GEC-ESTRO (ACROP)-ABS-CBG Consensus Brachytherapy Target Definition Guidelines for Recurrent Endometrial and Cervical Tumors in the Vagina

Individual curved-needle interstitial template created using three-dimensional printing for brachytherapy for distal parauterine tumor recurrence

BACKGROUND

Achieving a clinically acceptable dose distribution with commercial vaginal applicators for brachytherapy of recurrent parauterine tumors is challenging. However, the application of three-dimensional (3D) printing technology in brachytherapy has been widely acknowledged and can improve clinical treatment outcomes.

PURPOSE

This study aimed to introduce an individual curved-needle interstitial template (ICIT) created using 3D printing technology for high-dose-rate (HDR) brachytherapy with interstitial treatment to provide a clinically feasible approach to distal parauterine and vaginal cuff tumors. The entire workflow, including the design, optimization, and application, is presented.

METHODS

Ten patients with pelvic cancer recurrence were examined at our center. The vaginal topography was filled with gauze strips soaked in developer solution, and images were obtained using computed tomography (CT) and magnetic resonance imaging (MRI). Curved needle paths were designed, and ICITs were 3D-printed according to the high-risk clinical target volume (HRCTV) and vaginal filling model. The dose and volume histogram parameters of the HRCTV (V100, V200, D90, and D98) and organs at risk (OARs) (D2cc) were recorded.

RESULTS

All patients completed interstitial brachytherapy treatment with the 3D-printed ICIT. One patient experienced vaginal cuff tumor recurrence, and nine patients experienced parametrial tumor recurrence (four on the left and five on the right). We used two to five interstitial needles, and the maximum angle of the curved needle was 40°. No source obstruction events occurred during treatment of these 10 patients. The doses delivered to the targets and OARs of all patients were within the dose limits and based on clinical experience at our center.

CONCLUSION

The ICIT is a treatment option for patients with distal parauterine tumor recurrence. This method addresses the limitations of vaginal intracavitary and standard interstitial applicators. The ICIT has the advantages of biocompatibility, personalization, and magnetic resonance imaging compatibility.

Salvage interstitial brachytherapy for treatment of recurrent endometrial cancers in the vagina: Seven-year single institution experience and review of second recurrence patterns

INTRODUCTION

Interstitial brachytherapy (ISBT) is a known treatment for vaginal recurrence of endometrial cancer. This study reviews a large tertiary institution's ISBT experience and outcomes for vaginal recurrences.

MATERIAL AND METHODS

Patients who underwent salvage ISBT for vaginal recurrence of endometrial cancer from January 1, 2014 to August 31, 2021, were identified. Initial and salvage disease factors and treatments were recorded. Outcomes were calculated including overall survival, local, and distant failure.

RESULTS

Thirty-nine patients were included; thirty received external beam radiotherapy and interstitial brachytherapy (EBRT + ISBT) while 9 received ISBT alone. At initial diagnosis, the ISBT alone group had an older median age, with stage IA-IV disease, frequently receiving adjuvant treatment, compared to the EBRT with ISBT group with mainly stage IA disease who did not. Median follow up was 22 months and median time to recurrence 14 months (16.5 months in EBRT + ISBT group and 14 in the ISBT alone group). Two-year overall survival was 85% for all patients, 85.6% and 83.3%in the EBRT + ISBT and ISBT alone groups, respectively. Local failure was 22.7% for all patients, 16.7% in the EBRT + ISBT group and 11.1% in the ISBT alone group. Median HRCTV D90 (EQD2) was 76.8 Gy in the EBRT + ISBT group, and 57.9 Gy in the ISBT alone group. Late grade 3 or higher toxicity occurred in only 3 patients.

CONCLUSIONS

EBRT + ISBT is an effective treatment for endometrial cancer vaginal recurrence, with acceptable toxicity. ISBT alone is an option for patients with contraindications to or with previous treatment of pelvic radiation.

Proof-of-concept of real-time electromagnetic guidance for gynecologic interstitial catheters in high dose rate brachytherapy

Background and Purpose

The addition of interstitial needles to intracavitary gynecologic (GYN) high dose rate (HDR) brachytherapy has been shown to improve target coverage and organs-at-risk (OAR) sparing. However, no commercial solution allows real-time guidance of interstitial catheter placement. This phantom study aimed to evaluate the feasibility of an electromagnetic (EM) tracking system guidance workflow for GYN HDR brachytherapy treatment in a magnetic resonance imaging (MRI) and real-time transrectal ultrasound (TRUS) fusion scenario.

