Severe gastrointestinal complications in the era of image-guided high-dose-rate intracavitary brachytherapy for cervical cancer

Interfraction dose deviation and catheter position in cervical interstitial and intracavitary image guided HDR brachytherapy

Interstitial and intracavitary gynecological HDR brachytherapy involve precise, localized delivery to targets with high dose gradients, sparing adjacent organs at risk (OAR). Due to the proximity of the rectum, bowel and bladder to the target, deviations in the applicator or catheter with respect to patient anatomy can significantly increase dose to OAR. The magnitude and direction of applicator and catheter migration at each fraction was assessed for template interstitial and tandem and ring (T&R) cohorts. The cohort included twelve gynecological patients with intact cervical lesions treated with external beam and brachytherapy. Pre-treatment CT images were registered to the simulation CT with respect to the target. Treatment catheter positions transformed into the planning CT coordinate system to evaluate localized catheter displacement and dose distributions calculated at each fraction. Dose was evaluated on the planning CT with planning contours and dwell locations at treatment position. Absolute deviation, depth and deflection angle for all patients were 4.6 ± 4.2 mm, -1.4 ± 4.0 mm, and 3.1 ± 2.3° respectively (n = 516 catheter positions for all treatment fractions and patients, mean ± SD). Absolute catheter deviation and deflection magnitude for interstitial treatments increased overall with each subsequent fraction with an overall increase of catheter retraction at each fraction (p < 0.005, n = 492 catheters, Kruskal-Wallis). A target EQD2 D90 reduction of 10 ± 10% and 7.7 ± 8.7% of the planned dose for interstitial and T&R cohorts respectively. There was an overall increase in bladder and rectal doses at each fraction. Catheter tracking in interstitial and intracavitary gynecological treatments with CT imaging revealed significant changes in catheter positioning with respect to the target volume. Overall deviations increased in magnitude with each subsequent fraction in the interstitial treatments. This caused patient dosimetry deviations, including target dose reduction and adjacent OAR doses changes.

Combining imaging- and gene-based hypoxia biomarkers in cervical cancer improves prediction of chemoradiotherapy failure independent of intratumour heterogeneity

Background

Emerging biomarkers from medical imaging or molecular characterization of tumour biopsies open up for combining the two and exploiting their synergy in treatment planning of cancer patients. We generated a paired data set of imaging- and gene-based hypoxia biomarkers in cervical cancer, appraised the influence of intratumour heterogeneity in patient classification, and investigated the benefit of combining the methodologies in prediction of chemoradiotherapy failure.

Methods

Hypoxic fraction from dynamic contrast enhanced (DCE)-MR images and an expression signature of six hypoxia-responsive genes were assessed as imaging- and gene-based biomarker, respectively in 118 patients.

Findings

Dichotomous biomarker cutoff to yield similar hypoxia status by imaging and genes was defined in 41 patients, and the association was validated in the remaining 77 patients. The two biomarkers classified 75% of 118 patients with the same hypoxia status, and inconsistent classification was not related to imaging-defined intratumour heterogeneity in hypoxia. Gene-based hypoxia was independent on tumour cell fraction in the biopsies and showed minor heterogeneity across multiple samples in 9 tumours. Combining imaging- and gene-based classification gave a significantly better prediction of PFS than one biomarker alone. A combined dichotomous biomarker optimized in 77 patients showed a large separation in PFS between more and less hypoxic tumours, and separated the remaining 41 patients with different PFS. The combined biomarker showed prognostic value together with tumour stage in multivariate analysis.

Interpretation

Combining imaging- and gene-based biomarkers may enable more precise and informative assessment of hypoxia-related chemoradiotherapy resistance in cervical cancer.

Funding

10.13039/100008730Norwegian Cancer Society, South-Eastern Norway Regional Health Authority, and Norwegian Research Council.

Treatment-Related Radiation Toxicity Among Cervical Cancer Patients

Objective

The purpose of this study is to identify incidence of and factors associated with severe late toxicity in women treated with radiation for cervical cancer.

Materials and Methods

All patients with cervical cancer treated with radiation as primary or adjuvant therapy from 2005 to 2017 in a single academic institution were included. Records were reviewed for demographic information, Charlson Comorbidity Index, treatment details, toxicities, and outcomes. Patients with and those without severe late gastrointestinal toxicity (SLGIT), severe late genitourinary toxicity (SLGUT), or any SLGIT or SLGUT, defined as any toxicity (AT), were compared. Overall survival and progression-free survival were also compared.

Results

Of 179 patients identified, 21.2% had AT, 17.3% had SLGIT, and 10% had SLGUT. Estimated AT rate at 3 years was 24.2%. The mean duration of follow-up was 37 months (range, 3–146 months). Most patients (84.1%) received 3-dimensional conformal therapy, and 15.9% received intensity-modulated radiation therapy. Factors associated with AT were lower body mass index (24.9 vs 28.3, P = 0.043), white race (63.2% vs 44%, P = 0.035), and active tobacco smoking during treatment (59.5% vs 40.2%, P = 0.036). Any toxicity was not associated with 3-dimensional versus intensity-modulated radiation therapy planning, low-dose versus high-dose–rate brachytherapy or time to complete radiation treatment. Higher total cumulative radiation dose to clinical target volume was associated with SLGIT. Progression-free survival and overall survival were similar among patients with AT compared to those without toxicity.

