The influence of Gleason score ≤ 6 histology on the outcome of high-risk localized prostate cancer after modern radiotherapy

We aimed to retrospectively review outcomes in patients with high-risk prostate cancer and a Gleason score ≤ 6 following modern radiotherapy. We analyzed the outcomes of 1374 patients who had undergone modern radiotherapy, comprising a high-risk low grade [HRLG] group (Gleason score ≤ 6; n = 94) and a high-risk high grade [HRHG] group (Gleason score ≥ 7, n = 1125). We included 955 patients who received brachytherapy with or without external beam radio-therapy (EBRT) and 264 who received modern EBRT (intensity-modulated radiotherapy [IMRT] or stereotactic body radiotherapy [SBRT]). At a median follow-up of 60 (2-177) months, actuarial 5-year biochemical failure-free survival rates were 97.8 and 91.8% (p = 0.017), respectively. The frequency of clinical failure in the HRLG group was less than that in the HRHG group (0% vs 5.4%, p = 0.012). The HRLG group had a better 5-year distant metastasis-free survival than the HRHG group (100% vs 96.0%, p = 0.035). As the HRLG group exhibited no clinical failure and better outcomes than the HRHG group, the HRLG group might potentially be classified as a lower-risk group.

Clinical Significance of Intraductal Carcinoma of the Prostate After High-Dose Brachytherapy With External Beam Radiation Therapy: A Single Institution Series and an Updated Meta-Analysis

BACKGROUND

We compared oncological outcomes between prostate cancer (PCa) patients with and without intraductal carcinoma of the prostate (IDC-P) after high-dose-rate brachytherapy (HDR-BT) with external beam radiation therapy (EBRT).

METHODS

We performed a retrospective analysis of 138 patients with clinically high-risk, very high-risk, or locally advanced PCa who received HDR-BT with EBRT. Of these, 70 (50.7 %) patients were diagnosed with IDC-P; 68 (49.3 %) patients with acinar adenocarcinoma of prostate. The oncological outcomes, including biochemical recurrence-free survival (BCRFS) and clinical progression-free survival (CPFS), were assessed using Kaplan-Meier curves. Additionally, Cox proportional hazards models were used to identify significant prognostic indicators or biochemical recurrence (BCR). Meta-analysis of existing literatures was performed to evaluate the risk of BCR in patients with IDC-P after radiation therapy, compared to those without IDC-P.

RESULTS

Kaplan-Meier curves demonstrated significantly inferior BCRFS and CPFS in patients with IDC-P. Multivariate analysis revealed that IDC-P and Grade Group 5 status were associated with increased BCR risk. in our meta-analysis, IDC-P was associated with BCR (HR = 2.13, P = .003).

CONCLUSION

Amongst the patients who received HDR-BT, patients with IDC-P displayed significantly more rapid disease progression, compared with patients who did not have IDC-P.

Long-term outcomes of salvage transurethral high-dose-rate brachytherapy combined with external beam radiation therapy for anastomotic recurrence of prostate cancer after radical prostatectomy: A retrospective analysis

BACKGROUND

High-dose-rate brachytherapy (HDR-BT) delivers high-dose radiation to local lesions within a short treatment period. There are no reports of salvage transurethral HDR-BT for biochemical recurrence (BCR) after radical prostatectomy. Thus, we aimed to evaluate the usefulness of salvage transurethral HDR-BT with external beam radiation therapy (EBRT) for anastomotic prostate cancer recurrence.

METHODS AND MATERIALS

Patients with postoperative prostate cancer who underwent salvage transurethral HDR-BT with EBRT for anastomotic recurrence at our hospital between January 2002 and July 2009 were retrospectively evaluated. The Kaplan-Meier method was used to estimate biochemical freedom from failure (bFFF), cause-specific survival (CSS), and overall survival (OS) rates.

RESULTS

Nine patients were included in this study. The median follow-up period and age were 13.1 (range 4.3-18.4) years and 67 (range 63-78) years, respectively. The dose of HDR-BT ranged from 13 to 24 Gy per 2 to 5 fractions, while that of EBRT ranged from 30 to 44 Gy per 15 to 22 fractions. The 1-year, 5-year, and 10-year bFFF rates were 77.8%, 41.7%, and 13.9%, respectively. The 10-year and 15-year CSS rates were 100% each. The 10-year and 15-year OS rates were 100% and 64.3%, respectively. Six patients were diagnosed with BCR. Two patients experienced Grade 3 hematuria as a late adverse event. There was no exacerbation of urinary incontinence.

CONCLUSIONS

No prostate cancer-related deaths were observed, even after a long-term follow-up. Salvage transurethral HDR-BT after radical prostatectomy is safe and feasible and may be a useful treatment option.

Clinical application of 192Ir High-Dose-Rate brachytherapy in metastatic lymph nodes of the neck

OBJECTIVE

The objective of this study was to investigate the safety and effectiveness of high-dose-rate brachytherapy as a treatment modality for recurrent or residual neck metastatic lymph nodes following external radiotherapy.

METHODS

38 patients with 52 metastatic lymph nodes recurring or residual after previous external radiotherapy was completed to metastatic lymph nodes in the neck were collected from January 2019 to February 2022. High-dose-rate brachytherapy with 192Ir was performed with a prescribed dose of 20-30 Gy/1f (effective biological dose of 60-120 Gy), and imaging was performed at 1, 3, and 6 months after treatment to assess the local control rate and adverse effects of treatment.

RESULTS

All 38 patients received completed treatment, and they were followed up for 6 months. 52 patients with neck lymph node metastases had an objective response rate. (Complete response, CR + Partial response, PR) of 76.9%, which comprised 89.5% (34/38) for lymph nodes ≤ 3 cm and 42.9% (4/14) for > 3 cm, P = 0.028. P > 0.05 for CR + PR versus stable disease, SD + progressive disease, PD for lymph nodes between different subdivisions of the neck. Using the Radiation Therapy Oncology Group (RTOG) Acute Toxicity Scoring System, there were 6 cases of acute radioskin injuries of degree I and 4 cases of degree II with a 60% symptomatic relief rate.

CONCLUSIONS

High-dose-rate brachytherapy serves as a safe and effective method in treating recurrent residual neck metastatic lymph nodes in the field after external radiotherapy, exerting tolerable adverse effects.

Clinical characteristics of secondary bladder cancer developing after low-/high-dose-rate brachytherapy to treat localized prostate cancer

BACKGROUND

To explore correlations between the clinical attributes of secondary bladder cancer and brachytherapy, we retrospectively reviewed our institutional database on patients with localized prostate cancer who underwent low-dose-rate brachytherapy (LDR-BT) or high-dose-rate brachytherapy (HDR-BT) with or without external beam radiation therapy (EBRT) or radical prostatectomy (RP).

METHODS

From October 2003 to December 2014, 2551 patients with localized prostate cancer were treated at our institution. Of these, data on 2163 were available (LDR-BT alone: n = 953; LDR-TB with EBRT: n = 181; HDR-BT with EBRT: n = 283; RP without EBRT: n = 746). The times of secondary bladder cancer development subsequent to radical treatment, and their clinical characteristics, were studied.

RESULTS

Age-adjusted Cox's regression analyses indicated that brachytherapy did not significantly impact the incidence of secondary bladder cancer. However, the pathological characteristics of such cancer differed between patients treated via brachytherapy and RP without EBRT; invasive bladder cancer was more common in such patients.

CONCLUSION

The risk for secondary bladder cancer was not significantly increased after brachytherapy compared to non-irradiation therapy. However, brachytherapy patients exhibited a higher incidence of invasive bladder cancer. Therefore, meticulous follow-up is crucial for early detection and treatment of bladder cancer in such patients.

The prognostic significance of the clinical T stage and Grade Group in patients with locally advanced prostate cancer treated via high-dose-rate brachytherapy and external beam radiation

BACKGROUND

Although the optimal management of locally advanced prostate cancer (PCa) remains unclear, local definitive therapy, thus combined radiotherapy and androgen deprivation, is one option. We evaluated the long-term outcomes of patients with locally advanced PCa who underwent high-dose-rate brachytherapy (HDR-BT) and external beam radiation therapy (EBRT).

METHODS

We retrospectively analyzed 173 patients with locally advanced PCa (cT3a-4N0-1M0) who underwent HDR-BT and EBRT. We employed Cox's proportional hazards models to identify pre-treatment predictors of oncological outcomes. Treatment outcomes (biochemical recurrence-free survival [BCRFS], clinical progression-free survival [CPFS], and castration-resistant prostate cancer-free survival [CRPCFS] were compared according to the combination of the pre-treatment predictors.

RESULTS

The 5-year BCRFS, CPFS, and CRPCFS rates were 78.5, 91.7, and 94.4% respectively; there were two PCa deaths. Multivariate analysis revealed that the clinical T stage (cT3b and cT4) and Grade Group (GG) 5 status were independent risk factors for poor BCRFS, CPFS, and CRPCFS. In the GG ≤ 4 group, the Kaplan-Meier curves for BCRFS, CPFS, and CRPCFS revealed excellent outcomes. However, in the GG5 group, patients with cT3b and cT4 PCa evidenced significantly poorer oncological outcomes than those with cT3a PCa.

CONCLUSION

The clinical T stage and GG status were significantly prognostic of oncological outcomes in patients with locally advanced PCa. In patients of GG ≤ 4 PCa, HDR-BT was effective even in patients with cT3b or cT4 PCa. However, in patients with GG5 PCa, careful monitoring is essential, particularly of patients with cT3b or cT4 PCa.

Repeat re-irradiation with interstitial HDR-brachytherapy for an in-field isolated nodal recurrence in a patient with HPV-positive squamous cell carcinoma of the head and neck

PURPOSE

Locoregionally recurrent head and neck cancer is a complex clinical scenario that often requires multimodality treatment. These patients have often previously received definitive treatment with a combination of surgery, radiation therapy, and systemic therapy, which can make further management difficult. A second isolated locoregional failure is rare and clinicians are faced with a challenge to optimize disease control while minimizing treatment-related toxicity.

