Dosimetric Validation of 3D-Printed Bolus at Different Printing Infill Percentage in VMAT Plan

PURPOSE/OBJECTIVE(S)

The 3D printed bolus technology is rapidly evolving in external beam radiotherapy and printing parameters can have a significant impact on absorbed dose. In this study, a novel 3D printed bolus was designed to evaluate the time and material cost effects, dosimetry differences, and surface dose modulation capabilities in the volumetric-modulated arc therapy (VMAT) plan at different print filling percentages.

MATERIALS/METHODS

A hollow-type bolus, the middle 2.36 mm of 5 mm thickness infilled with different ratio, was designed and printed with polylactic acid (PLA). The ratio of printed material was defined by the infill percentage parameter ranging from 10% to 90%. For each bolus, two treatment plans were designed with AAA algorithm, considering the real computed tomography (CT) scan of the 3D printed bolus and modeling the 3D printed bolus as a virtual bolus structure. Percentage depth dose (PDD) profiles were calculated to build up the mapping equivalent CT value in treatment plan system (TPS). Measurement dose was performed by radiographic films. The PDD profiles were then compared between measured and calculated. A simulation VMAT treatment plan with planning target volume (PTV) close to the body surface was designed on a water-equivalent phantom, and the modulation capabilities of epidermal dose under different filling percentage was compared.

RESULTS

Compared with 100% percent infill 3D printed bolus, The maximum printing time could be reduced by 47.8% and material consumption could be reduced by 42.5%. The surface dose at single field irradiation can reach 69.6% to 85.8% of the maximum dose in different filling boluses. The PDD measurement and mapping equivalent CT calculation deviation was less than 3% when the infill percentage of the middle region is greater than 30%. The dose distribution of the VMAT plan is satisfying for infill percentages greater than 30%.

CONCLUSION

Using the 3D printing technology is possible to modulate the amount of shift of the build-up region by tuning the infill percentage of the 3D printed bolus. Patients could undergo CT simulation without bolus. Appropriate bolus could be selected according to the location of the PTV region and dose requirement.

Outcomes and Failure Patterns after Chemoradiotherapy for Locally Advanced Rectal Cancer with Positive Lateral Pelvic Lymph Nodes: A Propensity Score-Matched Analysis

PURPOSE/OBJECTIVE(S)

Locally advanced rectal cancer (LARC) combined with positive lateral pelvic lymph nodes (LPLN) tends to present worse prognosis. However, for those patients it remains unclear whether other combination high-risk factors affect the prognosis. This study aimed to use propensity score matching (PSM) to examine long-term outcomes and failure patterns in patients with positive vs. negative LPLN.

MATERIALS/METHODS

Patients with LARC were retrospectively divided into LPLN-positive and LPLN-negative groups. LPLN-positivity was defined as lymph node short diameter greater than or equal to 7 mm with specific morphological features. Clinical characteristics were compared between the groups using the chi-square test. PSM was applied to balance these differences. Progression-free survival (PFS) and overall survival (OS), and local-regional recurrence (LRR) and distant metastasis (DM) rates were compared between the groups using the Kaplan-Meier method and log-rank tests.

RESULTS

Prior to PSM, a total of 651 LARC patients were included. The LPLN-positive group had higher rates of lower location (53.1% vs. 43.0%, P = 0.025), mesorectal fascia (MRF)-positive (53.9% vs. 35.4%, P<0.001) and extramural venous invasion (EMVI)-positive (51.2% vs. 27.2%, P<0.001) disease than the LPLN-negative group. After PSM, there were 114 patients for each group along with the balanced clinical factors, and both groups had comparable surgery, pathologic complete response (pCR), and ypN stage rates. The median follow-up time was 45.9 months, 3-year OS (88.3% vs. 92.1%, P = 0.276) and LRR (5.7% vs. 2.8%, P = 0.172) rates were comparable between LPLN-positive and LPLN-negative groups. Meanwhile, despite no statistical difference, 3-year PFS (78.8% vs. 85.9%, P = 0.065) and DM (20.4% vs. 13.3%, P = 0.061) rates slightly differed between the groups. Among 10 patients with LRR, seven (70.0%) had lateral pelvic recurrence, among them, five patients were LPLN-positive, and four (80.0%) of these patients did not receive simultaneous integrated boost intensity-modulated radiotherapy (SIB- IMRT).45 patients were diagnosed with DM, 11 (40.7%) LPLN-positive and 3 (17.6%) LPLN-negative patients were diagnosed with oligometastases (P = 0.109).

