Intracavitary Irradiation Research Articles

Effects of Sintilimab Plus Radiotherapy on Levels of Spondin-2 and Glucose Transporter-1 in Patients with Cervical Cancer.

We aimed to evaluate the effects of sintilimab plus radiotherapy on levels of Spondin-2 and glucose transporter-1 (Glut-1) in patients with cervical cancer. A total of 112 patients with cervical cancer treated from January 2019 to January 2021 were selected in this randomized control trial and divided into a control group (n = 56) and a study group (n = 56) using the random number table method. Chemotherapy using docetaxel + cisplatin was performed for both groups, based on which the control group was given radiotherapy (external conformal radiotherapy + intracavitary irradiation), and the study group received sintilimab plus radiotherapy. The treatment lasted for six cycles, with 21 days as one cycle. The total response rate of the study group was higher than that of the control group (55.36% vs 33.93%) (P < 0.05). There were no significant differences in adverse effects between the two groups (P > 0.05). After six cycles of treatment, the levels of carcinoembryonic antigen, squamous cell carcinoma antigen, vascular endothelial growth factor-A, vascular endothelial growth factor receptor 2, Spondin-2 and Glut-1 decreased in both groups compared with those before treatment, and they were lower in the study group (P < 0.05). The survival rate of the study group was higher than that of the control group (87.50% vs 71.43%) (P < 0.05). Sintilimab plus radiotherapy can effectively reduce the levels of serum tumor markers, such as Spondin-2 and Glut-1, and enhance the clinical efficacy on patients with cervical cancer, without increasing adverse effects.

The care and management of patients with indication for intracavitary 3D brachytherapy

This paper evaluates the differences between two types of normalization of 3D intracavitary brachytherapy (3D-BT) treatment plans for malignant cervical lesions. Immediately after the end of the treatment, intracavitary irradiation was continued, three fractions with 7.5 Gy per session, using High Dose Rate (HDR) brachytherapy and 3D imaging. Tree plans were made, one for the 3 cm diameter vaginal applicator and two for the vaginal applications where 2.6 cm diameter intracavitary applicators were used. Treatment plans were made using the dedicated software Eclipse-BrachyVision version 10.0.42, manufacturer Varian Medical Systems. Dose Calculation Model-Linear source and step size 0.50 cm. The normalization was done in the first phase at the surface of the applicator, at the prescription line. The next normalization was by volume. We present the results of the two normalizations. The data obtained from the 2 normalization methods was entered into an Excel spreadsheet. We took into account the dose prescribed for EBRT, the number of fractions, the dose/fr, the dose prescribed for 3D-BT and the dose absorbed by the OAR in 2 cm. We also took into account the isodose obtained for 90%, 100% and 150% of the volume of interest. In the first optimization, the absorbed dose was between 7.45–8 Gy. We also tracked BED and EQD2 in the spreadsheet. Results: In the second optimization, on the target volume, we obtained for the plan with a cylinder with a diameter of 3 cm (Ф = 3 cm), 90% of the IR volume the dose of 7.5 Gy. For Ф = 2.6 cm, of the IR volume with a dose of 7.5 Gy and for the last plane also with Ф = 2.6 cm, of the IR2 volume with a dose of 7.5 Gy. Calculated data for EQD2 in the three planes with normalization to the line on the applicator surface resulted in higher doses for OARs compared to EQD2 data from volume optimization. The volume of interest according to EQD2 calculations in the first optimization had 77.8 Gy and in the second optimization it had 78.4 Gy. After volume optimization, we achieved 78.4 Gy for all three brachytherapy fractions and the 25 EBRT fractions, the rectum totaling a dose of 67.1 Gy and the bladder 77.5 Gy. With the volume-optimized plans, we obtained a coverage between V90% = D100%.

