Pulsed Dose Rate Brachytherapy Research Articles

Protocol-based CT-guided brachytherapy for patients with prostate cancer and previous rectal extirpation-acurative approach.

There are numerous curative treatment possibilities for prostate cancer. In patients who have undergone rectal extirpation for rectal cancer treatment, curative options are limited due to anatomic changes and previous irradiation of the pelvis. In this analysis, we validate the feasibility of CT-guided transperineal interstitial brachytherapy for this specific scenario. We analyzed the treatment procedures and outcomes of 5patients with metachronic nonmetastatic prostate cancer. Ultrasound-guided brachytherapy was not possible in any of the patients. Of these 5patients, 3were treated for prostate cancer using temporary brachytherapy with Ir-192 only, and 2were treated with external-beam radiation therapy and temporary brachytherapy as aboost. CT-guided brachytherapy was performed in all patients. We analyzed the feasibility, efficacy, treatment-related toxicity, and quality of life (EORTC-30, IEFF, IPSS, and ICIQ questionnaires) of the treatments. Median follow-up was 35months. Two out of five patients received boost irradiation (HDR 2 × 9Gy, PDR 30 Gy). Three out of five patients were treated with PDR brachytherapy in two sessions up to atotal dose of 60 Gy. Dosimetric parameters were documented as median values as follows: V100 94.7% (94.5-98.4%), D2bladder 64.3% (50.9-78.3%), D10urethra 131.05% (123.2%-141.2%), and D30urethra 122.45% (116.2%-129.5%). At the time of analysis, no biochemical recurrence had been documented. Furthermore, neither early nor late side effects exceeding CTCAE grade2 were documented. CT-guided transperineal brachytherapy of the prostate in patients with previous rectal surgery and radiation therapy is safe and represents apossible curative treatment option. Brachytherapy can be considered for patients with metachronic prostate cancer in this specific scenario, albeit preferably in experienced high-volume centers.

Redefining the role of pulsed-dose-rate brachytherapy in cervical cancer treatment using a preplanned approach

IntroductionThis study aims to determine predictive factors for cervical cancer patients who would benefit more from high-dose-rate (HDR) or pulsed-dose-rate (PDR) brachytherapy. MethodsThe sample included 50 patients treated with brachytherapy following external radiochemotherapy. PDR plans were compared to HDR preplans, with a focus on patients who may benefit from PDR using preplan metrics and clinical variables. The expected clinical effect was quantified using a tumor control probability model. ResultsResults showed PDR plans with 60 pulses to be optimal for achieving target clinical goals for D90CTVHR. A CTVHR volume of >67.5cc and/or D90CTVHR dose on the HDR preplan of <31.1 Gy was the strongest indicator for patient selection who would gain >3% increase in TCP with PDR. The process showed 96% accuracy, 88% sensitivity, and 98% specificity. Only 16% of patients showed a relevant benefit from PDR over HDR, with a mean D90CTVHR of 7 Gy higher and a mean TCP at 3 years of 4.8% higher for PDR. The benefit of PDR is highly influenced by the choice of alpha/beta ratio and repair halftime. ConclusionA small subset of cervical cancer patients may gain from PDR over HDR. CTVHR volume and preplan D90CTVHR doses may be useful in selecting patients for PDR brachytherapy.

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

PurposeLow-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 methodsFrom 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. ResultsAmong 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). ConclusionHigh-dose- or low-dose-/pulsed-dose rate brachytherapy seemed to be as effective and well tolerated in our experience of 61 patients.

Brachytherapy boost in anal canal cancer - A GEC ESTRO PDR task force meta-analysis.

