Comparison of outcomes for MR-guided versus CT-guided high-dose-rate interstitial brachytherapy in women with locally advanced carcinoma of the cervix

The safety and efficacy of volumetric modulated Arc therapy combined with computer tomography-guided adaptive brachytherapy for locally advanced cervical cancer: a single institution experience

BACKGROUND

Volumetric modulated arc therapy (VMAT) is a novel form of IMRT, which can deliver more accurate dose distribution and shorten treatment time. Compared to MRI-guided adaptive brachytherapy, which is recommended as gold standard imaging for cervical cancer contours, CT-guided adaptive brachytherapy (CTGAB) is more available, more widespread, and more affordable in many centers. This study aims to retrospectively analyze the efficacy and the safety of VMAT combined with CTGAB for patients with locally advanced cervical cancer.

METHODS AND MATERIALS

This study retrospectively analyzed 102 patients with locally advanced cervical cancer who underwent VMAT and CTGAB. Clinical outcomes including local control (LC), overall survival (OS) and progression-free survival (PFS), tumor response to treatment evaluated by the Response Evaluation Criteria in Solid Tumors (RECIST) (version 1.1), and toxicities including gastrointestinal toxicity, urinary toxicity and hematologic toxicity evaluated by the Common Terminology Criteria for Adverse Events (CTCAE) (version 5.0) were analyzed. The Kaplan-Meier method was used to calculate LC, OS, and PFS.

RESULTS

Median follow-up time was 19 months. Complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD) occurred in 68 (66.7%), 24 (23.5%), 4 (3.92%), and 6 (5.88%), respectively. The 2-year and 3-year OS were 89.6% and 83%, respectively. The 2-year and 3-year PFS were 84.2% and 74.3%, respectively. The 2-year and 3-year LC were 90.1% and 79.3%, respectively. The average cumulative D2cm3 in the rectum, the bladder, the colon, and the small intestine were 78.07 (SD: 0.46) Gy, 93.20 (SD: 0.63) Gy, 63.55 (SD: 1.03) Gy and 61.07 (SD: 0.75) Gy, respectively. The average cumulative D90% of the high-risk clinical target volume (HR-CTV) was 92.26 (SD: 0.35) Gy. Grade ≥ 3 gastrointestinal and urinary toxicities occurred in 4.9% and 0.98%, respectively. 1.96% of patients were observed grade ≥ 4 gastrointestinal toxicities and none of the patients observed grade ≥ 4 urinary toxicities.

CONCLUSION

VMAT combined with CTGAB for locally advanced cervical cancer was an effective and safe treatment method, which showed satisfactory LC, OS, PFS, and acceptable toxicities.

Integration of Ultrasound in Image-Guided Adaptive Brachytherapy in Cancer of the Uterine Cervix

Cervical cancer continues to be a public health concern, as it remains the second most common cancer despite screening programs. It is the third most common cause of cancer-related death for women, and the majority of cases happen in developing nations. The standard treatment for locally advanced cervical cancer involves the use of external beam radiation therapy, along with concurrent chemotherapy, followed by an image-guided adaptive brachytherapy (IGABT) boost. The five-year relative survival rate for European women diagnosed with cervical cancer was 62% between 2000 and 2007. Updated cervical cancer treatment guidelines based on IGABT have been developed by the Gynecological working group, which is composed of the Group Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology. The therapeutic strategy makes use of three-dimensional imaging, which can be tailored to the target volume and at-risk organs through the use of computed tomography or magnetic resonance imaging. Under anaesthesia, the brachytherapy implantation is carried out. Ultrasonography is utilised to assess the depth of the uterine cavity and to facilitate the dilation of the uterine canal during the application insertion. In this study, we examine data from the international literature regarding the application of ultrasound in cervical cancer brachytherapy.

High-Dose-Rate Three-Dimensional Image-Guided Adaptive Brachytherapy (3D IGABT) for Locally Advanced Cervical Cancer (LACC): A Narrative Review on Imaging Modality and Clinical Evidence

Background: Brachytherapy (BT) is a critical component of radiotherapy for locally advanced cervical cancer (LACC), and it has rapidly developed in recent decades. Since the advent of three-dimensional image-guided adaptive brachytherapy (3D-IGABT), magnetic resonance imaging (MRI) has emerged as the primary modality for image guidance. Meanwhile, other imaging modalities, such as computed tomography, 18F-fluorodeoxyglucose positron emission tomography, ultrasound, and their combinations have also been widely studied. Materials and methods: We reviewed studies on different imaging modalities utilized for target delineation and planning. Emerging techniques in IGABT like real-time image guidance and 3D printing were also included. We summarized research on their feasibility and concentrated on their clinical outcomes. Results: MRI-guided BT was the gold standard, and CT-guided BT was the most widely applied. Other modalities have shown feasibility and promising efficacy in dosimetry studies and preliminary outcomes. The longer-term clinical outcomes associated with these approaches require further elucidation. Conclusions: As 3D-IGABT was validated by promising clinical outcomes, the future of BT for LACC is expected to progress toward the refinement of more effective image-guided procedures. Moreover, achieving operational consensus and driving technological advancements to mitigate the inherent limitations associated with different imaging modes remain essential.

Retrospective analysis of local recurrence pattern by computed tomography image-guided intracavitary and interstitial brachytherapy for locally advanced cervical cancer in a single Japanese institution

PURPOSE

The purpose of this study was to investigate the treatment results with focus on local control (LC) by computed tomography (CT)-guided intracavity brachytherapy and interstitial brachytherapy (ICBT/ISBT) for locally advanced cervical cancer (LACC).

METHODS AND MATERIALS

Patients with LACC undergoing ICBT/ISBT at least once in our institution between January 2017 and June 2019 were analyzed retrospectively. The primary endpoint was local control (LC), and the secondary endpoints were progression-free survival (PFS), overall survival (OS), and late toxicities. Differences between patient subgroups for prognostic factors in LC, PFS, and OS were analyzed using the log-rank test. The recurrence patterns of LC were also investigated.

