Reirradiation for recurrent gynecologic cancer using high-dose-rate brachytherapy in Japan: A multicenter survey on practice patterns and outcomes

BACKGROUND AND PURPOSE

The aim of the study is to examine the present status of reirradiation with high-dose-rate (HDR) brachytherapy for recurrent gynecologic cancer in Japan and to determine the role of this therapy in clinical practice.

MATERIALS AND METHODS

A retrospective multicenter chart review was performed for reirradiation for gynecologic cancer using HDR brachytherapy. Each center provided information on patient characteristics, treatment outcomes, and complications.

RESULTS

The study included 165 patients treated at 9 facilities from 2000 to 2018. The analysis of outcomes included 142 patients treated with curative intent. The median follow-up time for survivors was 30 months (range 1-130 months). The 3-year overall survival (OS), progression-free survival (PFS), and local control (LC) rates were 53 % (95 %CI: 42-63 %), 44 % (35-53 %), and 61 % (50-70 %) for cervical cancer; 100 % (NA), 64 % (30-85 %), and 70 % (32-89 %) for endometrial cancer; and 54 % (13-83 %), 38 % (6-72 %), and 43 % (6-78 %) for vulvar and vaginal cancer, respectively. In multivariate analysis, interval to reirradiation (<1 year) was a significant risk factor for OS, PFS and LC; Gross Tumor Volume (≥25 cm3) was a significant risk factor for OS. Toxicities were analyzed in all enrolled patients (n = 165). Grade ≥ 3 late toxicities occurred in 49 patients (30 %). A higher cumulative EQD2 (α/β = 3) was significantly associated with severe complications.

CONCLUSION

Reirradiation with HDR brachytherapy for recurrent gynecologic cancer is effective, especially in cases with a long interval before reirradiation.

Interstitial brachytherapy for lip carcinomas: Comparison between Ir-192 low-dose-rate and high-dose-rate treatment

PURPOSE

Low-dose-rate (LDR) and high-dose-rate (HDR) interstitial brachytherapy are known to be effective in the treatment of lip carcinomas. The aim of this study was to retrospectively compare oncologic and toxicity outcomes between the two techniques.

PATIENTS AND METHODS

From 2007 to 2018, patients at the Institut de cancérologie de Lorraine (France) who received exclusive or adjuvant interstitial brachytherapy for lip squamous carcinomas were studied. Two groups were defined: the LDR/PDR group, including patients treated with iridium-192 wires, or pulsed-dose rate technique, and the high-dose-rate group, with patients treated by high-dose-rate technique. The dose ranged between 50Gy and 65Gy (depending on previous surgery) for low-dose-/pulsed-dose rate treatments, and 39Gy for high-dose-rate (twice a day). Early, late toxicity events and oncologic control were reported.

RESULTS

Among the 61 patients whose data were analyzed retrospectively, 36 received the low-dose-/pulsed-dose rate treatment (59%) and 25 the high-dose-rate brachytherapy (41%). The median follow-up time was 44 months. At 36 months, the local control rates were 96.3% for LDR/PDR group and 100% for HDR (P=0.180). The regional control rates were 85.9% and 92% without any difference according to the two groups (P=0.179). The specific overall survival rate was 95.5% with no difference between groups. There were more grade 2 or higher mucositis in the HDR group than in LDR/PDR group (40% versus 16.7%, P=0.042). One case of grade 3 mucositis was recorded in each group. No grade 3 late complications were recorded. High-dose-rate brachytherapy reduced the length of hospitalization by 2 days (P<0.001).

CONCLUSION

High-dose- or low-dose-/pulsed-dose rate brachytherapy seemed to be as effective and well tolerated in our experience of 61 patients.

Prospective study of HDR brachytherapy (BT), external beam radiotherapy (EBRT) and androgen deprivation therapy (ADT): 10-years experience of an MRI-guided approach

OBJECTIVES

To evaluate the predictive factors for biochemical failure and distant metastases in a prospective cohort of patients with localized prostate cancer treated with the combination of HDR BT and EBRT.

METHODS AND MATERIALS

Patients with intermediate (IR) or high-risk (HR) prostate adenocarcinoma received a single fraction of HDR of 15 Gy combined with RT of 37.5 Gy in 15 fractions. ADT duration was used depending on risk-group. Descriptive analyses were performed. Univariate and multivariate Hazard Ratios were obtained. Finally, the Kaplan-Meier model was used to describe the survival of the events of interest.

RESULTS

309 patients were treated prospectively (199 were IR and 110 HR). Median age was 72 years; 58.3 % were MRI stage ≤ T2c, 34.1 % T3a and 7.6 % T3b; ISUP-grade 1-3 in 78.9 % and ISUP 4-5 in 21.1 %. 71.8 % of patients had ≤ 50 % positive-cores in biopsy and 28.2 % had > 50 %. Median pre-treatment PSA was 9.9 ng/mL. After a median follow-up of 88 months, 41 patients presented biochemical failure and 18 developed distant metastases. Multivariate cox-regression analyses found that MR-T3b Stage (HR 3.88, p = 0.001) and ADT use (HR 3.99, p = 0.03) were the only predictive factors for biochemical failure and the number of positive cores (>50 %) the only independent predictive factor of distant metastases (HR 4.36, p = 0.002).

CONCLUSIONS

Patients with mpMRI evidence of invasion of the SV and involvement of more than 50% of the cores in the prostate biopsy are patients with a higher risk of presenting a biochemical recurrence or developing metastasis due to their prostate cancer, respectively.

The impact of brachytherapy boost for anal canal cancers in the era of de-escalation treatments

PURPOSE

To analyze clinical outcomes of high-dose-rate (HDR) interstitial brachytherapy boost (ISBT) after external beam radiation therapy (EBRT) or chemoradiotherapy (CRT) for the treatment of anal canal cancers (ACC).

METHODS AND MATERIALS

A total of 78 patients with ACC were treated at our institution by ISBT. Local Control (LC), disease-free survival (DFS), overall survival (OS), colostomy-free survival (CFS) and toxicity rates were analyzed.

RESULTS

With a median followup (FU) of 59.8 months (95% CI [55.8-64.2]), six (7.7%) local recurrences with 2 patients (2.6%) having persistent disease at 3 months were observed. The 5-year rate of LC for the entire population was 92% [83-96%]. The 5-year DFS rate was 86% [76-93%]. The 5-year OS was 96% [88-99%]. In the univariate analysis, chemotherapy was significantly associated with morbidity grade ≥2. Late digestive toxicity grade ≥3 was reported in 8.9% patients, 1 patient underwent colostomy due to toxicity. The 5-year CFS rate was 88% [79-94%].

CONCLUSIONS

HDR interstitial brachytherapy boost provide excellent rates of tumor control and colostomy-free survival with a favorable profile of GI toxicity. Continence in anal cancer survivors is a challenge and the boost technique must be discussed in a multidisciplinary approach as part of de-escalation treatments.

First clinical implementation of Yttrium-90 Disc Brachytherapy after FDA clearance

PURPOSE

Herein, we study if high-dose-rate (HDR) yttrium-90 (⁹⁰Y) brachytherapy could be utilized by medical physicists, radiation oncologists, and ophthalmic surgeons.

METHODS AND MATERIALS

Yttrium-90 (⁹⁰Y) beta-emitting brachytherapy sources received United States Food and Drug Administration clearance for episcleral treatment of ocular tumors and benign growths. Dose calibration traceable to the National Institute of Standards and Technology as well as treatment planning and target delineation methods were established. Single-use systems included a ⁹⁰Y-disc affixed within specialized, multifunction, handheld applicator. Low-dose-rate to high-dose-rate prescription conversions and depth-dose determinations were performed. Radiation safety was evaluated based on live exposure rates during assembly and surgeries. Clinical data for radiation safety, treatment tolerability, and local control was collected.

RESULTS

Practice parameters for the medical physicist, radiation oncologist, and ophthalmic surgeon were defined. Device sterilizations, calibrations, assemblies, surgical methods, and disposals were reproducible and effective. Treated tumors included iris melanoma, iridociliary melanoma, choroidal melanoma, and a locally invasive squamous carcinoma. Mean calculated ⁹⁰Y disc activity was 14.33 mCi (range 8.8-16.6), prescription dose 27.8 Gy (range 22-30), delivered to depth of 2.3 mm (range 1.6-2.6), at treatment durations of 420 s (7.0 min, range 219 s-773 s). Both insertion and removal were performed during one surgical session. After surgery, each disc-applicator- system was contained for decay in storage. Treatments were well-tolerated.

CONCLUSIONS

HDR ⁹⁰Y episcleral brachytherapy devices were created, implementation methods developed, and treatments performed on 6 patients. Treatments were single-surgery, rapid, and well-tolerated with short-term follow up.

Novel portable apparatus for outpatient high-dose-rate (HDR) brachytherapy in penile cancer

BACKGROUND

Penile squamous cell carcinoma (PSC) is traditionally treated with surgical resection with significant morbidity. Penile sparing approaches, such as brachytherapy, require expertise, prolonged inpatient stays, poor patient convenience, and heterogenous plans with variable long-term toxicity. In this study, we describe the protocol for novel portable apparatus created for PSC, allowing outpatient hybrid interstitial/surface brachytherapy, improving homogeneity and patient convenience.

