Adequate pelvic lymphadenectomy and survival of women with early-stage epithelial ovarian cancer

Objective: To examine the trends and survival for women with early-stage epithelial ovarian cancer who underwent adequate lymphadenectomy during surgical treatment. Methods: This is a retrospective observational study examining the Surveillance, Epidemiology, End Results program between 1988 and 2013. We evaluated 21,537 cases of stage III epithelial ovarian cancer including serous (n=7,466), clear cell (n=6,903), mucinous (n=4,066), and endometrioid (n=3,102) histology. A time-trend analysis of the proportion of patients who underwent adequate pelvic lymphadenectomy (>= 8 per Gynecologic Oncology Group [GOG] criteria, >= 12 per Collaborative Group Report [CGR] criteria for bladder cancer, and >22 per Mayo criteria for endometrial cancer) and a survival analysis associated with adequate pelvic lymphadenectomy were performed. Results: There were significant increases in the proportion of women who underwent adequate lymphadenectomy: GOG criteria 3.6% to 28.6% (1988-2010); CGR criteria 2.4% to 22.4% (1988-2013); and Mayo criteria 0.7% to 9.5% (1988-2013) (all, p<0.05). On multivariable analysis, adequate lymphadenectomy was independently associated with improved cause-specific survival compared to inadequate lymphadenectomy: GOG criteria, adjusted-hazard ratio (HR)=0.75, CGR criteria, adjusted-HR=0.77, and Mayo criteria, adjusted-HR=0.85 (all, p<0.05). Compared to inadequate lymphadenectomy, adequate lymphadenectomy was significantly associated with improved cause-specific survival for serous (HR range=0.67-0.73), endometrioid (HR range=0.59-0.61), and clear cell types (HR range=0.66-0.73) (all, p<0.05) but not in mucinous type (HR range=0.80-0.91; p>0.05). Conclusion: Quality of lymphadenectomy during the surgical treatment for early-stage epithelial ovarian cancer has significantly improved. Adequate lymphadenectomy is associated with a 15%-25% reduction in ovarian cancer mortality compared to inadequate lymphadenectomy.