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

PurposeTo evaluate the local control and toxicities of three-dimensional image-guided combined intracavitary and interstitial (IC/IS) high-dose-rate brachytherapy (BT) in cervical cancer through a systematic review.Methods and MaterialsA systematic review of relevant studies was performed through the PubMed, Web of Science, and Cochrane Library databases through May 10, 2020. Articles reporting on IC/IS technology, volumetric doses to high-risk clinical target volume (HR-CTV) and organs at risk (OARs), tumor control and/or treatment-related side effects were identified. The key information, including the type of applicator, implantation technology, characteristics of implantation, volumetric doses, tumor control, and/or treatment-related side effects, was extracted. A probit model analysis between HR-CTV D90 and tumor local control was performed.ResultsTwelve studies encompassing 520 patients were included in the probit model between HR-CTV D90 and the local control rate. The probit model showed a significant relationship between the HR-CTV D90 value and the local control probability, p = 0.003. The prescribed dose of 85 Gy_EQD2,10 would in theory warrant an 87.4% (95% confidence interval 82.5%–90.5%) local control rate.ConclusionIC/IS BT is an appropriate method to achieve a high therapeutic ratio for tumors with large volumes or poor responses after external irradiation in cervical cancer. The probit model showed that the dose escalation of HR-CTV D90 was helpful to improve the local tumor control rate.     

A dosimetric evaluation of using a single treatment plan for multiple treatment fractions within a given applicator insertion in gynecologic brachytherapy

PurposeTo evaluate the dosimetric impact of using one treatment plan for multiple fractions from a single tandem and ring applicator insertion of high-dose-rate brachytherapy for cervical cancer.Methods and MaterialsThirteen cervical cancer patients undergoing high-dose-rate brachytherapy were followed. Patients received the total dose from a single applicator insertion in two fractions, given with at least 6 hours apart within 24 hours. The treatment plan was based on a CT scan taken before the first treatment fraction. A second CT was obtained before the second treatment fraction. The co-registered image series were used to evaluate the dosimetric impact of using a single treatment plan for both fractions. Applicator and catheters were measured to quantify interfraction displacement.ResultsWhen the Day 1 plan was applied to the Day 2 images, high-risk clinical target volume (HR-CTV) coverage was reduced by as much as 17.4 percentage points. The mean decrease was 9.4 ± 5.0 percentage points (p < 0.0001). The rectum V₇₅ increase was significant (p = 0.03), whereas the bladder V₇₅ increase was not significant (p = 0.28). Volume changes in the HR-CTV contour from Day 1 to Day 2 were also observed (p = 0.29). Maximum applicator and catheter displacements of 10–30 mm were seen, from Day 1 to Day 2.ConclusionsWhen the Day 1 plan was used on the Day 2, the HR-CTV coverage decreased significantly (p < 0.0001). Our study establishes the need for institutions to evaluate the necessity for replanning based on imaging obtained before each treatment fraction for their gynecologic brachytherapy techniques.     

Practically achievable maximum high-risk clinical target volume doses in MRI-guided intracavitary brachytherapy for cervical cancer: A planning study

PurposeTo explore maximum high-risk clinical target volume (HR-CTV) doses that can be practically achieved when organs at risk (OARs; bladder, rectum, and sigmoid) doses are allowed to equal current recommended thresholds in MRI-based intracavitary brachytherapy (BT) planning for cervical cancer.Methods and MaterialsPlanning MRI sets were retrieved for 21 patients who received pulsed-dose-rate BT boost. Plans were generated using manual optimization (MO) by adjusting dwell positions and times to obtain the prescribed HR-CTV isodose that includes 90% of target (D₉₀) coverage of 35 Gy while limiting OAR doses to below recommended tolerances (prescribed dose target [TGT] plans). Additional planning was performed with automatic volume optimization (VO) to evaluate target coverage relative to the MO plans. The MO and VO approaches were then applied with the objective of obtaining the highest possible HR-CTV coverage when OAR doses were allowed to equal threshold tolerance values (maximized [MAX] plans). A two-tailed paired t test was performed to determine the statistical significance of the results; significance level set at p < 0.013.ResultsMO and VO planning techniques could conform HR-CTV D₉₀ to the prescribed dose quite similarly for TGT plans. Using the MAX approach, the HR-CTV D₉₀ could be increased by 30% and 37% for MO and VO, respectively, without exceeding OAR thresholds. Sigmoid and often rectum were the dose-limiting structures during MAX planning.ConclusionsSimple differences in the approach to volumetric MRI-based cervix BT treatment planning can impact HR-CTV D₉₀. Consequently, dose escalation for MRI-guided cervix BT appears feasible in this manner should clinical circumstances warrant.     