METHODS

A portable brachytherapy apparatus was developed utilizing a foley catheter, prostate template, 6F interstitial catheters, 5 mm bolus, and a jock strap. The apparatus allowed for internal and external catheter placement housed in a jock strap to allow mobility and defecation without affecting the implant. High-dose-rate brachytherapy was performed as an outpatient.

RESULTS

The apparatus was then used on a 62-year-old male with cT2pN0M0 (stage IIA) PSC with bilateral glans and urethral meatus involvement, who elected for definitive brachytherapy (4000cGy in 10 fractions over 5-days). Given external dwell positions, heterogeneity correction of the template was calculated (AAPM TG186) with <2% variation. Patient had minimal impact on his active lifestyle during treatment and had complete clinical response at 3-months. Grade 2 skin desquamation resolved at 2-months, with no necrosis. At 6-months, he was able to resume sexual intercourse, and at 12-months, he remained disease-free with sexual and urinary function intact.

CONCLUSIONS

Novel portable implant allows for improved patient convenience, reduced inpatient stay, capable of optimizing dosimetry with hybrid brachytherapy. This outpatient treatment allows the opportunity to increase fractionation, offering high local-control and lower toxicity. Future studies utilizing this apparatus for more fractionated regimens with further lower dose-per-fraction (∼3 Gy/fraction) is recommended.

Feasibility of accelerated image-guided high-dose-rate interstitial brachytherapy with inverse planning simulated annealing (IPSA-HDRBT) for post-operative treatment of pathologically node-negative squamous cell carcinomas of the oral tongue

PURPOSE

Inverse planning simulated annealing (IPSA) produces highly conformal dose distributions and quick optimizations for high-dose-rate interstitial brachytherapy (HDRBT). We report our dosimetry and overall outcomes using this approach for the accelerated post-operative treatment of pathologically node-negative squamous cell carcinomas of the oral tongue (OTSCC) with high risk of local recurrence.

METHODS

Patients with newly diagnosed pN0 OTSCC treated with partial glossectomy, neck dissection, and post-operative HDRBT alone from 2007 to 2021 were retrospectively reviewed. Patients received 30 Gy in 5 fractions over 2.5 days. Target volume and mandible dosimetry are reported. Actuarial rates of local control, regional control, disease-specific survival, and overall survival were estimated using the Kaplan-Meier method. Toxicity was categorized using the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

RESULTS

19 consecutive patients were reviewed. Median follow-up was 3.2 years (IQR 1.4-8.2 years) with a 3-year estimated local control rate of 81%. Target volumes were generally small, as the median volume was 12.66 cc. Median V150% and V200% were 52% and 24%, respectively. D1cc and D2cc to the mandible were 17.31 Gy and 14.42 Gy, respectively.

CONCLUSIONS

IPSA-HDRBT is feasible and highly efficient for post-operative treatment of the primary tumor bed in patients with pathologically node-negative squamous cell carcinomas of the oral tongue. Further technical optimization and prospective clinical evaluation in a larger patient cohort are planned.

High-dose-rate brachytherapy boost for locally advanced cervical cancer: Oncological outcome and toxicity analysis of 4 fractionation schemes

•

Brachytherapy boost is a standard of care for locally advanced cervical cancer.

•

High-dose-rate brachytherapy (HDR-BT) boost procedure is not standardized.

•

The number of implants, fractions, doses and imaging differ in literature.

•

Bi-fractionated HDR-BT in 1 implant is feasible with good oncological outcome.

•

Bi-fractionated HDR-BT dose escalation slightly increases acute toxicity.

Purpose

Brachytherapy (BT) boost after radio-chemotherapy (RCT) is a standard of care in the management of locally advanced cervical cancer (LACC). As there is no consensus on high-dose-rate (HDR) BT fractionation schemes, our aim was to report the oncological outcome and toxicity profile of four different schemes using twice-a-day (BID) HDR-BT.

Patients and methods

This was an observational, retrospective, single institution study for patients with LACC receiving a HDR-BT boost. The latter was performed with a single implant and single imaging done on day 1. The different fractionation schemes were: 7 Gy + 4x3.5 Gy (group 1); 7 Gy + 4x4.5 Gy (group 2); 3x7Gy (group 3) and 3x8Gy (group 4). Local (LFS), nodal (NFS) and metastatic (MFS) recurrence-free survival as well as progression-free survival (PFS) and overall survival (OS) were analyzed. Acute (≤6 months) and late toxicities (>6 months) were reported.

Results

From 2007 to 2018, 191 patients were included. Median follow-up was 57 months [45–132] and median EQD2₁₀D₉₀CTV_HR was 84, 82 and 90 Gy for groups 2, 3 and 4 respectively (dosimetric data missing for group 1). The 5-year LFS, NFS, MFS, PFS and OS were 85% [81–90], 83% [79–86], 70% [67–73], 61% [57–64] and 75% [69–78] respectively, with no significant difference between the groups. EQD2₁₀D₉₀CTV_HR < 85 Gy was a prognostic factor for local recurrence in univariate analysis (p = 0.045). The rates of acute/late grade ≥ 2 urinary, digestive and gynecological toxicities were 9%/15%, 3%/15% and 9%/25% respectively.

Conclusion

Bi-fractionated HDR-BT boost seems feasible with good oncological outcome and slightly more toxicity after dose escalation.

Complications and side effects of high-dose-rate prostate brachytherapy

PURPOSE

To describe technical challenges and complications encountered during and after high-dose-rate prostate brachytherapy (HDR-BT) and review management of these complications.

METHODS AND MATERIALS

The authors performed a systematic review of the literature on toxicities encountered after prostate HDR-BT +/- external beam radiotherapy. A total of 397 studies were identified, of which 64 were included. A focused review of literature regarding the management of acute and late toxicities also performed.

RESULTS

Most acute toxicities include grade 0-2 genitourinary and gastrointestinal toxicity. Overall, Grade 3+ Common Terminology Criteria for Adverse Events toxicity after HDR-BT was low [genitourinary: 0-1%; gastrointestinal 0-3%]. Rates of fistula formation were <1%, and radiation cystitis/proctitis were <14% and more commonly reported in cohorts treated with HDR-BT boost and external beam radiotherapy.

CONCLUSIONS

HDR-BT both as monotherapy or combined with external beam radiotherapy for prostate cancer is well tolerated. Serious complications are rare.

Results of postoperative interstitial brachytherapy of resectable floor of mouth tumors

PURPOSE

The purpose of this study was to describe the results of postoperative sole interstitial brachytherapy (BT) in patients with resectable floor of mouth tumors.

METHODS AND MATERIALS

Between January 1998 and December 2017, 44 patients with squamous cell histology, stage T1-3N0-1M0 floor of mouth tumor were treated by excision of the primary lesion with or without neck dissection followed by sole high-dose-rate tumor bed BT with an average dose of 22.7 Gy (10-45 Gy) using rigid metal needles (n = 14; 32%) or flexible plastic catheters (n = 30; 68%).

RESULTS

During a median followup time of 122 months for surviving patients, the probability of 5- and 10-year local and regional tumor control, overall survival (OS), and disease-specific survival (DSS) was 89% and 89%, 73% and 67%, 52% and 32%, 66% and 54%, respectively. In univariate analysis, lymphovascular invasion was a negative predictor of regional tumor control (p = 0.0062), DSS (p = 0.0056), and OS (p = 0.0325), whereas cervical recurrence was associated with worse DSS (p < 0.0001) and OS (p < 0.0001). The incidence of local Grade 1, 2, and 3 mucositis was 25%, 64%, and 11%, respectively. Grade 4 side effect, that is soft tissue necrosis occurred in four cases (9%).

CONCLUSIONS

Results of postoperative sole high-dose-rate BT of floor of mouth tumors are comparable with those reported with low-dose-rate BT, and this method could improve local tumor control and DSS compared with exclusive surgical treatment.

Very accelerated partial breast irradiation Phase I-II multicenter trial (VAPBI): Feasibility and early results

PURPOSE

This is a multicenter Phase I-II trial endorsed by the GEC-ESTRO Breast Working Group, to analyze if very accelerated partial breast irradiation (VAPBI) with multicatheter interstitial brachytherapy is feasible and safe compared with the standard APBI treatment in 4-5 days for early stage breast carcinomas.

METHODS AND MATERIALS

We have included 81 patients with pT1-2 pN0 invasive carcinomas after breast-conserving surgery. Between August 2017 and July 2019, 33 women received high-dose-rate brachytherapy, four fractions of 6.25 Gy in 2-3 days, and 48 patients received three fractions of 7.45 Gy in 2 days. Thirty-six patients were implanted perioperatively and 45 postoperatively. Mean age was 68 (51-90). Free surgical margins were of 2 mm or greater.