Materials and Methods

A clinical investigational system combining a treatment planning system and the EM tracking technology was used. The 3D T2 weighted magnetic resonance (MR) image set of a patient treated with intracavitary and interstitial HDR brachytherapy was retrospectively chosen. The MR image set was used to delineate the target and the OARs. A preplan was generated to determine needles positions in advance. The implant was reproduced in a water phantom. A 3D TRUS scan was acquired, and a rigid registration between the MR and the TRUS images was performed.

Results

The accuracy of the EM tracking system was < 1 mm for both the sagittal and the transverse modes of the TRUS probe. Contours that were delineated on the MRI were propagated on the TRUS images after the rigid registration. Needle insertion was successfully guided in real time with the EM tracking system on the TRUS live image using the MRI contours for guidance.

Conclusion

Based on this proof-of-concept, real-time EM-guidance of interstitial needle for GYN HDR brachytherapy appears to be feasible.

Radiation Therapy With or Without Cisplatin for Local Recurrences of Endometrial Cancer: Results From an NRG Oncology/GOG Prospective Randomized Multicenter Clinical Trial

PURPOSE

Pelvic recurrence is a frequent pattern of relapse for women with endometrial cancer. A randomized trial compared progression-free survival (PFS) after treatment with radiation therapy alone as compared with concurrent chemotherapy.

MATERIALS AND METHODS

Between February 2008 and August 2020, 165 patients were randomly assigned 1:1 to receive either radiation treatment alone or a combination of chemotherapy and radiation treatment. The primary objective of this study was to determine whether chemoradiation therapy was more effective than radiation therapy alone at improving PFS.

RESULTS

The majority of patients had low-grade (1 or 2) endometrioid histology (82%) and recurrences confined to the vagina (86%). External beam with either the three-dimensional or intensity modulated radiation treatment technique was followed by a boost delivered with brachytherapy or external beam. Patients randomly assigned to receive chemotherapy were treated with once weekly cisplatin (40 mg/m2). Rates of acute toxicity were higher in patients treated with chemoradiation as compared with radiation treatment alone. Median PFS was longer for patients treated with radiation therapy alone as compared with chemotherapy and radiation (median PFS was not reached for RT v 73 months for chemoradiation, hazard ratio of 1.25 (95% CI, 0.75 to 2.07). At 3 years, 73% of patients treated definitively with radiation and 62% of patients treated with chemoradiation were alive and free of disease progression.

CONCLUSION

Excellent outcomes can be achieved for women with localized recurrences of endometrial cancer when treated with radiation therapy. The addition of chemotherapy does not improve PFS for patients treated with definitive radiation therapy for recurrent endometrial cancer and increases acute toxicity. Patients with low-grade and vaginal recurrences who constituted the majority of those enrolled are best treated with radiation therapy alone.

Dose-response relationship between volume base dose and tumor local control in definitive radiotherapy for vaginal cancer

OBJECTIVE

This study aimed to establish the dose-response relationship between volume base dose and tumor local control for vaginal cancer, including primary vaginal cancer and recurrent gynecologic malignancies in the vagina.

MATERIALS AND METHODS

We identified studies that reported volume base dose and local control by searching the PubMed, the Web of Science, and the Cochrane Library Database through August 12, 2023. The regression analyses were performed using probit model between volume based dose versus clinical outcomes. Subgroup analyses were performed according to stratification: publication year, country, inclusion time of patients, patients with prior radiotherapy, age, primaries or recurrent, tumor size, concurrent chemoradiotherapy proportion, dose rate, image modality for planning, and interstitial proportion.

RESULTS

A total of 879 patients with vaginal cancer were identified from 18 studies. Among them, 293 cases were primary vaginal cancer, 573 cases were recurrent cancer in the vagina, and 13 cases were unknown. The probit model showed a significant relationship between the HR-CTV (or CTV) D90 versus the 2-year and 3-year local control, P values were 0.013 and 0.014, respectively. The D90 corresponding to probabilities of 90% 2-year local control were 79.0 GyEQD2,10 (95% CI: 75.3-96.6 GyEQD2,10).

CONCLUSIONS

A significant dependence of 2-year or 3-year local control on HR-CTV (or CTV) D90 was found. Our research findings encourage further validation of the dose-response relationship of radical radiotherapy for vaginal cancer through protocol based multicenter clinical trials.

Design approach and benefits of the 3D-printed vaginal individualized applicator (VIA)

PURPOSE

Interstitial gynecologic brachytherapy necessitates precise needle placement, requiring time and expertise. We aimed to simplify interstitial procedures and facilitate optimal needle distribution with individualized vaginal templates to guide interstitial needles.

