Effects of lung tissue characterization in radiotherapy of breast cancer under deep inspiration breath hold when using Monte Carlo dosimetry

PurposeTo investigate the sensitivity of Monte Carlo (MC) calculated lung dose distributions to lung tissue characterization in external beam radiotherapy of breast cancer under Deep Inspiration Breath Hold (DIBH).MethodsEGSnrc based MC software was employed. Mean lung densities for one hundred patients were analysed. CT number frequency and clinical dose distributions were calculated for 15 patients with mean lung density below 0.14 g/cm³. Lung volume with a pre-defined CT numbers was also considered. Lung tissue was characterized by applying different CT calibrations in the low-density region and air-lung tissue thresholds. Dose impact was estimated by Dose Volume Histogram (DVH) parameters.ResultsMean lung densities below 0.14 g/cm³ were found in 10% of the patients. CT numbers below −960 HU dominated the CT frequency distributions with a high rate of CT numbers at −990 HU. Mass density conversion approach influenced the DVH shape. V_4Gy and V_8Gy varied by 7% and 5% for the selected patients and by 9% and 3.5% for the pre-defined lung volume. V_16Gy and V_20Gy, were within 2.5%. Regions above 20 Gy were affected. Variations in air- lung tissue differentiation resulted in DVH parameters within 1%. Threshold at −990 HU was confirmed by the CT number frequency distributions.ConclusionsLung dose distributions were more sensitive to variations in the CT calibration curve below lung (inhale) density than to air-lung tissue differentiation. Low dose regions were mostly affected. The dosimetry effects were found to be potentially important to 10% of the patients treated under DIBH.     

Postoperative endometrial carcinoma treated with external beam irradiation plus vaginal-cuff brachytherapy. Is there a dose relationship with G2 vaginal complications?

AimTo analyse the possible relationship between the EQD2_(α/β=3Gy) at 2 cm³ of the vagina and late toxicity in vaginal-cuff-brachytherapy (VBT) after external-beam-irradiation (EBRT) for postoperative endometrial carcinoma (EC).Materials and methodsFrom 2014 to 2016, 62 postoperative EC patients were treated with EBRT + VBT. The median EBRT dose was 45 Gy (44 Gy–50.4 Gy). VBT involved a single 7 Gy dose. Toxicity was prospectively evaluated using the RTOG score for the rectum and bladder and the objective LENT-SOMA criteria for the vagina. EQD2_{(α/β = 3Gy)} at 2 cm³ of the most exposed part of the vagina was calculated by the sum of the EBRT + VBT dose. Statistics: Boxplot, Student’s t and Chi-square tests and ROC curves.ResultsMean follow-up: 39.2 months (15–68). Late toxicity: bladder:0 patient; rectum:2 patients-G1; Vagina: 26 patients-17G1, 9G2; median EQD2_(α/β=3Gy) at 2 cm³ in G0-G1 patients was 70.4 Gy(SD2.36), being 72.5 Gy(SD2.94) for G2p. The boxplot suggested a cut-point identifying the absence of G2: 100 % of G2p received >68 Gy, ROC curves showed an area under the curve of 0.72 (sensitivity of 1 and specificity of 0.15).ConclusionsDoses >68 Gy EQD2_(α/β=3Gy) at 2 cm³ to the most exposed area of the vagina were associated with late G2 vaginal toxicity in postoperative EC patients treated with EBRT + VBT suggesting a very good dose limit to eliminate the risk of G2 late toxicity. The specificity obtained indicates the need for prospective analyses.     

Comparative dosimetrical analysis of intensity-modulated arc therapy,CyberKnife therapy and image-guided interstitial HDR and LDR brachytherapy of low risk prostate cancer