RESULTS

Acute effects were 11% dermatitis, 18.5% hematoma, 3.7% infection, and 14.8% pain. At a median followup of 20 months (range 8-35), no relapse has occurred. Pigmentation changes in the entrance and exit of tubes were visible in 16%, but 1 year later, few cases remained. Patients developed G1-2 induration or fibrosis in 18.5% and 2.5%, respectively. No patient developed telangiectasia. The cosmetic outcome was good/excellent in 97.5% and fair in 2.5%.

CONCLUSIONS

VAPBI with multicatheter interstitial brachytherapy using four fractions of 6.25 Gy or three fractions of 7.45 Gy in two or 3 days is feasible. No excess has been observed in acute effects. At a mean followup of 20 months, late side effects seem to be similar to standard fractionation. VAPBI in two to 3 days is beneficial for the patients and reduces the workload of the brachytherapy units.

The American Brachytherapy Society prostate brachytherapy LDR/HDR simulation workshops: Hands-on, step-by-step training in the process of quality assurance

PURPOSE

Education and training on prostate brachytherapy for radiation oncology and medical physics residents in the United States is inadequate, resulting in fewer competent radiation oncology personnel to perform implants, and is a factor in the subsequent decline of an important, potentially curative cancer treatment modality for patients with cancer. The American Brachytherapy Society (ABS) leadership has recognized the need to establish a sustainable medical simulation low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy workshop program that includes physician-physicist teams to rapidly translate knowledge to establish high-quality brachytherapy programs.

METHODS

The ABS, in partnership with industry and academia, has held three radiation oncology team-based LDR/HDR workshops composed of physician-physicist teams in Chicago in 2017, in Houston in 2018, and in Denver in 2019. The predefined key metric of success is the number of attendees who returned to their respective institutions and were actively performing brachytherapy within 6 months of the prostate brachytherapy workshop.

RESULTS

Of the 111 physician/physicist teams participating in the Chicago, Houston, and Denver prostate brachytherapy workshops, 87 (78%) were actively performing prostate brachytherapy (51 [59%] HDR and 65 [75%] LDR).

CONCLUSIONS

The ABS prostate brachytherapy LDR/HDR simulation workshop has provided a successful education and training structure for medical simulation of the critical procedural steps in quality assurance to shorten the learning curve for delivering consistently high-quality brachytherapy implants for patients with prostate cancer. An ABS initiative, intended to bend the negative slope of the brachytherapy curve, is currently underway to train 300 new competent brachytherapy teams over the next 10 years.

Predicting which patients may benefit from the hybrid intracavitary+interstitial needle (IC/IS) applicator for advanced cervical cancer: A dosimetric comparison and toxicity benefit analysis

PURPOSE

The purpose of this study is to compare the predicted rate of local control and bladder and rectum toxicity rates for image-guided adaptive brachytherapy plans using a tandem and ovoid (T/O) applicator versus using a simulated hybrid intracavitary/interstitial tandem and ring applicator with needles (T/R + N) for patients with locally advanced cervical cancer (LACC).

METHODS AND MATERIALS

Patients with ≥ FIGO Stage IIB locally advanced cervical cancer treated with T/O from a single institution were included. Simulated treatment plans were created with a T/R + N applicator for the best high-risk clinical target volume (CTV) coverage and minimal dose to organs at risk. Three-year local control rate was estimated using published dose-volume effect relationships. Next, the high-risk CTV EQD2 D90 of T/R + N plans were calculated, and bladder and rectum toxicity rates were estimated. Analysis was performed in subpatient groups defined based on tumor volume and ratio of maximal and minimal tumor radii (RR) that reflects tumor shape asymmetry.

RESULTS

Improvements in predicted local control rate for the T/R + N were 0.8, 4.1, 1.6, and 3.9% for groups with tumor volume <35 cc, ≥35 cc, RR < 2.0, and ≥2.0, respectively, with the latter three being statistically significant. Predicted reductions in Grade 2-4 toxicity rates of bladder and rectum were significant in all groups except bladder toxicity in tumor volume <35 cc, when T/R + N plans were normalized to the same CTV coverage as the T/O plans. Comparing unnormalized T/R + N plans and T/O plans, predicted toxicity reductions were significant in all groups except rectum toxicity in RR ≥ 2.0. Predicted reduction of toxicity rate was larger for patients with large tumor or large tumor RR, although some reductions were relatively small.

CONCLUSIONS

Cases with large tumor (volume ≥35 cc) or large tumor asymmetry (RR ≥ 2.0) would probably benefit more from the use of hybrid applicators.

Patient-reported functional outcomes following external beam radiation therapy for prostate cancer with and without a high-dose rate brachytherapy boost: A national population-based study

BACKGROUND AND PURPOSE

Little is known about the functional outcomes and health-related quality of life (HRQoL) following external beam radiation therapy (EBRT) combined with a high-dose rate brachytherapy boost (EBRT-BB) for the treatment of prostate cancer. We aimed to compare patient-reported outcomes of EBRT to those of EBRT-BB.

METHODS AND MATERIALS

Patients diagnosed with intermediate-risk, high-risk or locally advanced prostate cancer (April 2014 to September 2016), who received EBRT in the English National Health Service within 18 months of diagnosis and responded to a national patient questionnaire, were identified from the National Prostate Cancer Audit. Adjusted linear regression was used to estimate differences in functional EPIC-26 domains and HRQoL (EQ-5D-5L) between treatment groups. Non-inferiority of EBRT-BB was determined if the lower 95% confidence limit did not exceed the established minimal clinically important difference (MCID).

RESULTS

Of the 13,259 included men, 12,503 (94.3%) received EBRT and 756 (5.7%) received EBRT-BB. EBRT-BB was non-inferior compared to EBRT for the urinary incontinence, sexual, bowel and hormonal EPIC-26 domains. EBRT-BB resulted in significantly worse urinary irritation/obstruction scores than EBRT (-6.1; 95% CI: -8.8 to -3.4) but uncertainty remains as to whether this difference is clinically important (corresponding MCID of 5).

CONCLUSIONS

There is no evidence to suggest that EBRT-BB results in any clinically important detriment in functional outcomes or HRQoL compared to men receiving EBRT only. Whilst statistically significantly worse urinary irritation/obstruction outcomes were reported in the EBRT-BB cohort, the threshold for a clinically significant difference was not exceeded and further research is required for confirmation.

Evaluation of an MR-only interstitial gynecologic brachytherapy workflow using MR-line marker for catheter reconstruction

PURPOSE

Magnetic resonance imaging (MRI) offers excellent soft-tissue contrast enabling the contouring of targets and organs at risk (OARs) during gynecological interstitial brachytherapy procedure. Despite its benefit, one of the main challenges toward MRI-only workflows is that the implanted catheters are not reliably visualized on MR images. This study aims to evaluate the feasibility of MR-only workflow using an in-house MR line marker during interstitial gynecological high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

Ten patients diagnosed with locally advanced cervical cancer treated with HDR brachytherapy were included in this study. The hybrid CT/MR-treated plan was used as the study reference plan. Five users manually reconstructed the catheter's path on MR images (3D T1- and T2-weighted). Subsequently, the dwell positions from the users' plans were superimposed on the reference plans to evaluate the dosimetric impact of the using MR-only for catheter reconstruction in comparison with hybrid CT/MR approach. Variability of dwell positions between users and reconstruction time was also evaluated.

RESULTS

More than 96.90% of catheter reconstruction variations were < 2 mm. No statistical differences were reported between MR-only and hybrid CT/MR in gross tumor volume D₉₈ and high-risk clinical target volume D₉₀, respectively. For the OARs (bladder, sigmoid, rectum, and bowel), no significant changes were observed in any dose metrics between MR-only and hybrid CT/MR. The average reconstruction time was 51 ± 10 minutes across all ten patients.

CONCLUSION

The feasibility of MR-only workflow using MR line marker during interstitial gynecological HDR brachytherapy has been validated in this study. The results show that the MR-only workflow is equivalent to the conventional hybrid CT/MR approach in terms of gross tumor volume and high-risk clinical target volume coverage and respecting of OARs dose limits.

Time-driven activity-based costing of a novel form of CT-guided high-dose-rate brachytherapy intraoperative radiation therapy compared with conventional breast intraoperative radiation therapy for early stage breast cancer

INTRODUCTION

Intraoperative radiation therapy is an emerging option for adjuvant therapy for early stage breast cancer, although it is not currently considered standard of care in the United States. We applied time-driven activity-based costing to compare two alternative methods of breast intraoperative radiation therapy, including treatment similar to the techniques employed in the TARGIT-A clinical trial and a novel version with CT-guidance and high-dose-rate (HRD) brachytherapy.

METHODS AND MATERIALS

Process maps were created to describe the steps required to deliver intraoperative radiation therapy for early stage breast cancer at each institution. The components of intraoperative radiation therapy included personnel, equipment, and consumable supplies. The capacity cost rate was determined for each resource. Based on this, the delivery costs were calculated for each regimen. For comparison across centers, we did not account for indirect facilities costs and interinstitutional differences in personnel salaries.

