Risk factors associated with Para-Aortic Lymph Node Failure after pelvic irradiation in patients with Cervical Cancer

Objective: Previous studies have shown that prophylactic extended-field irradiation can reduce para-aortic lymph node failure (PALNF) rates in patients with cervical cancer. As such, this type of irradiation may particularly benefit patients with a high risk of PALNF. In the present study, we analyzed the risk factors for PALNF in patients with cervical cancer treated with pelvic irradiation in order to identify potential indications of prophylactic extended-field irradiation. Methods: We evaluated patients with 2018 FIGO stage IB3-IIIC1 cervical cancer who were treated with definitive pelvic radiotherapy or concurrent chemoradiotherapy at our institution between 2011 and 2014. Univariate and multivariate analyses were performed to identify risk factors for PALNF. Results: We included 572 patients in the study. The median follow-up period was 37.9 months. Eighteen patients (3.1%) first site of tumor relapse was the para-aortic lymph nodes, and thus showed PALNF. Using multivariate Cox regression analysis, we identified two significant risk factors for PALNF: tumor extension to the pelvic wall (hazard ratio, HR 3.60, p=0.026) and ≥ 2 pelvic MLNs (HR 5.30, p=0.005). For patients with and without risk factors, the 3-year overall survival, disease-free survival, and PALNF rates were 77.3% and 90.1% (p<0.001), 56.4% and 83.1% (p<0.001), and 12.0% and 2.3% (p<0.001), respectively. Conclusion: Tumor extension to the pelvic wall and ≥ 2 pelvic MLNs are positively associated with PALNF after pelvic irradiation in patients with cervical cancer. Further trials will be required to validate whether patients with these two risk factors may benefit from prophylactic extended-field irradiation.