Methodological considerations in the analysis of the therapeutic significance of lymphadenectomy in endometrial cancer.

There needs to be clarification on eligibility requirements and procedure standardization with regard to the therapeutic role of lymphadenectomy. If this is not done, consensus on the role of lymphadenectomy will not be reached. Although pelvic lymphadenectomy is not necessary for patients with low-risk Stage I endometrial cancer, it has been suggested that combined pelvic and para-aortic lymphadenectomy is useful for patients with intermediate-/high-risk endometrial cancer. Therefore, the therapeutic role of lymphadenectomy should be continuously evaluated. If such a study is planned, it should not include patients with low risk of nodal metastasis, and one experimental arm of the study should assess combined pelvic and para-aortic lymphadenectomy (fundamentally including the area above the inferior mesenteric artery and the renal vein). It is necessary to establish a pre-operative risk assessment for nodal metastasis and procedural classification of lymphadenectomy. Some pre-operative risk assessments for nodal metastasis have been proposed from Asian countries. The extent of the surgical field is defined as the pelvic area alone, or combined pelvic and para-aortic area. The thoroughness of removal can be split into removal of only suspicious nodes, selective dissection, or systematic dissection. Although randomized controlled trials provide the highest level of clinical evidence, special difficulties are presented in randomized surgical trials. Nonentry of surgeons is a threat to external validity. The role of observational studies, especially prospective cohort studies should be reconsidered when assessing the therapeutic significance of lymphadenectomy.