The dosimetric impact of single,dual, and triple tandem applicators in the treatment of intact uterine cancer

PurposeTo identify an optimal afterloading technique for high-dose-rate brachytherapy treatments in patients with medically inoperable uterine cancer.Methods and MaterialsEighteen treatment plans were generated using point and volume-based techniques for three patients using a single, dual, and triple tandem. Dosimetric parameters of the target and critical structures were evaluated.ResultsSimilar target coverage was achieved for each patient using volume-based planning; however, differences were evident when comparing point-based plans for the three applicators. In Patient 1, with a cylindrical uterus (8 cm by 4.5 cm), similar results were achieved with all three applicators (V₉₅ [Single] = 90.6%, V₉₅ [Dual] = 90.6%, and V₉₅ [Triple] = 91.5%). In Patient 2, who had a more spherical uterus (5 cm by 5.4 cm), the dual tandem was inferior to the others (V₉₅ = 65.9% vs. 83.7% with triple and 85.8% with single tandem). Analysis of isodose distributions showed that the dual tandem failed to achieve adequate coverage of the central portion of the fundus. In Patient 3, who had a uterus (6 cm by 5.5 cm) in close proximity to the bladder (0.5 cm) and bowel, both the triple and dual tandem point-based plans achieved better coverage than the single tandem, given dose constraints on the bladder and bowel, with uterus V₉₅ of 83.4% (Triple), 84.9% (Dual), and 73.7% (Single), respectively.ConclusionsFor inoperable uterine cancer, optimal high-dose-rate applicator selection depends on the anatomy and location of the uterus and critical organs. The triple tandem applicator provides greater latitude in dose and anatomic uterus coverage as compared with either single or dual tandem applicators.     

High-dose-rate interstitial brachytherapy vs external beam radiation for the treatment of complex keloids

Postoperative external beam radiation therapy (EBRT) with superficial X-rays or electrons and high-dose-rate brachytherapy (HDR BT) are both viable options for managing keloid scars. However, complex keloid scars are especially challenging to manage. We aim to compare the benefit and challenges between interstitial HDR BT and electron EBRT in treating the complex keloids. Three patients with 7 complex keloids: 3 jaw lines, 1 postauricular, 1 posterior neck, and 2 chest walls are included in this study. All patients are treated to 6 Gy x 3 fractions with HDR BT using the flexible interstitial catheters, and electron EBRT plans were created retrospectively for dosimetric comparison. The average D₉₀ is 21.8 ± 8.3 Gy (1 SD) (121%) and 16.9 ± 1.9 Gy (1SD) (94%) in HDR and EBRT plans, respectively. The average treatment time was 7 minutes per patient (range: 6 – 8.5 minutes) for the HDR BT. Dosimetric comparison reveals that HDR plans provide superior coverage to the keloid scars than the EBRT plans. Clinical workflow is streamlined with HDR procedures. The cosmetic outcome with the interstitial HDR BT is satisfactory.     