CONCLUSION

Our study shows there is a tendency of worse PFS and DM in LPLN-positive than LPLN-negative patients, for LPLN-positive patients, oligometastases account for a large proportion of all distant metastases.

CBCT Guided Interfraction Absolute Displacement and Setup Error Assessment during Breast Prone Radiotherapy

PURPOSE/OBJECTIVE(S)

To calculate interfraction absolute displacement/shift and setup error using cone beam computed tomography (CBCT) during breast prone radiotherapy.

MATERIALS/METHODS

Fifty-nine patients undergoing prone whole breast-irradiation after breast-conserving surgery (BCS) were studied as part of an institutional review board- approved prospective trial. Setup precision was monitored using a daily online CBCT. Translational shifts in 3 axes (AP: anterior posterior; LR: left right; and SI: superior inferior) and 3 rotations (pitch, roll, and rtn) after CBCT were analyzed for 1062 treatment fractions. The random and systematic setup errors (SE) were calculated and were analyzed for time trends during the course of radiotherapy.

RESULTS

For absolute inter-fractional shifts, the numbers of fractions exceeding 10 mm in the AP, LR, and SI directions were 6.5%, 17.42% and 8.92%, respectively; 0%, 0% and 1.31% fractions exceeded 3°for pitch, roll, and Rtn, respectively. The population systematic errors were 1.89/2.91/1.98 mm in AP/SI/LR directions, while the random error were 2.72/3.99/3.31 mm. In pitch, roll, rtn rotations, the population systematic error were 0.64°/0.49°/0.46°, and 0.89°/0.90°/0.93° for the random error. Without correction these would correspond to a clinical to planning target volume margin of 6.64/10.08/7.26 mm in AP/SI/LR directions and 2.22°/1.79°/1.8° in pitch, roll, rtn rotations. The magnitude of inter-fraction motion was not correlated with patient treatment time accept in AP direction (P = 0.000).

CONCLUSION

SE was larger in prone position in breast cancer patients, attributable mostly to random errors, which emphasize the need for on-line imaging guidance in breast prone radiotherapy. 10mm margins would adequately cover the target volume and account for setup errors in the absence of IGRT.

Weekly Image Guidance in Patients with Cervical Cancer Treated with Intensity Modulated Radiation Therapy: Results of a Large Cohort Study

PURPOSE/OBJECTIVE(S)

Given the motion of the cervix, uterus, and organs at risk, image guidance is recommended for patients undergoing intensity modulated radiation therapy (IMRT) for cervical cancer. However, daily image guidance can be resource intensive, particularly in developing countries. In this study, we evaluated the feasibility of a weekly image-guidance pattern and analyzed the long-term outcomes in a large cohort of patients.

MATERIALS/METHODS

The study enrolled patients with stage IB-IVA cervical cancer who received concurrent chemotherapy between 2005 and 2015. IMRT was delivered at a dose of 50.4 Gy in 28 fractions, with weekly cone-beam CT scans for image guidance. Following the image guidance, physicians would advise patients on the suitability of rectum and bladder preparation to help them prepare on non-imaging days. When significant tumor regression was observed, a second CT simulation and re-planning were performed. Intracavitary brachytherapy was delivered at a dose of 30 Gy in 5 fractions. The concurrent chemotherapy regimen consisted of weekly cisplatin.

