The Preliminary Results of 3-Dimensional Printed Individual Template Assisted 192Ir High-Dose Rate Interstitial Brachytherapy for Central Recurrent Gynecologic Cancer

Objective: To evaluate the feasibility and safety of high dose rate interstitial brachytherapy (HDR-IB) assisted with 3-dimensional printing individual template (3D-PIT) for central pelvic recurrent gynecologic cancer (CR-GYN).Methods: Totally 32 patients diagnosed with CR-GYN received iridium-192(192Ir) HDR-IB assisted with 3D-PIT that was classified in 2 types(Type I: transvaginal template/ applicator, and Type II: transvaginal combined transperineal template). The prescribed dose to gross tumor volume (GTV) was 10-36 Gy in 2-6 fractions. We rely on a few dosimetric parameters for quality control. The short-term efficacy was evaluated by RECIST v1.1, and the adverse event was evaluated by CTCAE V4.0.Results: The median V100, D100 and D90 of per fraction among all the patients were 88.9%±9.8%, 3.45Gy±0.54 Gy, and 5.79Gy±0.32 Gy, respectively. Dosimetric comparison between preplan and treatment plan of 20/32 patients with Type II 3D-PIT showed no significant difference in GTV volume, V100, D100, D90, conformation index (CI) and homogeneity index (HI). No severe treatment complications occurred. Grade 3 or 4 late toxicities (fistula) were observed in 3 patients (9%). The local response rate (complete remission, CR + partial remission, PR) was 84.4% (27/32) 1 month after completion of treatment. The median time to progression (TTP) was 15.4 months (95% CI 11.3- 19.6 months), 1-year local control (LC) rate were 51.7%.Conclusions: HDR-IB assisted by 3D-PIT was a reliable modality for CR-GYN due to the clinical feasibility and accepted complications.