METHODS AND MATERIALS

In this report, we present the diagnosis, management, and outcomes of a patient with an isolated locoregional recurrence who was previously treated with two courses of radiation. The patient was treated with a second course of reirradiation using interstitial brachytherapy as well as a discussion regarding patient selection and optimal management for recurrent head and neck cancer.

RESULTS

Repeat reirradiation using interstitial HDR-brachytherapy with the use of an alloderm spacer was successfully delivered to the patient for an in-field right neck nodal recurrence. He received a total EQD2/BED dose of 127.70/153.24 Gy. At 1-year followup, the patient was without evidence of recurrent disease or new significant side effects.

CONCLUSION

Recurrent head and neck cancer should be managed with a multidisciplinary approach given the complex clinical scenario. Reirradiation is a commonly used salvage measure for recurrent head and neck cancer that requires careful planning and patient selection due to prior treatment-related effects and dose constraints. We reported a case of a second course of reirradiation using interstitial HDR-brachytherapy for locoregionally recurrent head and neck cancer and showed no recurrence of disease or worsening long term side effects at 1 year.

Comparison of outcomes in high-risk prostate cancer patients treated with low-/high-dose-rate brachytherapy plus external beam radiotherapy

BACKGROUND

Although brachytherapy is a standard treatment option for patients with high-risk prostate cancer, only a few studies have compared low-dose-rate brachytherapy (LDR-BT) and high-dose-rate brachytherapy (HDR-BT). We applied propensity score-based inverse probability treatment weighting (IPTW) to compare oncological outcomes for LDR-BT and HDR-BT.

METHODS

We retrospectively assessed prognosis in 392 patients with high-risk localized prostate cancer who had undergone brachytherapy plus external beam radiation. IPTW was applied to adjust the Kaplan-Meier survival analyses and Cox proportional hazards regression analyses, with the goal of minimizing bias from patient background.

RESULTS

The IPTW-adjusted Kaplan-Meier survival analyses showed no statistically significant differences for time to biochemical recurrence, clinical progression, castration-resistant prostate cancer, or death from any cause. The IPTW-adjusted Cox regression analyses also showed that the modality of brachytherapy was not an independent factor in these oncological outcomes. Notably, the two groups differed regarding complications; LDR-BT was associated with a higher rate of acute grade ≥ 2 GU toxicity, and late grade 3 toxicity was noted only in HDR-BT.

CONCLUSION

Our analysis of long-term outcomes in patients with high-risk localized prostate cancer shows no significant differences in oncological outcomes between LDR-BT and HDR-BT, but some differences in toxicity, and offers patients and clinicians useful information in deciding management strategies for high-risk localized prostate cancer.

robotic and conventional stereotactic body radiotherapy for ultrahypofractionated treatment of prostate cancer

Background and purpose

Ultrahypofractionated radiation therapy is increasingly used in the treatment of prostate cancer. High-dose-rate brachytherapy (HDR-BT) and stereotactic body radiotherapy (SBRT) are representative methods of ultrahypofractionation. This study was performed to compare clinically applied treatment plans for patients who had been treated using HDR-BT vs. conventional or robotic SBRT.

Materials and methods

Calculated dose-volume indices between HDR-BT without a perirectal spacer (n = 20), robotic SBRT without a spacer (n = 40), and conventional (non-robotic) SBRT with a spacer (n = 40) were compared. Percentages against the prescription dose regarding the planning target volume (PTV), bladder, rectum, and urethra were statistically compared.

Results

The D50% of the PTV with HDR-BT (140.5% ± 4.9%) was significantly higher than that with robotic or conventional SBRT (116.2% ± 1.6%, 101.0% ± 0.4%, p < 0.01). The D2cm³ of the bladder with HDR-BT (65.6% ± 6.4%) was significantly lower than those with SBRT (105.3% ± 2.9%, 98.0% ± 1.3%, p < 0.01). The D2cm³ of the rectum with HDR-BT (60.6% ± 6.2%) was also significantly lower than those with SBRT (85.1% ± 8.8%, 70.4% ± 9.6%, p < 0.01). By contrast, the D0.1cm³ of the urethra with HDR-BT (117.1% ± 3.6%) was significantly higher than those with SBRT (100.2% ± 0.7%, 104.5% ± 0.6%, p < 0.01).

Conclusions

HDR-BT could administer a higher dose to the PTV and a lower dose to the bladder and rectum, at the cost of a slightly higher dose to the urethra compared with SBRT.

Brachytherapy boost improves survival and decreases risk of developing distant metastases compared to external beam radiotherapy alone in intermediate and high risk group prostate cancer patients

BACKGROUND AND PURPOSE

Despite several prospective trials showing a clinical benefit of combining external beam radiotherapy (EBRT) with brachytherapy boost (BTB) for the treatment of intermediate- and high-risk prostate cancer (PCa) patients, none of these trials were designed to test for a survival difference. In this study, we aimed to collect a large multi-institutional database to determine whether BT boost was associated with a statistically significant improvement in survival and a reduction of distant metastases based on real-world data.

MATERIAL AND METHODS

We collected the data of patients treated for intermediate- or high-risk PCa with definitive EBRT or BTB, with or without androgen deprivation therapy (ADT), between January 2003 and December 2014 at two tertiary institutions. The statistical endpoints included overall survival (OS), freedom from distant metastases (FFDM), and metastases-free survival (MFS). The impact of treatment modality was assessed using Cox regression models and log-rank testing after one-to-one propensity score matching.

RESULTS

A total of 1641 patients treated with EBRT (n=1148) or high-dose-rate BTB (n=493) were analyzed. The median survival and clinical follow-up were 117.8 (IQR 78-143.3) and 60.7 months, respectively. The radiotherapy modality (BTB) remained an independent prognostic factor for OS (HR 0.75; 95% CI 0.63-0.88; p<0.001), FFDM (HR 0.54; 95% CI 0.4-0.73; p<0.001), and MFS (HR 0.72; 95% CI 0.61-0.85; p<0.001). After propensity score matching, the remaining 986 patients were well-balanced in terms of age, maximum PSA, ISUP grade group, and TNM T stage. OS (p=0.001), FFDM (p<0.001) and MFS (p<0.001) were significantly higher in the BTB group.

CONCLUSIONS

There is a strong positive association between BTB and OS, FFDM, and MFS in PCa patients treated with definitive RT for intermediate- or high-risk PCa.

A novel approach for Venezia ovoid commissioning with a comprehensive analysis of source positions in high-dose-rate brachytherapy

PURPOSE

The lunar design of a Venezia ovoid makes commissioning of the applicator very challenging with traditional autoradiography. In this study, we propose a novel solution to ovoid commissioning and a quality assurance (QA) workflow to effectively assess the entire source path.

METHODS AND MATERIALS

A two-step commissioning process, using electron radiation and radiochromic films, was developed to verify the most distal source position. The ovoid was first attached to a film and was irradiated with a 12 MeV linac beam. This process was repeated on a separate, unexposed film, followed by irradiating it with a HDR source at the most distal position. Two lengths, including the ovoid thickness and the distance between the irradiated spot and the ovoid's outer surface, were obtained from the films' intensity maps. The offset value was calculated from the subtraction of the two measured lengths. Besides acquiring the offset, a source positional simulator (SPS) and a series of planar x-rays from two orthogonal orientations were used to characterize source movement within the ovoid.

RESULTS

Compared to x-ray-based autoradiography, the electron exposure significantly improved the ovoid's visibility on film. Our approach did not use surrogate, which further improved measurement outcomes by decreasing inherent uncertainties. The SPS results suggested the source movement was complex within the cervicovaginal area, but it was predictable with the proposed QA workflow.

CONCLUSION

We introduced a novel, surrogate-free method to commission the Venezia ovoid, which facilitated a manual applicator reconstruction. Additionally, we recommended QA multiple source positions to safely use the ovoid in clinical settings.

Intensity-modulated brachytherapy for vaginal cancer

This study aimed to evaluate the dose modulation potential of static and dynamic steel-shielded applicators using the Geant4 Application for Emission Tomography (GATE) Monte Carlo code for the treatment of vaginal cancer. The GATE TOOLKIT (version 9.0) was used to simulate vaginal cancer intensity-modulated brachytherapy (IMBT) in a pelvic water-equivalent phantom. IMBT performance of a multichannel static and single-channel dynamic steel-shielded applicator was compared to that of a conventional multichannel Plexiglas applicator. DoseActors were defined to calculate the absorbed dose and attached to the voxelized target and organs at risk (OARs). ⁶⁰Co and ¹⁹²Ir high-dose-rate seeds were used as irradiation sources. Dynamic IMBT decreased the D_2cc of the rectum and bladder by 28.67 and 28.11% using the ⁶⁰Co source and by 40.00 and 36.34% using the ¹⁹²Ir source, respectively. Static IMBT decreased the D_2cc for the rectum and bladder by 11.69 and 9.29% using the ⁶⁰Co source and by 22.21 and 17.71% using the ¹⁹²Ir source, respectively. In contrast, absorbed dose parameters (D₅, D₉₀, and D₁₀₀) for the target in the three techniques showed a mean relative variation of 0.96% (0.00-7.49%) for both sources. Static and dynamic IMBT using steel-shielded applicators provided relatively better OAR protection while maintaining similar target coverage in the treatment of vaginal cancer.

A deep learning-based self-adapting ensemble method for segmentation in gynecological brachytherapy

Purpose

Fast and accurate outlining of the organs at risk (OARs) and high-risk clinical tumor volume (HRCTV) is especially important in high-dose-rate brachytherapy due to the highly time-intensive online treatment planning process and the high dose gradient around the HRCTV. This study aims to apply a self-configured ensemble method for fast and reproducible auto-segmentation of OARs and HRCTVs in gynecological cancer.