BackgroundThe objective of the study was to dosimetrically compare the intensity-modulated-arc-therapy (IMAT), Cyber-Knife therapy (CK), single fraction interstitial high-dose-rate (HDR) and low-dose-rate (LDR) brachytherapy (BT) in low-risk prostate cancer.Materials and methodsTreatment plans of ten patients treated with CK were selected and additional plans using IMAT, HDR and LDR BT were created on the same CT images. The prescribed dose was 2.5/70 Gy in IMAT, 8/40 Gy in CK, 21 Gy in HDR and 145 Gy in LDR BT to the prostate gland. EQD2 dose-volume parameters were calculated for each technique and compared.ResultsEQD2 total dose of the prostate was significantly lower with IMAT and CK than with HDR and LDR BT, D90 was 79.5 Gy, 116.4 Gy, 169.2 Gy and 157.9 Gy (p < 0.001). However, teletherapy plans were more conformal than BT, COIN was 0.84, 0.82, 0.76 and 0.76 (p < 0.001), respectively. The D₂ to the rectum and bladder were lower with HDR BT than with IMAT, CK and LDR BT, it was 66.7 Gy, 68.1 Gy, 36.0 Gy and 68.0 Gy (p = 0.0427), and 68.4 Gy, 78.9 Gy, 51.4 Gy and 70.3 Gy (p = 0.0091) in IMAT, CK, HDR and LDR BT plans, while D_0.1 to the urethra was lower with both IMAT and CK than with BTs: 79.9 Gy, 88.0 Gy, 132.7 Gy and 170.6 Gy (p < 0.001). D₂ to the hips was higher with IMAT and CK, than with BTs: 13.4 Gy, 20.7 Gy, 0.4 Gy and 1.5 Gy (p < 0.001), while D₂ to the sigmoid, bowel bag, testicles and penile bulb was higher with CK than with the other techniques.ConclusionsHDR monotherapy yields the most advantageous dosimetrical plans, except for the dose to the urethra, where IMAT seems to be the optimal modality in the radiotherapy of low-risk prostate cancer.     

Anaplastic thyroid cancer: outcomes of trimodal therapy

BackroundThe purpose of this study is to assess the impact of trimodal therapy [surgery, chemotherapy and external beam radiotherapy (EBRT)] in patients with anaplastic thyroid cancer (ATC) treated with curative intent.Materials and methodsRetrospective review of patients with ATC treated at a tertiary referral centre between January 2009 and June 2020. Data were collected regarding demographics, histology, staging, treatment and outcomes.ResultsSeven patients (4 female) were identified. Median age was 58 years (range 52–83 years). All patients received EBRT with concurrent doxorubicin. Six patients received surgery followed by chemoradiotherapy (CRT), and one underwent neoadjuvant CRT followed by surgery. Median radiological tumour size was 50mm (range 40–90 mm). Six patients had gross extrathyroidal extension and three had N1b disease. Prescribed radiotherapy schedules were 46.4 Gy in 29 bidaily fractions (n = 2, treated 2010), 60 Gy in 30 daily fractions (n = 2), 66 Gy in 30 fractions (n = 2) and 70 Gy in 35 fractions (n = 1; patient received neoadjuvant CRT). CRT was discontinued early for two patients due to toxicities. At median follow up of 5.8 months, 42.9% (3/7) patients were alive and disease-free. Only one patient developed a local failure. Three patients died from distant metastases without locoregional recurrence.ConclusionsDespite poor prognosis of ATC, selected patients with operable tumours may achieve high locoregional control rates with trimodal therapy, with possibility of long-term survival in select cases.     

Dose to pelvic lymph nodes in image based high dose rate brachytherapy of carcinoma cervix

AimThe aim of this study is to analyse the dosimetry to the pelvic lymph nodes and its correlation to point B using CT based high dose rate brachytherapy of carcinoma cervix.BackgroundConventionally, dose to pelvic lymph nodes from intracavitary brachytherapy was reported by point B and by the reference points of the lymphatic trapezoid.Materials and methods30 consecutive CT based high dose rate applications were reviewed between February and March 2016. The high risk clinical target volume and the organs at risk and the pelvic nodal groups were contoured. DVH parameters for the right and left obturator nodal group, right and left external iliac nodal group and right and left internal iliac nodal group were recorded. Right and left point B doses were also recorded.ResultsOn analysis of the combined dose, it was found that all the DVH parameters were significantly different from point B, except the D100 obturator and D2cc internal iliac lymph node. There was a significant correlation between all DVH parameters and point B, except D2cc, D1cc and D0.1cc of external iliac. The obturator group received the highest dose contribution from brachytherapy. The mean D90 dose received per fraction for the obturator, external iliac and internal iliac nodes was 2.7 Gy, 1.17 Gy and 1.41 Gy, respectively.ConclusionsThere is a significant dose contribution to the pelvic lymph nodal groups during intracavitary brachytherapy. There is a low degree of correlation between point B dose and dosimetric parameters of the individual nodal groups. Hence, it is important to analyse the dose delivered to individual nodal groups during intracavitary brachytherapy, at least in patients with enlarged lymph nodes to calculate the cumulative dose delivered.     

