Adjuvant treatment in stage I clear cell endometrial carcinoma: A population-based study of survival outcomes

Uterine clear cell carcinoma (UCCC) is a rare but aggressive histologic type of endometrial cancer. Recommendations for adjuvant treatment of early-stage UCCC remain vague. The objective of this study is to assess the impact of adjuvant treatment on survival outcomes of patients with stage I UCCC.

Using the Surveillance, Epidemiology and End Results database (SEER), patients with stage I UCCC were identified. Disease-specific survival (DSS) as well as overall survival (OS) for patients who underwent observation alone versus adjuvant treatment with either chemotherapy alone, radiotherapy (RT) alone, or chemotherapy plus RT, were analyzed by Kaplan-Meier (K-M) survival estimates and multivariate Cox proportion hazards model.

The study included 881 patients with stage I UCCC. Kaplan-Meier estimates showed no difference in DSS among those who underwent observation versus adjuvant treatment. In the multivariate model for DSS, tumor size ≥40 mm was associated with an increased risk of death (HR 2.02, p = 0.0267) while living in a metropolitan county decreased the risk of death (HR 0.46, p = 0.009). The K-M curve for OS showed a significant difference among the four treatment groups (p = 0.0475), with a 10-year OS of 61 % for patients who received no adjuvant treatment versus 74 % for those receiving chemotherapy plus radiation. However, this difference was not significant in the multivariate analysis.

In this study of stage I UCCC, the use of adjuvant treatment did not confer a survival advantage. Observation may be considered an acceptable option although prospective research is needed.