Vaginal tolerance of CT based image-guided high-dose rate interstitial brachytherapy for gynecological malignancies

Definitive radiation for advanced cervix cancer is not associated with vaginal shortening-a prospective vaginal length and dose correlation

PURPOSE

Prospectively measure change in vaginal length after definitive chemoradiation (C-EBRT) with Intracavitary Brachytherapy (ICBT) for locally advanced cervix cancer (LACC) and correlate with vaginal dose (VD).

MATERIALS AND METHODS

Twenty one female patients with LACC receiving C-EBRT and ICBT underwent serial vaginal length (VL) measurements. An initial measurement was made at the time of the first ICBT procedure and subsequently at 3 month intervals up to 1 year post radiation. The vagina was contoured as a 3-dimensional structure for each brachytherapy plan. The difference in VL before and at least 6 months after the last fraction of brachytherapy was considered as an indicator of toxicity.

RESULTS

The mean initial VL was 8.7 cm (6.5-12) with median value of 8.5 cm. The mean VL after 6 months was 8.6 cm (6.5-12) and VL change was not found to be statistically significant. The median values (interquartile ranges) for vaginal D0.1cc, D1cc, and D2cc were 129.2 Gy (99.6-252.2), 96.9 Gy (84.2-114.9), and 89.6 Gy (82.4-102.2), respectively. No significant correlation was found between vaginal length change and the dosimetric parameters calculated for all patients.

CONCLUSION

Definitive C-EBRT and ICBT did not significantly impact VL in this prospective cohort probably related to acceptable doses per ICRU constraints. Estimate of vaginal stenosis and sexual function was not performed in this cohort which is a limitation of this study and which we hope to study prospectively going forward.

Phase I/II prospective clinical trial for the hybrid of intracavitary and interstitial brachytherapy for locally advanced uterine cervical cancer

OBJECTIVE

The purposes of this trial were to demonstrate the feasibility and effectiveness of the hybrid of intracavitary and interstitial brachytherapy (HBT) for locally advanced cervical cancer patients in the phase I/II prospective clinical trial.

METHODS

Patients with FIGO stage IB2-IVA uterine cervical cancer pretreatment width of which was ≥5 cm measured by magnetic resonance imaging were eligible for this clinical trial. The protocol therapy included 30-30.6 Gy in 15-17 fractions of whole pelvic radiotherapy concurrent with weekly CDDP, followed by 24 Gy in 4 fractions of HBT and pelvic radiotherapy with a central shield up to 50-50.4 Gy in 25-28 fractions. The primary endpoint of phase II part was 2-year pelvic progression-free survival (PPFS) rate higher than historical control of 64%.

RESULTS

Between October 2015 and October 2019, 73 patients were enrolled in the initial registration and 52 patients proceeded to the secondary registration. With the median follow-up period of 37.3 months (range, 13.9-52.9 months), the 2- PPFS was 80.7% (90% confidence interval [CI]=69.7%-88%). Because the lower range of 90% CI of 2-year PPFS was 69.7%, which was higher than the historical control ICBT data of 64%, therefore, the primary endpoint of this study was met.

CONCLUSION

The effectiveness of HBT were demonstrated by a prospective clinical study. Because the dose goal determined in the protocol was lower than 85 Gy, there is room in improvement for local control. A higher dose might have been needed for tumors with poor responses.

Dose-Volume Constraints fOr oRganS At risk In Radiotherapy (CORSAIR): An "All-in-One" Multicenter-Multidisciplinary Practical Summary

BACKGROUND

The safe use of radiotherapy (RT) requires compliance with dose/volume constraints (DVCs) for organs at risk (OaRs). However, the available recommendations are sometimes conflicting and scattered across a number of different documents. Therefore, the aim of this work is to provide, in a single document, practical indications on DVCs for OaRs in external beam RT available in the literature.

MATERIAL AND METHODS

A multidisciplinary team collected bibliographic information on the anatomical definition of OaRs, on the imaging methods needed for their definition, and on DVCs in general and in specific settings (curative RT of Hodgkin's lymphomas, postoperative RT of breast tumors, curative RT of pediatric cancers, stereotactic ablative RT of ventricular arrythmia). The information provided in terms of DVCs was graded based on levels of evidence.

RESULTS

Over 650 papers/documents/websites were examined. The search results, together with the levels of evidence, are presented in tabular form.

CONCLUSIONS

A working tool, based on collected guidelines on DVCs in different settings, is provided to help in daily clinical practice of RT departments. This could be a first step for further optimizations.

The association of vagina equivalent dose in 2Gy fraction (EQD2) to late vagina toxicity in patients of cervical cancer treated with WPRT plus IGABT

AIM

To evaluate the associations of vaginal dose parameters and incidence of vaginal stenosis in patients with cervical cancer treated with image-guided brachytherapy (IGBT).

MATERIALS AND METHODS

Fifty-four patients with cervical cancer treated with IGBT were included. The vagina contouring was done on previously treated CT images and the vaginal dose points were marked. The cumulative dose in EQD2 from EBRT and IGBT was calculated for both aspects and the vaginal toxicity was evaluated.

RESULTS

At median follow-up time of 18.5 months, grade 2 or higher vaginal stenosis was observed in 24% of patients. On univariate analysis, parameters that were associated with ≥ grade 2 vaginal stenosis were age, mean dose of lateral 5 mm vagina, dose at PIBS-2 cm, mid vaginal D0 .03cc, mid vagina D1cc, lower vagina D0.03cc, lower vagina D0.1cc, lower vagina D1cc and lower vagina D2cc. On multivariate analysis, the significant parameters were age > 68.5 years old (P = 0.038), mean dose of lateral 5-mm (P = 0.034), and dose at PIBS-2 cm (P = 0.042).