Dosimetric accuracy of three dose calculation algorithms for radiation therapy of in situ non-small cell lung carcinoma

BackgroundStudy determines differences in calculated dose distributions for non-small cell lung carcinoma (NSC LC) patients. NSC LC cases were investigated, being the most common lung cancer treated by radiotherapy in our clinical practice.Materials and methodsA retrospective study of 15 NSCLC patient dose distributions originally calculated using standard superposition (SS) and recalculated using collapsed cone (CC ) and Monte Carlo (MC) based algorithm expressed as dose to medium in medium (MCD_m) and dose to water in medium (MCD_w,) was performed so that prescribed dose covers at least 99% of the gross target volume (GTV). Statistical analysis was performed for differences of conformity index (CI), heterogeneity index (HI), gradient index (GI), dose delivered to 2% of the volume (D_2%), mean dose (D_mean) and percentage of volumes covered by prescribed dose (V_70Gy). For organs at risk (OARs), D_mean and percentage of volume receiving 20 Gy and 5Gy (V_20Gy, V_5Gy) were analysed.ResultsStatistically significant difference for GTVs was observed between MCD_w and SS algorithm in mean dose only. For planning target volumes (PTVs), statistically significant differences were observed in prescribed dose coverage for CC, MCD_m and MCD_w. The differences in mean CI value for the CC algorithm and mean HI value for MCD_m and MCD_w were statistically significant. There is a statistically significant difference in the number of MUs for MCD_m and MCD_w compared to SS.ConclusionAll investigated algorithms succeed in managing the restrictive conditions of the clinical goals. This study shows the drawbacks of the CC algorithm compared to other algorithms used.     

Automatic VMAT planning for post-operative prostate cancer cases using particle swarm optimization: A proof of concept study

ObjectiveTo investigate the potential of Particle Swarm Optimization (PSO) for fully automatic VMAT radiotherapy (RT) treatment planning.Material and MethodsIn PSO a solution space of planning constraints is searched for the best possible RT plan in an iterative, statistical method, optimizing a population of candidate solutions. To identify the best candidate solution and for final evaluation a plan quality score (PQS), based on dose volume histogram (DVH) parameters, was introduced.Automatic PSO-based RT planning was used for N = 10 postoperative prostate cancer cases, retrospectively taken from our clinical database, with a prescribed dose of EUD = 66 Gy in addition to two constraints for rectum and one for bladder. Resulting PSO-based plans were compared dosimetrically to manually generated VMAT plans.ResultsPSO successfully proposed treatment plans comparable to manually optimized ones in 9/10 cases. The median (range) PTV EUD was 65.4 Gy (64.7–66.0) for manual and 65.3 Gy (62.5–65.5) for PSO plans, respectively. However PSO plans achieved significantly lower doses in rectum D_2% 67.0 Gy (66.5–67.5) vs. 66.1 Gy (64.7–66.5, p = 0.016). All other evaluated parameters (PTV D_98% and D_2%, rectum V_40Gy and V_60Gy, bladder D_2% and V_60Gy) were comparable in both plans. Manual plans had lower PQS compared to PSO plans with −0.82 (−16.43–1.08) vs. 0.91 (−5.98–6.25).ConclusionPSO allows for fully automatic generation of VMAT plans with plan quality comparable to manually optimized plans. However, before clinical implementation further research is needed concerning further adaptation of PSO-specific parameters and the refinement of the PQS.     

Should high-dose-rate brachytherapy boost be used in early nasopharyngeal carcinomas?

BackgroundRadiation with or without chemotherapy is the main treatment of nasopharyngeal carcinomas (NPC). Local recurrence is difficult to manage. Local control is dose-dependent.AimTo analyze the effect of an endocavitary brachytherapy boost after external beam radiation (EBRT) to decrease local recurrence.Material and methodsThirty patients with T0-T2 NPC were treated: 70% T1, 20% T2 and 10% T0; 33.3% N0, 20% N1, 43.3% N2 and 3.3% N3; 90% were undifferentiated carcinoma. All they received a 192-Ir high dose rate brachytherapy (HDR-BT) boost after 60 Gy of EBRT. The Rotterdam applicator was used in most cases, 3-4 fractions of 3.75-3 Gy in two days.ResultsWith median follow-up (FU) of 63 months, a single parapharyngeal failure resulted in local control of 100% at 3 years and 95% at 5 years. Local control for T0-1 was 100% and for T2 67% at five years (p = 0.02). Regional-free recurrence survival was 92% at 5 years. Metastasis-free survival was 84% at 5 years. All cases of metastasis had histopathology of undifferentiated. The overall and cause-specific survival was 96% and 86% at 3 and 5 years. No late complications related to brachytherapy were described.ConclusionA HDR-BT boost is useful to decrease the incidence of local recurrence of NPC to 5%. With a fractionated schedule of 3-4 fractions in two days, Rotterdam applicator and 3-D planning, no late complications are described. Therefore we recommend to use brachytherapy boost in all early NPC.     