RESULTS

Forty-four patients were included in the present study. The median high-risk clinical target volume (HR-CTV) at the initial brachytherapy was 48.2 cc. The median total dose of HR-CTV D90 (EQD2) was 70.7 Gy. The median followup period was 39.4 months. The 3-year LC, PFS and OS rates in all patients were 88.2%, 56.6%, and 65.4% (95% CI 50.3-78.0%), respectively. Corpus invasion and large HR-CTV (70 cc or more) were significant prognostic factors in LC, PFS, and OS. Marginal recurrences at the fundus of the uterus were detected in 3 of 5 patients in whom local recurrence was observed. Late toxicities of Grade 3 or higher were detected in 3 patients (6.8%).

CONCLUSIONS

Favorable LC was achieved by performing CT-guided ICBT/ISBT for LACC. The brachytherapy strategy for patients with corpus invasion or large HR-CTV may need to be reconsidered.

Change in image-guided planning strategies over time impacts oncologic and survival outcomes for intracavitary cervical cancer brachytherapy

PURPOSE

Intracavitary cervical brachytherapy (BT) has transitioned from a two-dimensional nonvolumetric (NV) dosimetry system to three-dimensional computed tomography (CT) and/or magnetic resonance imaging (MRI)-based planning techniques. The purpose of this study is to retrospectively evaluate the relative improvements in image-guided planning strategies over time with regards to dosimetry, survival, and toxicity.

METHODS AND MATERIALS

A single site retrospective review of 95 locally advanced cervical cancer patients treated with concurrent chemoradiation and high dose rate BT from 2009 to 2016 were divided into three BT planning groups: point-A based NV dosimetry using CT imaging (n = 37), CT-based volumetric dosimetry (n = 33), and MRI-based volumetric dosimetry (n = 25). Overall survival (OS), progression free survival (PFS), and pelvic control (PC) at 5 years were plotted using Kaplan-Meier curves. Univariate and multivariate (MVA) cox proportional-hazards models calculated hazard-ratios (HZ). Finally, acute and late grade 3-4 toxicities were compared between the cohorts.

RESULTS

Both MRI and CT had significantly less D2cc to bowel (p < 0.001) and sigmoid (p < 0.001) compared to NV-based planning. On MVA, age (<60 vs. ≥60 years) was significant for worse 5-year OS (HZ: 2.48) and PC (HZ: 5.25). MRI, with NV as the reference, had significantly improved 5-year OS (HZ: 0.26), PFS (HZ: 0.34) and PC (HZ: 0.16). There was no significant difference in grade ≥3 toxicities between the cohorts.

CONCLUSIONS

CT and MRI-based 3D planning had significantly less D2cc to bowel and sigmoid. MRI-based planning had significant improvement in 5-year OS, PFS, and LC compared to NV on MVA.

Clinical Outcomes of MRI-Guided Adaptive Brachytherapy for Each Fraction in Locally Advanced Cervical Cancer: A Single Institution Experience

Purpose

This study aims to evaluate clinical outcomes of MRI-guided adaptive brachytherapy (MR-IGABT) for each brachytherapy fraction in patients with locally advanced cervical cancer (LACC).

Methods and Materials

A retrospective analysis was performed on 97 consecutive patients with LACC treated with 44.0–50.4 Gy external beam radiotherapy (EBRT) ± concurrent platinum-containing chemotherapy followed by 4 × 7 Gy MR-IGABT between September 2014 and April 2019. Intracavitary (IC)/interstitial (IS)/hybrid intracavitary and interstitial (IC/IS) brachytherapy was used in MR-IGABT. Brachytherapy planning and dose reporting followed the GEC-ESTRO recommendations. Clinical outcomes including overall survival (OS), cancer-specific survival (CSS), progression-free survival (PFS), local control (LC), and treatment-related toxicity evaluated by the RTOG criteria were analyzed. Kaplan–Meier and univariable and multivariable Cox regression analyses were used to analyze the prognostic factor.

Results

Median follow-up was 21.1 months. Median dose to 90% (D₉₀) of the high-risk clinical target volume (HR-CTV) was 91.7 Gy (range 76.7~107.2 Gy). Two-year OS, CSS, PFS, and LC were 83.5%, 84.1%, 71.1%, and 94.8%, respectively. Four patients (4.1%) suffered from grade 3 late gastrointestinal radiation toxicity, and no other grade 3 or greater radiation toxicity occurred. Initial HR-CTV was an independent factor of OS (p = 0.001, HR = 1.018/cm³), PFS (p = 0.012, HR = 1.012/cm³), and LC (p = 0.011, HR = 1.028/cm³). The HR-CTV D₉₀ (p = 0.044, HR = 0.923/Gy) was an independent factor of PFS. Age was an independent factor of LC (p = 0.010, HR = 1.111/year).

Conclusion

For patients with LACC, MR-IGABT was effective and safe. It showed favorable LC, OS, and minimal toxicity. Moreover, initial HR-CTV, HR-CTV D₉₀, and age were significant prognostic factors.

Dosimetric comparison of high-dose rate cervix brachytherapy with and without interstitial needles and the impact on target volume coverage, and organ at risk constraints

INTRODUCTION

The aim of this audit was to compare the data from the Wellington Blood and Cancer Centre (WBCC) with international reported experience by quantifying the dosimetric impact of interstitial needles on target coverage and organ at risk (OAR) doses.

METHODS

All patients identified as having had interstitial needles as part of their treatment out of a cohort of 120 radically treated cervical cancer patients between 2013 and 2019 were included. Each patient acted as their own control with two treatment plans optimised for each fraction; the clinically treated plan and a re-optimisation without the use of interstitial needles. Plan optimisation was completed according to the departmental protocol and cumulative equivalent doses for 2 Gy fractions (EQD2) were calculated.

RESULTS

Eighteen patients were suitable for evaluation. A total of 52 insertions with interstitial needles were performed, of the 148 needles inserted, 119 (80.4%) were loaded. HRCTV D90% coverage mean was EQD2 5.4 Gy (0.5-10.6 Gy) higher for the course containing loaded interstitial needles, while no significant change was observed with regards to OAR doses. This improved coverage is in line with international standards which report 4.4-9.0 Gy.