Proof of principle: Applicator-guided stereotactic IMRT boost in combination with 3D MRI-based brachytherapy in locally advanced cervical cancer

PurposeTo describe a new technique involving high-precision stereotactic intensity-modulated radiation therapy (IMRT) boost in combination with intracavitary-interstitial (IC-IS) brachytherapy (BT) in cervical tumors that cannot be sufficiently covered by IC-IS-BT due to extensive residual disease and/or difficult topography at the time of BT.Methods and MaterialsThree patients with stage IIIB-IVA cervical cancer had significant residual disease at the time of BT. MRI-guided IC-IS-BT (pulsed-dose rate) was combined with a stereotactic IMRT boost guided according to the BT applicator in situ, using cone beam CT. The planning aim dose (total external beam radiotherapy and BT) for the high-risk clinical target volume (HR-CTV) was D90 >70–85 Gy, whereas constraints for organs at risk were D_2cm3 <70 Gy for rectum, sigmoid, and bowel and <90 Gy for bladder in terms of equivalent total dose in 2 Gy fractions. An IMRT boost adapted to the BT dose distribution was optimized to target the regions poorly covered by BT.ResultsHR-CTV doses of D90 >81 Gy were obtained in the central HR-CTV and D90 >69 Gy in the distal regions of HR-CTV. Image-guided set up of the IMRT boost with the applicator in situ was feasible. The dose plans were robust to intra-fraction uncertainties of 3 mm. Local control with acceptable morbidity was obtained at a followup of 3, 2.5, and 1 year, respectively.ConclusionsThe combination of MRI-guided BT with an applicator-guided stereotactic IMRT boost is feasible. This technique seems to be useful in the few cases where HR-CTV coverage cannot be obtained even with IS-IC-BT.     

Postoperative management of keloids: Low-dose-rate and high-dose-rate brachytherapy

PurposeWe report the experience of the Radiation Oncology Department of the European Institute of Oncology in Milan, Italy, on the adjuvant low-dose-rate (LDR) and high-dose-rate (HDR) interstitial brachytherapy. Brachytherapy might be useful to improve keloids recurrence rate or reduce keloids treatment side effects instead of external beam radiotherapy.Methods and MaterialsData on 70 consecutive patients treated after complete keloid surgical excision were retrospectively analyzed. First 38 patients and 46 keloids were treated with adjuvant LDR brachytherapy and the following 39 patients and 50 keloids underwent HDR treatment. Median delivered dose of LDR therapy was 16 Gy; HDR median dose was 12 Gy. Sixty-four keloids (66.7%) were symptomatic at diagnosis with pain, itching, or stress.ResultsFourteen relapses over 46 treated keloids (30.4%) were observed in the LDR group and 19 of 50 keloids (38%) in the HDR group (p = 0.521). Recurrence rate was significantly higher in males (p = 0.009), in patients younger than 44 years (p < 0.0001), for arms, neck, and chest wall anatomic sites (p = 0.0001) and for symptomatic keloids (p = 0.017). Aesthetic outcome was better in case of larger keloids (>8 cm) (p = 0.064). Symptomatic relief was achieved in 92% of HDR patients and only 68% of LDR patients (p = 0.032).ConclusionsPostoperative brachytherapy is an effective treatment for keloids. In our study, LDR and HDR treatments resulted in similar recurrence rate. Better symptomatic relief was reported in case of HDR treatment compared with the LDR regimen.     

Is stereotactic CyberKnife radiotherapy or multicatheter HDR brachytherapy the better option dosimetrically for accelerated partial breast irradiation?

