Purpose: To estimate whether pelvic and para-aortic lymphadenectomy was associated with increased survival in stage I endometrioid endometrial cancer.
Methods: We performed matched cohort analyses of women with stage I endometrioid endometrial cancer who underwent hysterectomy with no lymphadenectomy, pelvic lymphadenectomy, or combined pelvic and para-aortic lymphadenectomy. Cox proportional hazards survival analyses were performed with inverse probability weights. Hazard ratios (HRs) were covariate and propensity score adjusted. Covariates included cancer center type, age, race, Hispanic ethnicity, insurance type, community median income quartile, comorbidity score, history of prior cancer, depth of myometrial invasion, tumor grade, tumor size, lymphovascular space invasion, cytology status, surgical margin status, hospital volume, and use of adjuvant radiotherapy or chemotherapy. Additional analyses included subset analyses by grade, sensitivity analyses with imputation of missing data, and testing for sensitivity to possible unmeasured confounding.
Results: Median (interquartile range [IQR]) lymph node counts were 0, 10 (5-15), and 20 (15-27) nodes in the no lymphadenectomy, pelvic, and combined pelvic and para-aortic lymphadenectomy-matched cohorts, respectively. Matched cohorts were well balanced. Two analyses were performed: no lymphadenectomy (n = 7,487) versus pelvic lymphadenectomy (n = 7,487), and pelvic lymphadenectomy (n = 7,060) versus combined pelvic and para-aortic lymphadenectomy (n = 7,060). Performance of pelvic lymphadenectomy was associated with increased survival compared with no lymphadenectomy (5-year survival [95% CI], 91.4% [90.2% to 92.6%] v 87.3% [85.9% to 88.8%]; HR, 0.71 [95% CI, 0.64 to 0.78]; P < .001). Addition of para-aortic lymphadenectomy was associated with increased survival compared with pelvic lymphadenectomy alone (5-year survival [95% CI], 91.0% [89.8% to 92.2%] v 89.8% [88.4% to 91.1%]; HR, 0.85 [95% CI, 0.77 to 0.95]; P = .003). Associations were robust to sensitivity analyses.
Conclusion: Lymphadenectomy was associated with increased survival in stage I endometrioid endometrial cancer. An adequately powered randomized trial is needed.