involving all the patients indentified five factors that were associated with a significant outcome: menopause, histological grade, FIGO stage, COX-2 or VEGF expression level (p < 0.05). The expression of COX-2 was positive in 140 (76.5%) of these 183 cases, but was not associated with menopause, histological type, histological grade, lymph node metastasis or FIGO stage. Median survival time was 24.56 months for the patients with COX-2 positive expression, and 47.52 months for those with COX-2 negative expression (p < 0.05). VEGF protein overexpression was examined in 117 (63.93%) of all 183 cases, and was associated with lymph node metastasis (p <0.05), but not associated with menopause, histological grade, histological type or FIGO stage. The median survival time was 23.36 months for the patients with VEGF detected expression, and 42.09 months for those with no VEGF detected expression (p < 0.05). When the interactive effects of these factors were taken into account, COX-2 expression, FIGO stage, VEGF expression and histological grade were the four most important prognostic factors by multivariate analysis using the Cox proportional hazards model. Risk of death for the patients with COX-2 positive expression was 2.8 times than that with COX-2 negative expression, and for FIGO stage, VEGF expression and histological grade, risk of death was 2.2, 2.1, and 1.84 times, respectively.
CONCLUSION: COX-2 expression, FIGO stage, VEGF expression and histological grade are the most important prognostic factors for EOC after curative resection.