A meta-analysis is presented comparing clinical outcomes and toxicities between high dose rate (HDR) and pulsed dose rate (PDR) brachytherapy (BT) for anal cancer. Retrospective or prospective clinical trials were identified on electronical databases. Data were collected per Preferred Reporting Items for Systematic Reviews and meta-Analyses guidelines. Pooled effect size for HDR and PDR BT were compared using subgroup analyses. Nine retrospective studies with a total of 481 patients treated were included of which 219 with HDR and 262 with PDR. Significant differences were observed between the two groups for baseline characteristics and treatment. The cumulative proportion of stage T3-T4 was lower in the HDR group, 0.15 [95% confidence interval (CI) 0.07-0.29] vs 0.27 [95%CI 0.09-0.57] in the LDR group, p<0.001. Lower BT doses (in equivalent 2-Gy fraction dose) were given for patients in the HDR group, 11.9Gy [95%CI 8.2-15.5] vs 19.5Gy [95%CI 15.0-24.0] in the PDR group, p<0.001. No significant differences were found for clinical outcomes or toxicities. The pooled effect size of the overall survival at 5years for HDR and PDR was respectively 0.82 [95%CI 0.70-0.94] and 0.82 [95%CI 0.73-0.91], p>0.99. The 5years local control was 0.86 [95% confidence interval (CI) 0.81-0.91] and 0.83 [95%CI 0.77-0.89], p=0.62. Cumulative toxicity-related colostomy proportion was 0.04 [95%CI 0.02-0.09] and 0.03 [95%CI 0.02-0.07], p=0.85. Both modalities provided a good profile of tolerance and are effective organ conservative strategies for patients with anal canal cancer. In parallel with ongoing developments to better determine the optimal fractionation and dose for HDR-BT treatments, especially in large tumors, PDR BT still has a crucial role for dose escalation strategy in advanced cases.

Long-term oncological follow-up after mold-based pulsed dose rate brachytherapy for early stage squamous cell carcinoma of the nasal vestibule: A single center experience of 68 patients over a 17-year period

PURPOSECancer of the nasal vestibule is a rare type of malignancy constituting less than one percent of all head and neck cancers. These tumors are typically diagnosed at an early stage. Both surgery and radiotherapy provide excellent oncological results, but esthetic results are better after radiotherapy. The aim of this study was to evaluate the long-term oncological follow-up after brachytherapy for early stage squamous cell carcinoma of the nasal vestibule. METHODS AND MATERIALSRetrospective analysis of patients with carcinoma of the nasal vestibule who were treated with primary brachytherapy in the Utrecht University Medical Center. RESULTSIn this single center experience over a 17-year period 68 patients with early stage squamous cell carcinoma of the nasal vestibule were treated with brachytherapy. Two patients had lymph node metastases at first clinical presentation. Median follow-up duration was 46.5 months. Five-year locoregional recurrence-free survival, disease-specific survival, and overall survival were 91.1%, 96.1%, and 66.2%, respectively. All recurrences occurred within the first 3 years of follow-up. CONCLUSIONSBrachytherapy offers excellent oncological outcomes and is a safe and effective treatment for early stage carcinoma of the nasal vestibule. Recurrences typically occur within 3 years after treatment.

PO24 Presentation Time: 7:40 AM: Impact of Intra-Operative MRI-Guidance on Dose Escalation to the HR-CTV Using Advanced Gynecological Applicators