Stereotactic Intracavitary Irradiation for Cystic Craniopharyngiomas with Rhenium-186

Abstract Objective The intracavitary irradiation of cystic tumors has been used as a therapeutic alternative modality in the management of cystic craniopharyngiomas. In the present study, we review our experience, considering the technical issues, outcomes, and complications associated with the use of stereotactic intracavitary irradiation (SICI) with colloidal rhenium-186 (186Re) for cystic craniopharyngioma. Material and Methods The records of 33 patients with cystic craniopharyngiomas treated by SICI with colloidal 186Re were retrospectively reviewed. The median radiation dose to the cyst wall was of 408 Gy (range: 175 Gy to 500 Gy). All tumors were composed of a large cyst cavity, and 9 (27.3%) also had a solid component. The mean follow-up period was of 3.7 years. Results After SICI, 31 (93.9%) patients showed radiological evidence of cyst regression, and, in 2 (6.1%), no response was observed. An improvement in the visual deficits was observed in 8 cases (24.2%), and an improvement in endocrinogical disturbances, in 2 cases (6.1%). We observed complications in 3 patients (9.1%): diabetes insupidus in 1 case (3%), aggravation of visual acuity in 1 case (3%), and severe headache after infusion of the colloid in 1 case (3%); and 1 patient (3%) died after meningitis. Conclusion Stereotactic intracavitary irradiation with colloidal 186Re is a safe procedure, with satisfactory results in the present series, and should be considered, in the management of cystic craniopharyngiomas, the first-intention therapy or as an adjuvant to other therapeutical modalities, with acceptable morbidity and mortality rates.

OR2804 Endocrine And Vision Outcomes Following 90Yttrium Therapy For Cystic Sellar Lesions—A Prospective Cohort Study

Abstract Disclosure: M.A. MacLean: None. S. Ahmad: None. A.L. Hebb: None. A. Tahir: None. R. Greene: None. D.B. Clarke: None. S.A. Imran: None. Background: Untreated cystic sellar lesions can cause vision loss, endocrine dysfunction, and obstructive hydrocephalus related to growth and mass effect. Microsurgical resection, stereotactic aspiration, and radiation treatment strategies are limited by significant complications and high risk of recurrence. Stereotactic intracavitary irradiation with the beta-emitting isotope 90Yttrium (90Yt) has been proposed as an alternative to mitigate these challenges. Long term-efficacy data is lacking. Here, our objective was to prospectively assess the effect of 90Yt on cyst volume, endocrine, and vision outcomes. Methods: We conducted a Health Canada approved, single-centre, prospective cohort study. Clinical outcome measures included cyst volume measured on magnetic resonance imaging, formal visual field (VF) testing, and hypothalamic-pituitary (HP) hormonal function. All patients provided informed consent and underwent right frontal stereotactic insertion of 90Yt colloid (200 Gy cyst wall). Results: Twenty-two patients (55% females) received 90Yt therapy. Mean age was 63.5 (SD 15.4) years with no difference between genders (p = 0.055). Mean duration of follow-up was 52 months (range 5-113). Cystic lesions included: craniopharyngioma (86%), Rathke’s cleft cyst (9%) and cystic prolactinoma (5%). Mean tumor cyst volumes were reduced by 77% at 12-month follow-up (pre-operative: 5.2, SD 4.5 cc; 12 months post-operative: 1.2, SD 1.5 cc; p = 0.002). Males had larger tumor volumes at baseline (7.7, SD 5.0 cc vs. 3.2, SD 2.8; p = 0.02) and 3 months (4.7, SD 3.4 vs. 1.8, SD 2.0; p = 0.04) but these differences had resolved by 9-month follow-up. Pre-operative clinical features included: VF deficit (36%), VF deficit plus headache (36%), headache alone (9%), hydrocephalus (5%), and 14% were asymptomatic. HP hormone dysfunction was observed in 59% of patients pre-operatively (27% complete; 73% partial) and 68% post-operatively (p = 0.50); specifically, no differences were found pre- and post-operatively for secondary hypogonadism (50% vs. 55%), hypothyroidism (45% vs. 59%), hypoadrenalism (36% vs. 27%), growth hormone deficiency (27% vs. 23%), diabetes insipidus (23% vs. 27%), and hyperprolactinemia (36% vs. 36%) (all p &amp;gt; 0.05). Pre-operative VF deficits were found in 68% of patients, of which 32% normalized and 36% remained stable (p = 0.180). Worsened vision was detected in 9% of patients post-operatively. Treatment failure requiring conventional surgery occurred in 18% of patients. Conclusions:90Yt therapy significantly reduced tumor cyst size and stabilized both endocrine function and vision in patients with cystic lesions of the sellar region. Presentation: Sunday, June 18, 2023

Prognostic role of the controlling nutritional status (CONUT) score in patients with biliary tract cancer: a meta-analysis

