Clinical and dosimetric factors associated with acute rectal toxicity in patients treated with 131Cs brachytherapy for prostate cancer

Purpose¹³¹Cs has been recently introduced for use in prostate brachytherapy. We wished to identify clinical and dosimetric factors associated with acute bowel/rectal toxicity in patients treated with ¹³¹Cs.Methods and MaterialsPatients treated with ¹³¹Cs prostate brachytherapy at the University of Pittsburgh were asked to complete expanded prostate cancer index composite surveys preoperatively and at 2–4 weeks and 3 months postimplant. We identified patients who experienced acute and persistent acute bowel toxicity to determine if any factors could correlate with either situation.ResultsOne hundred six patients were treated with ¹³¹Cs from September 2006 to May 2008. Thirty-eight percent of patients met our criteria for patient-appreciated acute bowel symptoms. On multivariate analysis, the volume of rectum receiving 50% of the prescribed dose (R-V₅₀; 4.1 vs. 2.6 cc, p = 0.01), R-V₇₅ (1.3 vs. 0.62 cc, p = 0.01), the percentage of the prescribed dose received by 1 cc of the rectum (R-D-1cc; 75% vs. 64%, p = 0.02), and R-D-2cc (63% vs. 54%, p = 0.003) were found to be factors associated with a greater risk of severe acute bowel toxicity. At 3-month followup, 28% of patients had persistent acute bowel toxicity. On multivariate analysis, no factors were identified that correlated with persistent acute bowel toxicity.ConclusionsThis study identifies R-V₅₀, R-V₇₅, R-D-1cc, and R-D-2cc as factors associated with patient-appreciated acute rectal toxicity. We are performing dosimetric analysis to determine the optimal distance for the posterior needles from the prostate–rectal interface to decrease rectal dose while still maintaining adequate coverage of prostate.     

The impact of a rectal hydrogel spacer on dosimetric and toxicity outcomes among patients undergoing combination therapy with external beam radiotherapy and low-dose-rate brachytherapy

PurposeRectal hydrogel spacers have been shown to decrease rectal radiation dose and toxicity. In this study, we compared prostate and rectal dosimetry and acute toxicity outcomes in patients who had and had not received a rectal hydrogel spacer prior to combination therapy with external beam radiotherapy and low-dose-rate brachytherapy.Materials and MethodsAll patients with intermediate-risk and high-risk prostate cancer who received combination therapy at our institution were identified between 2014 and 2019. Dosimetric outcomes of brachytherapy implants and quality of life (QOL) outcomes were compared between patients who had and had not received a hydrogel spacer.ResultsA Total of 168 patients meeting our inclusion criteria were identified. Twenty-two patients had received a rectal hydrogel spacer, among whom the mean separation between the rectum and prostate was 7.5 mm, and the V100_rectum was reduced by 47% (0.09 cc vs. 0.17 cc, p = 0.04). There was no difference in the percentage of patients achieving a D90 of ≥100 Gy between those who had and had not received a spacer. The mean rate of change in I-PSS and SHIM scores did not differ between the two groups at 2 months after PID.ConclusionLDR brachytherapy appears feasible after the placement of a rectal hydrogel spacer. While there was a significantly reduced V100_rectum among patients who had received a hydrogel spacer, there was no statistically significant difference in patients achieving a D90_prostate of ≥100 Gy. Although there was no difference appreciated in QOL scores, the length of follow-up was limited in the rectal-spacer group.     

A comparative dosimetric analysis of virtual stereotactic body radiotherapy to high-dose-rate monotherapy for intermediate-risk prostate cancer