CONCLUSION

WBCC's early experience of interstitial cervix brachytherapy has shown our target coverage improvements meet previously published international standards and confirms the value of this technique. This audit supports ongoing use of interstitial needles at the WBCC.

Radiotherapy of cervical cancer

External beam radiotherapy and brachytherapy are major treatments in the management of cervical cancer. For early-stage tumours with local risk factors, brachytherapy is a preoperative option. Postoperative radiotherapy is indicated according to histopathological criteria. For advanced local tumours, chemoradiation is the standard treatment, followed by brachytherapy boost, which is not optional. We present the update of the recommendations of the French Society of Oncological Radiotherapy on the indications and techniques for external beam radiotherapy and brachytherapy for cervical cancer.

An endovaginal MRI array with a forward-looking coil for advanced gynecological cancer brachytherapy procedures: Design and initial results

PURPOSE

To develop an endovaginal MRI array that provides signal enhancement forward into the posterior parametrium and sideways into the vaginal wall, accelerating multiple-contrast detection of residual tumors that survive external beam radiation. The array's enclosure should form an obturator for cervical cancer brachytherapy, allowing integration with MRI-guided catheter placement, CT, and interstitial radiation dose delivery.

METHODS

The endovaginal array consisted of forward-looking and sideways-looking components. The forward-looking element imaged the cervix and posterior endometrium, and the sideways-looking elements imaged the vaginal wall. Electromagnetic simulation was performed to optimize the geometry of a forward-looking coil placed on a conductive-metallic substrate, extending the forward penetration above the coil's tip. Thereafter, an endovaginal array with one forward-looking coil and four sideways-looking elements was constructed and tested at 1.5 Tesla in saline and gel phantoms, and three sexually mature swine. Each coil's tuning, matching, and decoupling were optimized theoretically, implemented with electronic circuits, and validated with network-analyzer measurements. The array enclosure emulates a conventional brachytherapy obturator, allowing use of the internal imaging array together with tandem coils and interstitial catheters, as well as use of the enclosure alone during CT and radiation delivery. To evaluate the receive magnetic field ( B 1 - ) spatial profile, the endovaginal array's specific absorption-rate (SAR) distribution was simulated inside a gel ASTM phantom to determine extreme heating locations in advance of a heating test. Heating tests were then performed during high SAR imaging in a gel phantom at the predetermined locations, testing compliance with MRI safety standards. To assess array imaging performance, signal-to-noise-ratios (SNR) were calculated in a saline phantom and in vivo. Swine images were acquired with the endovaginal array combined with the scanner's body and spine arrays.

RESULTS

Simulated B 1 - profiles for the forward-looking lobe pattern, obtained while varying several geometric parameters, disclosed that a forward-looking coil placed on a metal-backed substrate could double the effective forward penetration from approximately 25 to ∼40 mm. An endovaginal array, enclosed in an obturator enclosure was then constructed, with all coils tuned, matched, and decoupled. The ASTM gel-phantom SAR test showed that peak local SAR was 1.2 W/kg in the forward-looking coil and 0.3 W/kg in the sideways-looking elements, well within ASTM/FDA/IEC guidelines. A 15-min 4 W/kg average SAR imaging experiment resulted in less than 2^o C temperature increase, also within ASTM/FDA/IEC heating limits. In a saline phantom, the forward-looking coil and sideways-looking array's SNR was four to eight times, over a 20-30 mm field-of-view (FOV), and five to eight times, over a 15-25 mm FOV, relative to the spine array's SNR, respectively. In three sexually mature swine, the forward-looking coil provided a 5 + 0.2 SNR enhancement factor within the cervix and posterior endometrium, and the sideways-looking array provided a 4 + 0.2 SNR gain factor in the vaginal wall, relative to the Siemens spine array, demonstrating that the array could significantly reduce imaging time.

CONCLUSIONS

Higher SNR gynecological imaging is supported by forward-looking and sideways-looking coils. A forward-looking endovaginal coil for cervix and parametrium imaging was built with optimized metal backing. Array placement within an obturator enhanced integration with the brachytherapy procedure and accelerated imaging for detecting postexternal-beam residual tumors.

Radiomic signature of the FOWARC trial predicts pathological response to neoadjuvant treatment in rectal cancer

Background

We aimed to develop a radiomic model based on pre-treatment computed tomography (CT) to predict the pathological complete response (pCR) in patients with rectal cancer after neoadjuvant treatment and tried to integrate our model with magnetic resonance imaging (MRI)-based radiomic signature.

Methods

This was a secondary analysis of the FOWARC randomized controlled trial. Radiomic features were extracted from pre-treatment portal venous-phase contrast-enhanced CT images of 177 patients with rectal cancer. Patients were randomly allocated to the primary and validation cohort. The least absolute shrinkage and selection operator regression was applied to select predictive features to build a radiomic signature for pCR prediction (rad-score). This CT-based rad-score was integrated with clinicopathological variables using gradient boosting machine (GBM) or MRI-based rad-score to construct comprehensive models for pCR prediction. The performance of CT-based model was evaluated and compared by receiver operator characteristic (ROC) curve analysis. The LR (likelihood ratio) test and AIC (Akaike information criterion) were applied to compare CT-based rad-score, MRI-based rad-score and the combined rad-score.

Results

We developed a CT-based rad-score for pCR prediction and a gradient boosting machine (GBM) model was built after clinicopathological variables were incorporated, with improved AUCs of 0.997 [95% CI 0.990–1.000] and 0.822 [95% CI 0.649–0.995] in the primary and validation cohort, respectively. Moreover, we constructed a combined model of CT- and MRI-based radiomic signatures that achieve better AIC (75.49 vs. 81.34 vs.82.39) than CT-based rad-score (P = 0.005) and MRI-based rad-score (P = 0.003) alone did.

Conclusions

The CT-based radiomic models we constructed may provide a useful and reliable tool to predict pCR after neoadjuvant treatment, identify patients that are appropriate for a 'watch and wait' approach, and thus avoid overtreatment. Moreover, the CT-based radiomic signature may add predictive value to the MRI-based models for clinical decision making.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-021-02919-x.