Background Previous reports have not reached consistent results regarding the prognostic significance of the controlling nutritional status (CONUT) score in biliary tract cancer (BTC). Therefore, the present meta-analysis was conducted to investigate the precise role of the CONUT score in predicting the prognosis of BTC. Methods Electronic platforms including Web of Science, PubMed, Cochrane Library, and Embase were comprehensively searched up to May 2, 2023. We also determined combined hazard ratios (HRs) and 95% confidence intervals (CIs) to estimate the role of the CONUT score in predicting the prognosis of patients with BTC. Results Ten studies involving 1,441 patients were included in the present study. Nine studies treated patients with surgical resection, and one study used percutaneous transhepatic biliary stenting (PTBS) plus 125I seed intracavitary irradiation. Based on the combined data, a higher CONUT score significantly predicted dismal overall survival (OS) (HR = 1.94, 95%CI = 1.41–2.66, p < 0.001), inferior recurrence-free survival (RFS) (HR = 1.79, 95%CI = 1.48–2.17, p < 0.001) in BTC, and low differentiation (OR = 1.57, 95%CI = 1.15–2.14, p = 0.004). Nonetheless, the CONUT score was not related to sex, lymph node metastasis, microvascular invasion, perineural invasion, distant metastasis, TNM stage, or tumor number in patients with BTC. Conclusion Higher CONUT scores significantly predicted worse OS and RFS in patients with BTC. Moreover, BTC patients with high CONUT scores tended to have poor tumor differentiation. The CONUT score could help clinicians stratify high-risk patients with BTC and devise individualized treatment plans.

High-dose (60 Gy) intensity-modulated radiotherapy with concurrent weekly cisplatin followed by intracavitary radiation in locally advanced cervical cancer: A phase II prospective clinical trial

ObjectiveRadiotherapy dose-escalation using intensity-modulated radiotherapy (IMRT) has been necessary to improve treatment results in cervical cancer. MethodsThis was a phase II prospective clinical trial. 88 patients with FIGO II-IVa cervical cancer were enrolled in a single center. They received high-dose (60 Gy) IMRT with weekly cisplatin to the primary tumor and clinically positive nodes followed by intracavitary radiation. The primary endpoint was 30-month PFS rate (Target; 82%, an increase of 20% compared to GOG 120 trial using standard-dose radiotherapy). Secondary endpoints were tumor response, toxicity, recurrence, distant metastasis, and overall survival. ResultsProgression-free survival rate at 30 months was 82.8%. Overall survival, locoregional recurrence, distant metastasis, and para-aortic recurrence rates at 30 months were 93.6%, 8.2%, 9.2%, and 2.4%, respectively. Forty-five (51.1%) of 88 patients achieved downstaging on MRI during radiotherapy and 80 (90.9%) patients had clinically complete response at three months after high-dose IMRT and intracavitary radiotherapy. The 30-month recurrence-free survival (92.9% vs. 73.1%, P = 0.009) and overall survival (100% vs. 87.0%, P = 0.006) were significantly higher in the downstaged group than in the non-downstaged group during radiotherapy. Grade 3 or higher hematologic toxicity was found in 11 (12.5%) patients and grade 3 or higher non-hematologic toxicity was found in 3 (3.4%) patients. Fourteen had chronic urinary (8.0%), intestinal (5.7%) toxicity, pelvic insufficiency fracture (2.3%) or vesicovaginal fistula (2.3%). ConclusionHigh-dose (60 Gy) IMRT with concurrent weekly cisplatin in locally advanced cervical cancer yielded favorable progression-free survival outcome. Tumor response during radiotherapy can be a significant prognostic factor for PFS.Clinical trial information: This prospective trial is registered at ClinicalTrials.gov Identifier: NCT02993653.