PurposeStereotactic body radiotherapy (SBRT) is being used with increasing frequency as definitive treatment of early stage prostate cancer. Much of the justification for its adoption was derived from earlier clinical results using high-dose-rate (HDR) brachytherapy. We determine whether HDR's dosimetry can be achieved by virtual SBRT.Methods and MaterialsPatients with intermediate-risk prostate cancer on a prospective trial evaluating the efficacy of HDR monotherapy treated to dose of 9.5 Gy × 4 fractions were used for this study. A total of 5 patients were used in this analysis. Virtual SBRT plans were developed to reproduce the planning target volume (PTV) HDR dose distributions. Both normal tissue– and PTV-prioritized plans were generated.ResultsFrom the normal tissue–prioritized plan, HDR and virtual SBRT achieved similar PTV V₁₀₀ (93.8% vs. 93.1%, p = 0.20) and V₁₅₀ (40.3% vs. 42.9%, p = 0.69) coverage. However, the PTV V₂₀₀ was not attainable with SBRT (15.2% vs. 0.0%, p < 0.001). The rectal D_max was significantly lower with HDR (94.2% vs. 99.42%, p = 0.05). The rectal D_{2 cc} was also lower (60.8% vs. 71.1%, p = 0.07). Difference in D_{1 cc} urethral dose was not significantly different (87.7% vs. 75.2%, p = 0.33). Comparing the PTV-prioritized plans, the rectal D_max (94.2% vs. 111.1%, p = 0.05) and mean dose (27.1% vs. 33.3%, p = 0.03) were significantly higher using SBRT, and the rectal D_{2 cc} was higher using SBRT (60.8% vs. 81.8%, p = 0.07).ConclusionsHDR achieves significantly higher intraprostatic doses while achieving a lower maximum rectal dose compared with our virtual SBRT treatment planning. Future studies should compare clinical outcomes and toxicity between these modalities.     

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

PurposeTo investigate the dosimetric impact of interobserver catheter reconstruction variability in transrectal ultrasound–guided prostate high-dose-rate (HDR) brachytherapy.Methods and MaterialsTwenty 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).ResultsGreater 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.ConclusionsLimiting 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.     

High-dose-rate prostate brachytherapy based on registered transrectal ultrasound and in-room cone-beam CT images

PurposeTo present a high-dose-rate (HDR) brachytherapy procedure for prostate cancer using transrectal ultrasound (TRUS) to contour the regions of interest and registered in-room cone-beam CT (CBCT) images for needle reconstruction. To characterize the registration uncertainties between the two imaging modalities and explore the possibility of performing the procedure solely on TRUS.Methods and MaterialsPatients were treated with a TRUS/CBCT-based HDR brachytherapy procedure. For 100 patients, dosimetric results were analyzed. For 40 patients, registration uncertainties were examined by determining differences in fiducial marker positions on TRUS and registered CBCT. The accuracy of needle reconstruction on TRUS was investigated by determining the position differences of needle tips on TRUS and CBCT. The dosimetric impact of reregistration and needle reconstruction on TRUS only was studied for 8 patients.ResultsThe average prostate V₁₀₀ was 97.8%, urethra D₁₀ was 116.3%, and rectum D_{1 cc} was 66.4% of the prescribed dose. For 85% of the patients, registration inaccuracies were within 3 mm. Large differences were found between needle tips on TRUS and CBCT, especially in cranial–caudal direction, with a maximum of 10.4 mm. Reregistration resulted in a maximum V₁₀₀ reduction of 0.9%, whereas needle reconstruction on TRUS only gave a maximum reduction of 9.4%.ConclusionsHDR prostate brachytherapy based on TRUS combined with CBCT is an accurate method. Registration uncertainties, and consequently dosimetric inaccuracies, are small compared with the uncertainties of performing the procedure solely based on static TRUS images. CBCT imaging is a requisite in our current procedure.     

Dose to the dominant intraprostatic lesion using HDR vs. LDR monotherapy: A Phase II randomized trial