Dosimetric feasibility of computed tomography-based image-guided brachytherapy in locally advanced cervical cancer: a Japanese prospective multi-institutional study

The aim of this study was to assess the feasibility of planning dose-volume histogram (DVH) parameters in computed tomography-based 3D image-guided brachytherapy for locally advanced cervical cancer. In a prospective multi-institutional study, 60 patients with stage IIA2-IVA cervical cancer from eight institutions were treated with external beam radiotherapy using central shielding and intracavitary or hybrid (combined intracavitary/interstitial) brachytherapy (HBT). The dose constraints were set as a cumulative linear quadratic equivalent dose (EQD2) of at least 60 Gy for high-risk clinical target volume (HR-CTV) D90, D2cc ≤ 75 Gy for rectum, D2cc ≤ 90 Gy for bladder and D2cc ≤ 75 Gy for sigmoid. The median HR-CTV D90 was 70.0 Gy (range, 62.8-83.7 Gy) in EQD2. The median D2cc of rectum, bladder and sigmoid was 57.1 Gy (range, 39.8-72.1 Gy), 68.9 Gy (range, 46.5-84.9 Gy) and 57.2 Gy (range, 39.2-71.2 Gy) in EQD2, respectively. In 76 of 233 sessions (33%), 23 patients underwent HBT, and the median number of interstitial needles was 2 (range, 1-5). HBT for a bulky HR-CTV (≥40 cm3) significantly improved the HR-CTV D90 compared with intracavitary brachytherapy alone (P = 0.010). All patients fulfilled the dose constrains for target and at risk organs by undergoing HBT in one-third of sessions. We conclude that the planning DVH parameters used in our protocol are clinically feasible.

Non-anesthetist-administered moderate sedation with midazolam and fentanyl for outpatient MRI-aided hybrid intracavitary and interstitial brachytherapy in cervix cancer: a single-institution experience

Purpose

The aim of the study was to determine the feasibility of interstitial brachytherapy under non-anesthetist-administered moderate sedation, to identify factors influencing the insertion, and the total procedural time.

Material and methods

A total of 47 insertions with hybrid intracavitary and interstitial applicators were performed in 23 patients from March 2017 to March 2020. Moderate sedation was achieved with intravenous midazolam and fentanyl administered by non-anesthetist. Insertion time and procedural time was recorded. Univariate and multivariate analysis were performed to evaluate the impact of different factors on insertion and procedural time.

Results

A total of 238 needles (range, 2-8 per insertion) were implanted, with an average insertion depth of 30 mm (range, 20-40 mm). The mean doses for midazolam and fentanyl were 3 mg (standard deviation [SD] = 1) and 53.3 mcg (SD = 23.9) per insertion, respectively. The median insertion time was 30 minutes (interquartile range [IQR] = 22-40), and the median total procedural time was 4.3 hours (IQR = 3.6-5.2). First time insertion, insertions performed before 2019, and higher midazolam dose were associated with significantly longer insertion time, whereas longer insertion time, MRI-based planning, and insertions performed before 2019 were associated with significantly longer total procedural time.

Conclusions

Outpatient interstitial brachytherapy with non-anesthetist-administered sedation is achievable and well-tolerated. This method may significantly lessen the burden on hospital resources and has the potential to be cost-effective.

Radiotherapy for cervical cancer: Chilean consensus of the Society of Radiation Oncology

Background

Cervical cancer is a public health problem in Latin America. Radiotherapy plays a fundamental role both as definitive or adjuvant treatment. There are important intra and inter-country differences regarding access and availability of radiotherapy facilities in this region. The aim of a study was to standardize the basic clinical and technical criteria for the radiation treatment of patients with CC in Chile and provide a guide for Latin American Radiation Oncologists.

Materials and methods

Forty-one expert radiation oncologists from the Chilean Radiation Oncology Society made a consensus using the Delphi methodology.

Results

There was a high degree of agreement for each of the recommendations. Those with the lowest percentage were related to the definition of the conformal 3D technique as the standard for definitive external radiotherapy (81%) and the criteria for extended nodal irradiation (85%).

Conclusions

These recommendations present an updated guide for radiotherapy treatment of patients with cervical cancer for Latin America. Those should be implemented according to local resources of each institution.

Hybrid tandem and ovoids brachytherapy in locally advanced cervical cancer: impact of dose and tumor volume metrics on outcomes

PURPOSE

To report the impact of dose and tumor volume metrics at brachytherapy on outcomes for locally advanced cervical cancer treated with tandem and ovoids intracavitary/interstitial brachytherapy.

MATERIAL AND METHODS

FIGO stage IB1-IIIB locally advanced cervical cancer treated with intracavitary/interstitial brachytherapy via a tandem and ovoids hybrid applicator were analyzed. Median high-risk clinical target volume (HR-CTV), rate of tumor volume reduction, EQD2 D90, organ at risk doses, and outcomes were recorded. Univariable and multivariable Cox regression was applied for survival analysis, and logistic regression was used for toxicity analysis.

RESULTS

Seventy-one patients were identified. Median follow-up was 24.9 months, with a 2-year local control of 83.6%, loco-regional control of 72.0%, and overall survival of 88.6%. Median HR-CTV D90 was 87.4 Gy (IQR = 85.7-90.2). Median HR-CTV D90 > 90 Gy10 showed a trend toward improved local control (LC) (p = 0.19). Median HR-CTV was 37.9 cm3, and median V100 was 86.5%. A median HR-CTV of ≥ 40 cm3 demonstrated worse loco-regional control (LRC) (p = 0.018) and progression-free survival (p = 0.021). Two-year LC and LRC for stage IIB patients with a median HR-CTV < 40 cm3 were significantly improved as compared to ≥ 40 cm3 at 100% and 71.8%, respectively (p = 0.019) and 100% and 56.5%, respectively (p = 0.001). However, this trend was not statistically significant for stage IIIB patients. Higher percent per day reduction in HR-CTV during brachytherapy showed improved LRC (p = 0.045). Four percent of patients experienced acute grade 3 genitourinary toxicity, 1% late grade 3 genitourinary and 1% late grade 3 gastrointestinal toxicity.