CONCLUSIONS

Age > 68.5 years old, mean dose of lateral 5 mm vagina and dose at PIBS-2 cm were associated with grade 2 or higher vaginal stenosis.

Japanese Society for Radiation Oncology Consensus Guidelines of combined intracavitary and interstitial brachytherapy for gynecological cancers

It has been postulated that the combination of intracavitary and interstitial brachytherapy (IC/IS) is effective and safe for large and irregularly shaped uterine cervical cancer patients. However, due to its invasiveness compared to conventional intracavitary brachytherapy (ICBT), it has to be said that the implementation speed of IC/IS is slow. Until now, there have been no guidelines for required equipment, human resources, and procedural guide focusing solely on IC/IS. The purpose of this guideline is to provide radiation oncologists and medical physicists who wish to start IC/IS with practical and comprehensive guidance for a safe IC/IS introduction and to help accelerate the spread of the utilization of IC/IS nationwide. This is the English translation of the Japanese IC/IS Guidelines, and it was created in an effort to share the Japanese approach to the management of locally advanced uterine cervical cancer worldwide.

Dosimetric predictors of local control and complications in gynecologic transperineal implant patients: The medical college of wisconsin experience

PURPOSE

Investigate the relationship between dosimetric parameters with local control (LC) and complications following transperineal high-dose rate (HDR) interstitial brachytherapy (ISBT) for gynecologic (GYN) malignancies.

METHODS AND MATERIALS

Between 2001 and 2016, 59 patients were treated for primary or recurrent GYN malignancies. Most patients received external beam irradiation, followed by transperineal ISBT via the Syed-Neblett applicator set with CT-based planning. Treatment plans were retrospectively reviewed to evaluate for an association among LC or toxicity with the equivalent dose at 2 Gy per fraction (EQD2) for the clinical target volume (CTV), 0.1 cc (D0.1cc), and 2 cc (D2cc) volumes of the organs at risk (OAR), low/high dose volumes for the OAR and CTV, and ratio of dose at the core vs. the implant periphery.

RESULTS

The median follow-up among survivors was 24 months. 34% of patients had a component of local failure and in 12%, this was isolated. Late grade 3 (G3) toxicity occurred in 15% of patients. There were no G4-5 toxicities. Rectal D0.1cc > 75 Gy trended toward significance in predicting the development of non-fistula late G2-3 rectal complications. Bladder D0.1cc > 94 Gy significantly predicted for the development of late G2-3 vesicovaginal fistula formation. The ratio of the total dose at the vaginal surface to the needle periphery above 121% trended in predicting for any complication or fistula formation.

CONCLUSIONS

HDR ISBT combined with EBRT achieved LC in 66% of patients with advanced or recurrent GYN cancers. Rectal and bladder D0.1cc doses may be predictive of complications as may the ratio of the implant dose at the core vs. periphery.

Interstitial brachytherapy for gynecologic malignancies: Complications, toxicities, and management

From both a disease and management perspective, locally advanced gynecologic cancers present a significant challenge. Dose escalation with brachytherapy serves as a key treatment, providing conformal radiation while sparing at-risk organs. Intracavitary brachytherapy techniques have been shown to be effective, with improving tumor control and toxicity profiles with the advent of three-dimensional image planning. Despite this, the variations in tumor size, location, and pelvic anatomy may lead to suboptimal dosimetry with standard intracavitary applicators in some clinical scenarios. The addition of interstitial needles (interstitial brachytherapy (ISBT)) can improve the conformality of brachytherapy treatments by adding needles to peripheral (and central) regions of the target volume, improving the ability to escalate doses in these undercovered regions while sparing organs at risk. Interstitial brachytherapy can be delivered by intracavitary and interstitial hybrid applicators (ICBT/ISBT), perineal template (P-ISBT), or by free-hand technique. ISBT has however yet to be widely available because of concerns of complications and toxicities from this specialized treatment. However, with the increasing use of three-dimensional image-guided brachytherapy, there is an opportunity to increase the level of expertise in the gynecologic radiation oncology community with an improved understanding of the potential complications and morbidity. In this article, we review the acute and long-term toxicity in both ICBT/ISBT and P-ISBT using image-guided brachytherapy.

Vaginal dose-surface maps in cervical cancer brachytherapy: Methodology and preliminary results on correlation with morbidity

PURPOSE

The purpose of the study was to develop a methodology for vaginal dose-surface maps (DSMs) in patients with cervix cancer and to investigate dose-surface histogram metrics as predictors for vaginal stenosis (St) and mucositis (Muc).

METHODS AND MATERIALS

Thirty-one patients with locally advanced cervix cancer with no vaginal St/Muc (CTCAE-v3) G ≥ 2 at baseline were analyzed. Patients were divided in four morbidity groups: 15 with St/Muc G0/1, 6 with St G ≥ 2, 4 with St/Muc G ≥ 2, and 6 with Muc G ≥ 2. Patients received external beam radiotherapy and 4-fraction intracavitary/interstitial high-dose-rate brachytherapy using tandem and ovoids. DSMs were generated from inner/outer vaginal surfaces. DSMs of external beam radiotherapy and brachytherapy (Gy EQD2₃) were added based on a system of homologous points, to generate cumulative DSMs. Dose-surface histogram/dose-volume histogram parameters, location of high/intermediate-dose regions, rectovaginal reference point, vaginal lateral 5 mm point doses, and vagina/implant dimensions were investigated for St and Muc prediction. Average/difference DSMs and one-way analysis of variance were used to compare between groups.