PurposeTo present the dosimetric results of a Phase II randomized trial comparing dose escalation to the MRI-defined dominant intraprostatic lesion (DIL) using either low-dose-rate (LDR) or high-dose-rate (HDR) prostate brachytherapy.Material and MethodsPatients receiving prostate brachytherapy as monotherapy were randomized to LDR or HDR brachytherapy. Prostate and DILs were contoured on preoperative multiparametric MRI. These images were registered with transrectal ultrasound for treatment planning. LDR brachytherapy was preplanned using I-125 seeds. HDR brachytherapy used intraoperative transrectal ultrasound–based planning to deliver 27 Gy/2 fractions in separate implants. DIL location was classified as peripheral, central, or anterior. A student t-test compared DIL D₉₀ between modalities and DIL locations.ResultsOf 60 patients, 31 underwent LDR and 29 HDR brachytherapy. Up to three DILs were identified per patient (100 total) with 74 peripheral, six central, and 20 anterior DILs. Mean DIL volume was 1.9 cc (SD: 1.7 cc) for LDR and 1.6 cc (SD 1.3 cc) for HDR (p = 0.279). Mean DIL D₉₀ was 151% (SD 30%) for LDR and 132% (SD 13%) for HDR. For LDR, mean peripheral DIL D₉₀ was 159% (SD 27%) and central or anterior 127% (SD 13%). HDR peripheral DILs received 137% (SD 12%) and central or anterior 119% (SD 7%). DIL D₉₀ for peripheral lesions was higher than anterior and central (p < 0.001).ConclusionsDIL location affects dose escalation, particularly because of urethral proximity, such as for anterior and central DILs. HDR brachytherapy may dose escalate better when target DIL is close to critical organs.     

Placement of an absorbable rectal hydrogel spacer in patients undergoing low-dose-rate brachytherapy with palladium-103

PurposeRates of rectal toxicity after low-dose-rate (LDR) brachytherapy for prostate cancer are dependent on rectal dose, which is associated with rectal distance from prostate and implanted seeds. Placement of a hydrogel spacer between the prostate and rectum has proven to reduce the volume of the rectum exposed to higher radiation dose levels in the setting of external beam radiotherapy. We present our findings with placing a rectal hydrogel spacer in patients following LDR brachytherapy, and we further assess the impact of this placement on dosimetry and acute rectal toxicity.Methods and MaterialsBetween January 2016 and April 2017, 74 patients had placement of a hydrogel spacer, immediately following a Pd-103 seed-implant procedure. Brachytherapy was delivered as follows: as a monotherapy to 26 (35%) patients; as part of planned combination therapy with external beam radiotherapy to 40 (54%) patients; or as a salvage monotherapy to eight (11%) patients. Postoperative MRI was used to assess separation achieved with rectal spacer. Acute toxicity was assessed retrospectively using Radiation Oncology Therapy Group radiation toxicity grading system. Rectal dosimetry was compared with a consecutive cohort of 136 patients treated with seed implantation at our institution without a spacer, using a 2-tailed paired Student's t test (p < 0.05 for statistical significance).ResultsOn average, 11.2-mm (SD 3.3) separation was achieved between the prostate and the rectum. The resultant mean rectal volume receiving 100% of prescribed dose (V_100%), dose to 1 cc of rectum (D_1cc), and dose to 2 cc of rectum (D_2cc) were 0 (SD 0.05 cc), 25.3% (SD 12.7), and 20.5% (SD 9.9), respectively. All rectal dosimetric parameters improved significantly for the cohort with spacer placement as compared with the nonspacer cohort. Mean prostate volume, prostate V₁₀₀ and dose to 90% of gland (D₉₀) were 29.3 cc (SD 12.4), 94.0% (SD 3.81), and 112.4% (SD 12.0), respectively. Urethral D₂₀, D_5cc, and D_1cc were 122.0% (SD 17.27), 133.8% (SD 22.8), and 144.0% (SD 25.4), respectively. After completing all treatments, at the time of first the followup, 7 patients reported acute rectal toxicity—6 experiencing Grade 1 rectal discomfort and 1 (with preexisting hemorrhoids) experiencing Grade 1 bleeding.ConclusionsInjection of rectal spacer is feasible in the post-LDR brachytherapy setting and reduces dose to the rectum with minimal toxicity. Prostate and urethral dosimetries do not appear to be affected by the placement of a spacer. Further studies with long-term followup are warranted to assess the impact on reduction of late rectal toxicity.     