RESULTS

The CT-guided, HRD form of intraoperative radiation therapy costs more to deliver ($4,126.21) than the conventional method studied in the TARGIT-A trial ($1,070.45). The cost of the brachytherapy balloon applicator ($2,750) was the primary driver of the estimated differences in costs. Consumable supplies were the largest contributor to the brachytherapy-based approach, whereas personnel costs were the largest contributor to costs of the standard form of intraoperative radiation therapy.

CONCLUSIONS

When compared with the more established method of intraoperative radiation therapy using a portable superficial photon unit, the delivery of treatment with CT guidance and HDR brachytherapy is associated with substantially higher costs. The excess costs are driven primarily by the cost of the disposable brachytherapy balloon applicator and, to a lesser extent, additional personnel costs. Future work should include evaluation of a less expensive brachytherapy applicator to increase the anticipated value of brachytherapy-based intraoperative radiation therapy.

Focal high-dose-rate brachytherapy for localized prostate cancer: toxicity and preliminary biochemical results

BACKGROUND

This study aimed to evaluate the outcomes and the toxicity of focal high-dose-rate (HDR) brachytherapy in selected localized prostate cancer patients.

METHODS

Fifty patients were treated with focal high-dose-rate brachytherapy between March 2013 and November 2017, representing 5% of the cases treated by our group during this period. Only patients with very limited and localized tumors, according to strict criteria, were selected for the procedure. The prescribed dose for the focal volume was 24 Gy.

RESULTS

The treated volume corresponded to a mean value of 32% of the total prostatic volume. The mean focal D₉₀ in our series was 23 Gy (range 16-26 Gy). The mean initial IPSS was 8.2 (range 0-26), at 6 months 7.5 (range 0-23), and at 24 months 6.7 (range 0-18). No acute or late urinary retention was seen. When the ICIQ-SF score was 0 at the end of treatment, it remained nil thereafter at 1 and 2 years for all patients. No intraoperative or perioperative complications occurred. No rectal toxicity was reported after treatment. Of the total patients identified as potent, only three patients had a very slight decrease of the mean IIEF5. The mean initial PSA was 6.9 ng/mL (range 1.9-13.4). At the last follow-up visit, the mean PSA was 3 ng/ml (range 0.48-8.11).

CONCLUSION

HDR focal brachytherapy in selected patients with low intermediate-risk prostate cancer could achieve the same satisfactory results in terms of relapse-free survival as conventional whole prostate brachytherapy with less toxicity.

Deep-learning-assisted automatic digitization of applicators in 3D CT image-based high-dose-rate brachytherapy of gynecological cancer

PURPOSE

Applicator digitization is one of the most critical steps in 3D high-dose-rate brachytherapy (HDRBT) treatment planning. Motivated by recent advances in deep-learning, we propose a deep-learning-assisted applicator digitization method for 3D CT image-based HDRBT. This study demonstrates its feasibility and potential in gynecological cancer HDRBT.

METHODS AND MATERIALS

Our method consisted of two steps. The first step used a U-net to segment applicator regions. We trained the U-net using two-dimensional CT images with a tandem-and-ovoid (T&O) applicator and corresponding applicator mask images. The second step applied a spectral clustering method and a polynomial curve fitting method to extract applicator central paths. We evaluated the accuracy, efficiency, and robustness of our method in different scenarios including other T&O cases that were not used in training, a T&O case scanned with cone-beam CT, and Y-tandem and cylinder-applicator cases.

RESULTS

In test cases with a T&O applicator, average 3D Dice similarity coefficient between automatic and manual segmented applicator regions was 0.93. Average distance between tip positions and average Hausdorff distance between applicator channels determined by our method and manually were 0.64 mm and 0.68 mm, respectively. Although trained only using CT images of T&O cases, our tool can also digitize Y-tandem, cylinder applicator, and T&O applicator scanned in cone-beam CT with error of tip position and Hausdorff distance <1 mm. Computation time was ∼15 s per case.

CONCLUSIONS

We have developed a deep-learning-assisted applicator digitization tool for 3D CT image-based HDRBT of gynecological cancer. The achieved accuracy, efficiency, and robustness made our tool clinically attractive.

Influence of transitioning of planning techniques in high-dose-rate brachytherapy monotherapy for clinically localized prostate cancer from two- to three-dimensional planning

PURPOSE

The purpose of this study was to examine the influence of transitioning treatment planning techniques in high-dose-rate interstitial brachytherapy monotherapy for localized prostate cancer.

METHODS AND MATERIALS

We compared 113 patients treated with initial two-dimensional treatment planning (2D: 74% received 54 Gy/nine fractions) to 240 patients treated with three-dimensional planning (3D: 70 CT image-guided 3D [CT-3D]: 84% 45.5 Gy/seven fractions and 170 MRI image-guided [MRI-3D]: 87% received 49 Gy/nine fractions).

RESULTS

The actuarial 5-year biochemical failure-free survival rates for 2D and 3D planning were 88.4% and 95.1% (p = 0.0285 between 2D and 3D) (89.4% in CT-3D and 97.5% in MRI-3D), respectively; the rates for 2D and 3D planning were not available and 100% in the low-risk group (100% and 100%), 97.7% and 94.5% (p = 0.7626) (85.1% and 100%) in the intermediate-risk group, and 82.5% and 94.4% (p = 0.0507) (93.8% and 94.7%) for the high-risk group. Late gastrointestinal (GI) toxicity Grade 1, Grade 2, and Grade 3 was found in 13%, 4%, and 1% in 2D, whereas 8%, 2%, and 0% in 3D group (p = 0.0699), respectively. 3D decreased GI toxicity Grade 2 ≤ than 2D (19% and 10%, p = 0.0169). Late genitourinary toxicity Grade 1, Grade 2, and Grade 3 was 21%, 12%, and 3% for 2D and 32%, 18%, and 3% for 3D, respectively (p = 0.0217).

CONCLUSIONS

The 3D technique has the potential to reduce GI toxicity and improve biochemical control rate compared to 2D planning, whereas 3D resulted in increased mild genitourinary toxicity.

Concurrent chemoradiation for cervical cancer: Comparison of LDR and HDR brachytherapy

PURPOSE

To compare clinical outcomes between low-dose-rate (LDR) brachytherapy and high-dose-rate (HDR) brachytherapy for cervical cancer patients.

METHODS AND MATERIALS

All consecutive newly diagnosed cervical cancer patients undergoing pretreatment 18-fluorodeoxyglucose positron emission tomography imaging and treated with curative-intent definitive chemoradiation from 1997 to 2016 at a U.S. academic center were included. Brachytherapy boost was LDR or HDR 2D treatment planning from 1997 to 2005 and HDR with MR-based 3D planning from 2005 to 2016. Local control (LC), cancer-specific survival (CSS), and late bowel/bladder complications were evaluated.

RESULTS

Tumor stages were International Federation of Gynecology and Obstetrics IB1-IIB (n = 457; 75%) and III-IVA (n = 152; 25%). Brachytherapy was LDR for 104 patients and HDR for 505 patients. Concurrent weekly cisplatin was administered to 536 patients (88%). With median followup of 9.4 years, there was no difference in LC (p = 0.24) or CSS (p = 0.50) between LDR and HDR brachytherapy. Cox multivariable regression showed that only International Federation of Gynecology and Obstetrics stage III-IVA (HR=2.4, p = 0.004) was associated with worse LC. A propensity-matched cohort (90 LDR vs. 90 HDR) was created, and the 5-year LC rates were 88% LDR and 82% HDR, p = 0.26; 5-year CSS rates were 66% LDR and 58% HDR, p = 0.19; 5-year grade ≥3 bowel/bladder toxicities were 23% LDR and 16% HDR, p = 0.44. For all patients, the 5-year late toxicity in stage III-IVA patients was higher with LDR 47% vs. HDR 15%, p = 0.03, with no difference in LC, 86% and 75%, respectively (p = 0.09).

CONCLUSIONS

There was no difference in LC with either LDR or HDR brachytherapy. The late complication rate was reduced with HDR and 3D-planned brachytherapy compared to LDR and 2D-planned brachytherapy.

Technique for the administration of high-dose-rate brachytherapy to the bile duct using a nasobiliary catheter

PURPOSE

Cholangiocarcinoma patients who are potential candidates for liver transplantation may be treated with high-dose-rate (HDR) brachytherapy using a minimally invasive nasobiliary catheter in an effort to escalate the radiotherapy dose to the tumor and maximize local control rates. This work describes the equipment, procedures, and quality assurance (QA) that enables successful administration.

METHODS AND MATERIALS

This work describes the nasobiliary catheter placement, simulation, treatment planning, treatment delivery, and QA. In addition, a chart review was performed of all patients who received endoscopic retrograde cholangiopancreatography for HDR bile duct brachytherapy at our institution from 2007 to 2017. The review evaluated how many patients were treated and the number of patients who could not be treated because of anatomic and/or equipment limitations.

