Objective: To use a number of methods to control for confounding and selection bias to examine the association between lymphadenectomy and survival in a large cohort of women with endometrial cancer.
Methods: A retrospective cohort study using the National Cancer Data Base was performed to identify women with endometrioid adenocarcinoma of the endometrium who underwent hysterectomy with or without lymphadenectomy from 1998 to 2011. Traditional regression analysis, propensity score, and an instrumental variable using regional variation in the rate of lymphadenectomy as an instrument were used to examine the association between lymphadenectomy and survival.
Results: A total of 151,089 women treated at 1,336 hospitals were identified; 99,052 (65.6%) patients underwent lymphadenectomy, whereas 52,037 (34.4%) did not. In a multivariable regression model, lymphadenectomy was associated with a 16% reduction in mortality (hazard ratio [HR] 0.84, 95% confidence interval [CI] 0.81-0.87). The results were similar after adjustment for adjuvant therapy (HR 0.85, 95% CI 0.82-0.87). The results were largely unchanged and suggested that lymphadenectomy was associated with improved survival after application of a propensity score analysis. In contrast, in the instrumental variable analysis, there was not a statistically significant association between lymphadenectomy and survival (HR 0.75, 95% CI 0.53-1.06), even after adjustment for adjuvant treatment (HR 0.76, 95% CI 0.54-1.06). The results were unchanged for women with T1A and T1B tumors.
Conclusion: Lymphadenectomy is associated with a modest, if any, effect on survival for women with endometrial cancer.