Materials and methods

We applied nnU-Net (no new U-Net), an automatically adapted deep convolutional neural network based on U-Net, to segment the bladder, rectum and HRCTV on CT images in gynecological cancer. In nnU-Net, three architectures, including 2D U-Net, 3D U-Net and 3D-Cascade U-Net, were trained and finally ensembled. 207 cases were randomly chosen for training, and 30 for testing. Quantitative evaluation used well-established image segmentation metrics, including dice similarity coefficient (DSC), 95% Hausdorff distance (HD95%), and average surface distance (ASD). Qualitative analysis of automated segmentation results was performed visually by two radiation oncologists. The dosimetric evaluation was performed by comparing the dose-volume parameters of both predicted segmentation and human contouring.

Results

nnU-Net obtained high qualitative and quantitative segmentation accuracy on the test dataset and performed better than previously reported methods in bladder and rectum segmentation. In quantitative evaluation, 3D-Cascade achieved the best performance in the bladder (DSC: 0.936 ± 0.051, HD95%: 3.503 ± 1.956, ASD: 0.944 ± 0.503), rectum (DSC: 0.831 ± 0.074, HD95%: 7.579 ± 5.857, ASD: 3.6 ± 3.485), and HRCTV (DSC: 0.836 ± 0.07, HD95%: 7.42 ± 5.023, ASD: 2.094 ± 1.311). According to the qualitative evaluation, over 76% of the test data set had no or minor visually detectable errors in segmentation.

Conclusion

This work showed nnU-Net’s superiority in segmenting OARs and HRCTV in gynecological brachytherapy cases in our center, among which 3D-Cascade shows the highest accuracy in segmentation across different applicators and patient anatomy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-022-02121-3.

Impact of detector selection on commissioning of Leipzig surface applicators with improving immobilization in high-dose-rate brachytherapy

PURPOSE

Commission and treatment setup of Leipzig surface applicators, because of the steep dose gradient and lack of robust immobilization, is challenging. We aim to improve commissioning reliability by investigating the impact of detector choice on percentage depth dose (PDD) verifications, and to enhance accuracy and reproducibility in calibration/treatment setup through a simple and novel immobilization device.

METHODS AND MATERIALS

PDD distributions were measured with radiochromic films, optically stimulated luminescent dosimeters (OSLDs), a diode detector, and both cylindrical and parallel plate ionization chambers. The films were aligned to the applicators in parallel and transverse orientations. PDD data from a benchmarking Monte Carlo (MC) study were compared with the measured results, where surface doses were acquired from extrapolation. To improve setup accuracy and reproducibility, a custom-designed immobilization prototype device was made with cost-effective materials using a 3D printer.

RESULTS

The measured PDD data with different detectors had an overall good agreement (<±10%). The parallel plate ionization chamber reported unreliable doses for the smallest applicator. There was no remarkable dose difference between the two film setups. The two-in-one prototype device provided a rigid immobilization and a flexible positioning of the applicator. It enhanced accuracy and reproducibility in calibration and treatment setup.

CONCLUSION

We recommend using radiochromic films in the transverse orientation for a reliable and efficient PDD verification. The applicator's clinical applicability has been limited by a lack of robust immobilization. We expect this economical, easy-to-use prototype device can promote the use of Leipzig applicators in surface brachytherapy.

High-dose-rate remote brachytherapy for metachronous second primary carcinoma of soft palate by iridium 192 isotope in an afterload surface mold

Conservative management of metachronous second primary carcinoma of head and neck is preferred in order to preserve form and function. The purpose of the case report is to describe the treatment of metachronous second primary carcinoma of soft palate by high-dose-rate, remote, afterload brachytherapy. The brachytherapy was done in remote settings by afterloading Iridium 192 isotope carried through a custom fabricated surface mold. The mold enabled good adaptation, stability, and repeatable positioning of the radiation source at each treatment session of fractionated brachytherapy offering consistent dosimetric advantage through a single dosimetry calculation. Collaborative efforts of radiation oncologist and prosthodontist ensured conservative treatment in outpatient set up with minimal adverse effects.

Preoperative high-dose-rate brachytherapy for high-risk early-stage cervical cancer: Long-term clinical outcome analysis

OBJECTIVE

To report long-term oncological and toxicity outcomes after high-dose-rate brachytherapy (HDB) followed by oncologic surgery for patients with early-stage cervical cancer.

METHODS AND MATERIALS

From 2005 to 2019, all patients treated with preoperative HDB at Antoine Lacassagne Cancer Center for early-stage (IB1-IB2-IIA - FIGO 2018) cervical cancer with local relapse risk factors were included. HDB was performed followed by hysterectomy. Oncological and toxicity outcomes were evaluated prospectively.

RESULTS

We identified 61 patients, with a median follow-up of 84 months. Posthysterectomy complete pathological response was observed in 46 patients (75.4%). Six patients (9.8%) experienced recurrence, including 4 local relapses (6.6%), and 2 deaths (3.3%) due to cervical cancer. Five-year local, nodal and metastatic relapse-free survivals were 94% (95% CI 87-100%), 96% (95% CI 90-100%) and 93% (95% CI 86-100%) respectively. Five-year overall survival was 98% (95% CI 95-100%). No grade ≥ 3 acute toxicity was observed, and 3 patients (4.9%) experienced grade 2 acute toxicity. One patient presented grade 4 late digestive toxicity, and 6 patients had grade 2 late toxicity. Only 1 patient still had grade 2 toxicity, after 9 years follow-up.

CONCLUSIONS

To our knowledge, we are reporting the longest follow-up of a preoperative HDB cohort. With similar oncological outcomes and less morbidity compared to primary surgery treatment followed more or less by adjuvant radiotherapy, HDB followed by hysterectomy could be a promising therapeutic option for early-stage cervical cancers with poor prognostic factors.

Dosimetric study of Varian Universal Multi-Channel Cylinder System for High-Dose-Rate 192Ir Brachytherapy

PURPOSE

Recently, the Varian multichannel vaginal cylinder (MCVC) set for high-dose-rate ¹⁹²Ir brachytherapy was commercially released. This MCVC was distinct from our existing MCVC in its peripheral channel layout and tip design. This investigation sought to assess the dosimetric impact of these changes.

METHODS AND MATERIALS

The dimensions of the virtual model for each applicator were compared against both physical and radiographic measurements. Volumetric dose distributions were generated in silico using a model-based dose calculation algorithm (MBDCA). To characterize the effects of the new peripheral channel layout on dose to adjacent areas ("dose-spill"), point doses were compared using two sets of applicator-based reference points: at surface or 5 mm radially from surface. To evaluate the dose-shaping capabilities, a dose distribution was generated for the new applicator and assessed against a representative dose distribution for a patient previously treated with existing equipment.

RESULTS

Based on both physical and radiographic measurements, virtual models were representative of each applicator within ±1 mm. Commissioning of the MBDCA was benchmarked based on AAPM Working Group on Dose Calculation Algorithms in Brachytherapy. The layout of the new applicator reduced dose-spill to other reference points significantly, as much as a factor of 16.3, compared with the existing equipment. The rounded tip shape and curve of the peripheral channels in the new applicator produced more conformity to its HR-CTV than existing equipment.

CONCLUSIONS

Compared with our existing equipment, the design changes in the new Varian MCVC set offered improved control of dose spill and better conformality to HR-CTV.

Steering a Tendon-Driven Needle in High-Dose-Rate Prostate Brachytherapy for Patients with Pubic Arch Interference

High-dose-rate brachytherapy (HDR BT) is a radiation therapy that places radioactive sources at cancerous tissue using needles. HDR BT offers better dose conformality and sparing of clinical structures, lower operator dependency, and fewer acute irritative symptoms compared to the other form of BT (low-dose-rate (LDR)). However, use of HDR BT is limited for patients with pubic arch interference, where the transperineal path to the prostate is blocked. This study aims to introduce a tendon-driven needle that can bend inside tissue to reach desired positions inside prostate. Initial experiments in a phantom tissue showed the feasibility of the needle to get around the pubic arch for placement at hard-to-reach target positions.

ACR-ABS-ASTRO practice parameter for the performance of radionuclide-based high-dose-rate brachytherapy

PURPOSE

This practice parameter aims to detail the processes, qualifications of personnel, patient selection, equipment, patient and personnel safety, documentation, and quality control and improvement necessary for an HDR brachytherapy program.

METHODS AND MATERIALS

This practice parameter was revised collaboratively by the American College of Radiology (ACR), the American Brachytherapy Society (ABS), and the American Society for Radiation Oncology (ASTRO).

RESULTS

Brachytherapy is a radiotherapeutic modality in which radionuclide or electronic sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface, intracavitary, intraluminal, or interstitial application. Brachytherapy alone or combined with external beam radiotherapy plays an important role in the management and treatment of patients with cancer. High-dose-rate (HDR) brachytherapy uses radionuclides, such as iridium-192, at dose rates of ≥12 Gy/hr to a designated target point or volume, and it is an important treatment for a variety of malignant and benign conditions. Its use allows for application of high doses of radiation to defined target volumes with relative sparing of adjacent critical structures.

CONCLUSIONS

HDR brachytherapy requires detailed attention to personnel, equipment, patient and personnel safety, and continuing staff education. Coordination between the radiation oncologist and treatment planning staff and effective quality assurance procedures are important components of successful HDR brachytherapy programs.

The effectiveness of high-dose-rate brachytherapy with external beam radiotherapy for clinically locally advanced and node-positive prostate cancer: long-term results of a retrospective study

BACKGROUND

No standard treatment exists for locally advanced prostate cancer (PC). This study evaluated the long-term treatment outcomes and toxicity in patients with clinically locally advanced and/or lymph node (LN)-positive PC who underwent high-dose-rate brachytherapy (HDR-BT) with external beam radiotherapy (EBRT).

METHODS

The treatment outcomes and toxicities of 152 patients with PC who underwent HDR-BT with EBRT and had at least 2 years of observation were examined. The treatment dose was 19- and 13-Gy HDR-BT in two and single fractions, respectively, both combined with external irradiation of 46 Gy in 23 fractions. Long-term androgen deprivation therapy (ADT) for patients harboring very high-risk tumors was used in combination.