Predictive factors of long-term rectal toxicity following permanent iodine-125 prostate brachytherapy with or without supplemental external beam radiation therapy in 2216 patients

PurposeWe analyzed factors associated with rectal toxicity after iodine-125 prostate brachytherapy (BT) with or without external beam radiation therapy (EBRT).Methods and MaterialsIn total, 2216 prostate cancer patients underwent iodine-125 BT with or without EBRT between 2003 and 2013. The median followup was 6.9 years. Cox proportional hazards modeling was used for univariate and multivariate analyses to assess clinical and dosimetric factors associated with rectal toxicity. Dosimetric parameters from 1 day after implantation (Day 1) and 1 month after implantation (Day 30) were included in the analyses.ResultsThe 7-year cumulative incidence of Grade 2 or higher rectal toxicity was 5.7% in all patients. The multivariate analysis revealed that antiplatelet or anticoagulant therapy, neoadjuvant androgen deprivation therapy, treatment modality, Day 1 rectal volume receiving 100% of the prescribed dose (RV₁₀₀), and the Day 30 minimal percent of the prescribed dose delivered to 30% of the rectum (RD₃₀) were associated with rectal toxicity. Day 1 RV₁₀₀ was a common predictor in both BT-alone and the BT + EBRT groups. The 5-year cumulative incidence of Grade 2 or higher rectal toxicity was 12.6%, 5.9%, and 1.7% for BT + 3-dimensional conformal radiation therapy, BT + intensity-modulated radiation therapy, and the BT-alone groups, respectively (p < 0.001).ConclusionsRectal dosimetric parameters in BT were associated with late rectal toxicity. Although the risk of rectal toxicity was higher when EBRT was combined with BT, with proper and achievable rectal dose constraints intensity-modulated radiation therapy yielded less toxicity than 3-dimensional conformal radiation therapy.     

Brachytherapy provides comparable outcomes and improved cost-effectiveness in the treatment of low/intermediate prostate cancer

PurposeTo evaluate the cost-effectiveness and outcomes of low-dose-rate (LDR) and high-dose-rate (HDR) brachytherapy compared with intensity-modulated radiation therapy (IMRT) in patients with low/intermediate risk of prostate cancer.Methods and MaterialsOne thousand three hundred twenty-eight patients with low or intermediate risk of prostate cancer were treated with LDR (n = 207), HDR with four fractions (n = 252), or IMRT (n = 869) between January 1992 and December 2008. LDR patients were treated with palladium seeds to a median dose of 120 Gy, whereas HDR patients were treated to a median dose 38.0 Gy (four fractions). IMRT patients received 42–44 fractions with a median dose of 75.6 Gy. Clinical outcomes were compared, including biochemical failure, cause-specific survival, and overall survival.ResultsOverall, no differences in 5-year biochemical control (BC) or cause-specific survival were noted among treatment modalities. The calculated reimbursement for LDR brachytherapy, HDR brachytherapy with four fractions, and IMRT was $9,938; $17,514; and $29,356, respectively. HDR and LDR brachytherapy were statistically less costly to Medicare and the institution than IMRT (p < 0.001), and LDR brachytherapy was less costly than HDR brachytherapy (p = 0.01 and p < 0.001). Incremental cost-effectiveness ratios for cost to Medicare for BC with IMRT were $4045 and $2754 per percent of BC for LDR and HDR brachytherapy, respectively. Incremental cost-effectiveness ratio using institutional cost comparing IMRT with LDR and HDR brachytherapy was $4962 and $4824 per 1% improvement in BC.ConclusionsIn this study of patients with low and intermediate risk of prostate cancer, comparable outcomes at 5 years were noted between modalities with increased costs associated with IMRT.     

Sector analysis of dosimetry of prostate cancer patients treated with low-dose-rate brachytherapy