RESULTS

Best predictors of stenosis were D_15-25cm2 and upper-vagina S_65-120Gy(%). Cutoffs of ∼90 Gy EQD2₃ for D_20cm2 and ∼80% for S_65Gy to top 3 cm inner vaginal surface suitably discriminated for stenosis. Spatial dose location on average/difference DSMs showed significantly higher doses (by > 20 Gy, p < 0.001) over longer parts of the dorsolateral vagina and higher rectovaginal reference point doses for any G ≥ 2 morbidity, over the whole circumference of the upper vagina for G ≥ 2 stenosis. Dose-volume histogram parameters were dependent on vaginal wall thickness. An increase of wall thickness from 2 to 4 mm resulted in an increase of D_2cm3 (D_4cm3) of 16% (32%).

CONCLUSIONS

A novel method was developed to generate vaginal DSMs and spatial-dose metrics. DSMs were found to correlate with vaginal stenosis. The findings of this study are promising and should be further validated on a larger patient cohort, treated with different applicators.

Image-Guided Brachytherapy for Salvage Reirradiation: A Systematic Review

Simple Summary

Local recurrence in gynecological malignancies occurring in a previously irradiated field is a difficult clinical issue. Curative-intent treatment is salvage surgery and is associated with non-negligible peri-operative morbidity and has a substantial impact on long-term quality of life. Reirradiation, using three-dimensional image-guided brachytherapy (3D-IGBT), might be a suitable alternative, especially in non-operable patients. The aim of this review is to report outcomes and toxicities of reirradiation 3D-IGBT in this context. 3D-IGBT appears to be a feasible alternative to salvage surgery in inoperable patients, with an acceptable outcome for patients who have no other curative therapeutic options, however long-term toxicities were high in some studies. Each case should be referred to highly experienced expert centers.

Abstract

Background: Local recurrence in gynecological malignancies occurring in a previously irradiated field is a challenging clinical issue. The most frequent curative-intent treatment is salvage surgery. Reirradiation, using three-dimensional image-guided brachytherapy (3D-IGBT), might be a suitable alternative. We reviewed recent literature concerning 3D-IGBT for reirradiation in the context of local recurrences from gynecological malignancies. Methods: We conducted a large-scale literature research, and 15 original studies, responding to our research criteria, were finally selected. Results: Local control rates ranged from 44% to 71.4% at 2–5 years, and overall survival rates ranged from 39.5% to 78% at 2–5 years. Grade ≥3 toxicities ranged from 1.7% to 50%, with only one study reporting a grade 5 event. Results in terms of outcome and toxicities were highly variable depending on studies. Several studies suggested that local control could be improved with 2 Gy equivalent doses >40 Gy. Conclusion: IGBT appears to be a feasible alternative to salvage surgery in inoperable patients or patients refusing surgery, with an acceptable outcome for patients who have no other curative therapeutic options, however at a high cost of long-term grade ≥3 toxicities in some studies. We recommend that patients with local recurrence from gynecologic neoplasm occurring in previously irradiated fields should be referred to highly experienced expert centers. Centralization of data and large-scale multicentric international prospective trials are warranted. Efforts should be made to improve local control while limiting the risk of toxicities.

Vaginal necrosis: A rare late toxicity after radiation therapy

Vaginal necrosis is a late radiation tissue injury with serious morbidity complications. It is rare, and its incidence is not well assessed in prospective trials. Patient comorbidities and radiation dose can significantly increase the risk. As treatment of gynecologic malignancies often involve a multidisciplinary approach, timely diagnosis and appropriate management by physicians of the team are crucial. Untreated vaginal necrosis can lead to infection, hemorrhage, necrosis-related fistulation to the bladder or rectum, perforation, and death. In this review, we describe the pathophysiology of vaginal necrosis, its clinical course, and management options.

EQD2 Analyses of Vaginal Complications in Exclusive Brachytherapy for Postoperative Endometrial Carcinoma

Background: To evaluate whether EQD2(α/β = 3Gy) at 2 cm3 of the most exposed area of the vagina is related to late vaginal toxicity in postoperative endometrial cancer (PEC) patients (p) treated with exclusive brachytherapy (BT). Methods: From 2014 to 2017, 43p were included in this study. BT was administered: 3-fractions of 6Gy in 37p and 2-fractions of 7.5Gy in 6p. The dose was prescribed at a depth of 5 mm from the applicator surface with dose-point optimization based on distance. The active treatment length was 2.5 cm. CTV-D90 and the dose to the most exposed 2 cm3 of the vagina was calculated for each patient. Late toxicity of the bladder and rectum was assessed using Radiation Therapy Oncology Group (RTOG) criteria, and vaginal toxicity by objective Late Effects Normal Tissue Task Force (LENT)-Subjective, Objective, Management, Analytic (SOMA) (LENT-SOMA) criteria. Statistics: frequency tables, mean, median, range, standard deviation, and box plot. Results: The median follow-up was 51 months (12-68). 20 p (46.5%) and 2 p (4.7%) developed G1 and G2 vaginal complications, respectively. Only 1/2 p-G2 receiving EQD2(α/β = 3Gy) at 2 cm3 >68Gy presented vaginal shortening and 18/20 p-G1 received doses < 68Gy. Conclusions: PECp receiving exclusive brachytherapy with doses < 68Gy EQD2(α/β = 3Gy) at 2 cm2 of the vagina presented only G0-G1 vaginal toxicity, except for one with bleeding telangiectasias. Larger prospective studies are necessary to confirm the present results.

