Comparative outcomes of adjuvant chemotherapy alone versus combined chemotherapy and radiation therapy in patients with stage III endometrial cancer: a propensity score matching study.

OBJECTIVE: We compared the outcomes of adjuvant chemotherapy (CT) alone vs. adjuvant CT combined with radiation therapy (CRT) in patients with stage III endometrial cancer. All patients received 6 cycles of CT before radiation therapy (RT) were initiated. We also explored specific patient subgroups that might benefit from the addition of RT.

METHODS: Between 2007 and 2019, we analyzed 118 patients after propensity score matching, with 59 patients in each group (CT alone vs. CRT). The primary endpoint was pelvic recurrence; the secondary endpoints were progression-free survival (PFS). We conducted exploratory subgroup analyses stratifying patients by stage, histological grade, lymphovascular space invasion (LVSI), and cervical involvement to assess whether these factors influenced outcomes between the 2 treatments.

RESULTS: Patients receiving CRT had significantly lower 5-year pelvic recurrence rates than those receiving CT alone (1.8% vs. 17.9%; hazard ratio [HR]=0.09 [0.01-0.71]; p=0.004). There was no significant difference in 5-year PFS between the 2 groups overall (67.6% vs. 72.3%; HR=0.75 [0.39-1.46]; p=0.393). However, in high-risk subclass III patients (stage IIIC, grade 3 endometrioid or non-endometrioid carcinoma, LVSI, and cervical involvement), CRT significantly improved 5-year PFS (62.5% vs. 90.9%; p=0.049) and 5-year pelvic recurrence rates (0% vs. 54.6%; p=0.008). No differences in distant recurrence or overall survival were identified.

CONCLUSION: Compared with CT alone, CRT improved pelvic control overall and significantly improved pelvic control and PFS in high-risk subclass III patients. Therefore, RT may be considered for these subclasses to optimize treatment outcomes.