PurposeBrachytherapy is an effective single treatment modality for low- and intermediate-risk prostate cancer. Here, we compare the radiation doses in different prostate sectors between the preimplant planning images and the postimplant dosimetry.Methods and MaterialsTwo hundred fifteen consecutive patients treated for prostate cancer by ¹²⁵I seed brachytherapy were assessed. Pretreatment plans using transrectal ultrasound images of the prostate were compared with the dose calculated on posttreatment MRI and CT scans obtained 1 month after seed implantation. Twelve sectors were generated by dividing the prostate base, midgland, and apex into four quadrants each. Pretreatment and posttreatment dosimetry were compared between the 12 different sectors of the prostate.ResultsAverage V₁₀₀ (percentage of prostate volume that receives 100% of the prescribed dose) in the preimplant planning images of the prostate was 99.9 ± 0.25% compared with postimplant V₁₀₀ of 94.8 ± 3.77% (p < 0.0001). Prostate V₁₀₀ in the postimplant dosimetry was >91% in all sectors, except the anterior base sector, in which it was 64.87 ± 20.96%. Average 1-month D₉₀ (the dose to 90% of the prostate volume) was 114.5 ± 10.55%. D₉₀ at 1 month compared with preimplant planning was lower in the prostate base and higher in the prostate apex (p < 0.001).ConclusionsOur results show that in ¹²⁵I seed brachytherapy, prostate base receives a lower dose and apex receives a higher dose compared with preimplant planned dose coverage.     

Feasibility of improving patient’s safety with in vivo dose tracking in intracavitary and interstitial HDR brachytherapy

PurposeThe in vivo dosimetric monitoring in HDR brachytherapy is important for improving patient safety. However, there are very limited options available for clinical application. In this study, we present a new in vivo dose measurement system with a plastic scintillating detector (PSD) for GYN HDR brachytherapy.MethodsAn FDA approved PSD system, called OARtrac (AngioDynamics, Latham, NY), was used with various applicators for in vivo dose measurements for GYN patients. An institutional workflow was established for the clinical implementation of the dosimetric system. Action levels were proposed based on the measurement and system uncertainty for measurement deviations. From October 2018 to September 2019, a total of 75 measurements (48 fractions) were acquired from 14 patients who underwent HDR brachytherapy using either a multichannel cylinder, Venezia applicator, or Syed-Neblett template. The PSDs were placed in predetermined catheters/channels. A planning CT was acquired for treatment planning in Oncentra (Elekta, Version-4.5.2) TPS. The PSDs were contoured on the CT images, and the PSD D_90% values were used as the expected doses for comparison with the measured doses.ResultsThe mean difference from patient measurements was ?0.22% ± 5.98%, with 26% being the largest deviation from the expected value (Syed case). Large deviations were observed when detectors were placed in the area where dose rates were less than 1 cGy/s.ConclusionsThe establishment of clinical workflow for the in vivo dosimetry for both the intracavitary and interstitial GYN HDR brachytherapy will potentially improve the safety of the patient treatment.     

MRI-based sector analysis enhances prostate palladium-103 brachytherapy quality assurance in a phase II prospective trial of men with intermediate-risk localized prostate cancer

PurposePalladium-103 (¹⁰³Pd) may be superior to other isotopes in brachytherapy for localized intermediate-risk prostate cancer because of its relatively short half-life, higher initial dose rate, and greater dose heterogeneity within the target volume; these properties also underscore the need for accurate target delineation and postimplant quality assurance. We assessed the use of prostate sector analysis based on MRI for quality assurance after ¹⁰³Pd monotherapy.Methods and MaterialsFifty men with intermediate-risk prostate cancer underwent ¹⁰³Pd monotherapy in a prospective phase II trial at MD Anderson Cancer Center. Dosimetric analyses on day 30 after the implant were done using both CT and fused CT/MRI scans. Dosimetric variables were assessed for the entire prostate and for each of three or six sectors. Volumes and dosimetric variables were compared with paired t tests.ResultsPostimplant dosimetric variables for the entire prostate were significantly different on CT vs. CT/MRI (p = 0.019 for V₁₀₀ and p < 0.01 for D₉₀). Prostate volumes were smaller on the CT/MRI scans (p < 0.00001). The base sector contributed the greatest difference, with doses based on CT/MRI lower than those based on CT (p < 0.01 for V₁₀₀ and D₉₀). To date, these lower base doses have not affected biochemical outcomes for patients with disease in prostate base biopsy samples.ConclusionsCT/MRI is more precise than CT for prostate volume delineation and dosimetric quality assessment and thus provides superior heterogeneity control assessment after ¹⁰³Pd monotherapy implants.     