CONCLUSIONS

Tandem and ovoids intracavitary/interstitial brachytherapy provides satisfactory outcomes with modest toxicity. Higher HR-CTV D90 coverage demonstrated a trend toward improved tumor control. Tumor volume based on median HR-CTV ≥ 40 cm3 at brachytherapy was prognostic for poor outcomes, even within initial FIGO stage groups warranting caution.

Three-dimensional image-guided combined intracavitary and interstitial high-dose-rate brachytherapy in cervical cancer: A systematic review

PURPOSE

To evaluate the local control and toxicities of three-dimensional image-guided combined intracavitary and interstitial (IC/IS) high-dose-rate brachytherapy (BT) in cervical cancer through a systematic review.

METHODS AND MATERIALS

A systematic review of relevant studies was performed through the PubMed, Web of Science, and Cochrane Library databases through May 10, 2020. Articles reporting on IC/IS technology, volumetric doses to high-risk clinical target volume (HR-CTV) and organs at risk (OARs), tumor control and/or treatment-related side effects were identified. The key information, including the type of applicator, implantation technology, characteristics of implantation, volumetric doses, tumor control, and/or treatment-related side effects, was extracted. A probit model analysis between HR-CTV D90 and tumor local control was performed.

RESULTS

Twelve studies encompassing 520 patients were included in the probit model between HR-CTV D90 and the local control rate. The probit model showed a significant relationship between the HR-CTV D90 value and the local control probability, p = 0.003. The prescribed dose of 85 Gy_EQD2,10 would in theory warrant an 87.4% (95% confidence interval 82.5%-90.5%) local control rate.

CONCLUSION

IC/IS BT is an appropriate method to achieve a high therapeutic ratio for tumors with large volumes or poor responses after external irradiation in cervical cancer. The probit model showed that the dose escalation of HR-CTV D90 was helpful to improve the local tumor control rate.

Aiming for 100% Local Control in Locally Advanced Cervical Cancer: The Role of Complex Brachytherapy Applicators and Intraprocedural Imaging

The use of brachytherapy for the treatment of gynecologic malignancies, particularly cervical cancer, has a long and rich history that is nearly as long as the history of radiation oncology itself. From the first gynecologic brachytherapy treatments in the early 20th century to the modern era, significant transformation has occurred driven largely by advancements in technology. The development of high-dose rate sources, remote afterloaders, novel applicators, and 3-dimensional image guidance has led to improved local control, and thus improved survival, solidifying the role of brachytherapy as an integral component in the treatment of locally advanced cervical cancer. Current research efforts examining novel magnetic resonance imaging sequences, active magnetic resonance tracking, and the application of hydrogel aim to further improve local control and reduce treatment toxicity.

Comparison of accuracy and long-term prognosis between computed tomography-based and magnetic resonance imaging-based brachytherapy for cervical cancer: A meta-analysis

High-dose-rate brachytherapy (HDR-BT) has been shown to play an important role in the treatment of cervical cancer patients. The aim of this systematic review and meta-analysis was to compare the dose parameters and long-term effects of MRI-based, CT-based and hybrid imaging (MRI/CT)-based volumetric planning. A systematic search was conducted to identify the clinical studies of BT treatment on cervical cancer patients. After study selection, a total of 13 clinical studies were enrolled for further analysis. No obvious differences were observed among the treatment parameters and the patients included. In detail, no significant difference was observed among these three techniques of volumetric planning in the parameters of high-risk clinical target volume (HR-CTV), total dose of D90 or mean fraction dose of D90. Meanwhile, MRI-based planning was superior to CT-based treatment in the total dose D2cc to organs at risk (OAR) for the bladder, rectum and sigmoid. Furthermore, no significant difference was observed among MRI-, CT- or hybrid-based treatments with the mean fraction dose D2cc to OAR for the bladder, rectum or sigmoid. In conclusion, MRI provides good anatomical delineation of the relevant HR-CTV and OAR, and performed better in the analyses of dose parameters compared with CT. At least one MR image is required to assess the tumour extension, with clinical findings and MRI information facilitating much more accurate CT-based contouring.

Is there a role for carbon therapy in the treatment of gynecological carcinomas? A systematic review

This Systematic Review summarizes the literatures of clinical trials on the efficacy and safety of carbon ion therapy for gynecological carcinomas. The protocol is detailed in the online PROSPERO database, registration no. CRD42019121424, and a final set of eight studies were included. In the treatment of cervical carcinomas, both carbon ion therapy alone and carbon ion therapy concurrent chemotherapy have presented good efficacy. Besides, the efficacy of inoperable endometrial carcinomas and gynecological melanoma are similar to that of surgical treatment. In terms of safety, gastrointestinal and genitourinary toxicities are low and could be controlled by limiting the volume and dose of intestinal tract and bladder. Carbon ion radiotherapy could be considered a safe, effective and feasible therapy for gynecological carcinomas.

Clinical Outcomes of Volumetric Modulated Arc Therapy Following Intracavitary/Interstitial Brachytherapy in Cervical Cancer: A Single Institution Retrospective Experience

Purpose: To evaluate treatment outcomes and toxicity in patients with cervical cancer (CC) treated with volumetric modulated arc therapy (VMAT), followed by three-dimensional high-dose-rate intracavity combined with interstitial brachytherapy (IC/IS BT) compared with intensity-modulated radiation therapy (IMRT) treatment.

Materials and Methods: A total of 398 patients with stage IA–IVB CC treated with definitive radiotherapy with or without chemotherapy were retrospectively analyzed (331 VMAT and 67 IMRT). A total prescription dose of 45–50 Gy was delivered to pelvic field with VMAT/IMRT in 25/28 fractions, with five fractions per week. Every patient further received IC/IS BT for four to six 6.0-Gy fractions. Local control (LC), disease-free survival (DFS), overall survival (OS), and distant metastasis-free survival (DMFS) rates were calculated. Acute hematotoxicity and late toxicity were recorded.