<h3>Purpose</h3> To quantify the impact of intraoperative MRI-guidance on implant quality for patients receiving brachytherapy (BT) for cervical cancer by calculating dose to the HR-CTV and OARs at three stages of the implant procedure. <h3>Materials and Methods</h3> Three patients enrolled on an IRB-approved prospective clinical trial were treated with EBRT followed by two fractions of pulsed-dose rate (PDR) brachytherapy. For each patient, one of the two PDR implants was performed in a dedicated MRI-Operating Room (MRI-OR) using 3.0 T MRI-guidance (Discovery MR750w, GE Healthcare, Waukesha, WI). An Advanced Gynecological Applicator (AGA) was used for each of the implants. Straight or straight and oblique needle trajectories were used. 3D T2-weighted MRI scans were acquired at three time points during the procedure: (1) following placement of the intracavitary components of the hybrid applicator (initial); (2) following initial needle selection and advancement (intermediate); and (3) following final modifications of implant position (final). The first scan was used to inform needle selection and estimate the appropriate advancement depth for each needle. The second scan was used to determine if modifications to the implant were necessary, including advancement of additional needles, removal of previously advanced needles, or modification of advancement depth. The final scan was used to generate a clinical plan for patient treatment. The titanium obturators used to advance the needles were replaced with C4 positive-contrast imaging markers (C4 Imaging, Houston, TX) prior to each scan to facilitate needle digitization during treatment planning. Retrospective plans were generated on the initial and intermediate scans for each of the three patients and compared to the final plans used for treatment. AGA solid applicator models were registered to the initial and intermediate MRI scans. Needles present at the time of scanning were manually digitized in the Oncentra Treatment Planning System (Elekta, Stockholm, Sweden). Clinical treatment plans were optimized to meet EMBRACE dose constraints. For a given patient, the initial and intermediate plans were optimized to escalate dose to the HR-CTV without exceeding the clinical doses delivered to the OARs. The dose-limiting structure varied based on the patient's anatomy and implant geometry. For each patient, the HR-CTV D90 and bladder, rectum, and sigmoid D2cc doses were compared between the initial, intermediate, and final plans. <h3>Results</h3> One needle was advanced during the first patient's implant. Activity was loaded into the tandem, ovoids, needle, and vaginal caps. The dose to the HR-CTV increased by 4.6 Gy between the initial and intermediate plans and 3.0 Gy between the intermediate and final plan used for treatment. The final dose to the HR-CTV was 10.2% greater than the initial HR-CTV dose. Five needles were advanced for the second patient. The dose to the HR-CTV increased by 3.8 Gy between the initial and intermediate implants and 0.96 Gy between the intermediate and final plan used for treatment. The final dose to the HR-CTV was 5.8% greater than the initial HR-CTV dose. Eight needles were advanced for the third patient. Dose to the HR-CTV increased by 8.3 Gy between the initial and intermediate implants and 5.7 Gy between the intermediate and final plans. The final dose to the HR-CTV was 19.7% greater than the initial HR-CTV dose. None of the OAR doses in the initial or intermediate plans exceeded the OAR doses delivered clinically. <h3>Conclusions</h3> Performing interstitial implants using an AGA under MRI-guidance improves implant quality, defined by dose escalation to the HR-CTV and maintenance of OAR doses.

Saturday, June 18, 20222:00 PM - 3:00 PM PL01 Presentation Time: 2:00 PM: Kinetic Antigen-Specific T-cell Receptor Profiling in Cervical Cancer Patients Treated with Standard-of-Care Chemoradiation and Brachytherapy

<h3>Purpose</h3> Chemoradiation (CRT) may modulate the intratumoral and peripheral immune milieu by serving as an <i>in situ</i> vaccine. The impact of the rapid dose delivery of brachytherapy (BT) on the T-cell repertoire has not been examined. HPV-related cancers express viral oncoproteins E6/E7, which could function as tumor antigens (Ag) and are thus ideal for investigating the impact of CRT in generating tumor-specific immunity. <h3>Methods</h3> 11 pts with cervical cancer were enrolled on a multi-institutional prospective tissue banking protocol from 1/2020—2022. Pts underwent standard external beam RT (EBRT) spanning 5-7 wks with concurrent weekly 40mg/m² cisplatin, then BT boost with either high dose rate (HDR) in 5 fx or pulse dose rate (PDR) in 2 fx. Cervical tumor swabs were taken at 5 timepoints: <b>baseline</b> (<b>T1</b>), <b>wk 1</b> (<b>T2</b>, after 5 fx), <b>wk 3</b> (<b>T3</b>, after 10-15 fx), <b>wk 5</b> (<b>T4</b>, at conclusion of EBRT and prior to 1st BT), prior to 2nd BT (<b>T4B</b>), and at <b>1st follow-up</b> (<b>T5</b>, 12 wks post-treatment). Samples underwent functional expansion of HPV Ag-specific T cells before DNA extraction and multiplex deep sequencing of the CDR3 region of TCR-β using immunoSEQ PCR (Adaptive Biotech). TCR productive frequency (freq), templates, clonality, and rearrangements were compared across timepoints. Separately, HPV-responsive T-cell clones underwent <i>ex vivo</i> expansion by incubation with HPV long peptide sequences of E6/E7 overnight (ON). TCR sequences were compared between HPV-stimulated T cells and evaluated against incubations with CEF (positive control peptides) or media (negative control). Statistical analysis was via Mann-Whitney U. <h3>Results</h3> Median age was 47 yrs (range 27-57). 6 pts (54.5%) had SCC; 5 (45.5%) had adenocarcinoma. 4 pts (36.4%) had FIGO 2018 ≤Stage IIB disease, 45.5% were Stage III, and 18.2% were Stage IVA/B. 7 pts (63.6%) received PDR BT and 4 pts (36.4%) underwent HDR BT. At median follow-up of 7.5 mo, all pts are alive and with NED. In serially sampled peritumoral microenvironment (TME) isolates, TCR productive clonality increased after first BT, culminating in a significant increase at T5 during the first post-treatment follow-up (<b>Fig 1A</b>). There was a trend (ns) toward increased productive templates throughout CRT and BT (<b>Fig 1B</b>), but this decreased by T5. Productive freq was significantly higher at T5 compared to prior to BT (T1—T4), <b>Fig 1C</b>. Productive rearrangements trended toward abundance throughout CRT and BT (ns), but decreased at T5 (<b>Fig 1D</b>). Functional HPV Ag stimulation assays of peritumoral T-cells in the full cohort did not show significant changes in the TCR repertoire after ON incubation with HPV E6/7 peptides. However, 4 pts had notable E6/E7-responsive increases in these metrics at either T4 or T4B—namely, abundance of productive templates (ranges: 1.9—30.3 fold-increase from baseline), freq (1.25—5.5), rearrangements (1.5—13.8), and clonality (1.31—3.8). <h3>Conclusions</h3> We characterized TCR remodeling during BT in this first translational analysis, demonstrating (i) increased peritumoral TCR productive freq and clonality post-BT at T5, and (ii) transient rise in productive templates and rearrangements through CRT and BT, with a numeric return to baseline post-BT at T5. Some pts had functional Ag-specific activation upon HPV stimulation during and after BT. These findings suggest that despite the cytotoxic effects of radiation, BT alters the TME to facilitate expansion of specific T-cell populations, which may contribute to treatment efficacy.