RESULTS

From 2007 to 2017, 122 cholangiocarcinoma patients have been treated with HDR brachytherapy using a nasobiliary catheter. Three patients underwent catheter placement but did not receive brachytherapy treatment due to catheter migration between placement and treatment or because the HDR afterloader was unable to extend the source wire into the treatment site. Periodic QA is recommended for ensuring whether the HDR afterloader is capable of extending the source wire through an extensive and curved path.

CONCLUSIONS

Intraluminal HDR brachytherapy with a nasobiliary catheter can be successfully administered. Procedures and QA are described for ensuring safety and overcoming technical challenges.

Patient-reported health-related quality of life outcomes after HDR brachytherapy between small (<60 cc) and large (≥60 cc) prostate glands

PURPOSE

Patients with large prostate glands are underrepresented in clinical trials incorporating brachytherapy due to concerns for excessive toxicity. We sought to compare health-related quality of life (HRQOL) outcomes between small (<60 cc) and large (≥60 cc) prostates treated with high-dose-rate brachytherapy (HDR-B).

METHODS AND MATERIALS

One hundred thirty patients at Emory University were treated with HDR-B monotherapy (n = 75) or HDR-B in combination with external beam radiation therapy (n = 55). American Urologic Association Symptom Score (AUASS) and expanded prostate cancer index composite for clinical practice (EPIC-CP) scores were recorded. A linear mixed model was performed dichotomizing prostate volume (<60 and ≥ 60 cc) with AUASS, individual EPIC-CP domains (urinary incontinence, urinary irritation/obstruction [UIO], bowel function, sexual function, and vitality/hormonal function), and overall EPIC-CP HRQOL scores.

RESULTS

Median followup was 22.6 months (range 2.2-55.8). The median gland volume for the entire cohort (n = 130), <60 cc cohort (n = 104), and ≥60 cc cohort (n = 26) was 44 cc, 41.1 cc, and 68.0 cc, respectively. There were no baseline differences in HRQOL scores between cohorts. At 2 months, AUASS and UIO scores increased similarly between cohorts (AUASS p = 0.807; UIO p = 0.539), then decreased (longitudinal effect p < 0.001 and p = 0.005, respectively) to remain not significantly different at 12 months (AUASS p = 0.595; UIO p = 0.673). Overall, prostate volume was not significantly associated with change in AUASS (p = 0.403), urinary incontinence (p = 0.322), UIO symptoms (p = 0.779), bowel symptoms (p = 0.757), vitality/hormonal symptoms (p = 0.503), or overall HRQOL (p = 0.382).

CONCLUSIONS

In appropriately selected patients, HDR-B appears well tolerated in patients with ≥60 cc prostate glands without an increase in patient-reported toxicity. Volume should not be a strict contraindication in those with adequate baseline function.

CT-guided interstitial HDR-brachytherapy for recurrent glioblastoma multiforme: a 20-year single-institute experience

PURPOSE

To report our results of computed tomography-guided interstitial high-dose-rate (HDR) brachytherapy (BRT) in the treatment of patients with recurrent inoperable glioblastoma multiforme (GBM).

PATIENTS AND METHODS

Between 1995 and 2014, 135 patients were treated with interstitial HDR BRT for inoperable recurrent GBM located within previously irradiated volumes. Patient's median age was 57.1 years (14-82 years). All patients were pretreated with surgery, postoperative external beam radiation therapy (EBRT) and systemic chemotherapy (ChT). The median recurrent tumor volume was 42 cm³ (2-207 cm³). The prescribed HDR dose was median 40 Gy (30-50 Gy) delivered in twice-daily fractions of 5.0 Gy over consecutive days. No repeat surgery or ChT was administered in conjunction with BRT. Survival from BRT, progression-free survival (PFS), toxicity as well as the impact of several prognostic factors were evaluated.

RESULTS

At a median follow-up of 9.2 months, the median overall survival following BRT and the median PFS were 9.2 and 4.6 months, respectively. Of the prognostic variables evaluated in univariate analysis, extent of surgery at initial diagnosis, tumor volume at recurrence, as well as time from EBRT to BRT reached statistical significance, retained also in multivariate analysis. Eight patients (5.9%) developed treatment-associated complications including intracerebral bleeding in 4 patients (2.9%), symptomatic focal radionecrosis in 3 patients (2.2%), and severe convulsion in 1 patient (0.7%).

CONCLUSIONS

For patients with recurrent GBM, interstitial HDR BRT is an effective re-irradiation method for even larger tumors providing palliation without excessive toxicity.

Extended duration of dilator use beyond 1 year may reduce vaginal stenosis after intravaginal high-dose-rate brachytherapy

BACKGROUND

Vaginal dilators (VD) are recommended following vaginal or pelvic radiotherapy for patients with endometrial carcinoma (EC) to prevent vaginal stenosis (VS). The time course of VS is not fully understood and the optimal duration of VD use is unknown.

METHODS

We reviewed 243 stage IA-II EC patients who received adjuvant brachytherapy (BT) at an academic tertiary referral center. Patients were instructed to use their VD three times per week for at least 1-year duration. The primary outcome was development of grade ≥ 1 VS using CTCAEv4 criteria during the follow-up period. The log-rank test and multivariable Cox proportional hazards modeling were used to evaluate the effect of VD use (noncompliance vs. standard compliance [up to 1 year] vs. extended compliance [over 1 year]) on VS.

RESULTS

The median follow-up was 15.2 months over the 5-year study period. At 15 months, the incidence of VS was 38.8% for noncompliant patients, 33.5% for those with standard compliance, and 21.4% for those with extended compliance (median time to grade ≥ 1 VS was 17.5 months, 26.7 months, and not yet reached for these groups, respectively). On multivariable Cox regression analysis, extended compliance remained a significant predictor of reduced VS risk when compared to both noncompliance (HR 0.38, 95% CI 0.18-0.80, p = 0.012) and standard compliance (HR 0.43, 95% CI 0.20-0.89, p = 0.023).

CONCLUSIONS

The risk of VS persists beyond 1 year after BT. Extended VD compliance beyond 1 year may mitigate this risk.

Endoluminal high-dose-rate brachytherapy for locally recurrent or persistent esophageal cancer

PURPOSE

Management of locally recurrent or persistent esophageal cancer (EC) after standard chemoradiation is challenging. This study updates our experience of treating medically inoperable EC patients with endoluminal high-dose-rate brachytherapy (EHDRBT) including the patients treated with a novel multiballoon channel centering esophageal applicator.

METHODS AND MATERIALS

Thirty-three consecutive patients with early-stage primary (n = 7), posttreatment persistent (n = 7), and recurrent (n = 19) EC treated with EHDRBT at our institution were included. Median dose and treatment lengths were 14 Gy (range 10-17.5 Gy) and 6 cm (3.5-9.0 cm), respectively. Endoscopy and biopsy were performed 3 months after EHDRBT and then every 3-6 months thereafter.

RESULTS

Median followup was 17.4 months (range 5.0-88.3). Grade 1 and 2 toxicities were observed in 13 (44.8%) and 11 (37.9%) patients, respectively. Grade 3 toxicity (tracheoesophageal fistula) was observed in 1 patient who had previously received two courses of external beam radiotherapy as well as a stent insertion. Median overall survival (OS) for entire cohort was 20.9 months, and 1-year OS was 78%. Complete response was achieved in 58.6% of patients with median time to failure and 1-year disease-free survival of 10.3 months (range 5.4-28.2) and 27%, respectively.

CONCLUSIONS

For medically inoperable patients with early-stage primary or local posttreatment residual or recurrent EC, EHDRBT is a well-tolerated treatment option with minimal Grade ≥3 toxicity. Brachytherapy in our hands continues to be a safe treatment option. Although 58.6% of patients achieved a complete response and the OS of this cohort is relatively good, long-term local control and cure remains a challenge.

Dosimetric impact of inter-observer catheter reconstruction variability in ultrasound-based high-dose-rate prostate brachytherapy

PURPOSE

To investigate the dosimetric impact of interobserver catheter reconstruction variability in transrectal ultrasound-guided prostate high-dose-rate (HDR) brachytherapy.

METHODS AND MATERIALS

Twenty consecutive patients with intermediate- or high-risk prostate cancer were treated with a single, 15-Gy HDR brachytherapy boost as part of this study. The treated plan was used as the study reference plan (P_R). Three expert treatment planners (observers) manually reconstructed the catheter paths on the static three-dimensional transrectal ultrasound images, and new plans were generated from the updated positions (P_OBS); subsequently, the dwell time and positions from the P_OBS plans were superimposed on the P_R catheter paths to evaluate the dosimetric effect of the interobserver variations (P_EVAL). Plans from each group were stratified by observer and by number of catheters (12 or 16) and then compared using a one-way Kruskal-Wallis H test with post hoc Mann-Whitney U tests reserved for significant variations (α = 0.05).

RESULTS

Greater than 98.9% of catheter reconstruction variations were <3 mm. When stratified by observer, there was a significant decrease (p << 0.05) in planning target volume (PTV) V_100% and increases in the urethral D_max between the P_OBS plans propagated to the P_R catheter paths and dosimetry evaluated and P_R plans only. Stratification of plans by catheter number showed nonclinically significant decreases in PTV V_100%, and D_90% and increases in urethral D_max for the 12-catheter plans.