P.107 Endocrine and vision outcomes following 90Yttrium therapy for cystic sellar lesions: a prospective cohort study

Background: Due to high risk of recurrence and complications associated with microsurgical resection or aspiration of enlarging cystic sellar lesions, stereotactic intracavitary irradiation with 90Yttrium (90Yt) has been proposed as an alternative to mitigate these challenges. Long-term efficacy data for this procedure is lacking. Methods: We conducted a Health Canada approved, single-centre, prospective cohort study to assess the effect of 90Yt therapy on cyst volume, visual field (VF) testing and endocrine function. All patients underwent right frontal stereotactic insertion of 90Yt colloid (200 Gy cyst wall). Results: 22 patients [mean age = 63.5 (± 15.4) years] received 90Yt therapy. Mean follow-up was 52 (5-113) months. Cysts included: craniopharyngioma (86%), Rathke’s cleft cyst (9%) and cystic prolactinoma (5%). Mean cyst volume reduction was 77% at 12-months (5.2 ± 4.5 cc to 1.2 ± 1.5 cc; p = 0.002). Rate of pre- and post-op hormonal dysfunction was 59% and 68%, respectively (p = 0.50). Pre-operative VF deficits were found in 68% of patients, of which 32% normalized and 36% remained stable (p = 0.180). Worsened vision was detected in 9% of patients post-operatively. Conclusions: 90Yttrium therapy significantly reduces sellar cyst size without having a deleterious effect on vision and endocrine function.

A retrospective study of locally advanced cervical cancer cases treated with CT-based 3D-IGBT compared with 2D-IGBT.

To retrospectively review locally advanced cervical cancer (CC) cases treated with three-dimensional image-guided brachytherapy (3D-IGBT) and two-dimensional (2D)-IGBT. Patients with Stage IB-IVa CC who underwent intracavitary irradiation between 2007 and 2021 were divided into the 3D-IGBT and 2D-IGBT groups. Local control (LC), distant metastasis-free survival (DMFS), progression-free survival (PFS), overall survival (OS), and gastrointestinal toxicity (G3 or more) were investigated at 2/3years post-treatment. Seventy-one patients in the 2D-IGBT group from 2007 to 2016 and 61 patients in the 3D-IGBT group from 2016-2021 were included in the study. The median follow-up period was 72.7 (4.6-183.9) months in the 2D-IGBT group and 30.0 (4.2-70.5) months in the 3D-IGBT group. The median age was 65.0 (40-93) years in the 2D-IGBT group and 60.0 (28-87) years in the 3D-IGBT group, but there was no difference in FIGO stage, histology, or tumor size between the groups. In treatment, the median A point dose was 56.1 (40.0-74.0) Gy in the 2D-IGBT group and 64.0 (52.0-76.8) Gy in the 3D-IGBT group (P < 0.0001), and the proportion of patients who underwent chemotherapy more than five times was 54.3% in the 2D-IGBT group and 80.8% in the 3D-IGBT group (P = 0.0004). The 2/3-year LC, DMFS, PFS, and OS rates were 87.3%/85.5%, 77.4%/65.0%, 69.9%/59.9%, and 87.9%/77.9% in the 2D-IGBT group, and 94.2%/94.2%, 81.8%/81.8%, 80.5%/80.5%, and 91.6%/83.0% in the 3D-IGBT group, respectively. A significant difference was observed in PFS (P = 0.02). There was no difference in gastrointestinal toxicity, but there were four intestinal perforations in the patients from the 3D-IGBT group, three of whom had a history of bevacizumab treatment. The 2/3-year LC of the 3D-IGBT group was excellent and PFS also tended to improve. Care should be taken with concomitant use of bevacizumab after radiotherapy.

Prognostic Value of Systemic Immune-Inflammation Index-Based Nomogram in Patients with Extrahepatic Cholangiocarcinoma Treated by Percutaneous Transhepatic Biliary Stenting Combined with 125I Seed Intracavitary Irradiation.

This study aimed to investigate the prognostic value of systemic immune-inflammation index (SII) in patients with extrahepatic cholangiocarcinoma (EHCC) treated by percutaneous transhepatic biliary stenting (PTBS) combined with 125I seed intracavitary irradiation and further develop a predictive model related to SII. A total of 145 patients with EHCC who received PTBS combined with 125I seed implantation were retrospectively analyzed. The optimal cut-off value of SII was identified by receiver operating characteristic (ROC) curve analysis. Kaplan-Meier curves and Cox regression were applied to estimate the prognostic value of SII and identify other significant factors of overall survival (OS). Additionally, a novel nomogram was constructed. The concordance index (C-index), calibration plots and decision curve analysis were used to evaluate the performance of the nomogram model. The optimal cut-off value for preoperative SII of 890.2 stratified the patients into High-SII (H-SII) and Low-SII (L-SII) groups. Univariate and multivariate analyses demonstrated that SII was an independent factor for OS. We also found that better therapeutic effect could be obtained with combined postoperative chemotherapy (P < 0.001). Moreover, we revealed that elevated preoperative CA19-9 (P = 0.038) and TBIL level (P = 0.024) were reason for poor prognosis of EHCC. A well-discriminated and calibrated nomogram was developed to predict the 1-year and 2-year OS of EHCC (C-index: 0.709). The SII may be a feasible and convenient prognosis predictor for EHCC. The comprehensive nomogram based on SII presented in this study is a promising model for predicting OS in EHCC patients after PTBS combined with 125I seed intracavitary irradiation.

