Juntendo University Faculty of Medicine Urayasushi, Chibaken
A. I. Saito1, K. Usui2, and Y. Kosugi3; 1Department of Radiation Oncology, Juntendo University Faculty of Medicine, Tokyo, Japan, 2Faculty of Health Science Juntendo University, Tokyo, Japan, 3Juntendo University, Department of Radiation Oncology, Tokyo, Japan
Purpose/Objective(s): Purpose was to analyze the adverse effects, and rate of sphincter preservation with the addition of hydrogen peroxide to neoadjuvant chemoradiotherapy of rectal cancer. Materials/
Methods: This was a prospective single-arm trial with historical controls. Inclusion criteria was operable patients; aged 18 years or older; pathologically proven rectal adenocarcinoma; distance from the tumor to anal verge (AV) <75 mm, no hematogenous metastasis; Eastern Cooperative Oncology Group Performance Status (PS) up to 2; and had not undergone prior treatment. Hydrogen peroxide was used twice a week in combination with radiotherapy (RT). A 3% hydrogen peroxide solution-soaked gauze was inserted into the rectum during RT. A total of 45 Gy was delivered in 25 fractions over 5 weeks to the whole pelvis with concurrent oral S-1. Regarding the historical control the protocol of neoadjuvant chemoradiotherapy in our institution was 45Gy external beam RT in 25 fractions over 5 weeks to the whole pelvis with concurrent oral S-1 since 2012. Therefore, we extract the patients from this period who met the eligibility criteria. Patients’ characteristics as gender, age, tumor stage, PS and tumor distance from the AV was compared between the two groups. Also, adverse effect using NCI-CTC version 5 and the number of patients who underwent sphincter-preserving surgery were analyzed and compared, too. Results: From July 2017 to November 2022, 27 patients (7 females, 20 males, median age 67, all PS0, 93% showed cT or higher stage) were accrued into the intervention group (IG) and 32 patients (10 females, 22 males, median age 64.5, all PS0, 69% showed cT or higher stage) were extracted as historical control (HC). There were more cT stage 3 or higher patients in the IG (p=0.02) but there was no statistically significant difference in other characteristics between the two groups. Regarding acute adverse effect, there was no grade 3 or worse ones but significantly more patients with grade 2 proctitis were observed in the IG (IG; 30%, HC; 0%; p<0.01) and 2 patients showed grade 2 hemorrhage in the IG but none in the HC. Regarding chronic adverse effect the median follow up of the IG was 27 (range 4-72) months. Out of them no patient showed Grade 3 or worse adverse effect in the pelvis. Patients who underwent sphincter-preserving surgery were 13 (48%) in the IG and 8 (25%) in the HC and showed a trend (p=0.06). On multivariate analysis employing age, cT stage, distance to AV and use of the use of hydrogen peroxide as a factor, the use of hydrogen peroxide (p=0.01) and the distance to AV (p<0.01) correlated statistically significantly to higher rate of sphincter-preserving surgery employment. Conclusion: Radiosensitization with hydrogen peroxide did not show grade 3 or higher adverse effects. The percentage of patients with sphincter-preserving surgery correlated with the distance to the AV and the use of hydrogen peroxide.