A case report of a patient with bulky uterine cervical neoplasm who achieved complete response with "intentional internal high-dose policy" high-dose-rate interstitial brachytherapy

RATIONALE

Gynecological high-dose-rate (HDR) brachytherapy has progressed for years, but it remains difficult for bulky tumors to be controlled locally. Dose limitations to organs at risk (OARs) are invariably obstacles in increasing the prescription dose. Additionally, it is controversial that the excessive hyperdose sleeve, the volume receiving a dose equal to or greater than twice the reference dose, should be eliminated in gynecological HDR brachytherapy. On the other hand, the technique of simultaneous integrated protection was reported for large hepatocellular carcinoma treatment, and similarly, internal high-dose brachytherapy could be used for treating bulky cervical carcinoma.

PATIENT CONCERNS

A 54-year-old female had irregular genital bleeding and lost 13 kg in one year.

DIAGNOSIS

She was diagnosed with T3bN1M0 cervical cancer in another hospital. The transverse diameter of the primary tumor was 10.5 cm.

INTERVENTIONS

The whole pelvis and para-aortic lymph node were irradiated with a total of 50 Gy in 25 fractions, but the size of the tumor showed only a slight decrease to 8.9 cm. After external beam radiotherapy, first-time high-dose-rate interstitial brachytherapy (HDR-ISBT) was administered without "intentional internal high-dose (IIHD) policy," the technique of high-dose administration to only the inside of the tumor. Considering the rectum dose limitation, in the additional 2 times of brachytherapy, "IIHD policy" HDR-ISBT was applied. In the second and third HDR-ISBT, the percentage of the volume exposed to 200% of the prescribed dose for high-risk clinical target volume increased by 241% and 204% compared with the first HDR-ISBT, while the doses to OARs were not significantly higher than those of the first-time HDR-ISBT.

OUTCOMES

Complete response was obtained, and no recurrence findings and side effects caused by HDR-ISBT have been detected for 2 years and 9 months.

LESSONS

To our knowledge, this is the first report of IIHD HDR-ISBT for bulky cervical cancer. This technique can be the solution for treating bulky cervical cancer.

Outcomes of freehand interstitial brachytherapy in advanced gynecologic malignancies

PURPOSE

The purpose of the study is to present the first results of freehand interstitial brachytherapy (ISBT) used to treat patients with carcinoma of the cervix and the vagina.

METHODS AND MATERIALS

Patients diagnosed with carcinoma of the cervix or carcinoma of the vagina who were not suitable for intracavitary brachytherapy were treated with freehand ISBT. The implant was performed transperineally using C arm or transrectal ultrasound guidance. Patients received an external beam radiotherapy dose of 50 Gy in 25 fractions. The dose delivered by high-dose-rate ISBT was 18 Gy in three fractions, 6 Gy per fraction, 6 h apart. The brachytherapy dose volume parameters were analyzed after CT-based planning using GEC ESTRO image-guided brachytherapy-based guidelines.

RESULTS

From June 2018 till November 2018, 14 patients were treated with freehand ISBT. The mean dose received by 90% of the high-risk clinical target volume (D₉₀) was 82 Gy EQD2₁₀ for patients with carcinoma of the cervix and 80 Gy EQD2₁₀ for patients with carcinoma of the vagina_. The mean dose received by 2 cc volume of the bladder and rectum was 80 Gy EQD2₃ and 70 Gy EQD2₃ for patients with carcinoma of the cervix and 75 Gy EQD2₃ and 72 Gy EQD2₃ for patients with carcinoma of the vagina, respectively. The mean dose received by 2 cc of the sigmoid was 65 Gy EQD2₃ for cervical carcinoma and 58 Gy EQD2₃ for vaginal carcinoma, respectively. At a median followup of 14 months, 2 patients developed local recurrence. Two patients developed Grade 2 gastro intestinal toxicity, and 1 patient developed Grade 2 genitourinary toxicity. None of the patients developed Grade 3 or 4 toxicities.

CONCLUSION

A freehand interstitial implant is feasible in resource limited settings and provides acceptable local control with minimal acute toxicity.

Hyaluronate gel injection for rectum dose reduction in gynecologic high-dose-rate brachytherapy: initial Japanese experience

Perirectal hyaluronate gel injection (HGI) appears to be a promising technique for healthy tissue dose sparing in pelvic radiotherapy. In this analysis, we report our initial experience of HGI in gynecologic brachytherapy, focusing on its safety and effectiveness for dose reduction to the rectum. Between July 2013 and May 2014, 36 patients received HGI for primary/salvage gynecologic brachytherapy. Dosimetric effect analysis was based on pre- and post-HGI computed tomography dataset registration with corresponding dose-volume histogram evaluation. The maximum dose to the most exposed 0.1 cm3 (D0.1cm3) and 2.0 cm3 (D2.0cm3) were used as index values for rectum and bladder dose evaluation. The dose indexes for target volume (TV) coverage were TV D90/V100. In all cases, HGI was well tolerated, with no acute or late adverse events documented at a median follow-up of 220 days (range, 18-1046 days). Rectum D2.0cm3 and D0.1cm3 were significantly decreased by HGI (P < 0.001 and P = 0.003, respectively), with no significant impact on dosimetric parameters of bladder and TV coverage. Factors correlating negatively with the dosimetric effect of HGI were an increasing number of interstitial catheters (P = 0.003) as well as Lcranial100% (P = 0.014) and Lcranial80% (P = 0.001) [i.e. the length from the anal verge to the most cranial point at which the 100% and 80% isodose lines, respectively, crossed the rectum]. The concept of HGI for gynecologic brachytherapy is plausible, and our initial experience indicates it to be an effective technique for rectal dose reduction in radiotherapy of intrapelvic tumours.