Evaluation of mercury (II) iodide dosimeter for digital quality assurance in intracavitary radiotherapy

In intracavitary radiotherapy, it is essential to verify the correct location of radiation source among quality control items because an incorrect location will irradiate an unnecessary dose to normal tissues. As a basic study of digital line dosimeters, this study fabricated a unit cell dosimeter based on polycrystalline mercury (II) iodide (HgI2) and compared its performance with a diode. The study result showed that for reproducibility, the relative standard deviation (RSD) was 1.21%, satisfying the RSD evaluation criterion of within 1.5%. Considering linearity, the coefficient of determination R2 showed an excellent result of 0.9997. Regarding the evaluation of distance dependence, it showed a similar trend in general with a difference of 0.035 cm for intensity 50% when compared with the inverse square value. The angular dependence gradually decreased in intensity as the angle increased, showing a difference of up to 25%. This study suggests the applicability of a digital dosimeter for brachytherapy quality control by evaluating the performance of the HgI2 dosimeter. However, to develop it into a quality assurance (QA) dosimeter, correction factor for sensitivity according to angle should be applied. This study on dosimeter for candidate photoconductor materials can be used as basic data in all areas using radiation.

Risk factors for lower extremity lymphedema after surgery in cervical and endometrial cancer.

Lower extremity lymphedema (LEL) is a well-known adverse effect related to cervical and endometrial cancer (CEC); however, very few studies have elucidated the clinicopathologic risk factors related to LEL. We investigated the incidence and risk factors in patients who received primary surgery and/or adjuvant radiotherapy (RT) or chemotherapy for CEC. We retrospectively reviewed 2,565 patients who underwent primary surgery following CEC diagnosis between January 2007 and December 2020. LEL diagnosis was based on objective and subjective assessments by experts. We identified important predictors of LEL to construct a nomogram predicting individual risks of LEL. For internal validation of the nomogram, the original data were separated using the split-sample method in a 7:3 ratio of training data and test data. Overall, 858 patients (33.5%) received RT, 586 received external beam RT (EBRT), and 630 received intracavitary RT. During follow-up period, LEL developed in 331 patients, with an overall cumulative 5-year incidence of 13.3%. In multivariate analysis, age at primary treatment, use of docetaxel-based chemotherapy, type of hysterectomy, type of surgical pelvic lymph node (LN) assessment, number of dissected pelvic and para-aortic LNs, and EBRT field were the independent predictors of LEL. We subsequently developed the nomogram showing excellent predictive power for LEL. LEL is associated with various treatment modalities, and their interactions may increase the possibility of occurrences. De-escalation strategies for treatment modalities should be considered to reduce LEL in patients with CEC.

Use of 3D planning of HDR brachytherapy in patients with cervical cancer

Background. Combined radiation therapy is the «gold standard» for the treatment of stages IIB-IVA of cervical cancer (cervical cancer). Given the data of statistical indicators of cervical cancer, the study of new approaches to treatment and implementation in clinical practice of modern technologies of radiation therapy of widespread cervical cancer is an extremely important area.&#x0D; Purpose – evaluate the benefits of using CT topometric preparation in planning brachytherapy for cervical cancer.&#x0D; Materials and Methods. 3D planning of brachytherapy of 24 patients with locally advanced cervical cancer (FIGO IIIB stage), who underwent a radical program of combined radiation therapy (remote radiation therapy with chemical modification with cisplatin followed by HDR-brachytherapy (High dose rate brachytherapy)).&#x0D; Results. The paper presents the results of the analysis of differences in brachytherapy planning according to orthogonal images and CT images. The analysis of the influence of the constitutional features of patients revealed that there are differences in the topographic anatomy of the pelvis depending on the surface area of the body. In patients with a body surface area of up to 1,65 m2 , a more intimate fit of the intestine to the target volume of irradiation was noted. No similar planning difficulties were found in patients with a body surface area above 1,65 m2 .&#x0D; Conclusions. The use of 3D images in the planning of intracavitary irradiation in patients with cervical cancer provides precision brachytherapy by simultaneously visualizing the irradiated volumes and spatial relationships of the anatomical structures of the pelvis, the introduced endostats and the corresponding volumetric dose distributions.