RESULTS

A total of 1,433 patients were included in the study. The median follow-up periods for all patients and surviving patients were 63 months (ranging from 2 to 125 months) and 70 months (ranging from 3 to 125 months), respectively. The 5-year overall survival (OS), disease-free survival (DFS), and local control (LC) rates were 79.6%, 73.2%, and 86.5%, respectively. The estimated 8-year OS, DFS, and LC rates were 75.6%, 69.2%, and 85.2%, respectively. For patients with stage IB1, IB2, IIA, IIB, IIIA, IIIB, and IVA diseases (according to the 2014 FIGO staging system), the 5-year OS and DFS rates were 90.2% and 86.7%, 95.1% and 86.5%, 87.9% and 79.8%, 82.2% and 75.5%, 64.3% and 58.2%, 61.8% and 57.4%, and 43.8% and 19.4%, respectively. For patients with squamous cell carcinoma and adenocarcinoma, the 5-year DFS rates were 75.1% and 57.3%, respectively. For patients with positive regional lymph nodes, the 5-year OS and DFS rates were 64.1% and 57.8%, respectively. A total of 66 patients (4.6%) experienced grade 3-5 chronic toxicities, including 38 patients (2.7%) with gastrointestinal toxicities and 36 patients (2.5%) with genitourinary toxicities.

CONCLUSION

IMRT with weekly image guidance resulted in high survival rates and acceptable toxicities. This indicates that weekly image guidance is acceptable in countries with limited medical resources.

Risk Stratification of Postoperative Adjuvant Therapy for Endometrial Cancer (POAT-ENDORISK) Based on Bayesian Network Model: A Development and Validation Study

PURPOSE/OBJECTIVE(S)

To establish a Bayesian network (BN) model for postoperative adjuvant treatment of early endometrial carcinoma (EC) patients.

MATERIALS/METHODS

We retrospectively analyzed the data of 1280 early EC patients treated by multiple institutions in China from 1999 to 2017. All patients received primary hysterectomy/bilateral salpingo-oophorectomy and adjuvant radiotherapy. The FIGO 2009 stage of all patients is stage I and stage II EC, and the median age is 57 years old. All patients are grouped according to the ESMO-ESGO-ESTRO risk stratification. The clinicopathologic factors, treatment-related factors, local regional recurrence, distant metastasis and cancer-specific survival rate (CSS) of all patients were reviewed. We divide the original data set into training set and Validation set according to the ratio of 7:3. The training of the Bayesian network model is completed on Netica, and the test of the model effect is finally completed on the test set.

RESULTS

After variable screening, a total of 14 characteristic variables entered the final model. A total of 896 patients were used for the development of BN model, and 384 patients were used for the validation of BN model. The results of the model showed that the factors directly related to CSS were locoregional failure (LRF), radiotherapy mode, distant metastasis (DM). Factors directly related to DM were chemotherapy, LRF, CSS. The factors directly related to LRF were risk stratification, preoperative serum CA125 and preoperative HB. The accuracy, sensibility, specificity, micro-f1, micro-f1, weighted-f1 and AUC of BN model in predicting DM and CSS were better than XGBoost model.

CONCLUSION

In this study, we integrated almost all clinical pathology and treatment information related to postoperative adjuvant treatment of early EC patients and established a BN model for personalized clinical decision-making of postoperative adjuvant treatment of early EC patients. The results showed the complex correlation among the variables, and the overall prediction ability and visualization effect of BN model was significantly better than XGBoost model. Prospective research is needed before clinical implementation.

Cost-Effectiveness of Short-Course Radiotherapy Based Total Neoadjuvant Therapy for Locally Advanced Rectal Cancer in China

PURPOSE/OBJECTIVE(S)

The phase III STELLAR (NCT02533271) trial demonstrated that four cycles of chemotherapy after short-course radiotherapy (SCRT-TNT) were not inferior to the standard care of long-course concurrent radiotherapy (LCRT) in patients with locally advanced rectal cancer (LARC). This study assessed the cost-effectiveness of SCRT-TNT versus LCRT in locally advanced rectal cancer in China on the basis of the STELLAR trial.