A machine-learning-based prediction model of fistula formation after interstitial brachytherapy for locally advanced gynecological malignancies

PURPOSE

External beam radiotherapy combined with interstitial brachytherapy is commonly used to treat patients with bulky, advanced gynecologic cancer. However, the high radiation dose needed to control the tumor may result in fistula development. There is a clinical need to identify patients at high risk for fistula formation such that treatment may be managed to prevent this toxic side effect. This work aims to develop a fistula prediction model framework using machine learning based on patient, tumor, and treatment features.

METHODS AND MATERIALS

This retrospective study included 35 patients treated at our institution using interstitial brachytherapy for various gynecological malignancies. Five patients developed rectovaginal fistula and two developed both rectovaginal and vesicovaginal fistula. For each patient, 31 clinical features of multiple data types were collected to develop a fistula prediction framework. A nonlinear support vector machine was used to build the prediction model. Sequential backward feature selection and sequential floating backward feature selection methods were used to determine optimal feature sets. To overcome data imbalance issues, the synthetic minority oversampling technique was used to generate synthetic fistula cases for model training.

RESULTS

Seven mixed data features were selected by both sequential backward selection and sequential floating backward selection methods. Our prediction model using these features achieved a high prediction accuracy, that is, 0.904 area under the curve, 97.1% sensitivity, and 88.5% specificity.

CONCLUSIONS

A machine-learning-based prediction model of fistula formation has been developed for patients with advanced gynecological malignancies treated using interstitial brachytherapy. This model may be clinically impactful pending refinement and validation in a larger series.

A hybrid technique of intracavitary and interstitial brachytherapy for locally advanced cervical cancer: initial outcomes of a single-institute experience

BACKGROUND

Locally advanced uterine cervical cancer (LAUCC) with lateral tumor extension may not always be covered adequately by conventional intracavitary brachytherapy (ICBT). Hybrid intracavitary and interstitial brachytherapy (HBT) seems to be an effective alternative by improving anatomy-oriented dose optimisation. The purpose of this study was to report initial clinical result for LAUCC treated by HBT.

METHODS

Between January 2012 and November 2015, 42 patients with LAUCC (T1b2-4a) were treated with primary radiation therapy including HBT. Patients with distant metastasis other than para-aortic lymph node spread were excluded from this study. A retrospective analysis was performed for toxicity evaluation and oncological outcome calculation.

RESULTS

Median follow-up was 23.2 months (range 13.2-71.4). Two-year overall survival, progression free survival, and local control rate were 81.6, 54.4, and 80.2%, respectively. Seven patients experienced local recurrence (16.6%). Of those, five were confined to the uterus and two at the parametria. Late adverse events ≥ grade 3 were seen in 3 patients.

CONCLUSIONS

HBT can generate favorable local control in tumors which cannot be adequately covered by ICBT.

Risk factors for fistula formation after interstitial brachytherapy for locally advanced gynecological cancers involving vagina

Purpose

To determine risk factors for fistula formation after interstitial brachytherapy (ISBT) in patients with advanced gynecologic cancers.

Material and methods

We performed an Institutional Review Board (IRB) approved retrospective review of 44 patients treated with transperineal template-based ISBT from 2011 to 2017 at a major metropolitan county and university health system. All patients were treated with image-guided high-dose-rate ISBT. Statistical analysis was performed using the χ² test to identify factors correlated with fistula formation. Survival and tumor control outcomes were calculated using Kaplan Meier analyses.

Results

Patients had a mean age of 53 years (range, 28-81 years), a mean external beam dose of 43.1 Gy (range, 42.5-51.3 Gy), and a mean brachytherapy dose of 22.8 Gy (range, 21.3-30 Gy). Two of 44 patients had fistulas that could be definitively attributed to therapy for a fistula rate of 4.5%. Six additional patients (13.6%) developed fistula after treatment with associated recurrent disease but were included in the causality analysis. We analyzed patient tumor and treatment factors, and on univariate analyses we found that age ≥ 60 years, Hispanic ethnicity, bladder involvement, rectal D2 cc ≥ 70 Gy, and whether patients had post-radiation biopsies were predictors for fistula formation. The 1-year overall survival (OS), progression-free survival (PFS), and local control (LC) were 85%, 58.5%, and 76.9%, respectively, with a mean follow-up time 23 months (range, 4.0-68.8 months).

Conclusions

We identified factors that predict fistula formation in patients with advanced gynecologic tumors treated with ISBT. These factors can be used to stratify patients into a high-risk group, with potential for modification of brachytherapy planning to reduce their risk of fistula formation.

3T multiparametric MRI-guided high-dose-rate combined intracavitary and interstitial adaptive brachytherapy for the treatment of cervical cancer with a novel split-ring applicator

PURPOSE

To evaluate the role of 3T-MRI-guided adaptive high-dose-rate (HDR) combined intracavitary and interstitial brachytherapy for cervical cancer using a novel intracavitary split-ring (ICSR) applicator adapter.

