Comparative Survival Assessment of Two-Dimension (2D) versus Three-Dimension (3D) Brachytherapy Treatment in Locally Advanced Cervical Cancer: A Retrospective Case Control Study

Abstract

Objective: To assess the efficacy as seen as overall survival, local control, progression free survival (PFS) and toxicities, between two-dimension (2D) and three-dimension (3D) computed tomography (CT) guided brachytherapy (BT) without using interstitial needles among patients with cervical cancer. Materials and Methods: A retrospective case control study was performed among patients with FIGO stage IB-IVA cervical cancer treated between March 1990 and August 2018. Concurrent chemoradiation using external beam radiotherapy followed by BT was the treatment method used in all patients. Patients were divided in two groups based on imaging type during BT to compare between 2D and 3D BT techniques. Clinical endpoints were overall survival, local control, progression free survival, acute toxicities, and late toxicities. Results: One hundred two patients with cervical cancer were included, which 52 patients had been treated with 2D and 50 patients with 3D using CT scan BT without interstitial needles. Baseline characteristics were similar between the groups. External beam was used among all patients during the concurrent chemoradiation period before BT. All patients completed the treatment. Similar 3-year overall survival and local control were reported between 2D and 3D techniques. Overall, the 3-year survival rate was 95.7% in 2D and 91.8% in 3D BT (p=0.188). Local control at the 3-year follow-up was 88.6% for 2D and 93.3% for 3D treatment (p-value=0.571). Progression free survival was better in the 2-D rather than the 3D group with 86.13% in 2D versus 27.4% in the 3D group (p-value=0.006). No grade 3 or 4 toxicity regarding the 3D technique was observed whereas 1.9% of grade 3 presented acute gastrointestinal toxicity (p-value=1), and grade 3 late gastrointestinal and genitourinary toxicities in the 2D technique group at 7.7 and 5.8%, respectively (p=1, both). The 3D BT significantly reduced acute grade 1 to 2 gastrointestinal side effect as 23% in the 2D versus 4% in 3D group (p-value=0.003), and grade 1 to 2 late genitourinary side effect as 50% in the 2D versus 16% in the 3D group (p-value=0.001). Conclusion: Using CT guided 3D BT to treat cervical cancer showed similar outcomes in survival and local control but reduced toxicity compared with the 2D technique. Disease progression including metastasis was better in the 2D BT technique group. CT guided BT helped reduce dose to organs at risk and long-term follow-up for survival outcome and toxicities was needed. Keywords: Cervical cancer; Brachytherapy technique; Brachytherapy; 3D brachytherapy; 2D brachytherapy