Wendy Zheng

Gastrointestinal and genitourinary toxicity following high dose rate vaginal cuff brachytherapy for endometrial cancer

There are currently no organs at risk dose constraints for adjuvant HDR vaginal cuff brachytherapy (VBT). This study evaluates OAR dosimetry and the association with acute and chronic gastrointestinal (GI) or genitourinary (GU) toxicity. Patients treated at a single institution with VBT of 21 Gray (Gy) in 3 fractions (Fx) prescribed to 5 mm depth twice weekly and CT-based 3D planning were reviewed. OAR doses (D2cc, D1cc, and D0.1cc) were recorded. Acute and chronic toxicities were graded by Common Terminology Criteria for Adverse Events v5.0. Boxplot and Wilcoxon-Mann-Whitney tests compared dose thresholds. 177 patients with stage I-IV endometrial cancer received a mean D2cc to rectum, sigmoid, small bowel, and bladder of 5.7 Gy (range: 2.8-8.7), 3.3 Gy (0.6-9.3), 3.8 Gy (0.0-9.1), and 5.4 Gy (2.0-8.2). Overall, 6.2% (n = 11) and 7.3% (n = 13) of patients experienced acute GI and GU toxicity of any grade. 14.7% (n = 26) and 14.7% (n = 26) of patients experienced chronic GI and GU toxicity of any grade, respectively. There were two grade 3 toxicities include one chronic GI and one acute GU. No dosimetric factors were identified that correlated with a higher likelihood of acute or chronic toxicity. The overall rate of GI and GU toxicity following VBT of 21 Gy in 3 Fx is low, and there are no dosimetric parameters that correlate with toxicity. The optimal dose fractionation schedule that balances high local control with minimal toxicity is yet to be determined.

A randomized trial evaluating a novel hydrogel packing system compared to standard packing during image-guided high-dose rate brachytherapy boost for cervical cancer

The purpose of this prospective randomized trial was to compare the use of a novel vaginal hydrogel packing system (BrachyGel) to standard vaginal packing (VP) during high dose rate (HDR) brachytherapy (BT) for locally advanced cervical cancer (LACC). This cross-over study included LACC patients receiving HDR BT boost (intracavitary +/- interstitial). All patients received alternating gauze or BrachyGel VP on Arms A and B. Patients, physicians, and physicists evaluated BT characteristics via a 4-point Likert scale. Adverse events (AEs) were prospectively collected and scored per CTCAE. The 20 patients enrolled. The mean bladder D2cc difference between gauze and BrachyGel in Arm A was 0.117 Gray (Gy) and in Arm B 0.013 Gy. The mean difference in rectum D2cc in Arm A and Arm B was -0.189 Gy and -0.191 Gy, respectively. The mean dose to 90% of the high-risk clinical target volume (HR-CTV) for gauze compared to BrachyGel was -0.032 Gy (95% CI: 0.472, 0.409). Patient-reported discomfort was similar with BrachyGel and gauze ("mild/moderate" 70.0% vs 74.0%, respectively). The clarity of VP was similar between BrachyGel and gauze (86.8% vs 89.7%, respectively). The completeness of VP was more frequently "excellent/good" with BrachyGel (79.0%) compared to gauze (56.4%). The ease of packing was more frequently "extremely easy" with BrachyGel (21.2% vs 0%). No serious AEs were reported. This randomized trial found no clinically significant difference in OAR or HR-CTV dosimetry between BrachyGel and standard VP. BrachyGel performed well compared to gauze for the patient and physician use experience.