Conclusions

In patients with cervical cancer, radiation toxicity is correlated with lower body mass index, white race, and smoking. Despite technologic advances in radiotherapy planning and delivery, toxicity remains high and interventions to reduce the burden of treatment are needed.

American Brachytherapy Task Group Report: A pooled analysis of clinical outcomes for high-dose-rate brachytherapy for cervical cancer

PURPOSE

Advanced imaging used in combination with brachytherapy (BT) has revolutionized the treatment of patients with cervical cancer. We present a comprehensive review of the literature for definitive radiation with high-dose-rate (HDR) BT. In addition, we investigate potential outcome improvement with image-based brachytherapy (IBBT) compared to studies using traditional Point A dosing. This review extensively investigates acute and late toxicities.

METHODS AND MATERIALS

This study reviews the literature from 2000 to 2015 with an emphasis on modern approaches including concurrent chemotherapy (chemoRT), radiation, and HDR BT and IBBT. Descriptive statistics and pelvic control (PC), disease-free survival (DFS), and overall survival (OS) outcomes were calculated using weighted means to report pooled analysis of outcomes.

RESULTS

Literature search yielded 16 prospective, 51 retrospective studies that reported survival outcomes, and 13 retrospective studies that focused on acute and late toxicity outcomes regardless of applicator type. There are 57 studies that report Point A dose specification with 33 having chemoRT, and 10 studies that use IBBT, 8 with chemoRT. Patients receiving radiation and chemoRT with HDR BT in the prospective studies, with >24 months followup, rates of PC were: for RT: 73%, SD: 11; CRT: 82%, SD: 8; DFS-RT: 55%, SD: 10; CRT: 65%, SD: 7; OS-RT: 66%, SD: 7; CRT: 70%, SD: 11. In the retrospective studies, the PC rates (weighted means) for the radiation and chemoradiation outcomes are 75% vs. 80%, and for DFS, the values were 55% vs. 63%, respectively. Comparing patients receiving chemoRT and IBBT to traditional Point A dose specification, there is a significant improvement in PC (p < 0.01) and DFS (p < 0.01) with IBBT. The range of genitourinary late toxicity reported for radiation was Grade 3: 1-6% and for chemoRT 2-20%. The range of late gastrointestinal toxicity for radiation was Grade 3: 4-11% and for chemoRT, 1-11%. For the late gynecologic toxicity, only 1 of the 16 prospective trials report a Grade 1-2 of 17% for radiation and 9% for chemoRT effects.

CONCLUSIONS

We present concise outcomes of PC, DFS, OS, and toxicity for cervical cancer patients treated with chemoradiation and HDR BT. Our data suggest an improvement in outcomes with the use of IBBT compared with traditional Point A dose prescriptions. In conclusion, HDR BT is a safe, effective modality when combined with IBBT.

Integrative Analysis of DCE-MRI and Gene Expression Profiles in Construction of a Gene Classifier for Assessment of Hypoxia-Related Risk of Chemoradiotherapy Failure in Cervical Cancer

PURPOSE

A 31-gene expression signature reflected in dynamic contrast enhanced (DCE)-MR images and correlated with hypoxia-related aggressiveness in cervical cancer was identified in previous work. We here aimed to construct a dichotomous classifier with key signature genes and a predefined classification threshold that separated cervical cancer patients into a more and less hypoxic group with different outcome to chemoradiotherapy.

EXPERIMENTAL DESIGN

A training cohort of 42 patients and two independent cohorts of 108 and 131 patients were included. Gene expression data were generated from tumor biopsies by two Illumina array generations (WG-6, HT-12). Technical transfer of the classifier to a reverse transcription quantitative PCR (RT-qPCR) platform was performed for 74 patients. The amplitude ABrix in the Brix pharmacokinetic model was extracted from DCE-MR images of 64 patients and used as an indicator of hypoxia.

RESULTS

Classifier candidates were constructed by integrative analysis of ABrix and gene expression profiles in the training cohort and evaluated by a leave-one-out cross-validation approach. On the basis of their ability to separate patients correctly according to hypoxia status, a 6-gene classifier was identified. The classifier separated the patients into two groups with different progression-free survival probability. The robustness of the classifier was demonstrated by successful validation of hypoxia association and prognostic value across cohorts, array generations, and assay platforms. The prognostic value was independent of existing clinical markers, regardless of clinical endpoints.

CONCLUSIONS

A robust DCE-MRI-associated gene classifier has been constructed that may be used to achieve an early indication of patients' risk of hypoxia-related chemoradiotherapy failure. Clin Cancer Res; 22(16); 4067-76. ©2016 AACR.