(Wednesday, 8/1/2018) 10:00 AM - 10:30 AM
Room: Exhibit Hall | Forum 4
Purpose: To evaluate the volumetric dose (EQD2) of vaginal wall and its correlation with the vaginal toxicity in locally advanced cervical cancer patients treated with external beam radiation therapy (EBRT) and high-dose-rate (HDR) brachytherapy.
Methods: Seventeen patients who underwent EBRT and HDR brachytherapy using a Split-ring & Tandem applicator were analyzed. Each patient was treated with either 27.5Gy or 30.0Gy in five fractions of HDR brachytherapy following 45Gy of pelvic EBRT. The left and right vaginal walls were contoured, where they touched the rings, using a 5mm diameter contouring brush. Point dose (D0.035cc), D0.1cc, D1cc, and D2cc were recorded for the left, right, posterior and the combination of the left, right and posterior vaginal walls. EQD2s were calculated and added to the primary. Dosimetric parameters (D0.035cc, D0.1cc, D1cc, and D2cc) for various parts of the vaginal wall as well as combined vaginal wall were analyzed and evaluated for vaginal toxicities including vaginal dryness, dyspareunia, discharge, and fistula.
Results: The average point dose (EQD2) to the combined vaginal wall was 226.6 ± 96.3 Gy (range: 128.6-469.6Gy), whereas EQD2 for D0.1cc, D1.0cc, and D2.0cc were 180.1± 68.6Gy, 95.9Gy ± 24.2Gy, and 75.2 ± 16.1Gy, respectively. The left and right vaginal wall points had mean dose of 40.6 ± 7.3Gy (range: 31.4-59.9Gy) and 38.2 ± 7.9Gy (range: 22.4-51.5Gy), respectively. Seven (41%) patients had either Grade 1 or Grade 2 toxicities and one (6%) patient had grade 3 rectovaginal fistula. We found no correlation between dosimetric parameters and the vaginal toxicities.
Conclusion: There is a lack of correlations between various dosimetric parameters and vaginal toxicities. Larger sample size may be useful in predicting the vaginal toxicities. For better understanding further research on this topic is warranted.
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