Abstract
Outcomes for patients with Stage IB1–IVA cervical cancer treated with computed tomography (CT)-based image-guided brachytherapy (IGBT) were examined in this study. A total of 84 patients were analyzed between March 2012 and June 2015. Whole-pelvic radiotherapy with a central shield was performed for each patient, and the total pelvic sidewall dose was 50 Gy. IGBT was delivered in 2–4 fractions. The initial prescription dose (6.8 Gy) was delivered at Point A, and the dose distribution was modified manually by graphical optimization. The total dose was calculated as the biologically equivalent dose in 2 Gy fractions (EQD2). Concurrent chemotherapy was administered to 64 patients (76%). The median follow-up period was 36 months (range 2–62 months). The 3-year overall survival, local control, and progression-free survival rates were 94%, 89% and 81%, respectively. The mean EQD2 for HR-CTV D90 was 73.4 Gy, and the EQD2 for HR-CTV D90 was not significantly associated with the local control rate. In multivariate analysis, adenocarcinoma (P = 0.03) and tumor size ≥45 mm (P = 0.06) were risk factors for local control. The patients were divided into four groups based on histology (squamous cell carcinoma vs adenocarcinoma) and tumor size (<45 vs ≥45 mm). Those with large adenocarcinomas had significantly worse outcomes. In conclusion, CT-based IGBT achieved favorable local control, but different treatment strategies may be necessary for large adenocarcinomas.
Highlights
Brachytherapy has played the most important role in the treatment of cervical cancer to date [1]
The purpose of optimization was to improve the coverage of HR-clinical target volume (CTV) in 33 patients (33%) and to reduce the dose to the organs at risk (OARs) in 66 patients (67%)
In patients with improvement in the high-risk CTV (HR-CTV) group, there were increases in the HR-CTV D90 (6.11 ± 0.68 to 6.70 ± 0.44 Gy), rectum D2cm3 (4.98 ± 1.01 to 5.33 ± 1.11 Gy) and bladder D2cm3 (4.97 ± 0.72 to 5.30 ± 0.76 Gy), but the rise in the D2cm3 for the OARs was within the limit of the dose constraints
Summary
Brachytherapy has played the most important role in the treatment of cervical cancer to date [1]. Brachytherapy combined with external beam radiotherapy (EBRT) has been established as a standard radical treatment in patients with cervical cancer. Since the Groupe Européen de Curietherapie/European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) working group recommendations were published in 2005 [2], magnetic resonance imaging (MRI)-based planning has been viewed as the gold standard for cervical cancer brachytherapy, and several studies have reported excellent local control (LC) and few complications with MRI-based planning [3, 4]. Many centers, including many of those in Japan, utilize computed tomography (CT) instead of MRI for brachytherapy planning. This is because of the cost of MRI, the need for dedicated devices, and the lack of accessibility for the radiotherapy (RT) department, and there are several reports of
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