Effects of rectal retractor use on dosimetric parameters, treatment-related adverse events, and clinical outcomes of cervical cancer brachytherapy: A retrospective tertiary-centre study.

BACKGROUND AND PURPOSE: We assessed whether rectal retractor use was associated with dose parameters, organ volumes, treatment-related adverse events, and oncological outcomes in patients who underwent cervical cancer brachytherapy.

MATERIALS AND

METHODS

This retrospective study included 148 patients treated with intracavitary brachytherapy between June 2020 and June 2025. Patients treated with and without a rectal retractor were compared regarding dosimetric, volumetric, adverse event, and survival outcomes. Adverse events were graded via RTOG criteria. Cumulative dose parameters were calculated using EQD2. ROC analysis and multivariable logistic regression were performed to evaluate factors associated with grade ≥ 2 adverse events.

RESULTS

Rectal retractor use occurred in 58 patients (39.2%). Baseline demographic characteristics and tumour size were comparable between groups, although rectal retractor use differed according to applicator type. Rectal retractor use was associated with lower rectal D2cc (no retractor vs. retractor: 65.70 Gy vs. 60.79 Gy, p = 0.002) but higher bladder D2cc (no retractor vs. retractor: 75.59 Gy vs. 80.08 Gy, p < 0.001) values. Prescribed EQD2, HR-CTV coverage, sigmoid D2cc, and volumetric parameters were similar. Grade ≥ 2 vaginal adverse events were less frequent in the retractor group than in the no-retractor group (32.8% vs. 56.7%, p = 0.004). No significant difference was observed in grade ≥ 2 rectal (p = 0.380) or urinary adverse events (p = 0.083). ROC analysis showed that first-fraction volumetric parameters had limited discriminatory ability for grade ≥ 2 adverse events (AUC range: 0.417-0.613). In multivariable analysis, rectal retractor use was associated with lower odds of grade ≥ 2 vaginal adverse events (OR 0.29; 95% CI, 0.13-0.63; p = 0.002).

CONCLUSIONS

Rectal retractor use was associated with rectal dose sparing and lower odds of grade ≥ 2 vaginal adverse events without compromising target coverage. However, this finding should be interpreted cautiously because rectal retractor placement was not randomised and was influenced by applicator compatibility.