Clinical Outcome and Risk Factors of Chronic Radiation Proctitis Following Pelvic Radiation Therapy.

Pelvic radiation therapy (RT) is a common treatment for malignancies, including gynecological, genitourinary, and lower gastrointestinal tract cancers. However, chronic radiation proctitis (RP) is an unavoidable side effect, and its clinical presentation varies from asymptomatic to potentially life-threatening. This study evaluated the clinical characteristics and risk factors of chronic RP. Patients with chronic RP (212) following RT for various pelvic cancers between January 2015 and December 2021 were enrolled. Clinical characteristics of RP were analyzed retrospectively. Severity was graded according to the Radiation Therapy Oncology Group (RTOG) modified rectal toxicity score and Vienna rectoscopy score (VRS), and risk factors were statistically analyzed. The most common pelvic cancer observed was cervical cancer. The patients received three-dimensional conformal RT (3D-CRT), intensity-modulated RT, or a combination of 3D-CRT and intracavitary RT (ICR). Rectal bleeding occurred in 70 (33.0%) patients. Previous abdominopelvic surgery and total radiation dose significantly correlated with the RTOG score and VRS. Previous abdominopelvic surgery, ICR, and total radiation dose were associated with chronic hemorrhagic RP. All patients with chronic hemorrhagic RP were treated with argon plasma coagulation (APC). 91.4% of cases required 1-3 APC sessions to resolve the bleeding, with a mean of 1.7 sessions. Our results showed that previous abdominopelvic surgery and total radiation dose were significant risk factors related to chronic RP, while total radiation dose was related to chronic hemorrhagic RP. We also showed that APC was effective and safe for chronic hemorrhagic RP.

Integration of Consolidation Chemotherapy After Concurrent Chemoradiation in the Treatment of Locally Advanced Uterine Cervical Cancer.

Despite the current standard of concurrent chemoradiation (CCRT), around 30-40% are still dying from locally advanced cervical cancer. Increasing the radiation dose further was not a feasible option, but addition of chemotherapy further was tried due to the different toxicity profiles of it. So, the use of consolidation chemotherapy beyond CCRT has been studied. To evaluate the efficacy, toxicity, tumour response and loco-regional control following consolidation chemotherapy after concurrent chemoradiation in locally advanced carcinoma cervix (LACC). The patients were randomized into two arms: the conventional arm (control arm, n = 30) patients received conventional treatment with weekly injection cisplatin (35mg/m2) concurrently with pelvic external beam radiation (50Gy/25 fraction, 2Gy/fraction, 5 fraction weekly) followed by intracavitary radiotherapy of 21Gy in 3 fractions of 7Gy each by HDR brachytherapy. In the interventional arm (study arm, n = 30), patients received the standard treatment followed by 3 cycles of consolidation chemotherapy (paclitaxel + carboplatin) every three weekly. Haematological toxicity (grade 3 anaemia and grade 1 leucopenia, grade 1 and 2 thrombocytopenia) was higher in the study group. Renal, hepatic and gastrointestinal toxicity was more in the study arm. Peripheral neuropathy was mostly seen in the study arm. Median follow-up was 9months. Treatment response was better, and the rate of recurrence was less in the study arm. Addition of few cycles of consolidation chemotherapy after standard treatment is beneficial in patients with LACC with manageable toxicity and good compliance.

A Retrospective Study of Chemotherapy and 3D-Image-Guided Afterloading Intracavitary Radiotherapy in Locally Advanced Cervical Cancer.