MATERIALS/METHODS

A Markov model was used to synthesize the healthcare costs and benefits of LARC patients based on results from the STELLAR trial. The model assumes that LARC who meet the inclusion criteria of the STELLAR trial experience four possible states: No Evidence of Disease (NED), locally recurrence, distant metastases, or any death from rectal cancer or other unrelated causes, where local recurrence continues to be classified as resectable and unresectable. The transition status period is 3 month, and 5 years is used to calculate direct medical costs and health benefits. The probabilities of states transition after SCRT-TNT or LCRT were derived from the results of the STELLAR trial and previous published article (Table.1). Costs were evaluated from the Chinese payer's perspective reported in early 2022 US dollars (US$1 = 6.78 Chinese Yuan). Sensitivity analyses were performed for key variables. Cost-effectiveness was evaluated using the incremental cost-effectiveness ratio and net monetary benefits. Effectiveness was defined as quality-adjusted life-years (QALYs). Willingness-to-pay (WTP) threshold was set at $43500/QALY. Data were collected from October 3, 2020, to September 20, 2021, and analyzed from November 15, 2020, to October 25, 2021.

RESULTS

During the 5-year horizon, for the base case scenario, SCRT-TNT incurred a lower total cost and higher QALYs compared with LCCRT. The total cost was $65767 and QALYs were 1.77 for SCRT-TNT; for LCCRT, the total cost was $72802 and QALYs were 1.64. This resulted in an ICER of -$ 55470.69 per QALY. Therefore, SCRT-TNT was a cost-saving and dominating treatment strategy compared with LCRT. Sensitivity analysis showed that ICERs were most sensitive to the parameters of distant metastases risk after treatment.

CONCLUSION

SCRT-TNT in locally advanced rectal cancer can be a cost-effective alternative to LCRT in China, and should be considered in appropriately selected patients.

4D-MRI Guided Stereotactic Body Radiation Therapy for Unresectable Colorectal Liver Metastases

PURPOSE/OBJECTIVE(S)

This study evaluated the feasibilities and outcomes following four-dimensional magnetic resonance imaging (4D-MRI) guided stereotactic body radiation therapy (SBRT) for unresectable colorectal liver metastases (CRLM).

MATERIALS/METHODS

From March 2018 to January 2022, we identified 76 unresectable CRLM patients with 123 lesions who received 4D-MRI guided SBRT in our institution. 4D-MRI simulation with or without abdominal compression was conducted for all patients. The prescription dose was 50-65 Gy in 5-12 fractions. The image quality of computed tomography (CT) and MRI were compared using the Clarity Score. Clinical outcomes and toxicity profiles were evaluated.

RESULTS

The 4D-MRI significantly improved the image quality compared with CT images (mean Clarity Score: 1.67 vs 2.88, P < 0.001). The abdominal compression significantly reduced motions in cranial-caudal direction (P = 0.03) with 2 phase T2 weighted images assessing tumor motion. The median follow-up time was 12.5 months. For 98 lesions assessed for best response, the complete response, partial response and stable disease rate were 57.1 %, 30.6 % and 12.2 %, respectively. The local control (LC) rate at 2 year was 97.3%. 46.1% of patients experienced grade 1-2 toxicities and only 2.6% patients experienced grade 3 hematologic toxicities.

CONCLUSION

The 4D-MRI technique allowed precise target delineation and motion tracking in unresectable CRLM patients. High LC rate and mild toxicities were achieved. This study provided evidence for using 4D-MRI guided SBRT as an alternative treatment in unresectable CRLM.

Reducing CTV to PTV Margins with Daily Adaptive Radiotherapy in the Postoperative Treatment of Endometrial and Cervical Cancer

PURPOSE/OBJECTIVE(S)

In the postoperative treatment of endometrial and cervical cancer, a PTV expansion of 1.5cm or greater would be generally recommended to ensure adequate coverage of CTV with no or minimal image guidance. Online adaptive radiotherapy (oART) has demonstrated to be feasible to reduce inter-fractional radiotherapy errors as it re-optimizes treatment plan every fraction. In this study, we hypothesized using daily cone-beam computed tomography (CBCT)-guided oART would reduce CTV to PTV margins in the postoperative treatment of endometrial and cervical cancer.