RESULTS

The median observation period was 59.7 (24.4-182.1) months. The 5-year prostate cancer-specific and recurrence-free (RFS) survival rates were 99.0% and 91.8%, respectively, with only two PC mortalities. When 5-year RFS was examined for each parameter, RFS was significantly lower in pre-radiotherapy (pre-RT) prostate-specific antigen (PSA) > 0.5 ng/mL (77.1%; p = 0.008), and presence of LN metastasis (68.1%; p = 0.017). Multivariable analysis demonstrated that pre-RT PSA (HR, 4.68; 95% CI, 1.39-15.67; p = 0.012) and presence of LN metastasis (HR, 4.70; 95% CI, 1.24-17.74; p = 0.022) were independent recurrence predictors. The 5-year cumulative incidence rate of grade ≥ 2 toxicities in genitourinary and gastrointestinal tracts were 15.4% and 1.3%, respectively.

CONCLUSIONS

HDR-BT combined with EBRT and long-term ADT shows promising disease control and tolerant toxicities for clinically locally advanced and LN-positive PC.

Palliative treatment with high-dose-rate endobronchial interventional radiotherapy (Brachytherapy) for lung cancer patients

PURPOSE

to report on the use of high-dose-rate (HDR) endobronchial interventional radiotherapy (brachytherapy, EBIRT) for palliation of symptoms in patients with lung cancer.

PATIENTS AND METHODS

retrospective review of lung cancer patients treated with HDR-EBIRT at our institution (1995-2017). Treatment results and treatment related toxicity were recorded. Clinical response was subjectively evaluated within 3 months after treatment. Overall survival (OS) was analyzed.

RESULTS

347 patients were identified. The median age was 69 years and the median follow-up time was 13.4 months. Most patients received external beam radiation therapy during the primary treatment. Within 3 months, 87.7% of the patients had complete or major response of their presenting symptoms. OS was 55.2% at 1 year, 18.3% at 2 years. Patients who had complete or major response had a longer median survival than other patients (13 versus 7 months, p = 0.03). Chronic bronchitis was found in 26.8%, while 7.8% of the patients died due to uncontrollable hemoptysis.

CONCLUSION

HDR-EBIRT is a safe and effective treatment option for the palliative treatment of lung cancer patients. HDR-EBIRT is most suitable as a re-irradiation technique. Further clinical studies are needed to validate its role.

Outcomes with multi-disciplinary management of central lung tumors with CT-guided percutaneous high dose rate brachyablation

BACKGROUND

Centrally located lung tumors present treatment challenges given their proximity to mediastinal structures including the central airway, esophagus, major vessels, and heart. Therapeutic options can be limited for medically inoperable patients, particularly if they have received previous thoracic radiotherapy. High dose rate (HDR) brachyablation was developed to improve the therapeutic ratio for patients with central lung tumors. The purpose of this study is to report initial safety and efficacy outcomes with this treatment for central lung malignancies.

METHODS

From September 2015 to August 2019, a total of 25 patients with 37 pulmonary tumors were treated with percutaneous HDR brachyablation. Treatment was delivered by a multi-disciplinary team of interventional radiologists, pulmonologists, and radiation oncologists. Twenty-three patients received a median dose of 21.5 Gy (range 15-27.5) in a single fraction, whereas two patients received median dose of 24.75 Gy (range 24-25.5) over 2-3 fractions. Tumor local control (LC) was evaluated by Response Evaluation Criteria in Solid Tumors v1.1. Treatment-related toxicities were graded by Common Terminology Criteria for Adverse Events v5.0, with adverse events less than 90 days defined as acute, and those occurring later were defined as late. LC, progression-free survival (PFS), and overall survival (OS) rates were estimated by the Kaplan-Meier method.

RESULTS

Of 37 treated tumors, 88% were metastatic. Tumor location was central and ultra-central in 24.3% and 54.1%, respectively. Average tumor volume was 11.6 cm³ (SD 12.4, range 0.57-62.8). Median follow-up was 19 months (range 3-48). Two-year LC, PFS, and OS were 96.2%, 29.7%, and 65.5%, respectively. Thirteen of 39 (33.3%) catheter implantation procedures were associated with trace minor pneumothorax requiring no intervention, 1 (2.5%) procedure with minor radiographic pulmonary hemorrhage, and 4 (10.3%) with major pneumothorax requiring chest tube insertions. All procedural complications resolved within 24 h from treatment. Acute grade 1-2 toxicity was identified in 4 patients, whereas none developed late toxicity beyond 90 days of follow-up.

CONCLUSION

Percutaneous HDR brachyablation is a safe and promising treatment option for centrally located primary and metastatic lung tumors. Future comparisons with stereotactic body radiotherapy and other ablative techniques are warranted to expand multi-disciplinary management options.

A multiobserver study investigating the effectiveness of prostatic multiparametric magnetic resonance imaging to dose escalate corresponding histologic lesions using high-dose-rate brachytherapy

PURPOSE

Using multiparametric MRI data and the pathologic data from radical prostatectomy specimens, we simulated the treatment planning of dose-escalated high-dose-rate brachytherapy (HDR-BT) to the Multiparametric MRI dominant intraprostatic lesion (mpMRI-DIL) to compare the dose potentially delivered to the pathologically confirmed locations of the high-grade component of the cancer.

METHODS AND MATERIALS

Pathologist-annotated prostatectomy midgland histology sections from 12 patients were registered to preprostatectomy mpMRI scans that were interpreted by four radiologists. To simulate realistic HDR-BT, we registered each observer's mpMRI-DILs and corresponding histology to two transrectal ultrasound images of other HDR-BT patients with a 15-Gy whole-gland prescription. We used clinical inverse planning to escalate the mpMRI-DILs to 20.25 Gy. We compared the dose that the histopathology would have received if treated with standard treatment plans to the dose mpMRI-targeting would have achieved. The histopathology was grouped as high-grade cancer (any Gleason Grade 4 or 5) and low-grade cancer (only Gleason Grade 3).

RESULTS

212 mpMRI-targeted HDR-BT plans were analyzed. For high-grade histology, the mpMRI-targeted plans achieved significantly higher median [IQR] D98 and D90 values of 18.2 [16.7-19.5] Gy and 19.4 [17.8-20.9] Gy, respectively, in comparison with the standard plans (p = 0.01 and p = 0.003). For low-grade histology, the targeted treatment plans would have resulted in a significantly higher median D90 of 17.0 [16.1-18.4] Gy in comparison with standard plans (p = 0.015); the median D98 was not significantly higher (p = 0.2).

CONCLUSIONS

In this retrospective pilot study of 12 patients, mpMRI-based dose escalation led to increased dose to high-grade, but not low-grade, cancer. In our data set, different observers and mpMRI sequences had no substantial effect on dose to histologic cancer.

Outcomes of Surgical Excision and High-Dose-Rate Brachytherapy for Earlobe Keloids

BACKGROUND

Radiotherapy as an adjuvant therapy to surgical resection has shown variable rates of recurrence treating earlobe keloids. The purpose of this study was to describe our experience with surgical excision followed by high-dose-rate brachytherapy and present our outcomes after 24 months of follow-up.

METHODS

Retrospective chart of 14 patients with 14 earlobe keloids treated with surgical excision followed by high-dose-rate brachytherapy, between January 2015 and May 2016 were enrolled. Database included demographics, Fitzpatrick skin type, laterality, lesion size, and follow-up visits information. Outcomes were assessed in terms of keloid recurrence rates, complications, and patient subjective aesthetical result satisfaction after 24 months of follow-up.

RESULTS

All procedures were completed without complications. Three patients experienced keloid recurrence after 6 (14.28%) and 12 months (7.14%). Three patients experienced mild signs of self-limited post-radiation dermatitis. Self-assessment of aesthetical result was considered "very good" in 71.43% of patients.

CONCLUSION

Surgical excision followed by high-dose-rate brachytherapy is secure and effective to treat earlobe keloids, and can be considered a first line combined treatment. Larger clinical trials comparing different irradiation protocols are still needed.

A Systematic Review and Meta-analysis of Local Salvage Therapies After Radiotherapy for Prostate Cancer (MASTER)

CONTEXT

Management of locally recurrent prostate cancer after definitive radiotherapy remains controversial due to the perceived high rates of severe genitourinary (GU) and gastrointestinal (GI) toxicity associated with any local salvage modality.

OBJECTIVE

To quantitatively compare the efficacy and toxicity of salvage radical prostatectomy (RP), high-intensity focused ultrasound (HIFU), cryotherapy, stereotactic body radiotherapy (SBRT), low-dose-rate (LDR) brachytherapy, and high-dose-rate (HDR) brachytherapy.

EVIDENCE ACQUISITION

We performed a systematic review of PubMed, EMBASE, and MEDLINE. Two- and 5-yr recurrence-free survival (RFS) rates and crude incidences of severe GU and GI toxicity were extracted as endpoints of interest. Random-effect meta-analyses were conducted to characterize summary effect sizes and quantify heterogeneity. Estimates for each modality were then compared with RP after adjusting for individual study-level covariates using mixed-effect regression models, while allowing for differences in between-study variance across treatment modalities.

EVIDENCE SYNTHESIS

A total of 150 studies were included for analysis. There was significant heterogeneity between studies within each modality, and covariates differed between modalities, necessitating adjustment. Adjusted 5-yr RFS ranged from 50% after cryotherapy to 60% after HDR brachytherapy and SBRT, with no significant differences between any modality and RP. Severe GU toxicity was significantly lower with all three forms of radiotherapeutic salvage than with RP (adjusted rates of 20% after RP vs 5.6%, 9.6%, and 9.1% after SBRT, HDR brachytherapy, and LDR brachytherapy, respectively; p ≤ 0.001 for all). Severe GI toxicity was significantly lower with HDR salvage than with RP (adjusted rates 1.8% vs 0.0%, p < 0.01), with no other differences identified.