Results: The median follow-up period was 25.47 (range, 0.93–58.93) months for the VMAT and 35.07 (4.8–90.37) months for IMRT. The 3-year OS, DFS, LC, and DMFS rate were 80.5, 65.4, 88.7, and 78.1% in VMAT group, and 76.2, 76.4, 83.1, and 86.1% in the IMRT group, respectively. No significant differences were found between VMAT and IMRT groups for OS, DFS, LC, and DMFS rate. However, patients in the VMAT group had lower incidence of chronic enterocolitis complication (26.6 vs. 38.8%, p = 0.004). In addition, a total of 3 (0.9%) patients developed grade 3 chronic cystitis, and 7 (2.1%) patients developed grade 3 or greater chronic enterocolitis in VMAT group.

Conclusion: VMAT combined with IC/IS BT can result in satisfactory curative outcomes and low incidences of late radiation enterocolitis and cystitis in CC treatment.

Fully automatic catheter segmentation in MRI with 3D convolutional neural networks: application to MRI-guided gynecologic brachytherapy

External-beam radiotherapy followed by high dose rate (HDR) brachytherapy is the standard-of-care for treating gynecologic cancers. The enhanced soft-tissue contrast provided by magnetic resonance imaging (MRI) makes it a valuable imaging modality for diagnosing and treating these cancers. However, in contrast to computed tomography (CT) imaging, the appearance of the brachytherapy catheters, through which radiation sources are inserted to reach the cancerous tissue later on, is often variable across images. This paper reports, for the first time, a new deep-learning-based method for fully automatic segmentation of multiple closely spaced brachytherapy catheters in intraoperative MRI. Represented in the data are 50 gynecologic cancer patients treated by MRI-guided HDR brachytherapy. For each patient, a single intraoperative MRI was used. 826 catheters in the images were manually segmented by an expert radiation physicist who is also a trained radiation oncologist. The number of catheters in a patient ranged between 10 and 35. A deep 3D convolutional neural network (CNN) model was developed and trained. In order to make the learning process more robust, the network was trained 5 times, each time using a different combination of shown patients. Finally, each test case was processed by the five networks and the final segmentation was generated by voting on the obtained five candidate segmentations. 4-fold validation was executed and all the patients were segmented. An average distance error of 2.0  ±  3.4 mm was achieved. False positive and false negative catheters were 6.7% and 1.5% respectively. Average Dice score was equal to 0.60  ±  0.17. The algorithm is available for use in the open source software platform 3D Slicer allowing for wide scale testing and research discussion. In conclusion, to the best of our knowledge, fully automatic segmentation of multiple closely spaced catheters from intraoperative MR images was achieved for the first time in gynecological brachytherapy.

Brachytherapy: A critical component of primary radiation therapy for cervical cancer: From the Society of Gynecologic Oncology (SGO) and the American Brachytherapy Society (ABS)

Brachytherapy is well-established as an integral component in the standard of care for treatment of patients receiving primary radiotherapy for cervical cancer. A decline in brachytherapy has been associated with negative impacts on survival in the era of modern EBRT techniques. Conformal external beam therapies such intensity modulated radiation therapy (IMRT) or stereotactic body radiation therapy (SBRT) should not be used as alternatives to brachytherapy in patients undergoing primary curative-intent radiation therapy for cervical cancer. Computed tomography or magnetic resonance image-guided adaptive brachytherapy is evolving as the preferred brachytherapy method. With careful care coordination EBRT and brachytherapy can be successfully delivered at different treatment centers without compromising treatment time and outcome in areas where access to brachytherapy maybe limited.

Review of strategies for MRI based reconstruction of endocavitary and interstitial applicators in brachytherapy of cervical cancer

Brachytherapy plays an essential role in the curative intent management of locally advanced cervical cancer. The introduction of the magnetic resonance (MR) as a preferred image modality and the development of new type of applicators with interstitial components have further improved its benefits. The aim of this work is to review the current status of one important aspect in the cervix cancer brachytherapy procedure, namely catheter reconstruction. MR compatible intracavitary and interstitial applicators are described. Considerations about the use of MR imaging (MRI) regarding appropriate strategies for applicator reconstruction, technical requirements, MR sequences, patient preparation and applicator commissioning are included. It is recommendable to perform the reconstruction process in the same image study employed by the physician for contouring, that is, T2 weighted (T2W) sequences. Nevertheless, a clear identification of the source path inside the catheters and the applicators is a challenge when using exclusively T2W sequences. For the intracavitary component of the implant, sometimes the catheters may be filled with some substance that produces a high intensity signal on MRI. However, this strategy is not feasible for plastic tubes or titanium needles, which, moreover, induce magnetic susceptibility artifacts. In these situations, the use of applicator libraries available in the treatment planning system (TPS) is useful, since they not only include accurate geometrical models of the intracavitary applicators, but also recent developments have made possible the implementation of the interstitial component. Another strategy to improve the reconstruction process is based on the incorporation of MR markers, such as small pellets, to be used as anchor points. Many institutions employ computed tomography (CT) as a supporting image modality. The registration of CT and MR image sets should be carefully performed, and its uncertainty previously assessed. Besides, an important research work is being carried out regarding the use of ultrasound and electromagnetic tracking technologies.

Development and preclinical testing of a novel biodegradable hydrogel vaginal packing technology for gynecologic high-dose-rate brachytherapy

Purpose

We evaluated the performance of a novel hydrogel-based strategy developed for clinical use as vaginal packing using phantoms and cadavers, and to compare the hydrogel to gauze and balloon packing.

Material and methods

The biocompatible hydrogel is based on a thiol-Michael addition reaction, with delivery of reagents into the vaginal cavity using a custom-made system. Soft-cured cadavers were used for soft tissue-like mechanical properties. Two cadavers with intact uteri had magnetic resonance imaging (MRI) compatible with tandem and ovoids. For one cadaver, the temperature of the vaginal canal was measured before hydrogel application, during polymerization, and after hydrogel removal. The hydrogel packing and applicator was kept in a second cadaver, which was imaged using computed tomography (CT) and MRI. The hydrogel packing and imaging was repeated for an open multichannel MRI compatible, titanium-based vaginal cylinder placed in a post-hysterectomy cadaver.

