KEY POINTS
- This retrospective study included 217 postoperative endometrial cancer patients: 120 received pelvic EBRT followed by vaginal-cuff brachytherapy, and 97 received vaginal-cuff brachytherapy alone.
- The combined group generally received pelvic doses of 1.8–2 Gy per fraction followed by one cuff fraction of approximately 7 Gy. Brachytherapy-alone schedules were 7.5 Gy × 2 or 6 Gy × 3.
- Grade 1–2 late vaginal effects occurred in 34 of 120 patients (28.3%) after EBRT plus brachytherapy and 35 of 97 patients (36.1%) after brachytherapy alone.
- In the combined-treatment cohort, patients developing toxicity had higher cuff CTV D90 per fraction (7.91 vs 7.71 Gy, p=0.040) and higher vaginal D2cc (10.10 vs 9.84 Gy, p=0.045).
- On multivariable analysis, vaginal D2cc remained independently associated with toxicity (HR 1.60, 95% CI 1.01–2.54; p=0.045), as did the CTV dose–volume histogram parameter (HR 0.77, 95% CI 0.61–0.97; p=0.027).
- No significant dose–toxicity relationship was identified in patients treated with vaginal brachytherapy alone. Most toxicity events in both cohorts developed within the first 48 months.
- Replanning showed that conventional prescription at a fixed 5-mm depth produced systematically higher D90, D100, EQD2, and vaginal D2cc than CTV-based volume or graphical optimization. Only the original 5-mm plans were delivered, so the alternative planning strategies were dosimetric simulations rather than clinical comparisons.
CLINICAL TAKEAWAY
Vaginal D2cc deserves attention when cuff brachytherapy follows pelvic EBRT, where cumulative dose and tissue exposure are greatest. The results support CTV-based planning and standardised dose reporting but do not establish a new validated constraint or prove that replanning would reduce toxicity.