METHODS AND MATERIALS

We retrospectively reviewed all HDR brachytherapy cases from 2013 to 2015 using an ICSR applicator. Initial optimization was performed using 3T multiparametric MRI (mpMRI) series with an applicator in place. The mpMRI series were discretionarily acquired before subsequent fractions for possible target adaptation. When necessary, interstitial needles (ISNs) were inserted through a novel ICSR adapter or freehand. Dosimetric parameters, clinical outcomes, and toxicities were compared between groups.

RESULTS

Seventeen patients were included, with a mean followup of 32 months. An mpMRI series preceded each initial fraction and 52.9% of patients underwent ≥1 additional pretreatment mpMRI. Among these subsequent fractions, the high-risk clinical target volume was reduced in 80% vs. 41% without pretreatment mpMRI. Five patients had ISN placement (seven insertions) to improve extracervical target coverage. Mean D₉₀ (Gy) per fraction to the high-risk clinical target volume and intermediate-risk clinical target volume with and without an ISN were 7.51 ± 1.07 vs. 6.14 ± 0.52 (p = 0.028) and 6.35 ± 0.75 vs. 5.21 ± 0.49 (p = 0.007), respectively. Mean fractional D_2cc (Gy) for organs at risk was comparable. No Grades 3-4 toxicity was reported. Disease-free survival and local control for the ICSR-ISN and ICSR-alone groups were 29.8 months/80.0% and 31.2 months/83.3%, respectively.

CONCLUSIONS

The mpMRI acquisition with ICSR applicator in place immediately before HDR brachytherapy for cervical cancer guided successful adaptive treatment optimization and delivery. Our initial experience with a novel interstitial adapter for the split-ring applicator demonstrated excellent target coverage without compromising organs at risk, resulting in good local control and disease-free survival.

American Brachytherapy Society recurrent carcinoma of the endometrium task force patterns of care and review of the literature

PURPOSE

The purpose of this American Brachytherapy Society task force is to present a literature review and patterns of care by a panel of experts for the management of vaginal recurrence of endometrial cancer.

METHODS AND MATERIALS

In 2016, the American Brachytherapy Society Board selected a panel of experts in gynecologic brachytherapy to update our current state of knowledge for managing vaginal recurrence of endometrial cancer. Practice patterns were evaluated via an online survey and clinical updates occurred through a combination of literature review and clinical experience and/or expertise.

RESULTS

There are various retrospective series of patients treated with radiation for vaginal recurrence of endometrial cancer, which include a varied group of patients, multiple treatment techniques, and a range of total doses and demonstrate a wide scope of local control and overall survival outcomes. In the era of image-guided brachytherapy, high local control rates with low significant late-term morbidities can be achieved. Lower rates of local control and higher late-term toxicity are reported in the retreatment setting. In patients with no previous history of radiation treatment, external beam radiation therapy followed by brachytherapy boost should be used. There are varying practices with regard to the definition and appropriate doses of both the high-risk clinical target volume and the intermediate-risk clinical target volume in the setting of vaginal recurrence of endometrial cancer. There are limited data to provide appropriate dose constraints for some organs at risk with the majority of guidance taken from the definitive cervical cancer literature.

CONCLUSIONS

A summary of literature and expert practice patterns for patient selection, dose recommendations, and constraints are provided as guidance for practitioners.

Outcomes of salvage high-dose-rate brachytherapy with or without external beam radiotherapy for isolated vaginal recurrence of endometrial cancer

Purpose

This study was designed to retrospectively analyze outcomes of high-dose-rate (HDR) brachytherapy, with or without external beam radiotherapy (EBRT), in patients with vaginal recurrence of endometrial carcinoma, and to identify factors prognostic of patient outcomes.

Material and methods

The medical records of all patients who underwent HDR brachytherapy for initial recurrence in the vagina of endometrial cancer after definitive surgery between 1992 and 2014 were retrospectively reviewed. All patients underwent either intracavitary brachytherapy (ICBT) or interstitial brachytherapy (ISBT) with or without EBRT. Late toxicity was graded using the EORTC (LENT/SOMA) scale, revised in 1995.

Results

Thirty-seven patients were identified. The median follow-up time was 48 months (range: 6-225 months). Of these 37 patients, 23 underwent ICBT, 14 underwent ISBT, and 26 underwent EBRT. Tumor size at first examination of initial relapse was significantly larger in the ISBT than in the ICBT group. The 4-year respective overall survival (OS), local control (LC), and progression-free survival (PFS) rates in the entire cohort were 81.0%, 77.9%, and 56.8%, respectively. The interval between diagnosis of first recurrence and radiotherapy (< 3 months, ≥ 3 months) was a significant predictor of LC and PFS. OS and LC rates did not differ significantly in the ICBT and ISBT groups. Two patients experienced grade 2 rectal bleeding, and four experienced grade 2 hematuria. No grade 3 or higher late complications were observed.

Conclusions

Salvage HDR brachytherapy is an optimal for treating vaginal recurrence of endometrial carcinoma with acceptable morbidity. Early radiotherapy, including brachytherapy, should be considered for women who experience vaginal recurrence of endometrial cancer.

Dosimetric comparison of interstitial brachytherapy with multi-channel vaginal cylinder plans in patients with vaginal tumors

BACKGROUND

To evaluate the dosimetric performance of multi-channel vaginal cylinder (MCVC) against interstitial brachytherapy (ISBT) for the treatment of vaginal tumors.