Results

The gel reaction occurred within 90 seconds, indicating polymerization at clinical quantities with a 5°C increase in vaginal temperature. CT and MRI imaging identified the hydrogel readily and showed a conformance to anatomy with few air pockets. The entire hydrogel packing was readily retrieved upon completion of imaging.

Conclusions

The novel strategy for polyethylene glycol (PEG)-based hydrogel intra-vaginal packing was able to rapidly polymerize in human cadavers with minimal heat production. Delivery was efficient and able to fill the contours of the vaginal cavity and displace tissue away from the applicator axis. The hydrogel has favorable imaging characteristics on CT and MRI, and shows a potential for clinical use, warranting additional studies for the use in humans.

Predicting the necessity of adding catheters to intracavitary brachytherapy for women undergoing definitive chemoradiation for locally advanced cervical cancer

PURPOSE

To identify if baseline patient or magnetic resonance imaging (MRI) features can predict which women are at risk for inadequate tumor coverage with only intracavitary tandem and ovoid (T + O) brachytherapy and to correlate tumor coverage with clinical outcomes.

METHODS AND MATERIALS

We performed a retrospective study of 50 women with cervical cancer treated with chemoradiation at a single institution between January 2014 and December 2015. All patients had a 3T-MRI performed at baseline (MRI1) and at the completion of external beam radiation therapy (MRI2). Gross tumor volume initial (GTV-T_init) was measured on MRI1 and high-risk clinical tissue volume (CTV_HR) on MRI2. CTV_HR extending beyond point A was classified as too large for adequate coverage with T + O and requiring interstitial needles. Multivariate analysis was performed to determine predictive factors of inadequate coverage. Kaplan-Meier and Cox Regression were performed to correlate inadequate coverage with outcomes.

RESULTS

Mean patient age was 49.2 ± 13.2 years, and 84% had Federation of Gynecology and Obstetrics IIB/IIIB disease. Forty-two percent of women were estimated to have inadequate tumor coverage with T + O brachytherapy. The GTV-T_init volume and dimensions (superior-inferior, left-right, anterior-posterior) on MRI1 were all important predictive factors of inadequate coverage on multivariate analysis. Receiver operating characteristics curves identified optimal thresholds of superior-inferior ≥ 4.5 cm (area under the curve [AUC] = 0.718), left-right ≥ 4.5 cm (AUC = 0.745), anterior-posterior ≥ 5.0 cm (AUC = 0.767), and GTV-T_init ≥ 85 cm³ (AUC = 0.842). Patients with inadequate coverage had worse clinical outcomes.

CONCLUSIONS

Baseline MRI tumor size may predict inadequate CTV_HR coverage at the time of brachytherapy (i.e., the need for interstitial needles). This may help identify a subset of women requiring early referral to adequately resourced centers to improve clinical outcomes.

Integration of MRI target delineation into rapid workflow cervical cancer brachytherapy: Impact on clinical outcomes

INTRODUCTION

We evaluated the impact of MRI-based target delineation on toxicity and tumour control after implementation of a protocol to incorporate MRI while minimizing impact on overall procedural time.

METHODS

We retrospectively reviewed outcomes for a cohort of 96 consecutive patients who received intracavitary brachytherapy for cervical cancer at our institution during 2012-2016. Starting in October 2014, an outpatient MRI was obtained for patients after Smit sleeve placement and first insertion to assess concurrent chemoradiotherapy tumour response. Then, for subsequent fractions, the MRI was co-registered by the Smit sleeve to the planning CT for target volume delineation. The primary and secondary outcomes were toxicity and local control, respectively.

RESULTS

Median follow-up for the pre- (n = 50) and post-MRI-based (n = 46) planning groups was 24.6 and 14.7 months, respectively. Median treatment duration for patients before and after MRI implementation was 56 and 58 days (P = 0.052), respectively. Cumulative rectal D2 cc was less for those with MRI-based target delineation (P = 0.005). On multivariable analysis, patients with MRI-based target delineation experienced fewer severe late (CTCAE grade ≥ 3) toxicities (P = 0.025, hazard ratio = 0.25). Local control was 86% and 91% of the pre- and post-MRI groups, respectively (P = 0.959).

CONCLUSIONS

Preliminary findings using this technique, which is applicable to other institutions without in-room MRI availability, are associated with lower radiation prescription doses, lower rectal doses and favourable toxicity rates while maintaining a rapid workflow. Longer follow-up is required to confirm equivalent local control.

Adjuvant therapy after radical trachelectomy for stage I cervical cancer

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Radical trachelectomy is a fertility sparing option for select stage I cervical patients.

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Indications for adjuvant treatment following trachelectomy are based on standard recommendations following hysterectomy.

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Case report outlining specifics of imaged-guided brachytherapy as part of the adjuvant treatment after trachelectomy.

Clinical outcomes of carbon ion radiotherapy with concurrent chemotherapy for locally advanced uterine cervical adenocarcinoma in a phase 1/2 clinical trial (Protocol 1001)

We conducted a phase 1/2 study to evaluate the efficacy and safety of carbon ion radiotherapy (C-ion RT) with concurrent chemotherapy for locally advanced uterine cervical adenocarcinoma. Thirty-three patients were enrolled between April 2010 and March 2014. Treatment consisted of C-ion RT with concurrent weekly cisplatin at a dose of 40 mg/m² . In the phase 1 component, the total dose was escalated from 68.0 Gy (relative biological effectiveness [RBE]) to 74.4 Gy (RBE) to determine the maximum tolerated dose of C-ion RT. In the phase 2 component, the efficacy and safety of C-ion RT with concurrent chemotherapy were evaluated using the dose determined in the phase 1 component. The median follow-up duration was 30 months. Two patients did not receive chemotherapy because of anemia or leukocytopenia immediately prior to commencing treatment; 31 patients were analyzed. None of the patients developed dose-limiting toxicities. The recommended dose (RD) was determined to be 74.4 Gy (RBE). In the phase 2 component, two patients developed Grade 3-4 toxicities in the gastrointestinal tract, due to repeated laser coagulation or peritonitis caused by appendicitis. In the patients treated with the RD, the 2-year local control, progression-free survival, and overall survival rates were 71%, 56%, and 88%, respectively. C-ion RT with concurrent weekly cisplatin was well tolerated in patients with locally advanced uterine cervical adenocarcinoma. Our findings support further investigations into the efficacy of this strategy.