Aim To investigate the value of neoadjuvant chemotherapy combined with 3D-image-guided afterloading intracavitary radiotherapy in locally advanced cervical cancer (LACC). Methods Patients with cervical cancer admitted to our hospital from January 1, 2020 to January 1, 2021 were retrieved and analyzed. Cases treated with neoadjuvant chemotherapy and 3D-image-guided afterloading intracavitary radiotherapy were assigned into the observation group (OG), while cases with neoadjuvant chemotherapy alone were assigned into the control group (CG). The short-term effects were determined by RECIST 1.1. Total effective rate (TR) = complete remission (CR) + partial remission (PR). The serum levels of squamous epithelial cell carcinoma antigen (SCC-Ag), glycoantigen 125 (CA125), carcinoembryonic antigen (CEA), and vascular endothelial growth factor (VEGF) were assessed. In view of the difference between tumor markers and diameters before and after treatment, the correlation between them was analyzed by Pearson test. The adverse events were compared, and the amount of operative bleeding and operation time were evaluated. Cox regression analysis was conducted to assess the influencing factors of 1-year disease-free survival time. Results Sixty-seven patients were retrieved, including 30 cases in the OG and 37 cases in the CG. There were no significant differences in age, pathological type, tumor size, FIGO stage, past medical history, or smoking history between the two groups (P > 0.05). The TR of patients in the OG was higher than that in the CG (P < 0.05). The SCC-Ag, CA125, CEA, and VEGF levels in the OG decreased markedly after treatment (P < 0.001). The difference in SCC-Ag, CA125, CEA, and VEGF was positively correlated with the difference in tumor diameter before and after treatment (P < 0.05). The incidence of adverse events revealed no obvious difference between the OG and CG (P > 0.05). Cox regression analysis showed that FIGO stage and treatment regimens were independent prognostic factors for 1-year disease-free survival (P < 0.05). Conclusion Neoadjuvant chemotherapy combined with 3D-image-guided afterloading intracavitary radiotherapy can improve the TR rate and 1-year disease-free survival of LACC patients without increasing the incidence of adverse events.

Verification of dose distribution in high dose-rate brachytherapy for cervical cancer using a normoxic N-vinylpyrrolidone polymer gel dosimeter.

The polymer gel dosimeter has been proposed for use as a 3D dosimeter for complex dose distribution measurement of high dose-rate (HDR) brachytherapy. However, various shapes of catheter/applicator for sealed radioactive source transport used in clinical cases must be placed in the gel sample. The absorbed dose readout for the magnetic resonance (MR)-based polymer gel dosimeters requires calibration data for the dose-transverse relaxation rate (R2) response. In this study, we evaluated in detail the dose uncertainty and dose resolution of three calibration methods, the multi-sample and distance methods using the Ir-192 source and the linear accelerator (linac) method using 6MV X-rays. The use of Ir-192 sources increases dose uncertainty with steep dose gradients. We clarified that the uniformly irradiated gel sample improved the signal-to-noise ratio (SNR) due to the large slice thickness of MR images and could acquire an accurate calibration curve using the linac method. The curved tandem and ovoid applicator used for intracavitary irradiation of HDR brachytherapy for cervical cancer were reproduced with a glass tube to verify the dose distribution. The results of comparison with the treatment planning system (TPS) calculation by gamma analysis on the 3%/2mm criterion were in good agreement with a gamma pass rate of 90%. In addition, the prescription dose could be evaluated accurately. We conclude that it is easy to place catheter/applicator in the polymer gel dosimeters, making them a useful tool for verifying the 3D dose distribution of HDR brachytherapy with accurate calibration methods.

Development and evaluation of a thallium (I) bromide dosimeter for intracavitary radiotherapy quality assurance

In intracavitary radiotherapy, incorrect source locations can result in excessive doses to normal tissues. Therefore, it is essential to accurately evaluate the source location. In this study, we investigated a digital line dosimeter based on thallium (I) bromide (TlBr) to improve the existing analogue verification method. Therefore, a polycrystalline TlBr unit cell dosimeter was manufactured, and the measurement performance of iridium-192 (Ir-192) sources was evaluated. We found that the dosimeter's reproducibility satisfied the evaluation criteria of 1.5% with a relative standard deviation of 1.44%. Moreover, the linearity showed excellent results (linear coefficient, R 2 = 0.9999). The distance dependence showed a difference of 0.03 cm at 50% intensity when compared to the inverse square value, whereas the angular dependence showed a large difference when compared to a diode. As the angle increased, the intensity gradually decreased, resulting in a difference of up to 41.9%. These results demonstrate the excellent performance of the TlBr dosimeter. However, because of the significant influence of angular dependence, a measurement distance that minimises this error should be applied when manufacturing line dosimeters in the future.