Outcome analysis of HDR compared to PDR IGABT in locally advanced cervical cancer: asingle-center cohort analysis.

This monocentric study aimed to assess the impact of technical advancement in brachytherapy (BT) on local control (LC) and cancer-specific survival (CSS) in locally advanced cervical cancer (LACC). Since 2010, 211patients with LACC have been treated with 45/50.4 Gy or 60 Gy radiochemotherapy (RTCT) followed by image-guided adaptive brachytherapy (IGABT) at the authors' institution. In 2013, combined intracavitary and interstitial brachytherapy (BT IC/IS) was implemented and in 2018, pulsed-dose-rate BT (PDR-BT) was replaced by high-dose-rate BT (HDR-BT). LC, CSS, and morbidity according to the RTOG/EORTC scoring system were analyzed. Dose-volume parameters for the high-risk clinical target volume (HRCTV) and organs at risk (OAR) were reported. While 27 (12.8%) patients died of LACC, complete local remission was achieved in 199(94.3%). Local relapse decreases with ahigh D95 in the HRCTV (hazard ratio, HR = 0.85, p = 0.0024). D95 in the HRCTV is lower after 60 Gy even if interstitial BT is used. Mean D95 in the HRCTV is 78.2 Gy, 83.3 Gy, and 83.4 Gy with PDR-BT IC, PDR-BT IC/IS, and HDR-BT IC/IS, respectively, after 45/50.4 Gy. D2cc of OARs is significantly reduced by using interstitial BT. The mean rectum and sigmoid D2cc are about 61.5 Gy with PDR-BT IC/IS and significantly decreased with HDR-BT IC/IS. This translates into alow fistula incidence. Avery low rate of severe gastrointestinal (3.4%) and genitourinary (2.3%) toxicity was observed with HDR-BT IC/IS. This large monocentric study provides further evidence that implementation of BT IC/IS has an impact on D95 in the HRCTV, LC, and CSS. There are no differences between HDR and PDR in terms of efficacy, D95 in the HRCTV, and toxicity grade ≥ 3.