MATERIALS/METHODS

Seven patients from a single-center with postoperative endometrial and cervical cancer treated with daily CBCT-guided oART were retrospectively reviewed. A total dose of 45Gy is prescribed in CTV-vaginal cuff (CTV-V) and CTV- regional lymph nodes (CTV-N) with daily fractions of 1.8Gy for five fractions per week. A total of 175 radiotherapy fractions of daily pre-treatment CBCTs and post-treatment CBCTs scans were uploaded to oART emulator for CTV-V and CTV-N contouring by a single observer. CTVpre to PTVpre margins of 5, 7, 10, 12, 15mm was used in all directions. Each post-treatment CBCT was rigidly registered to the pre-treatment CBCT with respect to bony anatomy. The CTVpost was projected onto the PTVpre and assess required planning margins to encompass the CTVpost.

RESULTS

The average total treatment time (post-treatment CBCTs - pre-treatment CBCTs) was 23 min 14s (range: 18min 53s ∼ 28min 53s). For all fractions, the adapted plan was selected, and the volume of the PTV-V and PTV-N receiving 100% of the prescribed dose or more (V100%) was more than required 95%. A uniform three-dimensional CTV-Npre to PTV-Npre margin of 5mm could encompass CTV-Npost in all fractions (100%; 175/175f). A uniform three-dimensional CTV-Vpre to PTV-Vpre margin of 10mm could encompass CTV-Vpost in all fractions (100%; 175/175f) and 5mm could encompass 98% fractions (172/175f). In the fractions of 5mm margins that failed to encompass CTV-Vpost, the volume of CTV missed three times in anterior-posterior directions and once in lateral direction. Compared with scheduled plan, adapted plan with 5mm margins significantly reduced the mean dose to bladder (Dmean: 103.97 cGy vs 107.20 cGy, P<0.05) and rectum (Dmean: 117.82 cGy vs 123.67 cGy, P<0.05), and achieved better PTV-N (V100%: 97.8% vs 90.0%, P<0.05) and PTV-V (V100%:96.8% vs 85.4%, P<0.05) dose coverage in 175 fractions.

CONCLUSION

In this study, 5mm CTV to PTV margins was adequate to encompass 100% fractions of CTV-N and 98% fractions of the CTV-V. Adapted plan with 5mm margins significantly reduced the dose to critical organ at risks while improving target coverage.

Chemoradiotherapy Combined with Nab-Paclitaxel plus Cisplatin in Patients with Locally Advanced Borderline Resectable or Unresectable Esophageal Squamous Cell Carcinoma: A Phase I/II Study

PURPOSE/OBJECTIVE(S)

To evaluate the efficacy and safety of nanoparticle albumin-bound paclitaxel (nab-PTX) plus cisplatin as the regimen of conversional chemoradiotherapy (cCRT) in locally advanced borderline resectable or unresectable esophageal squamous cell carcinoma (ESCC).

MATERIALS/METHODS

Patients with locally advanced ESCC (cT3-4, Nany, M0-1, M1 was limited to lymph node metastasis in the supraclavicular area) were enrolled. All the patients received the cCRT of nab-PTX plus cisplatin. After the cCRT, those resectable patients received esophagectomy; those unresectable patients continued to receive the definitive chemoradiotherapy (dCRT). The locoregional control (LRC), overall survival (OS), progression-free survival (PFS), distant metastasis free survival (DMFS), pathological complete response (pCR), R0 resection rate and adverse events (AEs) were calculated.