CONCLUSIONS

Limiting interobserver variability, and its effects on prostate HDR brachytherapy plan quality, is critical to achieving good dosimetric outcomes; small variations in catheter reconstruction may translate to inadequate PTV coverage, excessive urethral dose, or both.

Health-related-quality-of-life and toxicity after single fraction 19 Gy high-dose-rate prostate brachytherapy: Phase II trial

PURPOSE

To evaluate the safety, tolerance and impact on health-related-quality-of-life (HRQoL) of the high-dose-rate brachytherapy of 19 Gy (BRT-HDR-19 Gy) single fraction in prostate cancer.

METHODS

From January 2014 to July 2016, 43 patients with low/intermediate risk were treated with BRT-HDR-19 Gy. The patients were monitored prospectively for toxicity and HRQoL.

RESULTS

The median age, initial PSA and the International Prostate Symptom Score (IPSS) were 71 years (55-78), 7.0 ng/mL (4.2-17.8) and 5 (0-14) respectively. 44% were low-risk and 56% intermediate-risk. Median CTV-V100 (where Vn is the fractional volume of the organ that receives n% of the prescribed dose) was 96.5%, Urethral-Dmax 106% and rectum-2 cc (the dose to 2 cc of rectal wall) 53%. After a median follow-up of 20 months (4-26), acute grade-2 genitourinary (GU) toxicity occurred in 4 patients (9%) and none presented acute gastrointestinal (GI) toxicity. Similarly, four patients (9%) presented late GU grade-2 toxicity. No grade-3 toxicity occurred. In terms of HRQoL, there was a statistically significant decline in Expanded Prostate Cancer Index Composite (EPIC) urinary urgency/obstructive domain at month 3 (p = 0.047), and returned to baseline by month 6. Mean EPIC urinary incontinence, bowel, sexual and hormonal domains did not present significant post BRT-HDR-19 Gy changes. Patients rated their satisfaction at 6 months as "very-satisfied" (23%) or "extremely-satisfied" (77%).

CONCLUSIONS

BRT-HDR-19 Gy demonstrates excellent results in terms of toxicity, tolerance, safety, patient satisfaction and HRQoL.

High-dose-rate brachytherapy boost for prostate cancer: Comparison of three different fractionation schemes

PURPOSE

Dose escalation for prostate cancer can be achieved with a combination of external beam radiotherapy (EBRT) and brachytherapy (BT) boost to increase local control. For high-dose-rate (HDR)-BT, optimal fractionation remains under debate. The objective was to assess the clinical outcome of three schemes of HDR-BT boost.

METHODS AND MATERIALS

Retrospective single institution data collection was performed. Patients received 46 Gy EBRT then an HDR-BT boost: 3 × 6 Gy, 2 × 9 Gy, or 1 × 14 Gy. HDR needles were placed under general anesthesia with endorectal ultrasonography guidance. CT-scan and treatment were performed postoperatively.

RESULTS

Between 2009 and 2012, 159 patients were included. Nine patients (5.7%) were low, 32 (20.1%) intermediate, and 118 (74.2%) high risk (D'Amico classification) without significant difference between the three BT schemes. With a median followup of 61 months, 5-year biochemical relapse-free survival, 5-year local relapse-free survival, 5-year metastases-free survival, and 5-year overall survival rates were 86.6% (SE 2.7%), 98.3% (SE 1%), 95.3% (SE 1%), and 96.5% (SE 1.5%), respectively, with no significant difference between the BT schemes. The rates of acute ≥ G2 genitourinary and ≥G2 gastrointestinal toxicities were 11.3% and 6.3%, respectively (p = NS). The rates of late genitourinary ≥ G2 and gastrointestinal ≥ G2 toxicities (at last followup) were 9.4% and 0.6% with, respectively, 0.6% and 0% of G4 (p = NS).

CONCLUSIONS

Hypofractionation up to a single-fraction HDR-BT boost for prostate cancer yields similar results in terms of biochemical control and late toxicity compared with two or three-fraction schemes. Single fraction HDR-BT appears acceptable for boosting prostate cancer after definitive EBRT.

Iridium-Knife: Another knife in radiation oncology

PURPOSE

Intratarget dose escalation with superior conformity is a defining feature of three-dimensional (3D) iridium-192 (¹⁹²Ir) high-dose-rate (HDR) brachytherapy (BRT). In this study, we analyzed the dosimetric characteristics of interstitial ¹⁹²Ir HDR BRT for intrathoracic and cerebral malignancies. We examined the dose gradient sharpness of HDR BRT compared with that of linear accelerator-based stereotactic radiosurgery and stereotactic body radiation therapy, usually called X-Knife, to demonstrate that it may as well be called a Knife.

METHODS AND MATERIALS

Treatment plans for 10 patients with recurrent glioblastoma multiforme or intrathoracic malignancies, five of each entity, treated with X-Knife (stereotactic radiosurgery for glioblastoma multiforme and stereotactic body radiation therapy for intrathoracic malignancies) were replanned for simulated HDR BRT. For 3D BRT planning, we used identical structure sets and dose prescription as for the X-Knife planning. The indices for qualitative treatment plan analysis encompassed planning target volume coverage, conformity, dose falloff gradient, and the maximum dose-volume limits to different organs at risk.

RESULTS

Volume coverage in HDR plans was comparable to that calculated for X-Knife plans with no statistically significant difference in terms of conformity. The dose falloff gradient-sharpness-of the HDR plans was considerably steeper compared with the X-Knife plans.

CONCLUSIONS

Both 3D ¹⁹²Ir HDR BRT and X-Knife are effective means for intratarget dose escalation with HDR BRT achieving at least equal conformity and a steeper dose falloff at the target volume margin. In this sense, it can reasonably be argued that 3D ¹⁹²Ir HDR BRT deserves also to be called a Knife, namely Iridium-Knife.

Outcomes with volume-based dose specification in CT-planned high-dose-rate brachytherapy for stage I-II cervical carcinoma: A 10-year institutional experience

OBJECTIVE

To determine prognostic factors for progression-free survival (PFS) and overall survival (OS) for stage I-II cervical-cancer patients treated using computed-tomography (CT)-planned high-dose-rate (HDR) intracavitary brachytherapy (BT).

METHODS

A total of 150 patients were treated for Stage I-II cervical cancer using CT-planned BT between 4/2004 and 10/2014. Of these, 128 were eligible for inclusion. Kaplan-Meier local control (LC), pelvic control (PC), overall survival (OS), and PFS estimates were calculated.

RESULTS

After a median follow-up of 30months, the 2-year LC rate was 96%, PFS was 88%, and OS was 88%. Overall, 18 patients (14%) experienced any recurrence (AR), 8 had distant recurrence only and 10 had a combination of local, pelvic, regional, and distant recurrence. No patients had LR only. A prognostic factor for AR was tumor size >4cm (p=0.01). Patients with tumors >4cm were 3.3 times more likely to have AR than those with tumors ≤4cm (hazard ratio [HR]=3.3; 95% confidence interval [CI] 1.28-9.47). Point A was 85% of prescription for tumors < 4 cm and decreased approximately 3% over 5 fractions compared to 90% of prescription for tumors > 4 cm that decreased approximately 4% over 5 fractions. Two patients (2%) experienced grade≥2 late toxicity. There were no acute or late grade≥3 toxicities.

CONCLUSION

CT-planned BT resulted in excellent local control and survival. Large tumor size was associated with an increased risk of recurrence outside the radiation field and worse PFS and OS. A volume-optimized plan treated a smaller area than a point A standard plan for patients with Stage I-II cervical cancer that have received chemoradiation. Given the outstanding LC achieved with modern therapy including chemoradiation, HDR, and image-based BT, further efforts to combat spread outside the radiation field with novel therapies are warranted.

Rectal and bladder dose reduction with the addition of intravaginal balloons to vaginal packing in intracavitary brachytherapy for cervical cancer

PURPOSE

The use of intravaginal Foley balloons in addition to conventional packing during high-dose-rate (HDR) tandem and ovoids intracavitary brachytherapy (ICBT) is a means to improve displacement of organs at risk, thus reducing dose-dependent complications. The goal of this project was to determine the reduction in dose achieved to the bladder and rectum with intravaginal Foley balloons with CT-based planning and to share our packing technique.

METHODS AND MATERIALS

One hundred and six HDR-ICBT procedures performed for 38 patients were analyzed for this report. An uninflated Foley balloon was inserted into the vagina above and below the tandem flange separately and secured in place with vaginal packing. CT images were then obtained with both inflated and deflated Foley balloons. Plan optimization occurred and dose volume histogram data were generated for the bladder and rectum. Maximum dose to 0.1, 1.0, and 2.0 cm(3) volumes for the rectum and bladder were analyzed and compared between inflated and deflated balloons using parametric statistical analysis.

