Dose-effect relationship between vaginal dose points and vaginal stenosis in cervical cancer: An EMBRACE-I sub-study

Background and purpose: To evaluate dose-effect relationships between vaginal dose points and vaginal stenosis in patients treated for locally advanced cervical cancer with radio(chemo)therapy and image-guided adaptive brachytherapy. Material and methods: Patients from six centres participating in the EMBRACE-I study were included. Information on doses to different vaginal dose points, including the Posterior-Inferior Border of Symphysis (PIBS) points and recto-vaginal reference (RV-RP) point, were retrieved from the treatment planning system. In addition, the vaginal reference length (VRL) was evaluated. Vaginal stenosis was prospectively assessed according to the CTCAEv3.0 system at baseline and follow-up. Primary endpoint was grade 2 or higher (G >= 2) vaginal stenosis. Impact of dose to the vaginal dose points, and impact of VRL, age, vaginal involvement and applicator on vaginal stenosis G >= 2 was evaluated with a Cox proportional-hazard regression model. Results: 301 patients were included. Median follow-up was 49 months. During follow-up, the incidence of G0, G1, G2, and G3 vaginal stenosis was 25% (76), 52% (158), 20% (59) and 3% (8), respectively. Median total doses to PIBS+2 cm, PIBS, PIBS-2 cm and the RV-RP were 52.9 (IQR 49.3-64.7), 41.0 (IQR 15.4-49.0), 4.1 (IQR 2.9-7.0) and 64.6 (IQR 60.0-70.6) Gy EQD23, respectively. Higher doses to the PIBS, PIBS + 2 cm and RV-RP points were significantly associated with increased risk for vaginal stenosis G >= 2. Other risk factors for vaginal stenosis were: vaginal involvement at diagnosis, higher age, shorter VRL and use of a tandem-ovoid applicator. Conclusion: Higher doses to the PIBS+2 cm, PIBS and RV-RP dose points are associated with vaginal stenosis G >= 2. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study evaluated the relationship between vaginal dose points and vaginal stenosis in patients with locally advanced cervical cancer. The results showed that higher doses to specific vaginal dose points were significantly associated with G >= 2 vaginal stenosis. Other risk factors included vaginal involvement, older age, shorter vaginal reference length, and the use of a specific applicator.