METHODS

Vaginal tumors with extension of > 0.5 cm and ≤ 2 cm from the lateral vaginal wall and/or ≤ 1 cm in height above the vaginal vault were retrospectively selected from a ISBT registry trial database. The selected patients were treated with ISBT and targets included the intermediate (IRCTV) or high-risk (HRCTV) clinical target volumes. For technique comparison, a 35 mm MCVC was registered with the interstitial intra-vaginal cylinder. Bladder and rectum contours were transferred from the ISBT to the MCVC-BT plans. Vaginal mucosa was achieved by 3 mm uniform expansion from cylinder surface. Both the ISBT and MCVC-BT plans were optimized using the Inverse Planning Simulated Annealing optimization algorithm. After normalizing target D90 to 700 cGy, dose to organs at risk were measured and compared between ISBT and MCVC plans.

RESULTS

Six interstitial patient plans met the inclusion criteria for this study. Four patients had vaginal primaries and two recurrent cancers in the vagina. Lower doses to bladder and rectum were seen with ISBT plans. In half of the MCVC plans, the rectal dose met the recommended constraints. For plans in which the rectal constraint was not met, the target volumes were abutting the rectum and had a cranial-caudal length ≥ 5 cm. Dose to vaginal mucosa was lower in ISBT plans directed to the HRCTVs, although no difference was seen in circumferential IRCTVs.

CONCLUSIONS

Overall, ISBT results in decreased dose to OARs as compared to MCVC. However, MCVC BT results in acceptable doses to OARs with possible improvement in vaginal doses for circumferential targets. Careful consideration to tumor geometry and location may help guide optimal techniques in vaginal tumor brachytherapy.

The role of interstitial brachytherapy in the management of primary radiation therapy for uterine cervical cancer

Purpose

The aim of this study was to report the clinical results of uterine cervical cancer patients treated by primary radiation therapy including brachytherapy, and investigate the role of interstitial brachytherapy (ISBT).

Material and methods

All consecutive uterine cervical cancer patients who were treated by primary radiation therapy were reviewed, and those who were treated by ISBT were further investigated for clinical outcomes and related toxicities.

Results

From December 2008 to October 2014, 209 consecutive uterine cervical cancer patients were treated with primary radiation therapy. Among them, 142 and 42 patients were treated by intracavitary and hybrid brachytherapy, respectively. Twenty-five patients (12%) were treated by high-dose-rate (HDR)-ISBT. Five patients with distant metastasis other than para-aortic lymph node were excluded, and 20 patients consisted of the analysis. Three-year overall survival (OS), progression-free survival (PFS), and local control (LC) rate were 44.4%, 38.9%, and 87.8%, respectively. Distant metastasis was the most frequent site of first relapse after HDR-ISBT. One and four patients experienced grade 3 and 2 rectal bleeding, one grade 2 cystitis, and two grade 2 vaginal ulcer.

Conclusions

Feasibility and favorable local control of interstitial brachytherapy for locally advanced cervical cancer was demonstrated through a single institutional experience with a small number of patients.

Vaginal dose de-escalation in image guided adaptive brachytherapy for locally advanced cervical cancer

PURPOSE

Vaginal stenosis is a major problem following radiotherapy in cervical cancer. We investigated a new dose planning strategy for vaginal dose de-escalation (VDD).

MATERIALS AND METHODS

Fifty consecutive locally advanced cervical cancer patients without lower or middle vaginal involvement at diagnosis from 3 institutions were analysed. External beam radiotherapy was combined with MRI-guided brachytherapy. VDD was obtained by decreasing dwell times in ovoid/ring and increasing dwell times in tandem/needles. The aim was to maintain the target dose (D90 of HR-CTV⩾85Gy EQD2) while reducing the dose to the surface of the vagina to <140% of the physical fractional brachytherapy dose corresponding to a total EQD2 of 85Gy.

RESULTS

The mean vaginal loading (ovoid/ring) was reduced from 51% to 33% of the total loading with VDD, which significantly reduced the dose to the vaginal dose points (p<0.001) without compromising the target dose. The dose to the ICRU recto-vaginal point was reduced by a mean of 4±4Gy EQD2 (p<0.001), while doses to bladder and rectum (D_2cm³) were reduced by 2±2Gy and 3±2Gy, respectively (p<0.001).

CONCLUSIONS

VDD significantly reduces dose to the upper vagina which is expected to result in reduction of vaginal stenosis.

Multicentre evaluation of a novel vaginal dose reporting method in 153 cervical cancer patients

BACKGROUND AND PURPOSE

Recently, a vaginal dose reporting method for combined EBRT and BT in cervical cancer patients was proposed. The current study was to evaluate vaginal doses with this method in a multicentre setting, wherein different applicators, dose rates and protocols were used.

MATERIAL AND METHODS

In a subset of patients from the EMBRACE study, vaginal doses were evaluated. Doses at the applicator surface left/right and anterior/posterior and at 5mm depth were measured. In addition, the dose at the Posterior-Inferior Border of Symphysis (PIBS) vaginal dose point and PIBS±2cm, corresponding to the mid and lower vagina, was measured.

RESULTS

153 patients from seven institutions were included. Large dose variations expressed in EQD2 with α/β=3Gy were seen between patients, in particular at the top left and right vaginal wall (median 195 (range 61-947)Gy/178 (61-980)Gy, respectively). At 5mm depth, doses were 98 (55-212)Gy/91 (54-227)Gy left/right, and 71 (51-145)Gy/67 (49-189)Gy anterior/posterior, respectively. The dose at PIBS and PIBS±2cm was 41 (3-81)Gy, 54 (32-109)Gy and 5 (1-51)Gy, respectively. At PIBS+2cm (mid vagina) dose variation was coming from BT. The variation at PIBS-2cm (lower vagina) was mainly dependent on EBRT field border location.