RESULTS

Inflation of intravaginal balloons allowed significant reduction of dose to the bladder and rectum. Amount of reduction was dependent on the anatomy of the patient and the placement of the balloons. Displacement of the organs at risk by the balloons allowed an average of 7.2% reduction in dose to the bladder (D0.1 cm(3)) and 9.3% to the rectum (D0.1 cm(3)) with a maximum reduction of 41% and 43%, respectively.

CONCLUSIONS

For patients undergoing HDR-ICBT, a significant dose reduction to the bladder and rectum could be achieved with further displacement of these structures using intravaginal Foley balloons in addition to conventional vaginal packing.

Hypofractionated high-dose-rate plesiotherapy in nonmelanoma skin cancer treatment

PURPOSE

Nonmelanoma skin cancer (NMSC) is the commonest cancer in humans. NMSC treatment currently includes surgery, radiation therapy, and topical approaches. The objective was to analyze and compare the outcomes, toxicity, and cosmesis of NMSC treated by two hypofractionated high-dose-rate (HDR) plesiotherapy techniques.

METHODS AND MATERIALS

A retrospective institutional clinical study of 134 basal cell or squamous cell skin carcinomas treated at Radiation Oncology Department. Lesions were treated from November 2006 to December 2011 with a moderate hypofractionated HDR plesiotherapy using a fixed applicator or a customized mold.

RESULTS

After a median follow-up of 33 months, overall disease-free survival at 3 and 5 years was 95.12% and 93.36%, respectively. For Leipzig applicator, disease-free survival at 3 years was 94.9% and 94.9% at 5 years, for customized mold was 93.1% at 3 years and 88% at 5 years. Complete regression was achieved in 98% of lesions. Two lesions persisted after treatment; both had been treated by a Leipzig applicator. Six lesions suffered local recurrence (five Leipzig applicators and three molds, p = 0.404). Grade <2 acute toxicity noted in 57.3% of patients. Only 2.2% of lesions had Grade 4 acute toxicity. Borderline significant increase of toxicity was associated with customized molds (p = 0.067). Larger tumors were associated with higher acute skin toxicity. The cosmesis outcomes were excellent or good in 82% of patients, fair in 13%, and not available in 5%.

CONCLUSIONS

Hypofractionated HDR plesiotherapy is an effective and well-tolerated treatment for NMSC with different toxicity levels depending on the plesiotherapy technique used.

High-dose-rate vs. low-dose-rate intracavitary brachytherapy for carcinoma of the uterine cervix: Systematic review and meta-analysis

PURPOSE

We performed a meta-analysis to compare the treatment outcomes between high-dose-rate (HDR) and low-dose-rate (LDR) intracavitary brachytherapy (ICBT) for the treatment of cervical cancer.

METHODS AND MATERIALS

We searched the PubMed database for articles and the related referenced articles that compared HDR-ICBT and LDR-ICBT. A total of 15 published articles, 3 prospective randomized trials, and 12 retrospective studies performed between 1966 and December 2013 were selected using predefined inclusion and exclusion criteria for each study. The effect sizes were obtained from the odds ratios of the 5-year overall survival, 5-year disease-free survival (DFS), pelvic (locoregional) recurrence, and rectal and bladder complication rates in each study. The common effect sizes and 95% confidence intervals (CIs) were calculated using either the fixed or the random-effect model, according to the results of the homogeneity tests.

RESULTS

We analyzed the outcome data for 18,937 patients, including 10,807 patients in the HDR-ICBT treatment group and 8,130 patients in the LDR-ICBT group. The common effect sizes (95% CI) for the 5-year survival rate, 5-year DFS rate, and pelvic recurrence rate were 1.1350 (0.9231-1.3955), 1.0777 (0.4896-2.3720), and 0.9521 (0.7624-1.1890), respectively. The common effect sizes (95% CI) for moderate-to-severe complication rates of the rectum and the bladder were 0.7645 (0.5099-1.1463) and 0.9051 (0.6140-1.3342), respectively. There were no significant differences between HDR- and LDR-ICBT considering the 5-year survival, 5-year DFS, pelvic recurrence, and the rectal and bladder complication rates.

CONCLUSION

The treatment outcome after HDR-ICBT seems to be equivalent to that following LDR-ICBT in terms of survival, pelvic recurrence, and major complications.

Predictors of vaginal stenosis after intravaginal high-dose-rate brachytherapy for endometrial carcinoma

PURPOSE

Intravaginal high-dose-rate brachytherapy is an effective adjuvant treatment for localized endometrial carcinoma. However, relatively little is known about risk factors of post-treatment vaginal stenosis (VS).

METHODS AND MATERIALS

We included patients treated with brachytherapy for endometrial carcinoma from September 2011 to January 2014 with at least 3 months of followup. Patients who received external beam radiation therapy were excluded. VS was prospectively graded at each followup visit per Common Terminology Criteria for Adverse Events, version 4.03. χ(2) and t test analyses were used to assess the association of VS with various patient, tumor, treatment, and post-treatment factors. Multivariable logistic regression analysis was used to identify independent predictors of VS Grade ≥1 and ≥2.

RESULTS

All 101 patients were disease free at last followup. Mean followup was 12.9 months (range, 3-34). Highest VS grades were zero in 67%, one in 26%, two in 6%, and three in 1%. Borderline significant variables associated with Grade ≥1 VS included vagina length, proportion of vagina treated, and total dose. Dilator use was significantly associated with Grade ≥2. Multivariable analysis revealed that proportion of vagina treated >60% (odds ratio [OR], 3.48; p = 0.009) and total dose >14 Gy (OR, 4.27; p = 0.015) were independent predictors of Grade ≥1 VS, and lack of consistent dilator use was an independent predictor of Grade ≥2 VS (OR, 5.60; p = 0.047).

CONCLUSIONS

Patients treated with a higher total dose to a larger proportion of the vagina were more likely to develop Grade ≥1 VS. Consistent dilator use may also be protective against Grade ≥2 VS.

Ureteral stent insertion for gynecologic interstitial high-dose-rate brachytherapy

PURPOSE

To determine the utility of ureteral stents in interstitial gynecological brachytherapy.

METHODS AND MATERIALS

We reviewed 289 patients with cervix cancer treated with high-dose-rate interstitial brachytherapy who did not have pretreatment hydronephrosis to determine the relative incidence of benign ureteral strictures after treatment. We also did comparative dosimetry analysis in five cases of high-dose-rate brachytherapy. Bilateral ureteral stents were placed during the procedure. Three dosimetry plans were created to determine the impact of modifying clinical target volume (CTV) and applying ureteral dose constraints. In Plan 1, the ureters were contoured and excluded from the CTV and 120% dose constraints were applied. In Plan 2, the ureters were contoured and excluded, but no dose constraints were applied to the ureter. In Plan 3, the CTV was created as if the location of the ureters was unknown and then ureteral dose was determined.

RESULTS

There were 11 ureteral strictures observed in 255 nonstented cases and 0 ureteral strictures in 34 stented cases. Plan 1 reduced the ureter dose (D(0.1cc)) by a median 22% (7.0-53.8%) compared with Plan 2 and by a median of 30.9% (12.3-65%). compared with Plan 3.

CONCLUSIONS

Placement of stents and ureteral dose constraints facilitates dosimetry and reduces the dose to ureters. Temporary ureteral stents prevent obstruction during interstitial gynecologic brachytherapy and allows the ureters to be addressed as an organ at risk.

A sector-based dosimetric analysis of dose heterogeneity in high-dose-rate prostate brachytherapy

PURPOSE

High-dose-rate (HDR) prostate brachytherapy delivers a heterogeneous dose distribution throughout the prostate gland. There is however limited information regarding the spatial distribution of this dose heterogeneity. To this end, we analyzed the magnitude and location of intraprostatic dose heterogeneity in HDR prostate brachytherapy.

METHODS AND MATERIALS

Five consecutive prostate cancer patients treated with HDR were analyzed. Based on CT-simulation images, each prostate was divided into three sections (apex, base, and mid-gland). These were further subdivided into eight symmetrical sections to give a total of 24 sections. Dose-volume histograms were analyzed from V100-V200% for these 24 sections comparing the means of individual regions, left vs right, apex vs base vs mid-gland, lateral vs medial, and anterior vs posterior. A separate analysis on dose as a function of individual region volume was also performed.

RESULTS

Analyses comparing the 24 regions showed a maximum 62% difference (range, 21.9-83.9%) at V130% and 19.9% (1.9-20.8%) at V200%. Seven regions were significantly decreased and one significantly elevated from V130-V180% when compared with the mean. The means for lateral sections were 1.57-fold higher than medial sections from V110-V200% (p < 0.0001). The dose at the base was significantly higher than the rest of the gland from V120-V200 (V150, 35.6 ± 16.2% vs 20.9 ± 13.1%, p < 0.0001).

CONCLUSIONS

There is significant intra-prostatic dose heterogeneity in prostate HDR brachytherapy. This is most notable in the increased dose to base and lateral portions of the gland. Further studies are needed to determine the impact of heterogeneity on clinical outcomes.