CONCLUSIONS

Large differences in 5-yr outcomes were not uncovered when comparing all salvage treatment modalities against RP. Reirradiation with SBRT, HDR brachytherapy, or LDR brachytherapy appears to result in less severe GU toxicity than RP, and reirradiation with HDR brachytherapy yields less severe GI toxicity than RP. Prospective studies of local salvage for radiorecurrent disease are warranted.

PATIENT SUMMARY

In a large study-level meta-analysis, we looked at treatment outcomes and toxicity for men treated with a number of salvage treatments for radiorecurrent prostate cancer. We conclude that relapse-free survival at 5 years is equivalent among salvage modalities, but reirradiation may lead to lower toxicity.

Clinically-implementable template plans for multidwell treatments using Leipzig-style applicators in 192Ir surface brachytherapy

PURPOSE

Multiple dwell positions ("multidwell") within a Leipzig-style applicator can be used to increase dose uniformity and treatment area. Model-based dose calculation algorithms (MBDCAs) are necessary for accurate calculations involving these applicators because of their nonwater equivalency and complex geometry. The purpose of this work was to create template plans from MBDCA calculations and present their dwell times and positions for users of these applicators without access to MBDCAs.

METHODS AND MATERIALS

The Leipzig-style solid applicator model within our treatment planning system was used to design template plans. Five template plans, normalized to 0.3 cm depth within a water phantom, were optimized using the treatment planning system MBDCA. Each template plan contained unique dwell positions, times, and active lengths (0.5-1.5 cm). A single-dwell distribution was optimized for comparison. The stem of this applicator stops within the shell; therefore, one template plan contained an intrafraction rotation to determine the largest dose distribution achievable. Effects of imperfect applicator rotation were quantified by inserting rotational offsets and comparing the V_100%, D_95%, and minimum dose coverage for planning target volumes created from 80%/90% isodose lines.

RESULTS

The 90% (80%) isodose line dimensions at 0.3 cm depth for single-dwell increased from 0.94 × 0.97 (1.53 × 1.57) cm² to 2.09 × 1.24 (2.75 × 1.88) cm² in the largest template plan. Manually inserted angular offsets up to ±10° for the template plan requiring rotation preserved V_100%, D_95%, and minimum dose within 2.0%, 1.9%, and 8.0%, respectively.

CONCLUSION

A set of template plans was created to provide accessibility to the multidwell methodology, even for users without access to MBDCAs. Each template plan should be reviewed before clinical implementation.

Computed tomography versus magnetic resonance imaging in high-dose-rate prostate brachytherapy planning: The impact on patient-reported health-related quality of life

PURPOSE

High-dose-rate (HDR) prostate brachytherapy uses volumetric imaging for treatment planning. Our institution transitioned from computed tomography (CT)-based planning to MRI-based planning with the hypothesis that improved visualization could reduce treatment-related toxicity. This study aimed to compare the patient-reported health-related quality of life (hrQOL) and physician-graded toxicity outcomes of CT-based and MRI-based HDR prostate brachytherapy.

METHODS

From 2016 to 2019, 122 patients with low- or intermediate-risk prostate cancer were treated with HDR brachytherapy as monotherapy. Patients underwent CT only or CT and MRI imaging for treatment planning and were grouped per treatment planning imaging modality. Patient-reported hrQOL in the genitourinary (GU), gastrointestinal (GI), and sexual domains was assessed using International Prostate Symptom Score and Expanded Prostate Cancer Index Composite Short Form-26 questionnaires. Baseline characteristics, changes in hrQOL scores, and physician-graded toxicities were compared between groups.

RESULTS

The median follow-up was 18 months. Patient-reported GU, GI, and sexual scores worsened after treatment but returned toward baseline over time. The CT cohort had a lower baseline mean International Prostate Symptom Score (5.8 vs. 7.8, p = 0.03). The other patient-reported GU and GI scores did not differ between groups. Overall, sexual scores were similar between the CT and MRI cohorts (p = 0.08) but favored the MRI cohort at later follow-up with a smaller decrease in Expanded Prostate Cancer Index Composite Short Form-26 sexual score from baseline at 18 months (4.9 vs. 19.8, p = 0.05). Maximum physician-graded GU, GI, and sexual toxicity rates of grade ≥2 were 68%, 3%, and 53%, respectively, with no difference between the cohorts (p = 0.31).

CONCLUSION

Our study shows that CT- and MRI-based HDR brachytherapy results in similar rates of GU and GI toxicity. MRI-based planning may result in improved erectile function recovery compared with CT-based planning.

Dosimetry of a sonolucent material for an ultrasound-compatible gynecologic high-dose-rate brachytherapy cylinder using Monte Carlo simulation and radiochromic film

PURPOSE

he purpose of this study was to study the dosimetric characterization of sonolucent material "TPX" to be used toward gynecologic high-dose-rate brachytherapy treatments using ultrasound-compatible cylinders in non-model-based dose calculation workflows.

METHODS

Monte Carlo simulations were performed using EGSnrc application egs_brachy in cylinders of polymethylpentene (TPX) plastic, water, and PMMA. Simulations were performed of five 192Ir sources placed longitudinally in ∼3.7 cm diameter, 5.0 cm length cylinders (matching physical cylinders used in film measurements). TPX and PMMA dose distributions and percentage depth dose curves were compared relative to water. Film measurements were performed to validate egs_brachy simulations. TPX and PMMA cylinders were placed in a water tank using 3D-printed supports to position film radially and touching the surface of the cylinders. The same five 192Ir dwell positions were delivered as simulated in egs_brachy.

RESULTS

The egs_brachy and film percentage depth doses agreed within film uncertainties. The egs_brachy relative dose difference between TPX and water was (0.74 ± 0.09)% and between PMMA and water was (-0.79 ± 0.09)% over the dose scoring phantom. Dose differences for TPX and PMMA relative to water were less than ± 1% within 5 cm of the cylinder surface.

CONCLUSIONS

In a solid sonolucent sheath of TPX, the dosimetric differences are comparable with PMMA and other applicator materials in clinical use. No additional uncertainty to dose calculation is introduced when treating through TPX cylinders compared with current applicator materials, and therefore, it is acceptable to perform gynecologic brachytherapy treatments with a sonolucent sheath inserted during radiation delivery.

A comparison between revised Manchester Point A and ICRU-89-recommended Point A definition absorbed-dose reporting using CT images in intracavitary brachytherapy for patients with cervical carcinoma

PURPOSE

This study is a comparison between revised Manchester Point A and International Commission on Radiation Units and measurements (ICRU) 89 report-recommended Point A absorbed-dose reporting in intracavitary brachytherapy for patients with cervical carcinoma.

METHODS AND MATERIALS

The retrospective dosimetric study is based on the data of 32 patients with cervical carcinoma treated with high-dose-rate brachytherapy. Patients received 21 Gy in three fractions (7.0 Gy X three fractions) to Point A (A_flange, revised Manchester definition). All the patients were replanned with a new Point A (A_icru89) defined on CT images as per the American Brachytherapy Society/ICRU-89. The data collected were compared with the data obtained from Point A (A_flange).

RESULTS

When using the A_flange plan normalization method, the mean dose of 0.1 cc, 1 cc, and 2 cc bladder volumes was 820.79 ± 207.47 cGy, 654.66 ± 152.69 cGy, and 588.91 ± 136.35 cGy, respectively. Likewise, when using the ICRU-89 Point A_icru89 normalization method, the mean dose of 0.1 cc, 1 cc, and 2 cc bladder volumes was 869.30 ± 224.67 cGy, 693.24 ± 166.20 cGy, and 616.61 ± 150.32 cGy, respectively. For the rectum, Point A_flange normalization plans, the mean dose of 0.1 cc, 1 cc, and 2 cc volumes was 589.37 ± 163.26 cGy, 487.51 ± 126.03 cGy, and 442.70 ± 111.43 cGy, respectively. Likewise, using the A_icru89 plan, the mean 0.1 cc, 1 cc, and 2 cc rectum volume was 625.07 ± 171.31 cGy, 517.50 ± 131.05 cGy, 464.94 ± 121.81 cGy, respectively. The statistical mean difference of Total Reference Air Kerma rate, V₁₀₀ (cc), bladder, rectum and sigmoid, was found significant.

CONCLUSIONS

It has been found that the position of revised Manchester (A_flange) and ICRU-89 Point A does not match on CT images/radiograph, which resulted in variation in doses to the tumor, V₁₀₀ (cc), organ at risk, and Total Reference Air Kerma.

Evaluating the impact of real-time multicriteria optimizers integrated with interactive plan navigation tools for HDR brachytherapy

PURPOSE

Currently in high-dose-rate (HDR) brachytherapy planning, manual fine-tuning of an objective function is a common practice. Furthermore, automated planning approaches such as multicriteria optimization (MCO) are still limited to the automatic generation of a single treatment plan. This study aims to quantify planning efficiency gains when using a graphics processing unit-based MCO (gMCO) algorithm combined with a novel graphical user interface (gMCO-GUI) that integrates efficient automated and interactive plan navigation tools.

METHODS AND MATERIALS

The gMCO algorithm was used to generate 1000 Pareto optimal plans per case for 379 prostate cases. gMCO-GUI was developed to allow plan navigation through all plans. gMCO-GUI integrates interactive parameter selection tools directly with the optimization algorithm to allow plan navigation. The quality of each plan was evaluated based on the Radiation Treatment Oncology Group 0924 protocol and a more stringent institutional protocol (INSTp). gMCO-GUI allows real-time time display of the dose-volume histogram indices, the dose-volume histogram curves, and the isodose lines during the plan navigation.

RESULTS

Over the 379 cases, the fraction of Radiation Treatment Oncology Group 0924 protocol valid plans with target coverage greater than 95% was 90.8%, compared with 66.0% for clinical plans. The fraction of INSTp valid plans with target coverage greater than 95% was 81.8%, compared with 62.3% for clinical plans. The average time to compute 1000 deliverable plans with gMCO was 12.5 s, including the full computation of the 3D dose distributions.