ObjectiveTo compare dosimetrically the stereotactic CyberKnife (CK) therapy and multicatheter high-dose-rate (HDR) brachytherapy (BT) for accelerated partial breast irradiation (APBI).MethodsTreatment plans of 25 patients treated with CK were selected, and additional plans using multicatheter HDR BT were created on the same CT images. The prescribed dose was 6.25/25 Gy in both plans to the target volume (PTV). The dose-volume parameters were calculated for both techniques and compared.ResultsThe D90 total dose of the PTV was significantly lower with CK than with HDR BT, D90 was 25.7 Gy, and 27.0 Gy (p < 0.001). However, CK plans were more conformal than BT, COIN was 0.87, and 0.81 (p = 0.0030). The V50 of the non-target breast was higher with CK than with BT: 10.5% and 3.3% (p = 0.0010), while there was no difference in the dose of the contralateral breast and contralateral lung. Dose to skin, ipsilateral lung, and ribs were higher with CK than with BT: D₁ was 20.6 Gy vs. 11.5 Gy (p = 0.0018) to skin, 11.4 Gy vs. 9.6 Gy (p = 0.0272) to ipsilateral lung and 18.5 Gy vs. 12.3 Gy (p = 0.0013) to ribs, while D_0.1 to heart was lower, 3.0 Gy vs. 3.2 Gy (p = 0.0476), respectively.ConclusionsMulticatheter HDR BT yields more advantageous plans than stereotactic CyberKnife treatment in accelerated partial breast irradiation, except in terms of dose conformality and the dose to the heart. There was no difference in the dose of the contralateral breast and lung.     

Comparison of computed tomography with magnetic resonance imaging for imaging-based clinical target volume contours in cervical cancer brachytherapy

PurposeTo compare CT- and MRI-based brachytherapy (BT) target volumes for patients with advanced cervical cancer so as to identify those who benefit most from MRI-based planning. We also studied how the natural mobility of the organ at risks (OARs) affects the given doses.Methods and MaterialsSubjects were 60 patients with International Federation of Gynecology and Obstetrics (FIGO) Stage IB–IVA cervical cancer. The CT high-risk clinical target volume (HR-CTV) was first delineated, then the MRI HR-CTV, with volume discrepancies calculated by subtraction. The DICE coefficient (DC) of similarity was calculated from a superimposition of the volumes. Maximum doses delivered to D_2cc of OARs in CT and MRI plans were compared; the effect of time on the natural mobility was analyzed.ResultsThe mean HR-CTVs and the maximum doses given to OARs in CT- and MRI-based planes were similar. Multivariate analysis showed that deep infiltration affecting the uterine corpus and bowel loops adjacent to the cervix were the factors significantly impacting on the volume discrepancy between CT and MRI HR-CTV (p = 0.001, p = 0.045) and on the DC (p = 0.005, p = 0.028). Univariate analysis demonstrated that the FIGO stage had a significant impact on DC (p = 0.022). Patients with bowel loops adjacent to the cervix had lower body mass indices (p = 0.003). The median difference between the doses given in CT- and MRI-based plans, caused by mobility, were 0.5 Gy, 0.3 Gy, and 0.45 Gy per fraction for the rectum, bladder and sigmoid, respectively. No correlation of observed uncertainties and time between image acquisitions was detected.ConclusionsCT- or MRI-based scans at BT are adequate for OAR dose–volume histograms analysis. Cervical cancer patients with deep infiltration affecting the uterine corpus, a low body mass index with bowel loops adjacent to the cervix and an FIGO Stage III–IVA benefit most from MRI-based planning of BT.     

Analysis of dose-effect relationship between DVH parameters and clinical prognosis of definitive radio(chemo)therapy combined with intracavitary/interstitial brachytherapy in patients with locally advanced cervical cancer: A single-center retrospective study