OC-0448 Scintillator-based in vivo dosimetry during pulsed dose rate brachytherapy for cervical cancer

OC-0448 Scintillator-based in vivo dosimetry during pulsed dose rate brachytherapy for cervical cancer

BAIRDA: a novel in vitro setup to quantify radiobiological parameters for cervical cancer brachytherapy dose estimations

Objective. Brachytherapy (BT) dose prescriptions for locally advanced cervical cancer are made with account for the radiobiological parameters, α/β ratio and halftime of repair (T 1/2 ). However, a wide range of parameter values has been reported which can challenge commonly held equivalencies between dose prescriptions. This is the first reported study that aims to develop an in vitro experimental technique using clinical high-dose-rate (HDR) and pulsed-dose-rate (PDR) Ir-192 brachytherapy afterloaders to quantify these parameters in vitro and to contextualize findings within contemporary practice. Approach. To efficiently quantify α/β and T 1/2 , in vitro experiments more reflective of clinical BT practice than traditional clonogenic survival assays were developed and applied to four squamous cell carcinoma cell lines (CaSki, C-33A, SiHa, and SW756). Radiation was delivered using single acute and fractionated dose treatments with a conventional irradiator and clinical HDR and PDR BT afterloaders. For the latter, a novel brachytherapy afterloader in vitro radiation delivery apparatus (BAIRDA) was developed. Main Results. The α/β and T 1/2 values determined using BAIRDA and the conventional irradiator showed close agreement, validating the novel apparatus and technique. For CaSki, C-33A, SiHa, and SW756, the BAIRDA-measured α/β ratios (5.2 [4.6–5.8], 5.6 [4.5–6.6], 6.3 [4.9–7.7], and 5.3 [4.7–6.0] Gy, respectively) were consistently smaller, while the T 1/2 (3.3 [2.7–3.9], 2.7 [2.0–3.3], 2.8 (2.4–3.1], and 4.8 [4.1–5.4] hours) larger, than the widely accepted values in clinical practice (α/β = 10 Gy; T 1/2 = 1.5 h). Significance. In vitro experiments using BAIRDA provided evidence for differences between the conventionally selected and experimentally determined α/β ratio and T 1/2 . Treatment regimens using HDR-BT and PDR-BT, designed to deliver equivalent radiobiological doses based on conventional values, were shown to differ by up to 27 Gy EQD2 – an effect that could impact treatment outcomes in cervical cancer. Furthermore, with BAIRDA, we have developed a novel method for radiobiological research in BT.

Five-Year Follow-up After Multimodal Treatment Incorporating HDR Brachytherapy for Bladder Prostate Rhabdomyosarcoma in Children

Five-Year Follow-up After Multimodal Treatment Incorporating HDR Brachytherapy for Bladder Prostate Rhabdomyosarcoma in Children

GEC-ESTRO ACROP prostate brachytherapy guidelines

This is an evidence-based guideline for prostate brachytherapy. Throughout levels of evidence quoted are those from the Oxford Centre for Evidence based Medicine (https://www.cebm.ox.ac.uk/resources/levels-of-evidence/oxford-centre-for-evidence-based-medicine-levels-of-evidence-march-2009).Prostate interstitial brachytherapy using either permanent or temporary implantation is an established and evolving treatment technique for non-metastatic prostate cancer.Permanent brachytherapy uses Low Dose Rate (LDR) sources, most commonly I-125, emitting photon radiation over months. Temporary brachytherapy involves first placing catheters within the prostate and, on confirmation of accurate positioning, temporarily introducing the radioactive source, generally High Dose Rate (HDR) radioactive sources of Ir-192 or less commonly Co-60. Pulsed dose rate (PDR) brachytherapy has also been used for prostate cancer [1] but few centres have adopted this approach. Previous GEC ESTRO recommendations have considered LDR and HDR separately [2–4] but as there is considerable overlap, this paper provides updated guidance for both treatment techniques.Prostate brachytherapy allows safe radiation dose escalation beyond that achieved using external beam radiotherapy alone as it has greater conformity around the prostate, sparing surrounding rectum, bladder, and penile bulb. In addition there are fewer issues with changes in prostate position during treatment delivery. Systematic review and randomised trials using both techniques as boost treatments demonstrate improved PSA control when compared to external beam radiotherapy alone [5–7].

A high-Z inorganic scintillator-based detector for time-resolved in vivo dosimetry during brachytherapy.