CONCLUSIONS

Combining the gMCO algorithm with automated and interactive plan navigation tools resulted in simultaneous gains in both plan quality and planning efficiency.

A prototype open-ended multichannel intracavitary-interstitial hybrid applicator for gynecological high-dose-rate brachytherapy

This manuscript introduces a novel open-ended, multichannel intracavitary-interstitial hybrid applicator for gynecological high-dose-rate brachytherapy. A prototype was three-dimensionally (3D) printed using polylactic acid. The device was 25 mm in diameter and 150 mm in length, with eight evenly spaced peripheral channels around a central tandem channel, each 2.7 mm in diameter and with 2 mm source-to-cylinder-surface-distance. In contrast to conventional multichannel applicators, the new hybrid applicator was designed with open distal ends. Interstitial needles utilized in peripheral channels provided a closed environment for sources. The applicator body served as a template to aid in the placement of central tandem and peripheral needles. The physical prototype appropriately accommodated needles, tandem, and locking devices and, thus, was deemed magnetic resonance (MR) conditional. In our retrospective in silico studies of two representative prior patients, we simultaneously increased the target coverage and decreased the organ-at-risk (OAR) dose to 2 cc (D_2cc). Specifically, the minimum dose covering 90% of the volume (D_90%) was improved by 2.1% (9.2%) minimum (maximum) of the prescription dose. Additionally, the OAR D_2cc was decreased by 0.5% (4.5%), 8.2% (12.9%), 3.9% (9.2%), and 4.6% (19.8%) minimum (maximum) of the prescription dose to the sigmoid, bladder, rectum, and bowel, respectively. This prototype demonstrated significant potential for patients in whom it would be useful to provide multichannel capabilities beyond the applicator body.

Feasibility of using multiple-dwell positions in 192Ir Leipzig-style brachytherapy surface applicators to expand target coverage and clinical application

PURPOSE

Leipzig-style applicators for surface brachytherapy are traditionally used with a single-source dwell position. This study explores the feasibility of using multiple-source dwell positions ("multidwell") to improve the dose coverage and applicability of Leipzig-style applicators.

METHODS AND MATERIALS

A virtual model of the Leipzig-style applicator was commissioned for a model-based dose calculation algorithm (MBDCA) and compared against American Association of Physicists in Medicine working group 186 benchmarking data sets and ionization chamber point measurements. An absolute dosimetry technique based on radiochromic film was used to validate both single-dwell and multidwell plans.

RESULTS

Dose distributions generated from the MBDCA-based virtual model were consistent with working group data sets, ion chamber measurements, and radiochromic film analysis. In one multidwell configuration, at 3 mm prescription depth, the 80% isodose width was increased to 25 mm, compared with 15 mm in the same dimension for a single-dwell delivery. In the same multidwell configuration, the flatness, measured as >98% isodose line, was more than doubled to 8 mm, compared with 3 mm in the same dimension. For multidwell plans, 2-D planar agreement between radiochromic film and MBDCA exceeded 93% in gamma analysis (3%/1 mm criteria). Submillimeter positional agreement was found, with a total dosimetric uncertainty of 4.5% estimated for the entire system.

CONCLUSIONS

Leipzig-style surface applicators with multiple-source dwell positions have been benchmarked against radiochromic film dosimetry. Results show that the clinically viable coverage area can be increased significantly.

Rates of rectal toxicity in patients treated with high dose rate brachytherapy as monotherapy compared to dose-escalated external beam radiation therapy for localized prostate cancer

BACKGROUND

Using a prospectively collected institutional database, we compared rectal toxicity following high dose rate (HDR) brachytherapy as monotherapy relative to dose-escalated external beam radiotherapy (EBRT) for patients with localized prostate cancer.

METHODS

2683 patients treated with HDR or EBRT between 1994 and 2017 were included. HDR fractionation was 38 Gy/4 fractions (n = 321), 24 Gy/2 (n = 96), or 27 Gy/2 (n = 128). EBRT patients received a median dose of 75.6 Gy in 1.8 Gy fractions [range 70.2-82.8 Gy], using either 3D conformal or intensity modulated radiotherapy (IMRT). EBRT patients underwent 3D image guidance via an off-line adaptive process.

RESULTS

Median follow-up was 7.5 years (7.4 years for EBRT and 7.9 years for HDR). 545 patients (20.3%) received HDR brachytherapy and 2138 (79.7%) EBRT. 69.1% of EBRT patients received IMRT. Compared to EBRT, HDR was associated with decreased rates of acute grade ≥2 diarrhea (0.7% vs. 4.5%, p < 0.001), rectal pain/tenesmus (0.6% vs. 7.9%, p < 0.001), and rectal bleeding (0% vs. 1.6%, p = 0.001). Rates of chronic grade ≥2 rectal bleeding (1.3% vs. 8.7%, p < 0.001) and radiation proctitis (0.9% vs. 3.3%, p = 0.001) favored HDR over EBRT. Rates of any chronic rectal toxicity grade ≥2 were 2.4% vs. 10.5% (p < 0.001) for HDR versus EBRT, respectively. In those treated with IMRT, acute and chronic rates of any grade ≥2 GI toxicity were significantly reduced but remained significantly greater than those treated with HDR.

CONCLUSIONS

In appropriately selected patients with localized prostate cancer undergoing radiation therapy, HDR brachytherapy as monotherapy is an effective strategy for reducing rectal toxicity.

High-dose-rate brachytherapy for localized penile cancer: Evolution of a technique

PURPOSE

High-dose-rate (HDR) brachytherapy is a convenient treatment option for selected patients with T1-T2 penile squamous cell carcinoma (SCC), providing high rates of penile preservation and tumor control. We present the results of penile SCC treated with HDR brachytherapy either interstitially or via a surface mold.

METHODS AND MATERIALS

Between November 2009 and April 2019, seven patients (2 T1a and 5 T2) were treated with interstitial HDR and 8 (1 Tis, six T1a, and one T1b) with surface mold. Prescribed dose for interstitial patients ranged from 38.4 Gy in 6 days (3.2 Gy × 12) to 53 Gy in 9 days (3.12 × 17), BID. All patients treated with mold brachytherapy received 40 Gy in 10 fractions BID. Toxicity and oncological results were assessed for both groups, and their relation with dosimetry is described.

RESULTS

Median follow up was 90 months for interstitial and 27 months for those treated with surface mold. Fourteen of 15 patients are alive and disease-free; one surface mold patient died of non-small-cell lung cancer. There was one relapse in each group, each treated with salvage penectomy. The potency was preserved in 82%. For interstitial, G2 necrosis occurred in 43%, G2 meatal stenosis in 29% and G3 stenosis in 14%.

CONCLUSIONS

Both techniques have excellent rates of tumor control and organ preservation. Implant geometry and homogeneity constraints must be carefully designed to minimize toxicity in interstitial brachytherapy. Urethral contouring and reporting of dosimetric parameters should be defined.

Deployment and performance of model-based dose calculation algorithm in 192Ir shielded cylinder brachytherapy

PURPOSE

The purpose of the study was to integrate model-based dose calculation algorithm (MBDCA) and 3-D planning into our institutional capabilities for clinical cases with inherent heterogeneities, namely shielded cylinder cases, which were previously performed using templates.

METHODS AND MATERIALS

AcurosBV (Varian Medical Systems) was selected as MBDCA, and we compared results against the American Association of Physicists in Medicine working group (WG) reference Test Case #4, which contains a 36-mm-diameter 180-degree shielded cylinder. The last five clinically used template plans, as generated with ABACUS (Varian Medical Systems), were compared against MBDCA results. Clinical plans used 20-, 23-, and 26-mm-diameter cylinders, prescribed from 5 to 7 Gy, 50- to 110-mm active length, 7 to 21 dwell positions, with 5- or 10-mm spacing.

RESULTS

Compared with the WG reference plan, AcurosBV produced excellent agreement, within 1% at reference points. Larger deviations arose only within the applicator itself. Historical plans generated using ABACUS had higher point dose than AcurosBV by 3-4% or 2-3% using transport within medium at prescription points, with dose to medium or water, respectively.

CONCLUSIONS

To verify the accuracy of our MBDCA algorithm, we benchmarked against the WG data set available for shielded cylinders. We discovered a 3-4% difference in dose from our established historical templates, which is easily outweighed by daily positioning uncertainties. Dose distributions from MBDCA were used to assess and validate existing historical templates.

Accelerated partial-breast irradiation with high-dose-rate brachytherapy: Mature results of a Phase II trial

PURPOSE

The purpose of this study was to report mature clinical and cosmetic results of accelerated partial-breast irradiation with interstitial multicatheter high-dose-rate brachytherapy (HDR-BRT) in patients with early breast cancer.

METHODS AND MATERIALS

133 patients were recruited in a Phase II trial of exclusive HDR-BRT. Inclusion criteria were age ≥40 years, PS 0-2, unifocal invasive ductal cancer, intraductal cancer component <25%, negative axillary nodes, and tumor size ≤2.5 cm. Treatment schedule was 4 Gy twice a day up to a total dose of 32 Gy in eight fractions.

RESULTS

Median age was 67 years (range, 42-85). There were 7 (5%) pT1a, 48 (36%) pT1b, 72 (54%) pT1c, and 6 (5%) pT2. Estrogen and progesterone receptors were positive in 119 (89%) and 93 (70%) patients, respectively. The median followup was 110 months (range, 12-163). After HDR-BRT, there were 3 (2%) in-field breast recurrences and 1 (1%) out-field breast recurrence. 5 (4%) patients developed contralateral breast cancer, another one (1%) isolated regional relapse in axillary node and 3 (2%) distant progression of disease. 19 (14%) patients reported a second primary cancer. 5-, 10-, and 13-year overall survival and cancer-specific survival were 95% and 100%, 84.5% and 100%, and 81.4% and 100%, respectively. Cosmetic outcome was excellent in 80% of cases. Late toxicity was significantly related to the skin administered doses (≤55% vs. > 55% of the prescribed dose, p < 0.05).