Tracking,gating, free-breathing,which technique to use for lung stereotactic treatments? A dosimetric comparison

BackgroundThe management of breath-induced tumor motion is a major challenge for lung stereotactic body radiation therapy (SBRT). Three techniques are currently available for these treatments: tracking (T), gating (G) and free-breathing (FB).AimTo evaluate the dosimetric differences between these three treatment techniques for lung SBRT.Materials and methodsPretreatment 4DCT data were acquired for 10 patients and sorted into 10 phases of a breathing cycle, such as 0% and 50% phases defined respectively as the inhalation and exhalation maximum. GTV_ph, PTV_ph (=GTV_ph + 3 mm) and the ipsilateral lung were contoured on each phase.For the tracking technique, 9 fixed fields were adjusted to each PTV_ph for the 10 phases. The gating technique was studied with 3 exhalation phases (40%, 50% and 60%). For the free-breathing technique, ITV_FB was created from a sum of all GTV_ph and a 3 mm margin was added to define a PTV_FB. Fields were adjusted to PTV_FB and dose distributions were calculated on the average intensity projection (AIP) CT. Then, the beam arrangement with the same monitor units was planned on each CT phase.The 3 modalities were evaluated using DVHs of each GTV_ph, the homogeneity index and the volume of the ipsilateral lung receiving 20 Gy (V_20Gy).ResultsThe FB system improved the target coverage by increasing D_mean (75.87_(T)–76.08_(G)–77.49_(FB)Gy). Target coverage was slightly more homogeneous, too (HI: 0.17_{(T and G)}–0.15_(FB)). But the lung was better protected with the tracking system (V_20Gy: 3.82_(T)–4.96_(G)–6.34_(FB)%).ConclusionsEvery technique provides plans with a good target coverage and lung protection. While irradiation with free-breathing increases doses to GTV, irradiation with the tracking technique spares better the lung but can dramatically increase the treatment complexity.     

Dosimetric impact of Acuros XB on cervix radiotherapy using RapidArc technique: a dosimetric study

BackgroundAcuros XB (AXB) may predict better rectal toxicities and treatment outcomes in cervix carcinoma. The aim of the study was to quantify the potential impact of AXB computations on the cervix radiotherapy using the RapidArc (RA ) technique as compared to anisotropic analytical algorithm (AA) computations.Materials and methodsA cohort of 30 patients previously cared for cervix carcinoma (stages II–IIIB) was selected for the present analysis. The RA plans were computed using AA and AXB dose computation engines under identical beam setup and MLC pattern.ResultsThere was no significant (p > 0.05) difference in D_95% and D_98% to the planning target volume (PTV); moreover, a significant (p < 0.05) rise was noticed for mean dose to the PTV (0.26%), D_50% (0.26%), D_2% (0.80%) and V_110% (44.24%) for AXB computation as compared to AA computations. Further, AXB estimated a significantly (p < 0.05) lower value for maximum and minimum dose to the PTV. Additionally, there was a significant (p < 0.05) reduction observed in mean dose to organs at risk (OARs) for AXB computation as compared to AA, though the reduction in mean dose was non-significant (p > 0.05) for the rectum. The maximum difference observed was 4.78% for the rectum V_50Gy, 1.72%, 1.15% in mean dose and 2.22%, 1.48% in D_2% of the left femur and right femur, respectively, between AA and AXB dose estimations.ConclusionFor similar target coverage, there were significant differences observed between the AAA and AXB computations. AA underestimates the V_50Gy of the rectum and overestimates the mean dose and D_2% for femoral heads as compared to AXB. Therefore, the use of AXB in the case of cervix carcinoma may predict better rectal toxicities and treatment outcomes in cervix carcinoma using the RA technique.     