Throwing the dart blind-folded: comparison of computed tomography versus magnetic resonance imaging-guided brachytherapy for cervical cancer with regard to dose received by the 'actual' targets and organs at risk

Purpose

Computed tomography (CT) is inferior to magnetic resonance imaging (MRI) in cervical tumor delineation, but similar in identification of organs at risk (OAR). The trend to over-estimate high-risk and low-risk clinical target volume (HRCTV, IRCTV) on CT can lead to under-estimation of dose received by 90% (D₉₀) of the ‘actual’ CTV. This study aims to evaluate whether CT-guided planning delivers adequate dose to the ‘actual’ targets while spares the OAR similarly.

Material and methods

MRI-guided high-dose-rate image-guided brachytherapy (IGBT) was performed in 11 patients. The pre-brachytherapy CTs were retrospectively contoured to generate CT-guided plans. MRI-based contours (HRCTV_mri, IRCTV_mri, bladder_mri, rectum_mri, and sigmoid_mri) were fused to CT plans for dosimetric comparison with MRI-guided plans. Paired 2-tailed t-test and Wilcoxon signed-rank test were used to analyze data.

Results

63.6% of CT plans achieved the HRCTV_mriD₉₀ constraint (≥ 7.2 Gy in one fraction), compared with 90.9% for MRI plans. > 90% of both modalities achieved the OAR’s constraints (EMBRACE). The percentage of CT and MRI plans that achieved the aims (EMBRACE II) for bladder, rectum, and sigmoid were 36.4% vs. 81.8%, 63.6% vs. 63.6%, and 72.7% vs. 72.7%, respectively. There were no statistically significant differences in HRCTV_mriD₉₀, IRCTV_mriD₉₀, or dose received by the most exposed 2 cm³ (D_2cc) of OAR_mri between the modalities. Excluding the CT plans not achieving HRCTV_mriD₉₀ constraint, there were significant increase in bladder_mriD_2cc, rectum_mriD_2cc, and sigmoid_mriD_2cc, compared with MRI plans (0.9 Gy/Fr, 95% CI 0.2-1.5, p = 0.018; 0.9 Gy/Fr, 95% CI 0.3-1.4, p = 0.009; 0.5 Gy/Fr, 95% CI 0.2-0.9, p = 0.027, respectively).

Conclusions

MRI-based IGBT remains the gold standard. CT planning may compromise HRCTV_mriD₉₀ or increase OAR_mriD_2cc, which could decrease local control or increase treatment toxicity.

Accurate model-based segmentation of gynecologic brachytherapy catheter collections in MRI-images

The gynecological cancer mortality rate, including cervical, ovarian, vaginal and vulvar cancers, is more than 20,000 annually in the US alone. In many countries, including the US, external-beam radiotherapy followed by high dose rate brachytherapy is the standard-of-care. The superior ability of MR to visualize soft tissue has led to an increase in its usage in planning and delivering brachytherapy treatment. A technical challenge associated with the use of MRI imaging for brachytherapy, in contrast to that of CT imaging, is the visualization of catheters that are used to place radiation sources into cancerous tissue. We describe here a precise, accurate method for achieving catheter segmentation and visualization. The algorithm, with the assistance of manually provided tip locations, performs segmentation using image-features, and is guided by a catheter-specific, estimated mechanical model. A final quality control step removes outliers or conflicting catheter trajectories. The mean Hausdorff error on a 54 patient, 760 catheter reference database was 1.49  mm; 51 of the outliers deviated more than two catheter widths (3.4  mm) from the gold standard, corresponding to catheter identification accuracy of 93% in a Syed-Neblett template. In a multi-user simulation experiment for evaluating RMS precision by simulating varying manually-provided superior tip positions, 3σ maximum errors were 2.44  mm. The average segmentation time for a single catheter was 3 s on a standard PC. The segmentation time, accuracy and precision, are promising indicators of the value of this method for clinical translation of MR-guidance in gynecologic brachytherapy and other catheter-based interventional procedures.

Prospective Clinical Implementation of a Novel Magnetic Resonance Tracking Device for Real-Time Brachytherapy Catheter Positioning

PURPOSE

We designed and built dedicated active magnetic resonance (MR)-tracked (MRTR) stylets. We explored the role of MRTR in a prospective clinical trial.

METHODS AND MATERIALS

Eleven gynecologic cancer patients underwent MRTR to rapidly optimize interstitial catheter placement. MRTR catheter tip location and orientation were computed and overlaid on images displayed on in-room monitors at rates of 6 to 16 frames per second. Three modes of actively tracked navigation were analyzed: coarse navigation to the approximate region around the tumor; fine-tuning, bringing the stylets to the desired location; and pullback, with MRTR stylets rapidly withdrawn from within the catheters, providing catheter trajectories for radiation treatment planning (RTP). Catheters with conventional stylets were inserted, forming baseline locations. MRTR stylets were substituted, and catheter navigation was performed by a clinician working inside the MRI bore, using monitor feedback.

RESULTS

Coarse navigation allowed repositioning of the MRTR catheters tips by 16 mm (mean), relative to baseline, in 14 ± 5 s/catheter (mean ± standard deviation [SD]). The fine-tuning mode repositioned the catheter tips by a further 12 mm, in 24 ± 17 s/catheter. Pullback mode provided catheter trajectories with RTP point resolution of ∼1.5 mm, in 1 to 9 s/catheter.

CONCLUSIONS

MRTR-based navigation resulted in rapid and optimal placement of interstitial brachytherapy catheters. Catheters were repositioned compared with the initial insertion without tracking. In pullback mode, catheter trajectories matched computed tomographic precision, enabling their use for RTP.