Prognostic implications of tumor volume reduction during radiotherapy in locally advanced cervical cancer: a risk-stratified analysis

Background This study aimed to identify key risk factors in locally advanced cervical cancer (LACC) patients receiving radical radiotherapy and to evaluate the prognostic significance of MRI-determined tumor volume regression (TVR) among varying risk groups. Methods We retrospectively analyzed a cohort of 176 cervical cancer patients (stages IIA-IVA) treated with intensity-modulated radiotherapy from January 2012 to December 2020. Three-dimensional MRI scans were utilized to measure TVR and lymph node volume regression (NVR). Kaplan-Meier analysis was employed to assess overall survival (OS), progression-free survival (PFS), local relapse-free survival (LRFS), and distant metastasis-free survival (DMFS). Prognostic factors were further analyzed using Cox proportional hazards models. Results A tumor TVR of >= 94% was significantly associated with improved 5-year overall survival (OS; 82.7% vs. 49.8%, p < 0.001) and progression-free survival (PFS; 82.5% vs. 51.1%, p < 0.001). Patients with TVR >= 94% also demonstrated superior LRFS and DMFS compared to those with TVR < 94% (p < 0.001 and p = 0.012, respectively). In the concurrent chemoradiotherapy (CCRT) subgroup, higher TVR correlated with better prognosis, whereas in patients receiving radiotherapy alone, an increased TVR did not significantly impact OS. Notably, the prognostic value of TVR was most evident in patients with CYFRA21-1 levels below 7.7 ng/ml. In the NVR >= 94% subgroup, OS, PFS, and LRFS were significantly better than in patients with NVR < 94% (p < 0.01), with a trend towards improved DMFS observed (p = 0.138). Conclusion TVR serves as a pivotal prognostic marker in LACC patients with CYFRA21-1 levels below 7.7 ng/ml undergoing CCRT. Additionally, within the lymph node metastasis subgroup, patients achieving a NVR of >= 94% demonstrated a notably improved prognosis.