High-dose rate (HDR) and pulsed-dose rate (PDR) brachytherapy would benefit from an independent treatment verification system to monitor treatment delivery and to detect errors in real time. This paper characterizes and provides an uncertainty budget for a detector based on a fiber-coupled high-Z inorganic scintillator capable of performing time-resolved in vivo dosimetry during HDR and PDR brachytherapy. The detector was composed of a detector probe and an optical reader. The detector probe consisted of either a 0.5× 0.4 × 0.4 mm3 (HDR) or a 1.0 × 0.4 × 0.4 mm3 (PDR) cuboid ZnSe:O crystal glued onto an optical-fiber cable. The outer diameter of the detector probes was 1mm, and fit inside standard brachytherapy catheters. The signal from the detector probe was read out at 20Hz by a photodiode and a data acquisition device inside the optical reader. In order to construct an uncertainty budget for the detector, six characteristics were determined: (1) temperature dependence of the detector probe, (2) energy dependence as a function of the probe-to-source position in 2D (determined with 2 mm resolution using a robotic arm), (3) the signal-to-noise ratio (SNR), (4) short-term stability over 8h, and (5) long-term stability of three optical readers and four probes used for in vivo monitoring in HDR and PDR treatments over 21 months (196 treatments and 189 detector calibrations, and (6) dose-rate dependence. The total uncertainty of the detector at a 20 mm probe-to-source distance was<5.1% and<5.8% for the HDR and PDR versions, respectively. Regarding the above characteristics, (1) the sensitivity of the detector decreased by an average of 1.4%/°C for detector probe temperatures varying from 22 to 37°C; (2) the energy dependence of the detector was nonlinear and depended on both probe-to-source distance and the angle between the probe and the brachytherapy source; (3) the median SNRs were 187 and 34 at a 20 mm probe-to-source distance for the HDR and PDR versions, respectively (corresponding median source activities of 4.8 and 0.56Ci, respectively); (4) the detector response varied by 0.6% in 11 identical irradiations over 8h; (5) the sensitivity of the four detector probes decreased systematically by 0-1.2%/100Gy of dose delivered to the probes, and random fluctuations of 4.8% in the sensitivity were observed for the three probes used in PDR and 1.9% for the probe used in HDR; and (6) the detector response was linear with dose rate. ZnSe:O detectors can be used effectively for in vivo dosimetry and with high accuracy for HDR and PDR brachytherapy applications.

PO-0174 Cervix cancer treated with PDR brachytherapy boost

PO-0174 Cervix cancer treated with PDR brachytherapy boost

Pulsed Dose Rate Brachytherapy of Lip Carcinoma: Clinical Outcome and Quality of Life Analysis

Simple SummaryLip cancer accounts for 25–30% of all oral cancers, with 23,000 new cases per year in the world. Carcinomas of the lip can be successfully treated with different methods: surgery, external beam radiotherapy (EBRT) and brachytherapy. The choice of the treatment depends on the tumor size, location and expected functional and esthetic results with each option, but also depends on treatment type accessibility. There are no randomized studies comparing these different treatment strategies. In this article, we investigated the complications and outcomes of patients treated with interstitial pulsed dose rate brachytherapy in our institution.Purpose: Lip carcinoma represents one of the most common types of head and neck cancer. Brachytherapy is a highly effective therapeutic option for all stages of lip cancers. We report our experience of pulsed dose rate brachytherapy (PDR) as treatment of lip carcinoma. Methods and Materials: this retrospective single center study included all consecutive patients treated for a lip PDR brachytherapy in our institution from 2010 to 2019. The toxicities and outcomes of the patients were reported, and a retrospective quality of life assessment was conducted by phone interviews (FACT H&N). Results: From October 2010 to December 2019, 38 patients were treated in our institution for a lip carcinoma by PDR brachytherapy. The median age was 73, and the majority of patients presented T1-T2 tumors (79%). The median total dose was 70.14 Gy (range: 60–85 Gy). With a mean follow-up of 35.4 months, two patients (5.6%) presented local failure, and seven patients (19%) had lymph node progression. The Kaplan–Meier estimated probability of local failure was 7.2% (95% CI: 0.84–1) at two and four years. All patients encountered radiomucitis grade II or higher. The rate of late toxicities was low: three patients (8.3%) had grade II fibrosis, and one patient had grade II chronic pain. All patients would highly recommend the treatment. The median FACT H&N total score was 127 out of 148, and the median FACT H&N Trial Outcome Index was 84. Conclusions: This study confirms that an excellent local control rate is achieved with PDR brachytherapy as treatment of lip carcinoma, with very limited late side effects and satisfactory functional outcomes. A multimodal approach should help to improve regional control.