Evaluation of the rectal V30 parameter in patients diagnosed with postoperative endometrial cancer

BackgroundThe present paper reports on analysis of 184 patients who were diagnosed with endometrial cancer. The main objective of this study was to address parameter V_rec(30Gy) which determines a volume of the rectum irradiated with a dose of 30 Gy during radiotherapy.Materials and methodsAll patients were irradiated with an IMRT technique on linear accelerators. The planning target volume (PTV) contour was determined by a radiation oncologist. The clinical target volume (CTV) was drawn on CT images obtained in a prone position. For statistical analysis, appropriate tests (e.g. the Shapiro-Wilk, Wilcoxon) were used.Results and discussionThe performed analysis showed that the recommended condition for V_rec(30Gy) is met only in 3% of patients and the observed median value exceeds 90%. The obtained results were compared with the studies in which the V_rec(30Gy) values were related to various radiotherapy techniques.ConclusionsThe analysis showed that the condition for V_rec(30Gy) is satisfied in the case of only 3% of patients. Due to the difficulty with meeting the condition, it should be reconsidered based on real results.     

Clinical radiotherapy application of N-vinylpyrrolidone-containing 3D polymer gel dosimeters with remote external MR-reading

PurposeAdvanced 3D dosimetry is required for verifications of complex dose distributions in modern radiotherapy. Two 3D polymer gel dosimeters, coupled with magnetic resonance (MR) imaging (3 T MRI) readout and data processing with polyGeVero® software, were tested for the verification of calculated 3D dose distributions by a treatment planning system (TPS) and ArcCHECK®–3DVH®, related to eradication of a lung tumour.MethodsN-vinylpyrrolidone-containing 3D polymer gel dosimeters were used: VIC (containing ascorbic acid and copper sulfate pentahydrate) and VIC-T (containing tetrakis(hydroxymethyl)phosphonium chloride). Three remote centers were involved in the dosimeters preparation and irradiation (Poland), and MRI (Austria). Cross beam calibration of the dosimeters and verification of a 3D dose distribution calculated with an Eclipse External Beam TPS and ArcCHECK®–3DVH® were performed. The 3D-to-3D comparisons of the VIC and VIC-T with TPS and ArcCHECK®–3DVH® along with ArcCHECK®–3DVH® versus TPS dose matrixes were performed with the aid of the polyGeVero® by analyzing dose profiles, isodoses lines, gamma index, gamma angle, dose difference, and related histograms.ResultsThe measured MR-relaxation rate (R₂ = 1/T₂) for the dosimeters relates to the dose, as follows: R₂ = 0.0928 ± 0.0008 [Gy⁻¹ s⁻¹] × D [Gy] + 2.985 ± 0.012 [s⁻¹] (VIC) and 0.1839 ± 0.0044 [Gy⁻¹ s⁻¹] × D [Gy] + 2.519 ± 0.053 [s⁻¹] (VIC-T). The 3D-to-3D comparisons revealed a good agreement between the measured and calculated 3D dose distributions.ConclusionsVIC and VIC-T with 3T MRI readout and polyGeVero® showed potential for verifications of calculated irradiation plans. The results obtained suggest the implementation of the irradiation plan for eradication of the lung tumour.     

3D conformal hypofractionated radical radiotherapy in early glottic cancer

Aim

The purpose of this study was to evaluate acute and late toxicity and the locoregional control in patients treated with hypofractionated radical radiotherapy 2.25 Gy/fraction/day for early glottic carcinoma.

Materials and methods

A retrospective analysis was performed of 27 patients, stage T1–T2 N0 glottic squamous cell carcinoma, that underwent radical RT from April 2008 to October 2011. The mean age was 64.6 years (range 36–81). Seventeen patients were staged T1a, 3 patients T1b and 7 patients T2. All patients were 3D planned and treated in a 6 MV LINAC, 2.25 Gy/fraction/5 days per week, to a total dose between 63 Gy and 67.5 Gy. Biological Effective Dose (BED (α/β = 10)) ranged from 77.18 Gy to 82.69 Gy and EQD2 from 64.31 Gy to 68.91 Gy. Patients were evaluated in periodic follow-up. Toxicity was evaluated according to RTOG Toxicities Scales.

Results

With a median follow-time of 24.7 months (range 3.6–44.2 months), no evidence of locoregional recurrence was observed. The treatment was well tolerated and no unscheduled interruptions in treatments for toxicity were documented, with the median overall treatment time of 41 days (range 38–48). Only grades 1 and 2 acute toxicity were observed and no evidence of severe late toxicity.

