Low-grade endometrioid endometrial cancer with adnexal only metastasis: Evaluation of de-escalation of adjuvant therapy

Objective: To assess survival outcomes of stage IA3 endometrial cancer and the association of adjuvant therapy and survival.

Methods: The National Cancer Database was retrospectively queried to examine 594 and 1455 patients with stage IA3 and IIIA1 endometrial cancer, respectively, from 2010-2015. Overall survival (OS) was examined based on adjuvant therapy: multimodal combination chemotherapy and external beam radiotherapy, chemotherapy alone, external beam radiotherapy alone, and none.

Results: For stage IA3 disease, 109 (18.4%) patients did not receive adjuvant therapy. The 5-year OS rates for the no adjuvant therapy group and the combination group were 86.3% and 91.4%, respectively (adjusted-hazard ratio [aHR] 1.23, 95% confidence interval [CI] 0.70-2.18). This survival association was consistent when compared to chemotherapy alone (5-year OS rates 86.3% vs 86.3%, aHR 1.11, 95%CI 0.67-1.83). The results were similar among those who underwent nodal evaluation (5-year OS rates, 92.6%, 86.6%, and 89.4% for combination therapy, chemotherapy alone, and no adjuvant therapy), including grade 1 lesions (96.2%, 89.4%, and 100%, respectively). In grade 2 lesions, 5-year OR rates was modestly lower for no adjuvant therapy than combination therapy (89.4%, 84.0%, and 82.7% for combination, chemotherapy alone, and no adjuvant therapy, P = 0.03). For stage IIIA1 disease, omission of adjuvant therapy was associated with decreased OS compared to combination therapy (43.2% vs 73.1%, aHR 1.65, 95%CI 1.30-2.11) or chemotherapy alone (43.2% vs 67.1%, aHR 1.62, 95%CI 1.32-1.99).

Conclusion: The results of this investigation suggest that survival effects of adjuvant therapy differ for stage IA3 and IIIA1 diseases. Patients with stage IA3 disease have overall good prognosis regardless of adjuvant therapy particularly grade 1 lesions, partly supporting the FIGO committee suggestion for adjuvant therapy de-escalation in stage IA3 endometrial cancer.