Mid-treatment MRI-based tumor response assessment for tumor recurrence and patient survival in locally advanced adenocarcinoma of the cervix: A retrospective multicenter study of KROG 23-03.

Objective: To evaluate the significance of response assessment with magnetic resonance imaging (MRI) during chemoradiotherapy (CRT) for outcomes of adenocarcinoma of the cervix.

Methods: A retrospective analysis of 102 patients diagnosed with FIGO 1B3-IVa cervical adenocarcinoma was conducted. Patients underwent definitive CRT and brachytherapy. Mid-treatment MRI-assessments were used to evaluate tumor response during radiotherapy, focusing on tumor volume reduction rate (TVRR), which was defined as an optimal reduction rate from initial tumor volume for tumor progression. Locoregional recurrence (LRR), distant metastasis (DM), progression-free survival (PFS) and overall survival (OS) rates according to the tumor response were analyzed.

Results: Forty-five (44.1 %) of 102 patients experienced tumor downstaging during CRT, with 72 (70.5 %) demonstrating a complete response on post-treatment MRI three months after radiotherapy. With a median follow-up of 35.5 months, the 3-year PFS and overall OS rates for all patients were 60.0 % and 84.0 %, respectively. LRR and DM rates at 3 years were 25.2 % and 23.3 %, respectively. Patients with TVRR≥81.8 % had significantly longer 3-year PFS (75.4 % vs. 36.2 %, P < 0.001) and OS (93.2 % vs. 69.0 %, P = 0.002) rates than the other patients with TVRR<81.8 %. LRR (10.6 % vs. 45.6 %, P = 0.003) and DM (14.6 % vs. 33.5 %, P = 0.008) rates at 3 years were significantly lower in TVRR≥81.8 % group compared to TVRR<81.8 % group. In the multivariate analysis, positive initial lymph node (hazard ratio [HR], 2.11; confidence interval [CI], 1.25-3.87; P = 0.02] and TVRR (HR, 0.42; CI, 0.19-0.93; P = 0.03) were significantly associated with PFS.

Conclusion: Mid-treatment MRI assessment is crucial and higher rates of tumor volume reduction during radiotherapy indicates better prognosis for tumor recurrence and patient survival in cervical adenocarcinoma.