PurposeThe purpose of the study was to explore the dose-effect relationship between dose-volume histogram parameters and clinical prognosis of definitive radio(chemo)therapy followed by intracavitary/interstitial brachytherapy in locally advanced cervical cancer.Methods and MaterialsA retrospective analysis was performed on 110 patients with locally advanced cervical cancer who underwent external beam radiotherapy combined with intracavitary/interstitial brachytherapy with or without chemotherapy from July 2010 to September 2018. We reported D₁₀₀, D₉₈, and D₉₀ for high-risk clinical target volume (HR-CTV) and intermediate-risk clinical target volume, D_2cm³ for organs at risk. Multivariate Cox regression was used to screen independent factors. Dose-volume parameters screened by the Cox regression were incorporated into the probit model for investigating its relationship with survival.ResultsThe median followup time was 72.33 months. Multivariate Cox regression analysis showed that HR-CTV D₁₀₀, HR-CTV D₉₈, and HR-CTV D₉₀ were independent factors, affecting the 5-year overall survival (OS), cancer-specific survival (CSS), and local control (LC) rates. The probit model showed that HR-CTV D₉₈ had predictive values for the 5-year OS, CSS, and LC, and HR-CTV D₁₀₀ had predictive values for the 5-year OS, CSS, whereas HR-CTV D₉₀ had a predictive value only for the 5-year OS. The HR-CTV D₉₈ corresponding to OS _ED90, CSS _ED90, and LC _ED90 was 86.8, 85.6, and 78.6 Gy, respectively.ConclusionsA significant dependence of OS, CSS, and LC on D₉₈ for HR-CTV was found. When the long-term OS, CSS, and LC rate of the patient was >90%, HR-CTV D₉₈ > 86.8 Gy _EQD2, 85.6 Gy _EQD2, and 78.6 Gy _EQD2 were required.     

Comparative analysis of rectal dose parameters in image-guided high-dose-rate brachytherapy for cervical cancer with and without a rectal retractor

PurposeThe objective of this study was to determine if use of a rectal retractor (RR) in high-dose-rate intracavitary brachytherapy for cervical cancer reduces rectal dose parameters.Methods and MaterialsWe reviewed data obtained from patients treated with intracavitary brachytherapy for cervical cancer with and without an RR. Treatment plans for each brachytherapy fraction were separated into two groups; R group with use of an RR and P group with use of vaginal packing. Dose–volume parameters for high-risk clinical target volume (HR-CTV), rectum, sigmoid, small bowel, and vaginal surface were collected for each fraction. Rectal D_2cc and International Commission on Radiation Units & Measurements (ICRU) rectal point doses were compared between groups using Student's t tests. Predictors of higher rectal D_2cc were determined by univariate and multivariate regression analyses.ResultsFour hundred sixty-three brachytherapy fractions from 114 patients were used for analysis, 377 fractions with a RR (R group) and 86 with vaginal packing only (P group). Both groups were similar except for slightly higher mean HR-CTV and mean bladder volume in P group. Both mean ICRU rectal point dose (241.1 vs. 269.9 cGy, p = 0.006) and rectal D_2cc (240.6 vs. 283.6 cGy, p < 0.001) were significantly higher in P group. Point A dose, HR-CTV, stage, and use of an RR were significant predictors of rectal D_2cc on multivariate analysis.ConclusionsOur data show that use of an RR leads to lower rectal dose parameters compared with vaginal packing. Further study is needed to determine if this will lead to less long-term toxicity.     

Novel use of ViewRay MRI guidance for high-dose-rate brachytherapy in the treatment of cervical cancer

PurposeTo characterize image quality and feasibility of using ViewRay MRI (VR)–guided brachytherapy planning for cervical cancer.Methods and MaterialsCervical cancer patients receiving intracavitary brachytherapy with tandem and ovoids, planned using 0.35T VR MRI at our institution, were included in this series. The high-risk clinical target volume (HR-CTV), visible gross tumor volume, bladder, sigmoid, bowel, and rectum contours for each fraction of brachytherapy were evaluated for dosimetric parameters. Typically, five brachytherapy treatments were planned using the T2 sequence on diagnostic MRI for the first and third fractions, and a noncontrast true fast imaging with steady-state precession sequence on VR or CT scan for the remaining fractions. Most patients received 5.5 Gy × 5 fractions using high-dose-rate Ir-192 following 45 Gy of whole-pelvis radiotherapy. The plan was initiated at 5.5 Gy to point A and subsequently optimized and prescribed to the HR-CTV. The goal equivalent dose in 2 Gy fractions for the combined external beam and brachytherapy dose was 85 Gy. Soft-tissue visualization using contrast-to-noise ratios to distinguish normal tissues from tumor at their interface was compared between diagnostic MRI, CT, and VR.ResultsOne hundred and forty-two fractions of intracavitary brachytherapy were performed from April 2015 to January 2017 on 29 cervical cancer patients, ranging from stages IB1 to IVA. The median HR-CTV was 27.78 cc, with median D₉₀ HR-CTV of 6.1 Gy. The median time from instrument placement to start of treatment using VR was 65 min (scan time 2 min), compared to 105 min using diagnostic MRI (scan time 11 min) (t-test, p < 0.01). The contrast-to-noise ratio of tumor to cervix in both diagnostic MRI and VR had significantly higher values compared to CT (ANOVA and t-tests, p < 0.01).ConclusionsWe report the first clinical use of VR-guided brachytherapy. Time to treatment using this approach was shorter compared to diagnostic MRI. VR also provided significant advantage in visualizing the tumor and cervix compared to CT. This presents a feasible and reliable manner to image and plan gynecologic brachytherapy.     