MATERIALS/METHODS

We developed the 3D-printed vaginal individualized applicator (VIA), a cylindrical template containing individualized internal channels that guide interstitial needles to cover the tumor extent. Eight patients underwent VIA only interstitial implants (VIA only), and five intact cervical cases were treated using tandem and customized VIA (VIA + T). Procedure length, number of needles utilized and dosimetric measures were evaluated.

RESULTS

VIA was successfully designed and used clinically for 24 procedures (8 VIA only, 16 VIA + T). Average procedure needle insertion time reduced from 80.9 min for traditional interstitial to 42.9 min for VIA only, approximately 47% shorter with a similar mean high risk CTV volume (28.3 cc VIA only vs. 32.4 cc) and excellent dosimetry with average CTV V100% (94.3% and 94.4%). VIA + T was particularly useful in patients with small vaginal canals and large tumor size. For the five VIA + T patients average tumor size was 68.0cc (range 26.6-143.5 cc). VIA + T procedures were approximately 20% shorter than hybrid procedures with other applicators with mean length of 20.1 min and an average of 6.8 needles (range 3-12).

CONCLUSION

Our novel 3D-printed VIA facilitates gynecologic interstitial brachytherapy by simplifying needle placement, reducing procedure time, and maintaining excellent dosimetry. VIA can be customized for various clinical scenarios, particularly beneficial for large tumors or small vaginal canals.

Quantification of Artifacts and Image Distortions in 1.5 Tesla Magnetic Resonance Images of a Commercial Multi-Channel Vaginal Cylinder Brachytherapy Applicator Set

Background

The BEBIG Portio multi-channel applicator provides better target dose coverage and sparing organs-at-risk compared to a single-channel cylinder. However, artifacts and distortions of Portio in magnetic resonance images (MRI) have not yet been reported.

Objective

We aimed to quantify the artifacts and distortions in its 1.5-Tesla MR images before clinical use.

Material and Methods

In this experimental study, we employed a gelatin-filled phantom to conduct our measurements. T2-weighted (T2W) images were examined for artifacts and distortions. Computed tomography (CT) images were used as a reference to assess image distortions. Artifact severity was measured by recording the full-width-at-half-maximum (FWHM) image pixel values at various positions along the length of the applicator/channels. CT and MRI-based applicator reconstruction accuracy were then compared, and signal-to-noise ratio (SNR) and contrast were also determined for the applicator images.

Results

The applicator distortion level for the Portio applicator was less than the image spatial resolution (0.5±0.5 pixels). The average FWHM for the tandem applicator images was 5.23±0.39 mm, while it was 3.21±0.37 mm for all channels (compared to their actual diameters of 5.0 mm and 3.0 mm, respectively). The average applicator reconstruction difference between CT and MR images was 0.75±0.30 mm overall source dwell positions. The image SNR and contrast were both acceptable.

Conclusion

These findings indicate that the Portio applicator has a satisfactory low level of artifacts and image distortions in 1.5-Tesla, T2W images. It may, therefore, be a promising option for MRI-guided multi-channel vaginal brachytherapy.

MRI-guided Pelvic Radiation Therapy: A Primer for Radiologists

Radiation therapy (RT) is a core pillar of oncologic treatment, and half of all patients with cancer receive this therapy as a curative or palliative treatment. The recent integration of MRI into the RT workflow has led to the advent of MRI-guided RT (MRIgRT). Using MRI rather than CT has clear advantages for guiding RT to pelvic tumors, including superior soft-tissue contrast, improved organ motion visualization, and the potential to image tumor phenotypic characteristics to identify the most aggressive or treatment-resistant areas, which can be targeted with a more focal higher radiation dose. Radiologists should be familiar with the potential uses of MRI in planning pelvic RT; the various RT techniques used, such as brachytherapy and external beam RT; and the impact of MRIgRT on treatment paradigms. Current clinical experience with and the evidence base for MRIgRT in the settings of prostate, cervical, and bladder cancer are discussed, and examples of treated cases are illustrated. In addition, the benefits of MRIgRT, such as real-time online adaptation of RT (during treatment) and interfraction and/or intrafraction adaptation to organ motion, as well as how MRIgRT can decrease toxic effects and improve oncologic outcomes, are highlighted. MRIgRT is particularly beneficial for treating mobile pelvic structures, and real-time adaptive RT for tumors can be achieved by using advanced MRI-guided linear accelerator systems to spare organs at risk. Future opportunities for development of biologically driven adapted RT with use of functional MRI sequences and radiogenomic approaches also are outlined. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material.