RESULTS

A total of 45 patients with ESCC treated from October 2019 to May 2021 were finally included. The median follow-up time was 30.3 months. The LRC, OS, EFS, DMFS at 1and 2 years were 81.5%, 86.6%, 64.3%, 73.2% and 72.4%, 68.8%, 44.8%, 52.7% respectively. 21 patients (46.7%) received conversional chemoradiotherapy plus surgery (cCRT+S). The pCR rate and R0 resection rate were 47.6% and 84.0%. The LRC rate at 1 and 2 years were 95.0%, 87.1% in cCRT+S patients and 69.3%, 58.7% in dCRT patients respectively (HR, 5.14; 95% CI, 1.10-23.94; P = 0.021). The OS rate at 1 and 2 years were 95.2% and 84.2% in resectable patients compared to 78.8% and 54.4% in unresectable patients (HR, 3.41; 95% CI, 1.10-10.61; P = 0.024). The toxicities during chemoradiotherapy were tolerated, the most common grade 3-4 toxicities were radiation esophagitis (15.6%).

CONCLUSION

Nab-PTX plus cisplatin were effective and safe as the regimen of conversional chemoradiotherapy of ESCC. The patients receiving conversional chemoradiotherapy plus surgery (cCRT+S) were prone to have a better survival.

Clinical Outcomes with Thoracic Radiotherapy for Extensive-Stage Small-Cell Lung Cancer in the Era of Immunotherapy: A Retrospective Analysis

PURPOSE/OBJECTIVE(S)

Chemo-immunotherapy has shown significant benefits for extensive-stage small-cell lung cancer (ES-SCLC), which prolonged overall survival (OS) of nearly 2-4.5 months compared with platinum-based chemotherapy alone. However, thoracic radiotherapy (TRT), was not allowed to be used in previous trials. This retrospective study aimed to evaluate the safety and efficiency of TRT for ES-SCLC patients in the era of Immunotherapy.

MATERIALS/METHODS

We retrospectively reviewed ES-SCLC patients treated with chemo-immunotherapy between 2017 and 2021 in our center. Patients who accepted consolidative or salvage TRT were included. The overall survival, progression-free survival (PFS), local progression-free survival (LPFS), and distant progression free-survival (DPFS) were calculated using the Kaplan-Meier method. Toxicity was recorded based on CTCAE 5.0 scale.

RESULTS

We finally enrolled 30 patients in our study. The median follow-up time was 26.0 months (95% confidence interval, 18.2-33.8 months). 26(86.7%) patients have undergone first-line chemotherapy and immunotherapy, while 4(13.3%) have undergone immunotherapy as a second-line agent. 23(76.6%) patients achieved CR/PR/SD to initial systematic therapy. All patients were treated with TRT with a median dose of 51 Gy (24-60.2 Gy). The median interval between TRT and immunotherapy was 35 days. Median OS was 26 months (95% confidence interval, 17.8-34.2 months) and median PFS was 8 months (95% confidence interval, 5.3-10.7 months). 2-year OS, PFS, and DPFS were 51.4%, 21.4%, and 27.4%, respectively. 18 months LPFS was 59.6%. There was no ≥ G3 radiation-related adverse event except 2(6.7%) G3 esophagitis. G1-2 pneumonitis was reported in 8(26.7%) patients.

CONCLUSION

TRT is well-tolerated and effective for selected ES-SCLC patients in the modern era of immunotherapy. Prospective trials are still needed to further evaluate the combination of TRT and immunotherapy for patients with ES-SCLC.

First Demonstration of the Commissioning of a New Multi-Modality Radiotherapy Platform

PURPOSE/OBJECTIVE(S)

A new multi-modality radiotherapy platform was developed and introduced into clinical application, which has received US FDA 510k(K210921) and National Medical Products Administration (NMPA) clearance in China (20223050973). This study, for the first time, presents the technological characteristics and commissioning results of the new platform.