CONCLUSIONS

Accelerated partial-breast irradiation delivered with HDR-BRT in selected patients with breast cancer was associated to high local control and survival with excellent cosmetic outcomes overall when skin dose was ≤55%.

Salvage treatment with sole high-dose-rate endobronchial interventional radiotherapy (brachytherapy) for isolated endobronchial tumor recurrence in non-small-cell lung cancer patients: a 20-year experience

PURPOSE

The purpose of this study was to report on the use of high-dose-rate (HDR) endobronchial interventional radiotherapy (brachytherapy) for isolated endobronchial tumor recurrence in patients with non-small-cell lung cancer, in whom a surgery or external radiation treatment is not possible.

METHODS AND MATERIALS

A retrospective review of the patients with endobronchial tumors treated with HDR-endobronchial interventional radiotherapy at our institution (1995-2015) was performed. Treatment results and treatment-related toxicity were recorded. Clinical response was evaluated by bronchoscopy 3 months after treatment. Disease-free survival and overall survival were analyzed.

RESULTS

One hundred twenty-six patients were identified. The median age was 63 years, and median followup time was 67.2 months. Three-month complete local response was 86.5%. At 5 years, disease-free survival was 41.4% and overall survival was 23.6%. 12.7% of the patients died from massive hemoptysis.

CONCLUSION

HDR-endo brochial brachytherapy is an effective treatment option with acceptable toxicity for patients with endobronchial tumor recurrence in whom surgery and external beam radiotherapy are contraindicated.

High-dose-rate brachytherapy as monotherapy for prostate cancer: The impact of cellular repair and source decay

PURPOSE

This work quantifies the influence of intrafraction DNA damage repair and cellular repopulation on biologically effective dose (BED) in Ir-192 high-dose-rate brachytherapy for prostate cancer. In addition, it examines the effect of source-decay-induced BED variation for patients treated at different time points in a source exchange cycle.

MATERIALS AND METHODS

Current fractionation schemes are based on simplified-form BED = nd(1 + d/(α/β)), which assumes that intrafraction repair, interfraction repair, and repopulation are negligible. We took accepted radiobiological parameters of T_k, T_p, and α from the recommendations of the AAPM TG-137, and recalculated the full-form BED. Fraction times were normalized to require 15 min for 20 Gy at 10 Ci. Calculations were carried out for both α/β = 1.5 and 3 Gy.

RESULTS

After accounting for intrafraction repair, interfraction repair, and/or repopulation, full-form BED calculations showed significant values, as compared with simplified-form BED. For 1-fraction 20 Gy fractionation, the full-form BED was only 64-82% of the simplified-form BED. Dose protraction effects were milder for smaller prescriptions (6 Gy/Fx), where full form was 87-94%. With regard to source decay, BED varied >20% for patients treated at the beginning and the end of a source exchange cycle for 20 Gy single-fraction prescription.

CONCLUSIONS

Repair and repopulation can be significant in monotherapy high-dose-rate for prostate cancer. As fractionation schemes are established, the simplified BED calculation may not be appropriate. Investigators should consider evaluating BED as a range rather than a discrete value when presenting results unless source activity is explicitly incorporated as well.

A modified technique for fabrication of custom-made afterload brachytherapy appliance

Radiotherapy for carcinomas that involve the mouth and its related structures has been improved by the usage of different prostheses known as radiation carriers. These prostheses can accurately position radionuclide such as radium, iridium, cesium, and cobalt to allow adequate transfer of a concentrated radiation dose to a tumor region. At the same time, they minimize the exposure to radiation of nearby tissues due to rapid fall-off the radioactivity and thus minimizing the side effects of radiation. This study emphasizes the usage of a modified technique for the development of afterload mold brachytherapy appliance for squamous cell carcinoma patients of hard palate/soft palate.

Dose distribution verification in high-dose-rate brachytherapy using a highly sensitive normoxic N-vinylpyrrolidone polymer gel dosimeter

Rapid technological advances in high-dose-rate brachytherapy have led to a requirement for greater accuracy in treatment planning system calculations and in the verification of dose distributions. In high-dose-rate brachytherapy, it is important to measure the dose distribution in the low-dose region at a position away from the source in addition to the high-dose range in the proximity of the source. The aim of this study was to investigate the accuracy of a treatment plan designed for prostate cancer in the low-dose range using a normoxic N-vinylpyrrolidone-based polymer gel (VIPET gel) dosimeter containing inorganic salt as a sensitizer (iVIPET). The dose response was evaluated on the basis of the transverse relaxation rate (R₂) measured by magnetic resonance scanning. In the verification of the treatment plan, gamma analysis showed that the dose distributions obtained from the polymer gel dosimeter were in good agreement with those calculated by the treatment planning system. The gamma passing rate according to the 2%/2 mm criterion was 97.9%. The iVIPET gel dosimeter provided better accuracy for low doses than the normal VIPET gel dosimeter, demonstrating the potential to be a useful tool for quality assurance of the dose distribution delivered by high-dose-rate brachytherapy.

Development and dosimetric assessment of a patient-specific elastic skin applicator for high-dose-rate brachytherapy

PURPOSE

The purpose of this study was to develop a patient-specific elastic skin applicator and to evaluate its dosimetric characteristics for high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

We simulated the treatment of a nonmelanoma skin cancer on the nose. An elastic skin applicator was manufactured by pouring the Dragon Skin (Smooth-On Inc., Easton, PA) with a shore hardness of 10A into an applicator mold. The rigid skin applicator was printed using high-impact polystyrene with a shore hardness of 73D. HDR plans were generated using a Freiburg Flap (FF) applicator and patient-specific rigid and elastic applicators. For dosimetric assessment, dose-volumetric parameters for target volume and normal organs were evaluated. Global gamma evaluations were performed, comparing film measurements and treatment planning system calculations with various gamma criteria. The 10% low-dose threshold was applied.

RESULTS

The V_120% values of the target volume were 56.9%, 70.3%, and 70.2% for HDR plans using FF, rigid, and elastic applicators, respectively. The maximum doses of the right eyeball were 21.7 Gy, 20.5 Gy, and 20.5 Gy for the HDR plans using FF, rigid, and elastic applicators, respectively. The average gamma passing rates were 82.5% ± 1.5%, 91.6% ± 0.8%, and 94.8% ± 0.2% for FF, rigid, and elastic applicators, respectively, with 3%/3 mm criterion.

CONCLUSIONS

Patient-specific elastic skin applicator showed better adhesion to irregular or curved body surfaces, resulting in better agreement between planned and delivered dose distributions. The applicator suggested in this study can be effectively implemented clinically.

Radical dose escalation by high-dose-rate brachytherapy for localized prostate cancer-Significance of prostate-specific antigen nadir level within 18 months as correlation for long-term biochemical control

PURPOSE

High-dose-rate brachytherapy (HDR-BT) for dose escalation in localized prostate cancer has been established as one standard treatment option. However, long-term results at followup (FU) ≥5 years are usually needed to ensure robustness of reported outcomes. Potential benefit of salvage therapy is, nevertheless, higher when relapse is diagnosed early. This study aimed to solve this dilemma by evaluating the prostate-specific antigen (PSA) nadir for early prediction of long-term biochemical control.

METHODS AND MATERIALS

Combined pelvis-external beam radiation/HDR-BT boost to EQD2 >100 Gy (α/β = 3) was performed in 459 consecutively treated patients. These patients with an FU ≥ 24 months were analyzed and stratified in PSA nadir (nPSA)-groups by PSA nadir within 18 months after radiotherapy (nPSA18). Kaplan-Meier/log-rank tests and Cox-regression models were used to compare the study endpoints.

RESULTS

The mean FU was 77 months. A PSA nadir within 18 months (nPSA18) <0.5 ng/mL was achieved in 222 patients with median time to reach nPSA18 of 7 months. The 5-year American Society of Therapeutic Radiology and Oncology (ASTRO) biochemical control (prostate-specific antigen disease-free survival) for the nPSA18 group <0.5 ng/mL was 89% and for the group ≥ 0.5 ng/mL, it was 78.6% (p = 0.011). nPSA18 was an independent predictor of cancer-specific survival, distant metastasis-free survival, and biochemical control (ASTRO) (p = 0.026, p = 0.020, and p = 0.01, respectively).

CONCLUSIONS

The present results suggest that the PSA nadir level within 18 months after radiotherapy may serve as an early parameter for long-term biochemical control according to ASTRO definitions following radical dose escalation by HDR-BT for prostate cancer. Excellent outcomes were associated with nPSA18 < 0.5 ng/mL.

Retrospective analysis of multi-institutional, patient-specific treatment planning results of high-dose-rate intracavitary brachytherapy for gynecological cancer using V100

The objective of this study was to clarify the usefuleness of the K parameters of the independent verification method using V_100% (the volume of water receiving 100% of the prescription dose) for institutions implementing the high-dose-rate (HDR) intracavitary brachytherapy for gynecological cancer. The data of 249 plans of 11 institutions in Japan were used, and the constant K value obtained by a parameter fit for single-¹⁹²Ir, two-¹⁹²Ir, and three-¹⁹²Ir systems was calculated. The predicted total dwell time calculated using the constant K value was defined as T_pr, and the total dwell time calculated using a radiation treatment planning system was defined as T_RTP. The ratio of T_pr and T_RTP for each plan was calculated. The constant K values (95% CI) obtained for each system outlined above were 1233 (1227-1240), 1205 (1199-1211), and 1171 (1167-1175), respectively. Regarding the T_pr/T_RTP, the entire data were within 0.9-1.1. For accurate verification, it was clarified that constant K values should be calculated for each system. The Nuclear Regulatory Commission considers a difference of 20% between the prescribed total dose and the administered total dose as a reportable medical event. There is a need for a quick method to verify the accuracy with a minimum of 10% threshold of a plan. The constant K values in this study were obtained from multiple institutions, and the variation in the values among these institutions was small. The data obtained by this study may be used as a parameter of this verification method employed by numerous institutions, particularly those who have recently initiated HDR brachytherapy. In addition, for institutions already using this method, this data might be useful for the validation of the parameters which were used in such institutions.

