Is there any benefit of paraaortic field irradiation in pelvic lymph node positive endometrial cancer patients? A propensity match analysis

We evaluated the survival outcomes and recurrence patterns of endometrial cancer (EC) patients with pelvic lymph node metastases who received postoperative radiotherapy (RT) to the pelvis (P-RT) or to the pelvis plus paraaortic lymph nodes (PA-RT) with or without systemic chemotherapy (ChT). The data from 167 patients with stage IIIC1 EC treated with postoperative RT or RT and ChT were collected retrospectively. Those patients with pelvic lymph node metastases were treated with either P-RT (106 patients, 63%) or PA-RT (61 patients, 37%). The median follow-up time for the entire cohort was 49 (range = 5–199) months. The patients receiving adjuvant ChT and RT had significantly higher 5-year OS rates (77% vs. 33%, p <.001) and 5-year PFS rates (71% vs. 30%, p <.001) when compared to those receiving adjuvant RT alone. The patients receiving P-RT and ChT had significantly higher 5-year OS rates and 5-year PFS rates when compared to those treated with adjuvant PA-RT in the entire cohort and matched cohort. Adjuvant ChT together with RT is the strongest predictor of the OS and PFS. Prophylactic PA-RT is unnecessary, even if ChT is used together with P-RT in EC patients with pelvic lymph node metastasis.Impact statementWhat is already known on this subject? Local and distant recurrence risks are relatively higher in patients with stage IIIC disease, postoperative adjuvant treatment is required to reduce the recurrence risk. Adjuvant RT is a common approach for patients with locally advanced EC. Optimal target volume for RT in patients with stage IIIC EC remains controversial. We demonstrated that extended field RT is unnecessary, even if ChT is used together with pelvic RT in stage IIIC EC patients. What do the results of this study add? We demonstrated that adjuvant ChT together with RT is the strongest predictor of the OS and PFS for EC patients with pelvic lymph node metastases. Extended field RT is unnecessary, even if ChT is used together with pelvic RT in EC patients with pelvic lymph node metastases. What are the implications of these findings for clinical practice and/or further research? Although adjuvant treatment modalities are associated with improvements in survival, distant metastasis still remains the most common site of recurrence in advanced EC patients. Thus, further research is warranted to identify improved combined modality strategies to optimise the outcomes for EC patients with pelvic lymph node metastasis.