CONCLUSIONS

This novel method for reporting vaginal doses coming from EBRT and BT through well-defined dose points gives a robust representation of the dose along the vaginal axis. In addition, it allows comparison of vaginal dose between patients from different centres. The doses at the PIBS points represent the doses at the mid and lower parts of the vagina. Large variations in dose throughout the vagina were observed between patients and centres.

Vaginal Dose Is Associated With Toxicity in Image Guided Tandem Ring or Ovoid-Based Brachytherapy

PURPOSE

To calculate vaginal doses during image guided brachytherapy with volume-based metrics and correlate with long-term vaginal toxicity.

METHODS AND MATERIALS

In this institutional review board-approved study, institutional databases were searched to identify women undergoing computed tomography and/or magnetic resonance-guided brachytherapy at the Duke Cancer Center from 2009 to 2015. All insertions were contoured to include the vagina as a 3-dimensional structure. All contouring was performed on computed tomography or magnetic resonance imaging and used a 0.4-cm fixed brush to outline the applicator and/or packing, expanded to include any grossly visible vagina. The surface of the cervix was specifically excluded from the contour. High-dose-rate (HDR) and low-dose-rate (LDR) doses were converted to the equivalent dose in 2-Gy fractions using an α/β of 3 for late effects. The parameters D0.1cc, D1cc, and D2cc were calculated for all insertions and summed with prior external beam therapy. Late and subacute toxicity to the vagina were determined by the Common Terminology Criteria for Adverse Events version 4.0 and compared by the median and 4th quartile doses, via the log-rank test. Univariate and multivariate hazard ratios were calculated via Cox regression.

RESULTS

A total of 258 insertions in 62 women who underwent definitive radiation therapy including brachytherapy for cervical (n=48) and uterine cancer (n=14) were identified. Twenty HDR tandem and ovoid, 32 HDR tandem and ring, and 10 LDR tandem and ovoid insertions were contoured. The median values (interquartile ranges) for vaginal D0.1cc, D1cc, and D2cc were 157.9 (134.4-196.53) Gy, 112.6 (96.7-124.6) Gy, and 100.5 (86.8-108.4) Gy, respectively. At the 4th quartile cutoff of 108 Gy for D2cc, the rate of late grade 1 toxicity at 2 years was 61.2% (95% confidence interval [CI] 43.0%-79.4%) below 108 Gy and 83.9% (63.9%-100%) above (P=.018); grade 2 or greater toxicity was 36.2% (95% CI 15.8%-56.6%) below 108 Gy and 70.7% (95% CI 45.2%-96.2%) above (P=.004); and grade 3 or worse toxicity was 9.9% (95% CI 0.0%-23.6%) below 108 Gy and 30.0% (95% CI 4.7%-55.3%) above (P=.025). This association was maintained on multivariate analysis, independent of covariates such as applicator type, age, and dose rate.

CONCLUSIONS

Vaginal dose was associated with all grades of vaginal toxicity. Confirmation at other sites using this methodology will be necessary to establish reproducibility; however, the integration of routine calculation of vaginal dose may be warranted.

Brachytherapy for malignancies of the vagina in the 3D era

Vaginal cancer is an uncommon malignancy and can be either recurrent or primary. In both cases, brachytherapy places a central role in the overall treatment course. Recent technological advances have led to more advanced brachytherapy techniques, which in turn have translated to improved outcomes for patients with malignancies of the vagina. The aim of this manuscript is to outline the incorporation of modern brachytherapy into the treatment of patients with vaginal cancer including patient selection along with the role of brachytherapy in conjunction with other treatment modalities, various brachytherapy techniques, treatment planning, dose fractionation schedules, and normal tissue tolerance.

Computed tomography planned interstitial brachytherapy for recurrent gynecologic cancer

PURPOSE

To report outcomes and identify predictors of toxicity in patients undergoing reirradiation with interstitial brachytherapy (ISBT) for recurrent cancers of the female reproductive tract.

METHODS AND MATERIALS

Twenty-one patients received ISBT performed using (192)Ir sources (10 low dose rate and 11 high dose rate) at our institution between 2009 and 2013. Demographic, disease specific, treatment, toxicity, and outcome data were collected. Kaplan-Meier and proportional hazard models were used to estimate survival and logistic regression to model toxicity. A least absolute shrinkage and selection operator penalty was used to identify relevant predictors of outcome and toxicity.

RESULTS

Eleven patients had uterine cancer, 7 patients had cervical cancer, and 3 patients had vulvar cancer. One-year actuarial freedom from local-regional failure, progression-free survival (PFS), and overall survival were 71.5%, 66.0%, and 82.2%, respectively. Tumor size was a significant predictor of worse PFS and overall survival (1 cm increase in tumor size = hazard ratio [HR], 1.61; 95% confidence interval [CI]: 1.16, 2.62 for PFS; HR, 2.02; 95% CI: 1.21, 3.38). Grade 3 or higher vaginal, urinary, and rectal toxicity occurred in 28.5%, 9.5%, and 19% of patients, respectively. Urethra D0.1cc predicted for grade 2 or higher urinary toxicity (one equivalent dose in 2 Gy fraction increase = HR, 1.156; 95% CI: 1.001, 1.335).

CONCLUSIONS

Reirradiation with ISBT is both safe and effective. In patients with recurrent cancer, urethra D0.1cc predicts for increased urinary toxicity. Increased tumor size is a negative prognostic factor in patients receiving ISBT for cancer recurrence.