Does prostate-specific antigen nadir predict longer-term outcomes of prostate cancer after neoadjuvant and adjuvant androgen deprivation therapy in conjunction with brachytherapy?

PURPOSE

To evaluate whether nadir prostate-specific antigen (nPSA), time to nPSA (TnPSA), and nPSA 3-years post-treatment are prognostic for prostate cancer (PC) in patients treated with temporary brachytherapy plus external beam radiation therapy (EBRT) and hormonal manipulation.

METHODS AND MATERIALS

We retrospectively analyzed our database of 253 patients with Stage T1-T3 N0M0 PC who underwent brachytherapy with temporary brachytherapy plus EBRT. All patients received neoadjuvant androgen deprivation for a median of 6 months. Treatment consisted of three pulses of pseudo pulsed-dose-rate brachytherapy to a median dose of 18Gy with 50.4Gy in 28 fractions of EBRT. Treatment took place between December 1999 and March 2006.

RESULTS

At a median of 6-years followup, nPSA value was a predictor of biochemical control. Rising nPSA categories of <0.01, 0.01-<0.05, 0.05-≤0.1, 0.1-≤ 1.0, or >1.0 ng/mL correlated with a deteriorating 5-year biochemical control (nBED) by the Phoenix definition of 100%, 90.0%, 82.5%, 64.3%, and 10%, respectively. A highly statistically significant relationship between nPSA value and subsequent clinical failure is also demonstrated. The relationship between TnPSA and nBED was strongly significant (p<0.0001), with a significantly longer nPSA for patients who had Phoenix nBED. A PSA of <1.5 ng/mL achieved 3-year post radiation therapy was prognostic for biochemical and clinical disease control (p<0.0001).

CONCLUSION

The nPSA, TnPSA, and reaching a PSA cutoff level of <1.5 ng/mL at 3 years post-treatment can provide useful prognostic information on long-term biochemical and clinical control of PC in patients treated with pseudo PDR, EBRT, and hormone manipulation.

Tolerance of the vaginal vault to high-dose rate brachytherapy and concomitant chemo-pelvic irradiation: Long-term perspective

AIM/BACKGROUND

We sought to determine the tolerance level and complication rates of the vaginal vault to combined high-dose-rate intra-cavitary brachytherapy with concomitant chemo-radiotherapy.

PATIENTS AND METHODS

A retrospective review of medical records of all the patients who received definitive chemo-radiotherapy for cervical cancer between 1998 and 2002 was undertaken. The records were reviewed for doses and for radiation-associated early and late sequelae of the vagina, rectum and bladder. Cumulative biological effective dose was calculated for two reference vaginal surface points.

RESULTS

Fifty patients were included. Average age at diagnosis was 54 years. Median follow-up was 59 months. There were no recorded instances of acute grade IV toxicity. Maximal high-dose-rate vaginal surface dose (upper central point) was 103 Gy, and maximal brachytherapy lateral surface dose was 70 Gy. Maximal cumulative biological effective dose for the lateral surface reference point was 465.5 Gy3, and the maximal cumulative biological effective dose for the superior reference point was 878.6 Gy3. There were no cases of vaginal necrosis or fistulas, and no cases of grade IV late vaginal, rectal or bladder toxicity. No correlation was found between the maximal vaginal surface dose and vaginal, rectal or bladder toxicity.

CONCLUSIONS

The maximal surface HDR brachytherapy dose of 103 Gy and the maximal cBED of 878.6 Gy3 were not associated with fistula or necrosis or other grade 3-4 vaginal complications. Concomitant chemo-radiotherapy, including pelvic radiotherapy and high-dose-rate intracavitary brachytherapy, is relatively safe for cervical cancer patients.

A dosimetric study of polyethylene glycol hydrogel in 200 prostate cancer patients treated with high-dose rate brachytherapy±intensity modulated radiation therapy

BACKGROUND AND PURPOSE

We sought to analyze the effect of polyethylene glycol (PEG) hydrogel on rectal doses in prostate cancer patients undergoing radiotherapy.

MATERIALS AND METHODS

Between July 2009 and April 2013, we treated 200 clinically localized prostate cancer patients with high-dose rate (HDR) brachytherapy±intensity modulated radiation therapy. Half of the patients received a transrectal ultrasound (TRUS)-guided transperineal injection of 10mL PEG hydrogel (DuraSeal™ Spinal Sealant System; Covidien, Mansfield, MA) in their anterior perirectal fat immediately prior to the first HDR brachytherapy treatment and 5mL PEG hydrogel prior to the second HDR brachytherapy treatment. Prostate, rectal, and bladder doses and prostate-rectal distances were calculated based upon treatment planning CT scans.

RESULTS

There was a success rate of 100% (100/100) with PEG hydrogel implantation. PEG hydrogel significantly increased the prostate-rectal separation (mean±SD, 12±4mm with gel vs. 4±2mm without gel, p<0.001) and significantly decreased the mean rectal D2 mL (47±9% with gel vs. 60±8% without gel, p<0.001). Gel decreased rectal doses regardless of body mass index (BMI).

CONCLUSIONS

PEG hydrogel temporarily displaced the rectum away from the prostate by an average of 12mm and led to a significant reduction in rectal radiation doses, regardless of BMI.

Intraoperative and percutaneous iridium-192 high-dose-rate brachytherapy for previously irradiated lesions of the spine

PURPOSE

Advances in stereotactic radiosurgery have improved local control of spine metastases, but local failure is still a problem and repeat irradiation is limited by normal tissue tolerance. A novel high-dose-rate (HDR) brachytherapy technique has been developed to treat these previously irradiated lesions.

METHODS AND MATERIALS

Five patients with progressive disease at previously irradiated sites in the spine who were not amenable to further external beam radiation were treated. Catheters were placed intraoperatively in 2 patients and percutaneously implanted in 3 patients with image-guided techniques. Conformal plans were generated to deliver dose to target tissues and spare critical structures. Patients received single-fraction treatment using HDR iridium-192 brachytherapy.

RESULTS

Median dose was 14 Gy (range, 12-18 Gy) with a median gross total volume D90 of 75% (range, 31-94%); spinal cord/cauda equina dose constraints were met. At a median followup of 9 months, no local progression of disease has been observed. Four patients had reduction in pain 1-4 weeks after treatment. No brachytherapy-related complications have been observed.

CONCLUSIONS

Intraoperative and percutaneous iridium-192 HDR spine brachytherapy techniques were not associated with complications or acute toxicity. There has been no local progression at treated sites, and most patients experienced reduction in cancer-related pain.

Assessment of tumor regression by consecutive pelvic magnetic resonance imaging and dose modification during high-dose-rate brachytherapy for carcinoma of the uterine cervix

PURPOSE

To assess tumor regression, as determined by pelvic magnetic resonance imaging (MRI), and evaluate the efficacies and toxicities of the interim brachytherapy (BT) modification method, according to tumor regression during multi-fractionated high-dose-rate (HDR) BT for uterine cervical cancer.

MATERIALS AND METHODS

Consecutive MRI studies were performed pre-radiotherapy (RT), pre-BT and during interfraction of BT (inter-BT) in 69 patients with cervical cancer. External beam radiotherapy (EBRT) was performed, using a 10 MV X-ray, in daily fraction of 1.8 Gy with 4-fields, 5 d/wk. Radiation was delivered up to 50.4 Gy, with midline shielding at around 30.6 Gy. Of all 69 patients, 50 received modified interim BT after checking the inter-BT MRI. The BT was delivered in two sessions; the first was composed of several 5 Gy fractions to point A, twice weekly, using three channel applicators. According to the three measured orthogonal diameters of the regressed tumor, based on inter-BT MR images, the initial BT plan was modified, with the second session consisting of a few fractions of less than 5 Gy to point A, using a cervical cylinder applicator.

RESULTS

The numbers of patients in FIGO stages Ib, IIa, IIb and IIIb+IVa were 19 (27.5%), 18 (26.1%), 27 (39.2%) and 5 (7.2%), respectively. Our treatment characteristics were comparable to those from the literatures with respect to the biologically effective dose (BED) to point A, rectum and bladder as reference points. In the regression analysis a significant correlation was observed between tumor regression and the cumulative dose to point A on the follow-up MRI. Nearly 80% regression of the initial tumor volume occurred after 30.6 Gy of EBRT, and this increased to 90% after an additional 25 Gy in 5 fractions of BT, which corresponds to 73.6 Gy of cumulative BED(10) to point A. The median total fraction number, and those at the first and second sessions of BT were 8 (5 approximately 10), 5 (3 approximately 7) and 3 (1 approximately 5), respectively. The median follow-up time was 53 months (range, 9 approximately 66 months). The 4-year disease-free survival rate of all patients was 86.8%. Six (8.7%) patients developed pelvic failures, but major late complications developed in only two (2.9%).

CONCLUSION

Our study shows that effective tumor control, equivalent survival and low rates of major complications can be achieved by modifying the fraction size during BT according to tumor regression, as determined by consecutive MR images. We recommend checking the follow-up MRI at a cumulative BED(10) of around 65 Gy to point A, with the initial BT modified at a final booster BT session.