Interfraction Dose Variations in Organs at Risk during CT-Based High-Dose-Rate Brachytherapy in Locally Advanced Carcinoma Cervix: An Early Experience of a Tertiary Care Center

Purpose:

Dose received by organs at risk (OAR) in high-dose-rate (HDR) intracavitary brachytherapy (ICBT) for locally advanced cervical cancer impacts the late toxicity profile of the treatment. In the present study, we analyzed the inter-fraction variations of the minimum dose received by the most irradiated 2cc volumes (D_2cc) of the OARs in ICBT.

Methods and Materials:

This prospective study included 40 patients with cervical cancer stage FIGO IIB-IVA treated with HDR ICBT and concomitant chemoradiotherapy with Computerized tomography (CT)- based three-dimensional planning. In addition, for 20 (of the 40) patients, the first fraction plan was superimposed on the second fraction images for studying its dosimteric impact on the OAR. The D_2cc data for the OAR was statistically analyzed for interfraction variations with Chi-square test or Fisher exact test as applicable. Paired t-test was used to compare the difference in means for the D_2cc values between the three fractions.

Results:

The interfraction variations of the D_2cc values of the OAR were statistically insignificant having P = 0.41, 0.8, and 0.20 for bladder, rectum, and sigmoid, respectively. Further, in 6 out of 20 cases, wherein first fraction plan was superimposed on second fraction images, the OAR doses exceeded the prescribed tolerance limits.

Conclusion:

We did not find variations in the OAR doses when each fraction was planned and treated individually. However, we found that if a single plan is used to treat subsequent fractions, OAR doses may exceed tolerance in about 30% of the cases. We believe that a larger sample size with improved compliance of bladder and bowel protocols would be needed to arrive at definitive conclusions.

Impact of different Ir-192 source models on dose calculations in high-dose-rate brachytherapy

In high-dose-rate brachytherapy, the geometry of the radioactive source is sometimes updated. Some institutions use a different source model for the dose calculation in treatment planning and treatment. The effects of this discrepancy were examined for four types of treatment plans, and ten patients were selected for each treatment plan. The impact of different source models depended on the types of treatment plan, patients, and dose index. To reduce the uncertainty and improve the reliability of the data, it would be better to use more robust metrics (D90 and D2cc) for treatment planning evaluation in facilities with this problem.

A Medicare cost analysis of MRI- versus CT-based high-dose-rate brachytherapy of the cervix: Can MRI-based planning be less costly?

PURPOSE

While some institutions deliver multiple fractions per implant for MRI-based planning, it is common for only one fraction to be delivered per implant with CT-based cervical brachytherapy. The purpose of this study was to compare physician costs, hospital costs, and overall costs for cervical cancer patients treated with either CT-based or MRI-based high-dose-rate (HDR) cervical brachytherapy to determine if MRI-based brachytherapy as described can be financially feasible.

METHODS AND MATERIALS

We identified 40 consecutive patients treated with curative intent cervical brachytherapy. Twenty patients underwent CT-based HDR brachytherapy with five fractions delivered in five implants on nonconsecutive days in an outpatient setting with the first implant placed with a Smit sleeve under general anesthesia. Twenty patients received MRI-based HDR brachytherapy with four fractions delivered in two implants, each with MRI-based planning, performed 1-2 weeks apart with an overnight hospital admission for each implant. We used Medicare reimbursements to assess physician costs, hospital costs, and overall cost.

RESULTS

The median cost of MRI-based brachytherapy was $14,248.75 (interquartile range [IQR]: $13,421.32-$15,539.74), making it less costly than CT-based brachytherapy with conscious sedation (i.e., $18,278.85; IQR: $17,323.13-$19,863.03, p < 0.0001) and CT-based brachytherapy with deep sedation induced by an anesthesiologist (i.e., $27,673.44; IQR: $26,935.14-$29,511.16, p < 0.0001). CT-based brachytherapy with conscious sedation was more costly than CT-based brachytherapy with deep sedation (p < 0.001).

CONCLUSIONS

MRI-based brachytherapy using the described treatment course was less costly than both methods of CT-based brachytherapy. Cost does not need to be a barrier for MRI-based cervical brachytherapy, especially when delivering multiple fractions with the same application.

Image-guided interstitial high-dose-rate brachytherapy for locally recurrent uterine cervical cancer: A single-institution study

PURPOSE

The aim of this study was to investigate the efficacy and safety of image-guided high-dose-rate (HDR) interstitial brachytherapy (ISBT) for reirradiation of locally recurrent uterine cervical cancer.

METHODS AND MATERIALS

Between 2008 and 2015, patients receiving reirradiation using HDR-ISBT for local gross recurrence of uterine cervical cancer after definitive or postoperative radiotherapy were analyzed retrospectively. The prescription doses per fraction ranged 2.5-6.0 Gy, whereas the cumulative equivalent doses in 2 Gy fractions ranged 48.6-82.5 Gy. The effects of prognostic factors on the local control (LC), progression-free survival, and overall survival were analyzed, and late toxicity data were evaluated.

RESULTS

Eighteen patients were included in the analysis, with a median followup of 18.1 months. A tumor response was obtained in all patients, with radiological and pathological complete remission seen in 12 (66.7%) patients. The 2-year LC, progression-free survival, and overall survival rates for all patients were 51.3%, 20.0%, and 60.8%, respectively. The hemoglobin level and maximum tumor diameter were shown to be statistically significant prognostic factors for LC (p = 0.028 and 0.009, respectively). Late ≥ Grade 2 adverse events were observed in 5 patients (27.8%).

CONCLUSIONS

Image-guided HDR-ISBT for the reirradiation of locally recurrent uterine cervical cancer may play an important role for local tumor control in a subgroup of patients. However, the treatment indication must be weighed against the risk of higher-grade late toxicity.

Association of bladder dose with late urinary side effects in cervical cancer high-dose-rate brachytherapy

PURPOSE

The purpose of this work was to study the association between specific urinary sequelae and locally accumulated dose to the bladder wall and bladder neck in the treatment of cervical cancer with multifraction high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

A cohort of 60 cervical cancer patients, treated with both external beam and five HDR brachytherapy insertions between 2008 and 2014 at the BC Cancer Agency, was identified. The accumulated dose received over five brachytherapy sessions was evaluated for the bladder wall and bladder neck of each patient using dosimetric parameters calculated from deformably registered image data sets. These parameters were examined as potential predictors of urinary sequelae including hematuria, frequency, urgency, incontinence, stream, nocturia, and dysuria. Two different dichotomization schemes were evaluated for grouping patients into Case and Control groups. The two-sample Student's t test was used for normally distributed samples and the Mann-Whitney nonparametric U test for non-normal distributions.

RESULTS

A strong association between dose to the bladder neck and incontinence was found (p = 0.001). A statistically significant association (p < 0.05) was also observed between urgency and certain bladder-wall parameters.

CONCLUSIONS

Localized dose to the bladder neck is a potential predictor of urinary incontinence, whereas weaker associations were observed between urgency and some bladder-wall parameters.

The American College of Radiology and the American Brachytherapy Society practice parameter for the performance of radionuclide-based high-dose-rate brachytherapy

Brachytherapy is a radiation therapy method in which radionuclide sources are used to deliver a radiation dose at a distance of up to a few centimeters by surface, intracavitary, intraluminal, or interstitial application. This practice parameter refers only to the use of radionuclides for brachytherapy. Brachytherapy alone or combined with external beam therapy plays an important role in the management and treatment of patients with cancer. High-dose-rate (HDR) brachytherapy uses radionuclides such as iridium-192 at dose rates of 20 cGy per minute (12 Gy per hour) or more to a designated target point or volume. High-dose-rate (HDR) brachytherapy is indicated for treating malignant or benign tumors where the treatment volume or targeted points are defined and accessible.

Long-term results of a phase II prospective study

PURPOSE

We report the long-term results of phase II prospective study with accelerated partial breast irradiation (APBI) using interstitial multi-catheter high-dose-rate brachytherapy.

METHODS

240 patients received APBI (4Gy, twice daily; total dose 32Gy).

RESULTS

Median follow-up was 96months. Recurrences in the treated breast developed in 8 patients (3.3%) at a median of 73months after APBI. The 5- and 10-year cumulative incidences were respectively, 1.8% (95%CI: 0.6-4.3) and 6.6% (95%CI: 2.7-12.9). Regional recurrences developed in 5 patients (2%) at a median of 28months and distant metastases in 8 (3.3%) at a median of 32.5months. Breast cancer specific mortality occurred in 6 patients (2.5%) at a median of 60months. Acute toxicity developed in 71 (29.6%) patients (G1 in 60 and G2 in 11). Almost all were skin toxicity and hematomas. Late toxicity was observed in 90 patients (37.5%), G1 in 97 cases and G2 in 11. Some patients presented with more than one type of toxicity. Teleangectasia and fibrosis were the most common (48 and 44 cases respectively), followed by fat necrosis (in 18 patients) Tamoxifen emerged as the only risk factor for breast fibrosis (p=0.007). Cosmetic results were judged by the physicians as excellent in 174 (83.7%) patients, good in 25 (12%) fair in 8 (3.8%) and poor in 1 (0.5%); 174 patients (83.7%) judged outcomes as excellent, 26 (12.4%) as good, 7 (3.4%) as fair and 1 (0.5%) as poor. Physician/patient agreement was good (weighted k-value 0.72).

CONCLUSIONS

APBI with interstitial multi-catheter brachytherapy was associated with good outcomes, low relapse and toxicity rates. Few events during this long-term follow-up preclude identifying specific features of patients at risk of relapse and illustrate the need for a large data-base.