Abstract
BackgroundBrachytherapy (BT) is a vital component of the curative treatment of locally advanced cervical cancer. The American Brachytherapy Society has published guidelines for high dose rate (HDR) BT with recommended dose limits. However, recent reports suggest lower doses may be needed to avoid toxicity. The purpose of this study is to investigate incidence and predictive factors influencing gastrointestinal (GI) and genitourinary (GU) toxicity following HDR intracavitary brachytherapy for locally advanced cervical cancer.MethodsWe retrospectively evaluated a cohort of patients with locally advanced cervical cancer who received CT-based HDR BT. Cumulative doses were calculated using the linear-quadratic model. Statistical analyses were used to investigate clinical and dosimetric predictors of GI and GU toxicity following HDR brachytherapy according to CTCAE v4.0 grading criteria.ResultsFifty-six women with FIGO IB1 – IVA cervical cancer were included. The overall rate of any GU adverse event (Grade 1+) was 23.3% (n = 13) and severe adverse events (Grade 3+) was 7.1% (n = 4). Of those, the bladder equivalent dose in 2- Gray (Gy) fractions (EQD2) D2cc was ≥80 for three of the four patients. The overall rate of any GI adverse event was 26.8% (n = 15) and the rate of severe adverse events was 14.3% (n = 8). Of those, six of the eight patients had a rectal EQD2 D2cc ≥ 65 Gy and seven patients had a sigmoid D2cc ≥ 65 Gy. Amongst clinically meaningful factors for development of adverse events (i.e. diabetes, smoking status, ovoid size, and treatment duration), there were no statistically significant prognostic factors identified.ConclusionsSevere adverse events are observed even with adherence to current ABS guidelines. In the era of recent multi-institutional study results, our data also supports more stringent dosimetric goals. We suggest cumulative D2cc dose limits of: less than 80 Gy for the bladder and less than 65 Gy for the rectum and sigmoid.
Highlights
Brachytherapy (BT) is a vital component of the curative treatment of locally advanced cervical cancer
Patient population After obtaining approval from the institutional review board, retrospective data was collected for patients with cervical cancer who received high dose rate (HDR) tandem and ovoid BT and computed tomography (CT)-based treatment planning from 2012 to 2014 to assess for dosimetric predictors of toxicity Clinical stages IB - IVA via the International Federation of Gynecology and Obstetrics (FIGO) staging criteria were included if dosimetry and follow up toxicity information was available during the specified time period
Treatment External beam radiation therapy and chemotherapy In 2012, our institution transitioned from low dose-rate (LDR) to a 3-D image-guided BT (IGBT) HDR program, and we have previously described our technique in detail [13]
Summary
Brachytherapy (BT) is a vital component of the curative treatment of locally advanced cervical cancer. The purpose of this study is to investigate incidence and predictive factors influencing gastrointestinal (GI) and genitourinary (GU) toxicity following HDR intracavitary brachytherapy for locally advanced cervical cancer. BT allows for dose escalation of the tumor in a conformal manner that minimizes the toxicity of nearby organs at-risk (OARs). This essential role of BT in the curative treatment paradigm has been confirmed by multiple reports, as it confers a local control but a survival advantage when compared to cohorts where EBRT is the only radiation treatment modality utilized [3, 4]. The transient rise in severe toxicity represents a Romano et al Radiation Oncology (2018) 13:129 learning curve in the implementation of new technology and improvements were subsequently made including the incorporation of magnetic resonance imaging (MRI) to the image-guided BT (IGBT) workflow
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