Prognostic factors in patients with stage IIIC endometrial cancer. Could the number of metastatic lymph nodes justify a systematic full lymphadenectomy?

INTRODUCTION: The diagnostic role of nodal staging is well-established for defining risk classes and tailoring adjuvant treatment. When lymph node metastasis is identified, it significantly impacts survival. Due to the paucity of available data, it remains unclear if there is still a role for systematic lymphadenectomy in offering a therapeutic benefit. METHODS: This retrospective observational study included patients with FIGO stage IIIC endometrial cancer treated between 2008 and 2020. Patients were divided into two cohorts according to the number of harvested lymph nodes (<22 vs ≥ 22) and into three cohorts according to the number of metastatic lymph nodes (0-2, 3-9 and ≥10 positive lymph nodes). The main outcome measures were disease-free survival and overall survival. RESULTS: A total of 221 patients were analyzed. The number of harvested lymph nodes did not impact survival. Conversely, the number of metastatic lymph nodes significantly affected survival: 5-year Disease Free Survival decreased from 64.8% (0-2 positive lymph nodes) to 36.8% (≥10 positive lymph nodes) (p = 0.004), and 5-year Overall Survival decreased from 83.8% to 51.9% (p = 0.002). High grade hystotype and the use of chemotherapy alone without radiation were independently associated with an increased risk of recurrence. Although the number of metastatic lymph nodes was associated with recurrence and survival in the univariable analysis, it was not an independent predictor in the multivariable model. CONCLUSION: Tumor characteristics and adjuvant treatment are the most important independent prognostic factors in stage IIIC endometrial cancer, beyond the extent of lymphadenectomy and the number of metastatic lymph nodes.