Оптимизация проведения сочетанного курса лучевой терапии у больных раком прямой кишки

Due to the new rapidly developed technological equipment for radiotherapy available in cancer clinics, the study of the optimal combination of topometric preparation of a patient with planning and the delivery of treatment in order to achieve the main goal of radiation therapy – maximum exposure of the foci with minimal damage to healthy tissue. The reduction of dose to critical or-gans and healthy tissues in general is an important and urgent task. The purpose of the paper is to explore the possibility of optimization of the combined radiation therapy in patients with rectal cancer, with account of advanced approaches to topometric preparation of a patient and dosime-try planning. Six patients 47-59 years of age, with the stage III of the lower ampullary rectal can-cer, received two-phase pre-operative combined radiotherapy at the Tomsk Cancer Research In-stitute NMRC. The Phase 1 – distant radiation therapy delivery in standard mode with a single fo-cal dose (ROD) of 2 Gy, 5 times a week, totally 20 fractions, to focal dose (SOD) of 40 Gy. The Phase 2 – intracavitary radiation therapy, ROD – 3 Gy, SOD – 15 Gy, locally in the tumor area, 2 times a week, total number – 5 fractions. The conventional radiation therapy planning was carried out with the use of the XiO 3-D dosimetry planning system for the "Theratron Equinox 80" (radia-tion of the isotope Co-60, Egamma=1.25 MeV), gamma-therapeutic apparatus, and for the SL75-5-MT (Electron braking radiation, E=6 MeV) linear accelerator. For conformal radial therapy the plan-ning system for linear accelerator «Elekta Synergy» (electron brake radiation, E=6 MeV) is used. For intracavitary radiotherapy the dosimetry planning system HDRPlus for the apparatus "Multi-Source" (radiation of isotope Co-60, Egamma=1.25 MeV) is used. Radiation doses to critical organs of pa-tients with lower ampullary rectal cancer exposed to combined course of radiotherapy was calculated. It has been shown that the use of advanced techniques for pretreatment topometric preparation of a patient and dosimetry planning makes possible optimization of combined radiotherapy with account of radiation doses to critical organs.

Estimation of pelvic lymph node dose contribution from HDR ICBT in cervical cancer

Context: Dose received to each pelvic group of lymph nodes, namely obturator (OB), internal iliac (II), and external iliac (EI), is less certain. This study is conducted to evaluate the dose delivered to these nodal groups so that this can be considered while planning external beam radiotherapy external beam radiation therapy (EBRT) boost in patients with gross pelvic lymph nodes. Aims: This study aimed to estimate the dose contribution to pelvic lymph nodes in three-dimensional high-dose-rate intracavitary radiotherapy (HDR-ICRT) of cervical cancer patients. Settings and Design: This was a single-arm retrospective observational study among 25 locally advanced carcinoma cervix patients treated with definitive chemoradiation. Materials and Methods: EI, II, and OB groups of lymph nodes were delineated on computed tomography data sets of selected 25 patients, and D100, D50, and D2cc to each lymph node were analyzed. The dose received by each pelvic lymph node group from all the 3 fractions of HDR-ICRT, corresponding equivalent 2 Gy dose, and percentage of brachytherapy (BT) contribution to each pelvic lymph node were calculated. Results: Mean D100 received by EI, II, and OB lymph node groups after summation across 3 fractions was 1.1 Gy, 2.34 Gy, and 3.11 Gy, respectively. Mean 2 Gy equivalent doses (D100) were 1.66 Gy, 3.41 Gy, and 4.53 Gy, respectively. Corresponding percentage of the dose received by EI, II, and OB was 4.89%, 10.43%, and 13.83% when 7.5 Gy per fraction for 3 fractions was prescribed to Point A. Conclusions: There is a significant contribution from HDR intracavitary BT to the pelvic lymph nodes in the radical treatment of cervical cancer. The dosimetric results given in this work can be used by a radiation oncologist to estimate BT doses to affected lymph nodes and integrate them into the preceding EBRT planning phase.

Synthetic Computed Tomography Generation while Preserving Metallic Markers for Three-Dimensional Intracavitary Radiotherapy: Preliminary Study

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