MATERIALS/METHODS

The platform consists of 3 modules: linear accelerator, rotating gamma system, and a kV imaging system within an O-ring gantry. The O-ring gantry can rotate continuously achieved by using a slip ring. The Linac delivers a 6 MV FFF photon beam with a variable dose rate of 50 to 1400 MU/min. The delivery techniques include 3D-CRT, IMRT, and VMAT. The rotating gamma system utilizes 18 Co-60 sources with a reference dose rate of 350 cGy/min. The image-guided techniques consist of kV-kV pairs and kV-CBCT. The X-ray intensity-modulated radiotherapy and γ-ray stereotactic radiotherapy can be delivered on the same platform. The acceptance test and commissioning were performed following the vendor's customer acceptance tests (CAT) and several AAPM Task Group reports/guidelines. Regarding the Linac, all applicable validation tests recommended by the MPPG 5.a (basic photon beam model validation, IMRT/VMAT validation, E2E tests, and patient-specific QA) were performed. For the rotating gamma system, the absorbed doses were measured using a PTW31014 and PTW60016. EBT3 films were employed to measure the relative output factors (ROFs). The E2E tests were performed using a PTW31014 and EBT3 films. The coincidence between the imaging isocenter and the Linac/gamma treatment isocenter was investigated using EBT3 films. The image quality was evaluated regarding the contrast-to-noise ratio (CNR), spatial resolution, and uniformity.

RESULTS

All tests included in the CAT met the vendor's specifications. All MPPG 5.a tests complied with the tolerances. The confidence limits for IMRT/VMAT validation were achieved according to TG-119. The point dose differences were below 1.68% and gamma pass rates (3%/2 mm) were above 95.9% for the Linac E2E tests. All plans of patient-specific QA had point dose differences below 1.79% and gamma pass rates (3%/2 mm) above 96.1% suggested by TG-218. For the rotating gamma system, the differences between the calculated and measured absorbed doses were below 1.86%. The ROFs calculated by the TPS were independently confirmed within 2% using EBT3 films. The point dose differences were below 2.57% and gamma pass rates (2%/1 mm) were above 95.3% for the E2E tests. The coincidence between the imaging isocenter and the Linac/gamma treatment isocenter was within 0.5 mm. The image quality fully complied with the vendor's specifications regarding the CNR, spatial resolution, and uniformity.

CONCLUSION

This is the first report about the commissioning of a new multi-modality radiotherapy platform. The platform has been successfully commissioned and exhibits good performance in mechanical and dosimetry accuracy.

Poor Survival Outcomes in Patients with Stage IIIC2 Cervical Cancer Receiving Concurrent Chemoradiotherapy

PURPOSE/OBJECTIVE(S)

Patients with cervical cancer who have para-aortic lymph nodes metastasis are staged as IIIC2 according to the 2018 FIGO staging system. In this study, we evaluated the survival and toxicity outcomes of patients with stage IIIC2 cervical cancer who received concurrent chemoradiotherapy.

MATERIALS/METHODS

We included patients with stage IIIC2 cervical cancer who received definitive concurrent chemoradiotherapy at our institute between 2007 and 2015. The treatment consisted of intensity modulated radiation therapy (IMRT) delivering a dose of 50.4 Gy in 28 fractions to the pelvic and para-aortic lymph node regions, with escalated doses of 60-70 Gy for positive lymph nodes. A dose of 30 Gy in 5 fractions was delivered with intracavitary brachytherapy. The first-line chemotherapy regimen was weekly cisplatin.

RESULTS

A total of 88 patients were included in the study. The median follow-up periods for all patients and surviving patients were 20 months (range: 5-114 months) and 62 months (range: 5-114 months), respectively. The median survival was 20.9 months. The 1-year, 3-year, 5-year, and 8-year overall survival rates were 73.4%, 41.3%, 34.5%, and 25.3%, respectively, while the progression-free survival rates were 50.8%, 29.7%, 28.4%, and 21.2%. The local control rates were 58.6%, 52.2%, 52.2%, and 42.8%, respectively. Multivariate analysis showed that the number of positive para-aortic lymph nodes and histology type were independent factors affecting progression-free survival. The 5-year progression-free survival rates were 40.2% and 0% for patients with one and two or more positive para-aortic lymph nodes, respectively, and 30.1% and 21.4% for patients with squamous cell carcinoma and adenocarcinoma, respectively. Grade 3 or higher toxicities were observed in 8 patients (9.1%), including 4 patients (4.5%) with gastrointestinal toxicities and 4 patients (4.5%) with genitourinary toxicities.

