Application of small pelvic adjuvant radiotherapy in early cervical cancer without high-risk factors after hysterectomy

Objectives To evaluate the clinical efficacy and safety of adjuvant small pelvic radiotherapy in early-stage cervical cancer patients without high-risk factors following radical hysterectomy. Methods Patients were assigned to small pelvic (excluding common iliac nodes) or whole pelvic radiotherapy groups. Survival was compared before and after propensity score matching. Recursive partitioning analysis constructed risk stratification, and subgroup survival was analyzed. Organs-at-risk dosimetry and treatment-related adverse events were also compared. Results Prior to propensity score matching analysis, whole pelvic radiotherapy yielded significantly better 5-year disease-free survival than small pelvic radiotherapy (93.0% vs 86.8%, p =0.038), whereas this survival advantage disappeared after propensity score matching adjustment (90.8% vs 87.0%, p =0.2). No significant difference in 5-year locoregional control was observed between the two groups after propensity score matching. Three independent risk subgroups were identified via recursive partitioning analysis. In the high-risk subgroup defined by tumor diameter ≥3.2 cm, whole pelvic radiotherapy achieved superior survival benefits relative to small pelvic radiotherapy, with statistically higher 5-year overall survival (96.7% vs 77.1%, p =0.022) and disease free survival (96.7% vs 70.8%, p =0.006). Significant intergroup differences were detected in dosimetric metrics of the bone marrow and small intestine, while no obvious difference was found in rectal dosimetry. A borderline significant difference was noted in grade 1-2 gastrointestinal adverse events, with a higher incidence in the whole pelvic group (26.0% vs 13.7%, p =0.06). Conclusions Small pelvic radiotherapy may be less suitable for patients with tumor diameter ≥3.2cm, while it may reduce mild gastrointestinal toxicities.