(S035) Cervical Cancer Outcome Prediction to High-Dose-Rate Brachytherapy Using Quantitative Magnetic Resonance Imaging Analysis of Tumor Response to External Beam Radiotherapy

OncologyOncology Vol 29 No 4_Suppl_1
Volume 29
Issue 4_Suppl_1

Aside from the known benefits of IGBT, MRI-based planning allows for assessment of tumor regression and prognosticates patients, as shown in the present study. If these findings are replicated in prospective trials, alternative methods, such as dose escalation and surgical salvage, should be considered to offset poor prognoses.

Beant S. Gill, MD, David Minkoff, BA, Hayeon Kim, MS, DABR, Christopher Houser, MS, Sushil Beriwal, MD; Magee-Womens Hospital, University of Pittsburgh Medical Center

PURPOSE: Image-guided brachytherapy (IGBT) has been shown to improve outcomes for cervical cancer. Integration of magnetic resonance imaging (MRI) allows visualization of residual disease. In order to assess tumor regression and outcomes, a volumetric analysis was conducted among patients treated with MRI-based IGBT.

METHODS: Consecutive patients with International Federation of Gynecology and Obstetrics (FIGO) stage IB1–IVA cervical cancer receiving definitive chemoradiation from 2007–2013 were identified. Patients were excluded if they were undergoing perineal template-based interstitial brachytherapy or if MRI was not completed prior to therapy and at first brachytherapy application. All patients were treated using a ring and tandem with or without interstitial needles. High-dose-rate brachytherapy was delivered in five once- or twice-weekly fractions of 5–6 Gy/fraction. Optimization was completed to meet the following cumulative equivalent 2-Gy doses (EQD2): high-risk clinical target volume (HRCTV) 75–85 Gy and 2 cc of rectum ≤ 70 Gy, sigmoid ≤ 70 Gy, and bladder ≤ 85 Gy. T2-weighted imaging using 1.5-T MRI was completed following brachytherapy applicator insertion. Gross tumor volumes (GTVs) were retrospectively contoured and defined: GTV prior to therapy (GTVPre-EBRT), GTV at first application (GTVIGBT), and percentage residual GTV at first application (GTV%Residual).

RESULTS: Eighty-four patients were identified. The majority had FIGO stage IIB disease (57.1%) and squamous histology (82.1%) and received median external beam and brachytherapy doses of 45.0 Gy and 27.5 Gy, respectively. With a 20.8-month (range: 3–74 mo) median follow-up, the 2-year Kaplan-Meier estimates of local control (LC), disease-free survival (DFS), and overall survival (OS) were 91.3%, 79.8%, and 85.0%, respectively. Median GTVPre-EBRT, GTVIGBT, and GTV%Residual values were 31.9 cc (range: 2.6–171.3 cc), 3.5 cc (range: 0.0–36.6 cc), and 9.7% (range: 0.0%–67.3%). Multivariate Cox regression revealed adenocarcinoma (hazard ratio [HR] = 5.76; P = .03) and GTVIGBT (HR = 1.17; P < .01) as predictors for local failure. Additionally, GTVIGBT was associated with any disease recurrence (HR = 1.17; P < .01) and overall mortality (HR = 1.20; P < .01). GTVIGBT > 7.5 cc was associated with inferior 2-year LC (75.0% vs 96.6%; P < .01), DFS (42.6% vs 91.6%; P < .01), and OS (65.2% vs 91.5%; P < .01). No difference in mean HRCTV D90 EQD2 was seen between these groups (83.2±2.2 Gy vs 83.5±2.7 Gy; P = .61).

CONCLUSION: Aside from the known benefits of IGBT, MRI-based planning allows for assessment of tumor regression and prognosticates patients, as shown in the present study. If these findings are replicated in prospective trials, alternative methods, such as dose escalation and surgical salvage, should be considered to offset poor prognoses.

Proceedings of the 97th Annual Meeting of the American Radium Society- americanradiumsociety.org

Articles in this issue

(P005) Ultrasensitive PSA Identifies Patients With Organ-Confined Prostate Cancer Requiring Postop Radiotherapy
(P001) Disparities in the Local Management of Breast Cancer in the United States According to Health Insurance Status
(P002) Predictors of CNS Disease in Metastatic Melanoma: Desmoplastic Subtype Associated With Higher Risk
(P003) Identification of Somatic Mutations Using Fine Needle Aspiration: Correlation With Clinical Outcomes in Patients With Locally Advanced Pancreatic Cancer
(P004) A Retrospective Study to Assess Disparities in the Utilization of Intensity-Modulated Radiotherapy (IMRT) and Proton Therapy (PT) in the Treatment of Prostate Cancer (PCa)
(S001) Tumor Control and Toxicity Outcomes for Head and Neck Cancer Patients Re-Treated With Intensity-Modulated Radiation Therapy (IMRT)-A Fifteen-Year Experience
(S003) Weekly IGRT Volumetric Response Analysis as a Predictive Tool for Locoregional Control in Head and Neck Cancer Radiotherapy 
(S004) Combination of Radiotherapy and Cetuximab for Aggressive, High-Risk Cutaneous Squamous Cell Cancer of the Head and Neck: A Propensity Score Analysis
(S005) Radiotherapy for Carcinoma of the Hypopharynx Over Five Decades: Experience at a Single Institution
(S002) Prognostic Value of Intraradiation Treatment FDG-PET Parameters in Locally Advanced Oropharyngeal Cancer
(P006) The Role of Sequential Imaging in Cervical Cancer Management
(P008) Pretreatment FDG Uptake of Nontarget Lung Tissue Correlates With Symptomatic Pneumonitis Following Stereotactic Ablative Radiotherapy (SABR)
(P009) Monte Carlo Dosimetry Evaluation of Lung Stereotactic Body Radiosurgery
(P010) Stereotactic Body Radiotherapy for Treatment of Adrenal Gland Metastasis: Toxicity, Outcomes, and Patterns of Failure
(P011) Stereotactic Radiosurgery and BRAF Inhibitor Therapy for Melanoma Brain Metastases Is Associated With Increased Risk for Radiation Necrosis
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