Conclusion

The authors believe that this moderately hypofractionated scheme can provide a good locoregional control for T1–T2 glottic carcinomas with no increase of toxicity. As the limitation of this work is the reduced number of patients and the lack of long term follow-up, the authors hope to update this retrospective study in the future in order to improve the power of the results.     

Image-guided volumetric arc radiotherapy of pancreatic cancer with simultaneous integrated boost: Optimization strategies and dosimetric results

PurposeTo introduce volumetric modulated arc therapy treatments (VMAT) with simultaneous integrated boost (SIB) for pancreatic cancer and describe dosimetric results on a large patient series.Methods and materials45 patients with pancreatic malignancies were treated with 18 MV single-arc VMAT. Image guidance was performed with daily online kilo-volt cone-beam computed tomography (CBCT). The conformity index (CI) and homogeneity index (HI) to the target volumes, PTV_45Gy and PTV_54Gy, and dose–volume indices to OARs from the QUANTEC task group were reported. The risk of clinical nephritis was evaluated using normal tissue complication probability (NTCP). Treatments were verified in-phantom with the Delta4 system.ResultsAverage CI was 1.06 with 95% confidence intervals (95% CI) of 0.97–1.22 for PTV_45Gy and 1.17 (0.66–1.61) for PTV_54Gy. HI of PTV_54Gy was 1.06 (1.04–1.10). OAR constraints were achieved in all patients, except for kidneys V_12Gy of 48 (35.4–72.3)%. NTCP of the kidneys was 0.98 (0.6–1.7)%. Kidneys V_12Gy and V_20Gy were inversely related to PTV_54Gy CI and maximum dose. All in-phantom tests had gamma pass rates exceeding 95% with global 3% dose difference and 3 mm distance to agreement. Patient shifts measured with CBCT had 95% CI of −0.8, +0.8 in the RL, −0.7, +0.8 in the SI, and −0.8, +0.7 cm in the AP directions.ConclusionsDosimetric results of VMAT were excellent on PTVs and organs at risk. The kidneys represent the dose-limiting organ at risk for this technique. NTCP indicates that this technique is safe from radiation-induced side effects to the kidneys.     

Salvage I-125 brachytherapy for locally-recurrent prostate cancer after radiotherapy

PurposeRetrospective, single-institution analysis of clinical outcomes and treatment-related toxicity in patients treated with salvage I-125 low-dose rate (LDR) brachytherapy (BT) for locally-recurrent prostate cancer after radiotherapy.Materials and methodsBetween 2008 and 2018, 30 patients with biopsy-confirmed prostate cancer recurrence underwent salvage treatment with I-125 LDR-BT. Of these 30 patients, 14 were previously treated with primary external beam radiotherapy (EBRT; median dose, 73 Gy) and 16 with primary I-125 LDR-BT (145 Gy and 160 Gy in 14 and 2 cases, respectively). At seed implantation, the mean age was 75.8 years, with a median Gleason score of 7 and pre-salvage PSA of <10 ng/mL. Six patients received androgen deprivation therapy for six months after relapse diagnosis. The prescribed salvage I-125 BT dose to the gland was 120−130 Gy, with dose restrictions of Dmax <135% (urethra) and <100% (rectum). Toxicity was evaluated according to the CTCAE scale (v4.0).ResultsAt a median follow-up of 45 months, the biochemical recurrence-free survival rates at 1, 3 and 5 years were 86.7%, 56.7% and 53.3%, respectively. Overall survival at 5 years was 87%. On the multivariate analysis, two variables were significant predictors of recurrence: PSA at relapse and nadir PSA post-salvage. Grade 3 genitourinary toxicity was observed in 5 patients (radiation-induced cystitis in 3 cases and urethral stenosis in 2) and G3 gastrointestinal toxicity in 3 patients (rectal bleeding).ConclusionSalvage therapy with I-125 brachytherapy is a safe and effective treatment option for locally-recurrent prostate cancer in previously-irradiated patients. High pre-salvage PSA and post-salvage nadir PSA values were significantly associated with a worse disease control after salvage I-125 LDR-BT. In well-selected patients, I-125 LDR-BT is comparable to other salvage therapies in terms of disease control and toxicity. However, more research is needed to determine the optimal management of locally-recurrent prostate cancer.