Lucas Gomes Sapienza1, Matthew Stephen Ning2, Antônio Cássio de Assis Pellizzon3, Anuja Jhingran2, Ann H Klopp2, Lilie L Lin2, Marisa A Kollmeier4, Vinícius Fernando Calsavara5, Naira Dos Santos Gutierrez3, Rubens Chojniak6, Maria José Leite Gomes7, Glauco Baiocchi8. 1. Department of Radiation Oncology, A.C. Camargo Cancer Center, São Paulo, SP, Brazil; Department of Radiation Oncology, Hospital Central do Exército do Rio de Janeiro (HCE-RJ), Rio de Janeiro, RJ, Brazil. Electronic address: lucasgsapienza@gmail.com. 2. Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX. 3. Department of Radiation Oncology, A.C. Camargo Cancer Center, São Paulo, SP, Brazil. 4. Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, NY. 5. Department of Statistics and Epidemiology, A.C. Camargo Cancer Center, São Paulo, SP, Brazil. 6. Department of Imaging, A.C. Camargo Cancer Center, São Paulo, SP, Brazil. 7. Department of Radiation Oncology, Hospital Federal dos Servidores do Estado (HFSE-RJ), Rio de Janeiro, RJ, Brazil. 8. Department of Gynecologic Oncology, A.C. Camargo Cancer Center, São Paulo, SP, Brazil.
Abstract
PURPOSE: Postinsertion computed tomography (CT) can identify air gaps (AGs) around the cylinder in vaginal cuff brachytherapy (VCB). This study investigates the incidence and location of AGs. METHODS AND MATERIALS: Planning CTs of 22 prospectively recruited patients (NCT02091050) treated with 2.6 cm (n = 8) and 3.0 cm (n = 14) cylinders were evaluated. In addition, a systematic literature review and meta-analysis was performed (PubMed and EMBASE). The pooled incidence of AGs was calculated by using the random-effects model weighted by inverse variance. RESULTS: In 18 cases (82%), a total of 45 AGs were found: 26 within the 2 cm cranial length and 19 between 2 and 4 cm of the cylinder. The mean AG diameter was 3.7 mm (range: 1.3-11.8). Cylinder diameter, primary tumor site, and use of external beam radiotherapy were not associated with AG incidence. Systematic literature review revealed nine additional relevant studies, totaling 657 patients. The pooled incidence of patients with ≥1 AG was 67% (95% confidence interval: 50-83). AGs were located at the apex in 43.4%-94.4% of cases. In patients with ≥1 AG (n = 244), the pooled mean number of AGs was 2.18 per patient. The mean dose reduction varied from 9.6% to 29.3%. CONCLUSION: More than two-thirds of VCB cases present with AGs, which are most commonly at the apex and can potentially reduce mucosal dose. By identifying AGs, postinsertion CT can facilitate selection of optimal cylinder size in VCB.
PURPOSE: Postinsertion computed tomography (CT) can identify air gaps (AGs) around the cylinder in vaginal cuff brachytherapy (VCB). This study investigates the incidence and location of AGs. METHODS AND MATERIALS: Planning CTs of 22 prospectively recruited patients (NCT02091050) treated with 2.6 cm (n = 8) and 3.0 cm (n = 14) cylinders were evaluated. In addition, a systematic literature review and meta-analysis was performed (PubMed and EMBASE). The pooled incidence of AGs was calculated by using the random-effects model weighted by inverse variance. RESULTS: In 18 cases (82%), a total of 45 AGs were found: 26 within the 2 cm cranial length and 19 between 2 and 4 cm of the cylinder. The mean AG diameter was 3.7 mm (range: 1.3-11.8). Cylinder diameter, primary tumor site, and use of external beam radiotherapy were not associated with AG incidence. Systematic literature review revealed nine additional relevant studies, totaling 657 patients. The pooled incidence of patients with ≥1 AG was 67% (95% confidence interval: 50-83). AGs were located at the apex in 43.4%-94.4% of cases. In patients with ≥1 AG (n = 244), the pooled mean number of AGs was 2.18 per patient. The mean dose reduction varied from 9.6% to 29.3%. CONCLUSION: More than two-thirds of VCB cases present with AGs, which are most commonly at the apex and can potentially reduce mucosal dose. By identifying AGs, postinsertion CT can facilitate selection of optimal cylinder size in VCB.
Authors: Katarzyna Sikorska; Agnieszka Zolciak-Siwinska; Adam Kowalczyk; Michał Bijok; Wojciech Michalski; Ewelina Gruszczynska Journal: J Contemp Brachytherapy Date: 2020-06-30