Efficacy and the toxicity of the interstitial high-dose-rate brachytherapy in the management of recurrent keloids: 5-year outcomes

PurposeRecurring keloids are a clinical challenge. Interdisciplinary treatments are required in most cases. Owing to the wide variety of concepts, the optimal treatment regime remains unclear. Our clinic established a protocol of perioperative interstitial high-dose-rate brachytherapy with three fractions of 6 Gy and achieved an excellent 2-year local control rate of 94% (In search of the optimal treatment of keloids: Report of a series and a review of the literature). This report is an update on our long-term results of prospective study. Twenty-nine patients were included with a median followup of 5 years.Methods and MaterialsFrom 2009 to 2015, 29 patients with 37 recurrent keloids were treated with perioperative interstitial high-dose-rate brachytherapy; 3 patients had been previously treated with adjuvant external beam radiotherapy and presented with recurrences in the pretreated area. Brachytherapy was given in three fractions with a single dose of 6 Gy in 5-mm tissue depth and covered the scar in total length. Followup visits were scheduled at 6 weeks, 3 months, 6 months, 1 year, and annually thereafter. Therapeutic outcome was assessed in terms of recurrence, acute and late complications, and cosmetic results.ResultsNo procedure-related complications occurred. Improvement of keloid-related symptoms was noticed in all patients after treatment. After a median followup of 49.7 months (range: 7.9–91.9 months), three keloid recurrences and two hypertrophied scars were observed.ConclusionsOur results suggest that brachytherapy may be advantageous in the management of high-risk keloids, even after failure of external beam radiotherapy and other treatment procedures. Our three-fraction treatment schedule reduces the treatment period to 2 days and is therefore convenient for the patients.     

Impact of dosimetric parameters on local control for patients treated with three-dimensional pulsed dose-rate brachytherapy for cervical cancer

PurposeTo investigate the impact of dose-volume histograms parameters on local control of three-dimensional (3D) image-based pulsed dose-rate brachytherapy (BT).Methods and MaterialsWithin a French multicentric prospective study, the data of the 110 patients treated for cervical cancer with external beam radiotherapy followed by 3D image-based and optimized pulsed dose-rate BT were analyzed. Delineation procedures were performed on magnetic resonance imaging in a minority of cases and on CT for the majority of cases, adapted from the Gynaecological Groupe Européen de Curiethérapie—European Society for Therapeutic Radiology and Oncology recommendations. Optimization procedure was left to the discretion of the treating center.ResultsAt 2 years, local control rate reached 78%. Dose to Point A, total reference air kerma, and intermediate-risk clinical target volume (IR-CTV) V₆₀ were predictive factors for local control (p = 0.001, p = 0.001, and p = 0.013, respectively). Patients with IR-CTV V₆₀ <75% had a relative risk of local recurrence of 3.8 (95% confidence interval, 1.4–11.1). There was no correlation found between the high-risk clinical target volume dosimetric parameters and local control.ConclusionsThis multicentric study has shown that 3D image-based BT provides a high local control rate for cervical cancer patients. The V₆₀ for IR-CTV was identified as an important predictive factor for local control.     

