3725 - Prognostic and Therapeutic Significance of Common Iliac Lymph Node Involvement in Cervical Cancer in the Era of EMBRACE and INTERLACE

Purpose/Objective(s):

FIGO 2018 classifies all pelvic lymph node–positive cervical cancers as stage IIIC1, implying uniform prognosis and treatment requirements. However, contemporary data from EMBRACE demonstrate excellent outcomes with modern chemoradiation for selected node-positive patients, while INTERLACE suggests benefit of neoadjuvant chemotherapy (NACT) in high-risk subgroups. We evaluated whether common iliac lymph node involvement identifies a distinct high-risk population within FIGO IIIC disease with implications for treatment intensification.

Materials/Methods:

We retrospectively analyzed 510 patients with locally advanced cervical cancer treated with definitive chemoradiation consisting of pelvic external beam radiotherapy (45–50 Gy) with concurrent weekly cisplatin followed by image-guided intracavitary and/or interstitial brachytherapy to a total EQD2 =90 Gy. Pretreatment imaging (PET-CT/CT/MRI) was reviewed to determine lymph node status, including nodal size, number, and anatomic level of involvement. Patients were restaged according to FIGO 2019 criteria. Three-year disease-free survival (DFS) was analyzed, with exploratory subgroup analysis focusing on the prognostic impact of common iliac nodal involvement.

Results:

Under FIGO 2019, 224 patients were classified as stage IIIC1 and 42 as IIIC2. Three-year DFS was 67.4% for IIIC1 and 58% for IIIC2. Marked heterogeneity was observed within node-positive disease. Patients with pelvic nodal involvement confined below the common iliac region demonstrated favorable DFS (93%), comparable to node-negative stages when treated with contemporary chemoradiation. In contrast, patients with common iliac lymph node involvement had significantly inferior DFS (54%) and accounted for the majority of nodal and distant failures with less than 10% local failures. These outcomes remained consistent despite uniform delivery of EMBRACE-standard chemoradiation.

Conclusion:

Within FIGO IIIC cervical cancer, common iliac lymph node involvement identifies a distinctly high-risk subgroup with substantially inferior disease-free survival, whereas limited lower pelvic nodal disease demonstrates favorable outcomes with modern chemoradiation alone. These findings suggest that pelvic nodal positivity should not uniformly mandate treatment intensification. Instead, common iliac nodal involvement,along with para-aortic or bulky iliac nodal disease may represent a more appropriate population for consideration of neoadjuvant chemotherapy, consistent with emerging evidence from INTERLACE.