Predictors of urinary toxicity with MRI-assisted radiosurgery for low-dose-rate prostate brachytherapy

PurposeMRI-assisted radiosurgery (MARS) is a modern technique for prostate brachytherapy that provides superior soft tissue contrast. The purpose of this analysis was to evaluate treatment planning factors associated with urinary toxicity, particularly damage to the membranous urethra (MUL) and external urethral sphincter (EUS), after MARS.Material and MethodsWe retrospectively reviewed 227 patients treated with MARS. Comparisons were made between several factors including preimplantation length of the MUL and EUS dosimetric characteristics after implantation with longitudinal changes in American Urological Association (AUA) urinary symptom score.ResultsRates of grade 3 urinary incontinence and obstructive urinary symptoms were 4% and 2%. A piecewise mixed univariate model revealed that MUL and V₂₀₀, V₁₅₀, V₁₂₅, and D₅ to the EUS were all associated with increased rates of urinary toxicity over time. On univariate logistic regression, MUL >14.2 mm (odds ratio [OR] 2.03 per cm³, 95% confidence interval [CI] 1.10–3.77, p = 0.025), V₁₂₅ to the EUS (OR 3.21 cm³, 95% CI 1.18–8.71, p = 0.022), and use of the I-125 isotope (OR 3.45, 95% CI 1.55–7.70, p = 0.001) were associated with subacute urinary toxicity (i.e., that occurring at 4–8 months). Optimal dose-constraint limits to the EUS were determined to be V₂₀₀ < 0.04 cm³ (p = 0.002), V₁₅₀ < 0.12 cm³ (p = 0.041), V₁₂₅ < 0.45 cm³ (p = 0.033), D₃₀ < 160 Gy (p = 0.004), and D₅ < 218 Gy (p = 0.016).ConclusionsMARS brachytherapy provides detailed anatomic information for treatment planning, implantation, and quality assurance. Overall rates of urinary toxicity are low; however, several dosimetric variables associated with the EUS were found to correlate with urinary toxicity.     

Improved survival for patients with prostate cancer receiving high-dose-rate brachytherapy boost to EBRT compared with EBRT alone

PurposeHigh-dose-rate (HDR) brachytherapy boost is a treatment of intermediate- to high-risk prostate cancer, but long-term clinical outcome data are sparse. We report long-term survival and toxicity data in a cohort of patients treated in a single institution.MethodsBetween 1998 and 2004, 654 patients with localized prostate cancer received either 3-dimensional conformal radiotherapy (median 46 Gy) with an HDR (median 18 Gy in three fractions) boost (“3-D conformal radiotherapy [3DCRT] + HDR”; 215 patients) or 3DCRT alone (“3DCRT”; median 70 Gy; 439 patients) with curative intent. Men with National Comprehensive Cancer Network intermediate risk were offered neoadjuvant androgen deprivation and with high risk were also offered adjuvant androgen deprivation. Data collection included patient-reported outcome measures.ResultsThe 3DCRT + HDR group was older (72.3 vs. 68.9 yrs), had higher presenting PSAs (iPSA) (15.66 and 12.57 ng/mL, respectively), higher proportion of Gleason scores >7 (15.3% vs. 12.4%), and higher proportions of extracapsular disease (29.3% vs. 25.5%). 3DCRT + HDR men had lower proportions of low-risk patients (3.3% vs. 19.4%) and higher proportions of high-risk patients (50.7% vs. 37.4%) than the 3DCRT group. The 5-, 10-, and 15-year overall survival was superior at 92%, 81%, and 67%, respectively, for the 3DCRT + HDR group, compared with 88%, 71%, and 53%, respectively, in the 3DCRT group (p < 0.001). The 5-, 10-, and 15-year cause specific survival also favored the HDR boost group with survival of 96%, 93%, and 87% (3DCRT + HDR) and 95% 88% and 79% (3DCRT), respectively (p < 0.037).ConclusionsHDR brachytherapy boost in conjunction with 3DCRT offered superior overall survival and cause-specific survival in our patient population.