Clinical outcomes using image-guided interstitial brachytherapy for definitive cervical cancer patients with high-risk clinical target volumes greater than 30 cc

PurposeGiven the limited data using an interstitial approach with 3D-based planning for definitive cervical cancer utilizing the GEC-ESTRO defined high-risk clinical target volume (HR-CTV), we reviewed our institutional experience of cervical cancer patients with HR-CTVs ≥ 30 cc to determine whether our clinical and toxicity outcomes are acceptable.MethodsA retrospective review of 37 cervical cancer patients with high-risk clinical target volumes (HR-CTVs) ≥30 cc treated with interstitial image-guided brachytherapy (IS IGBT) was performed. All patients received external beam radiotherapy to a median dose of 45 Gy, followed by IS IGBT delivered in a single implant to a median dose of 6 Gy × 5 fractions. Median HR-CTV was 59 cc. A median HR-CTV D₉₀ of 87.44 Gy was achieved. Kaplan–Meier method was used to evaluate local control (LC), distant control, and overall survival (OS), with stratification by overall treatment time (OTT) ≤ 7 or >7 weeks.ResultsMedian followup was 17 months. The estimated 2-year LC, distant control, and OS were 77.6% (confidence interval [CI]: 63.8–94.5%), 56.8% (CI: 41.3–78.1%), and 54.4% (CI: 39.4–75%), respectively. The 2-year LC for OTT ≤7 weeks and >7 weeks were 100% and 58.3%, respectively (p = 0.026). The 2-year OS for OTT ≤7 weeks and >7 weeks were 77.8% and 38%, respectively (p = 0.021).DiscussionsIS IGBT can achieve a high D₉₀ to the HR-CTV even in the setting of large-volume disease and results in a favorable LC and toxicity profile. OTT > 7 weeks is associated with significant decrease in LC and OS.ConclusionsEfforts should be made to complete whole treatment within 7 weeks as this is associated with improved clinical outcomes.     

Dose–effect response in image-guided adaptive brachytherapy for cervical cancer: A systematic review and meta-regression analysis

PurposeThis study aimed to integrate and update the dose–effect relationship between volumetric dose and local control for cervical cancer brachytherapy.Methods and MaterialsWe identified studies that reported high-risk clinical target volume (HR-CTV) D₉₀ and local control probability by searching PubMed, Web of Science, and the Cochrane Library databases through Oct 27, 2019. The regression analyses were performed using a probit model between HR-CTV D₉₀, D₁₀₀, intermediate-risk clinical target volume (IR-CTV) D₉₀, and dose to Point A vs. local control probability. Subgroup analyses were performed according to stratification: time of local control, income level of the country or region, stage of cancer, pathology, mean volume of HR-CTV, dose rate, image modality, concurrent chemoradiotherapy proportion, interstitial proportion, and mean overall treatment time.ResultsThirty-three studies encompassing 2893 patients were included. The probit model showed a significant relationship between the HR-CTV D₉₀ value and the local control probability, p < 0.0001. The D₉₀ corresponding to a probability of 90% local control was 83.7 Gy_EQD2,10 (80.6–87.8 Gy_EQD2,10). Of the 33 studies included in our analysis, eight studies, including 1172 patients, reported the IR-CTV D₉₀ value, ranging from 59.1 Gy_EQD2,10 to 72.3 Gy_EQD2,10. The probit model also showed a significant relationship between the IR-CTV D₉₀ value and the local control probability, p = 0.0464. The 60 Gy_EQD2,10 for IR-CTV D₉₀ corresponded to an 86.1% local control probability (82.0%–89.8%).ConclusionsA significant dependence of local control on HR-CTV D₉₀ and IR-CTV D₉₀ was found. A tumor control probability of >90% can be expected at doses >84 Gy_EQD2,10 and 69 Gy_EQD2,10, respectively, based on an updated meta-regression analysis.     

Results of postoperative interstitial brachytherapy of resectable floor of mouth tumors

PurposeThe 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 MaterialsBetween 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%).ResultsDuring 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%).ConclusionsResults 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.