Pulse-dose-rate interstitial brachytherapy in anal squamous cell carcinoma: clinical outcomes and patients' health quality perception.

PurposeTo examine clinical outcomes and quality of life of patients with anal squamous cell carcinoma treated with interstitial pulsed-dose-rate brachytherapy (PDR-BT) with a boost to residual tumor after external radiotherapy.Material and methodsMedical records of patients receiving a brachytherapy boost after radiotherapy for anal squamous cell carcinoma in our Institute between 2008 and 2019 were retrospectively reviewed. After receiving pelvic irradiation ± concurrent chemotherapy, patients received PDR-BT boost to residual tumor, in order to deliver a minimal total dose of 60 Gy. Patients’ outcomes were analyzed, with primary focus on local control, sphincter preservation, morbidity, and quality of life.ResultsA total of 42 patients were identified, included 24, 13, and 5 patients with I, II, and III tumor stages, respectively. Median brachytherapy (BT) dose was 20 Gy (range, 10-30 Gy). Median dose per pulse was 42 cGy (range, 37.5-50 cGy). With median follow-up of 60.4 months (range, 5.4-127.4 months), estimated local control and colostomy-free survival rates at 5 years were both 88.7% (95% CI: 67.4-96.4%). The largest axis of residual lesion after external beam radiation therapy (EBRT) and poor tumor shrinkage were associated with more frequent relapses (p = 0.02 and p = 0.007, respectively). Out of 40 patients with more than 6 months follow-up, only one experienced severe delayed toxicity (fecal incontinence). Health quality perception was very good or good in 20 of 22 (91%) patients, according to their replies of quality-of-life surveys. A total dose ≥ 63 Gy was associated with higher number of anorectal grade 1+ toxicities (n = 1.5 vs. n = 0.61, p = 0.02).ConclusionsIn this cohort of 42 patients with mainly I and II tumor stages, PDR-BT boost allowed for local control in 88.7% of patients, with only one grade 3 anorectal toxicity.

PO-1105: Interstitial PDR brachytherapy for the treatment of squamous cell anal carcinoma

PO-1105: Interstitial PDR brachytherapy for the treatment of squamous cell anal carcinoma

Long-term results of a protocol-based ultrasound-guided salvage brachytherapy as re-irradiation for local recurrent prostate cancer

Background and purposeTo assess the long-term results of protocol-based ultrasound-guided salvage pulsed-dose rate brachytherapy in locally recurrent prostate cancer following previous radiation therapy. Materials and methodsA total of 82 patients (median age 69 years) with locally recurrent prostate cancer after previous external beam radiation therapy (43/82, 52.4%), prostatectomy and adjuvant radiation therapy (24/82, 29.3%) or brachytherapy (15/82, 18.3%) were treated with sole salvage interstitial pulsed-dose rate brachytherapy (PDR-BT). The treatment regimen consisted of two PDR-BT sections with 30 Gy (single pulse dose 0.6 Gy/h, 24 h per day) each up to a total reference dose of 60 Gy (EQD2 = 71.5 Gy-eq). The endpoints of the present analysis are cumulative local recurrence-rate, PSA-free survival, overall survival and the treatment-associated late toxicity according to the “Common Toxicity Criteria” with a median follow-up of 49 months (range, 12–129 months). ResultsThe 5-y. overall cumulative local recurrence rate was 17.7% with no significant differences between low, intermediate and high-risk groups. Differences in PSA-free survival were marginally non-significant, at 67.3%, 70.4% and 63.8% for low, intermediate and high risk group, respectively. No grade 3 gastrointestinal late side effects have been observed. The most common late side effect was urinary incontinence grade 1–3 and urinary frequency/urgency grade 1–3 in 18.3% (15/82) and 17.1% (14/82) of patients, respectively. ConclusionPDR salvage brachytherapy in local recurrent previously irradiated prostate cancer is efficient with low late toxicity. Salvage-brachytherapy represents a valuable therapeutic option for the treatment of previously irradiated locally recurrent prostate cancer.