Interventional Radiotherapy in Gynecological Cancer

This special issue of "Cancers" explores unusual and very particular aspects of interventional radiotherapy (brachytherapy) in gynecological cancer [...].

The Use of 3D Printing Technology in Gynaecological Brachytherapy-A Narrative Review

Radiation therapy, including image-guided adaptive brachytherapy based on magnetic resonance imaging, is the standard of care in locally advanced cervical and vaginal cancer and part of the treatment in other primary and recurrent gynaecological tumours. Tumour control probability increases with dose and brachytherapy is the optimal technique to increase the dose to the target volume while maintaining dose constraints to organs at risk. The use of interstitial needles is now one of the quality indicators for cervical cancer brachytherapy and needles should optimally be used in ≥60% of patients. Commercially available applicators sometimes cannot be used because of anatomical barriers or do not allow adequate target volume coverage due to tumour size or topography. Over the last five to ten years, 3D printing has been increasingly used for manufacturing of customised applicators in brachytherapy, with gynaecological tumours being the most common indication. We present the rationale, techniques and current clinical evidence for the use of 3D-printed applicators in gynaecological brachytherapy.

Brachytherapy training in India: Results from the GEC-ESTRO-India survey

INTRODUCTION

Brachytherapy (BT) is integral in treatment of gynecological malignancies and is also an option for many other cancers. Data on training and proficiency levels of early career oncologists is limited. Like other continents a survey was conducted for early career oncologists in India.

METHODS AND MATERIALS

An online survey was conducted from November 2019 to February 2020, through Association of Radiation Oncologists of India (AROI) for early career radiation oncologists expected to be within 6 years of training. The survey used a 22 item questionnaire that was also used for European survey. Responses to individual statements were recorded on a 1-5 Likert-type scale. Descriptive statistics were used to describe proportions.

RESULTS

One-hundred twenty-four (17%) of 700 recipients responded to the survey. Majority of the respondents (88%) stated that being able to perform BT at the end of their training was important. Two-thirds of the respondents (81/124) had performed >10 intracavitary procedure and 22.5% had performed >10 intracavitary-interstitial implants. Many respondents had not performed nongynecological procedure- breast (64%), prostate(82%), gastro-intestinal (47%). Respondents predicted that in next 10 years, the role of BT is likely to increase. Lack of dedicated curriculum and training was perceived as the greatest barriers to achieving independence in BT (58%). Respondents suggested that BT training should be prioritized during conferences (73%) and online teaching modules (56%), along with development of BT skills labs (65%).

CONCLUSION

This survey identified a lack of proficiency in gynecological intracavitary-interstitial brachytherapy and non-gynecological brachytherapy, despite BT training being regarded as highly important. Dedicated programs, including standardized curriculum and assessment need to be developed for training early- career radiation oncologists in BT.

Patient-specific cylinder templates for hybrid interstitial vaginal brachytherapy: Feasibility of automated 3-D design, 3D printing, and dosimetric outlook

PURPOSE

Delivering highly conformal treatment plans for high-dose rate vaginal brachytherapy using commercially available applicators can be challenging. A partially automated workflow is presented for the in-house modeling and 3D printing of patient-specific cylindrical templates (PSCTs), which facilitate placement of flexible intracavitary and interstitial needles. To demonstrate feasibility, we compare PSCT treatment plans to retrospective interstitial brachytherapy plans delivered at our center. PSCTs derived from these plans were 3D printed to test the validity of the auto-design process. To facilitate clinical implementation, we validated the steam sterilization compatibility of PSCTs printed using polyetheretherketone (PEEK).

METHODS AND MATERIALS

Plans for ten patients treated using a combination of vaginal cylinder and interstitial needles were compared to PSCT-based plans created for the same patient. DVH parameters for the HRCTV (V100, V150, V200, D90) and OARs (D2 cm3) were evaluated, as well as the number of needles used and the total interstitial length. Each planned PSCT was printed and compared to the intended needle geometry. 3D printed models were sterilization validated by an independent contractor for an autoclave protocol.

RESULTS

PSCT plans demonstrated advantages over template based perineal BT in reducing the total interstitial needle length required while preserving or improving HRCTV and OAR dosimetry. All printed PSCTs matched planned geometry.

CONCLUSIONS

PSCTs stand to be an alternative to current HDR-BT templates/applicators for patients with vaginal and locally recurrent endometrial cancers. Clinically equivalent or improved treatment plans can be created and devices to deliver these plans can be accurately printed and sterilized.