Lower Uterine Segment Involvement as a Predictor for Poor Prognosis in Patients Receiving Adjuvant Radiotherapy for Stage I Endometrial Carcinoma

  Objective  To explore the effect of lower uterine segment involvement (LUSI) in predicting the prognosis of stage Ⅰ endometrial carcinoma patients treated with postoperative radiotherapy.

  Methods  The data of a total of 265 patients with stage Ⅰ endometrial carcinoma treated with hysterectomy and adjuvant radiotherapy between January 1999 and December 2012 were retrospectively analyzed. The median age of the cohort was 53 years. The most common pathological type was endometrioid adenocarcinoma (226/265, 85.3%). The patients were divided into two groups according to the presence of LUSI:LUSI group and non-LUSI group. The prognostic factors and treatment outcomes were compared between the two groups, subgroup analysis was conducted in the high-risk and high-intermediate-risk patients in the two groups. Primary outcomes were overall survival (OS), progression-free survival (PFS), loco-regional recurrence (LR), distant metastasis (DM), and treatment failure (TF). The survival rates were calculated using the Kaplan-Meier method. The survival rates between different groups were compared using the Log-rank test. Prognostic factors for survival were analyzed using a Cox proportional hazards regression model.

  Results  The 5-year OS and PFS for all the patients were 92.8% and 89.7%, respectively; the 5-year LR, DM, and TF were 4.5%, 6.4%, and 7.8%, respectively. Univariate analysis revealed that LUSI was a significant predictor of OS and PFS (P=0.015, 0.035). Cox proportional hazard model demonstrated a significantly decreased OS and PFS in the LUSI group compared with the non-LUSI group(P=0.041, RR=0.346, 95% CI:0.125-0.959; P=0.041, RR=0.411, 95% CI:0.175-0.963). Subgroup univariate analysis showed that for high-risk and high-intermediate-risk patients, LUSI was a significant predictor of TF (P=0.034).

  Conclusions  LUSI may be a significant predictor of reduced OS and PFS in patients with stage Ⅰ endometrial carcinoma treated with adjuvant radiotherapy. In addition, LUSI may be associated with treatment failure in high-risk and high-intermediate-risk patients.