Three Dimensional Printed Individual Template Based 192ir High-Dose Rate Interstitial Brachytherapy for Central Recurrent Gynecologic Cancer: A Phase II Clinical Trial

Abstract

To evaluate the feasibility, safety, and accuracy of three-dimensional (3D)-printed individual template (3D-PIT) based with HDR interstitial brachytherapy (HDR-IB) for pelvic central recurrent gynecologic cancer (CR-GYN). 32 patients diagnosed CR-GYN in our institution were received 192Ir HDR-IB. 3D-PIT technique was carried out for all these patients in our center. They underwent procedure that firstly simulation; then preplan; thirdly 3D template design and printing and fourthly interstitial 192Ir HDR brachytherapy operation. There are two types of individual 3D-PIT designed. Type I: transvaginal template/applicator, and Type II: transvaginal combined transperineal template. The prescription dose to GTV was 10-36Gy, 5-6Gy/fraction, 2-6f. Dose parameters were D90, D100, V100, conformal index, external index and homogeneity index of the target volume, and the dose received by 2cm3 of normal tissue of organs at risk (rectum, bladder, and intestine) were recorded. We compared the dose parameters of the treatment plan with the preplan. The short-term efficacy was evaluated by RECIST v1.1, and the adverse event was evaluated by CTCAE V4.0. In total 32 patients, 205 needles were inserted for 153 applications, The mean V100, D100, and D90 per fraction were 88.9%±9.8%,3.45Gy±0.54Gy, and 5.79 Gy±0.32Gy respectively; the mean D2cc of rectum, bladder and colon per fraction were 3.14Gy±0.23Gy, 3.76Gy±0.72Gy and 2.47Gy±0.34Gy respectively. The mean CI, EI, and HI were 0.59±0.12, 0.31±0.16, and 0.47±0.22. Dosimetry parameters comparison between preplan and treatment plan of 20/32 patients with Type II 3D-PIT based HDR-IB show that there were no statistically significant (P > 0.05) difference in GTV volume, V100, D100, D90, CI and HI. Treatment plan EI was lower than preplan, and the difference was statistically significant (P = 0.022). Median follow up time was 10 months (3–28 months). No severe complications of procedures occurred. Grade 3 or 4 late toxicities (fistula ) were observed in 3 patients (9%). The local response rate (CR + PR) was 84.4% (27/32) one month later completion of treatment. In addition, the median TTP was 15.4 months (95% CI 11.3- 19.6ms), 1 year and 2 year local control rate were 51.7% and 51.7%. 3D-PIT based with CT-simulator for HDR-IB for central r-GYN has good dosimetry parameters consistently, was clinically feasible and efficient, and complications did not increased significantly.