Changes of CD68, CD163, and PD-L1 tumor expression during high-dose-rate and pulsed-dose-rate brachytherapy for cervical cancer

PurposeWe hypothesized that radiation doses delivered with high-dose-rate (HDR) and pulsed-dose-rate (PDR) brachytherapy in patients with cervical cancer could trigger immune stimulation by modulating immune cells in the tumor microenvironment. The objective was to determine CD68, CD163, and PD-L1 expression in biopsies from patients with cervical cancer and to compare the effects of HDR vs. PDR brachytherapy on the expression of these proteins. Methods and MaterialsNineteen consecutive women (mean age, 55.9 years) with histologically proven cervical cancer scheduled for brachytherapy after standard external beam irradiation therapy combined with platinum-based chemotherapy were included in a prospective study. Core tissue biopsies were obtained before radiochemotherapy (biopsy #1), after completion of radiochemotherapy and before brachytherapy (biopsy #2), and 2 weeks after completion of brachytherapy (biopsy #3). HDR or PDR brachytherapy was delivered according to availability of equipment. CD68, CD163, and PD-L1 immunohistochemical expression was estimated using a quantitative method. Conditional logistic regression models were used to assess the relationship between gene expression and time of biopsy for each brachytherapy technique. ResultsIn relation to CD68 and CD163, statistically significant relationships between gene expression and biopsy tissue samples were not found in any of the brachytherapy techniques, although there was trend toward downexpression of CD68 and CD163 in biopsies #2 and #3 in the HDR brachytherapy cohort only. There was a significant increase in PD-L1 expression in biopsy #3 also in the HDR cohort as compared with the PDR cohort. ConclusionsDecreased CD68 and CD163 expression did not reach statistical significance, but this trend may have clinical translational potential. Overexpression of PD-L1 in tissue biopsies taken at 14 days in the HDR brachytherapy cohort may tentatively suggest that this time period would be an adequate interval for blockade of the PD-1/PD-L1 axis.

CN119 - Vaginal moisturizing post PDR-pulse dose rate brachytherapy

BackgroundPDR (Pulsed Dose Rate) Brachytherapy is one of the treatments of choice for cervical cancer. Main side-effects are vaginal dryness, dyspareunia, pain, stenosis and sexual dysfunction that impacts on the patient’s well-being and on quality of life. To evaluate the efficacy of vaginal moisture to reduce dryness and pain associated with PDR Brachytherapy in cervical cancer patients treated at Catalan Institute of Oncology-Barcelona. MethodsA quasi-experimental randomized study. From 2016 to 2018 all women were assessed by nurses 4 times: basal at discharge, 1st, 3rd and 6th month post-treatment. Experimental intervention with moisturizing versus standard care. Inclusion criteria; women diagnosed of cervical cancer receiving PDR. Probabilistic sampling of patients assigned 42 to control group CG and 47 to experimental group (EG). Variables: vaginal hydration, pain, age, ethnicity, comfort perceived, socio-demographic, tobacco, sexual relationship and couples. Instruments: LENT/SOMA to assess vaginal toxicity and visual numeric for pain. ResultsOf the 96 eligible, some excluded for relapse, or study failure. N=89 women. Mean age: 52.78+12.8 (range 24-83) years old. Ethnicity; 63.8% white, Latina 3.1%, Arabic and Asiatic 0.8% each and gypsies 1.6%. Education; 3.1% illiteracy, primary 32.2%, secondary 25.2% and university 7.2%. Smokers 29.2%. For variable pain was 15-15-17-15 in CG and 20-17-15-13 in EG for consecutive points. Dyspareunia was present in 0-4-8-7 patients and 3-0-2-2 in EG. Dryness was 1-9-13-12 in CG and 6-1-8-10 in EG. Bleeding was 17-5-5-7 in CG and 16-10-0-6 in EG. Only significance differences on dryness variable. A total of 48.31% women avoid sexual intercourse, 22 (24.71%) in CG and 21 (23.59%). No significance differences. ConclusionsAn early vaginal moisturizing post-brachytherapy decreases the appearance of dyspareunia, allows start sexual relationships and improves the quality of life and sense of well-being. However some patients do not give the necessary importance to sexuality and it is something that they put aside during the treatment. Nursing education for patients at discharge helps to facilitate a healthy sexuality. Legal entity responsible for the studyThe authors. FundingHas not received any funding. DisclosureAll authors have declared no conflicts of interest.