CONCLUSION

The results of this study suggest that the survival outcomes of patients with stage IIIC2 cervical cancer receiving concurrent chemoradiotherapy were poor. Further treatment options, such as consolidation chemotherapy or immunotherapy, should be considered for these patients.

Genetically elevated bioavailable testosterone level was associated with the occurrence of benign prostatic hyperplasia

BACKGROUND

Recent studies identified several risk factors of benign prostatic hyperplasia (BPH), including dyslipidemia, type 2 diabetes mellitus, hypertension, and obesity. But they were not so reliable and some studies contradicted with one another. Hence, a reliable method is urgently needed to explore exact factors that facilitated BPH development.

METHODS

The study was based on Mendelian randomization (MR) design. All participants were from the most recent genome-wide association studies (GWAS) with large sample size. The causal associations between nine phenotypes (total testosterone level, bioavailable testosterone level, sex hormone-binding globulin, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, type 2 diabetes mellitus, hyper-tension, and body mass index) and BPH outcome were estimated. Two sample MR, bidirectional MR, and multivariate MR (MVMR) were performed.

RESULTS

Increase in bioavailable testosterone level was able to induce BPH based on nearly all combination methods [beta (95% confidence interval (CI)): 0.20 (0.06-0.34) for inverse variance weighted (IVW)]. The other traits seemed to interact with testosterone level and did not cause BPH generally. Higher triglycerides level was likely to raise bioavailable testosterone level [beta (95% CI): 0.04 (0.01-0.06) for IVW]. In MVMR model, bioavailable testosterone level was still associated with BPH occurrence [beta (95% CI) 0.27 (0.03-0.50) for IVW].

CONCLUSIONS

We for the first time validated the central role of bioavailable testosterone level in the pathogenesis of BPH. The complex associations between other traits and BPH should be further investigated.

Target Volumes Comparison between Postoperative Simulation MRI and Preoperative Diagnostic MRI for Prone Breast Radiotherapy after Breast-Conserving Surgery

PURPOSE/OBJECTIVE(S)

To investigate the correlation and difference between target volumes determined by postoperative prone positioning magnetic resonance imaging (MRI) and preoperative prone diagnostic MRI for breast radiotherapy after breast-conserving surgery (BCS) based on deformable image registration (DIR).

MATERIALS/METHODS

A total of 17 patients undergoing prone whole breast-irradiation after BCS were enrolled, all these patients were undergoing preoperative and postoperative prone MRI scans. The gross tumor volume (GTV) was delineated on the preoperative MRI images, then expanding 10 mm to simulate the preoperative lumpectomy cavity (LC). The LC were expended to clinical target volume (CTV), and planning target volume (PTV) on preoperative and postoperative MRI sequences, respectively. Preoperative and postoperative MRI was registered based on DIR by a commercially available software system. The target volume, the distance between the centers of mass (dCOM), conformity index (CI), degree of inclusion (DI) were compared to explore the target volume variation for pre- and post-surgery delineation. And evaluated the relationship between CILC/CIPTV and clinical factors.

RESULTS

The volume of GTVpre was 3.05cm3(range, 1-23.63cm3). The median volume of LCpre were 26.84 cm3 (range, 11.75-102.28 cm3). 0.85cm3 smaller than the LCpre, the LCpost were 25.99 cm3 (range, 5.98-41.95) (P = 0.04). The dCOM, CI, and DI between LCpre and LCpost were 1.371cm (range, 0.533-5.447), 0.221 (range, 0.041-0.516), and 0.472 (range, 0.108-0.804). There was no significant statistically difference between PTVpre and PTVpost (120.73cm3 vs 131.67cm3, p = 0.723). Compared with LC, the CI and DI between PTVpre and PTVpost were increased to 0.446 (range, 0.233-0.700), 0.636 (range, 0.362-0.834), respectively. Meanwhile, the dCOM was reduced to 1.239cm (range, 0.413-3.642). There was no obvious linear correlation between the CI with the GTV volume, the ratio of the primary tumor volume to the breast volume, the distance from the primary tumor to the nipple and chest wall, and the Body Mass Index (BMI), respectively.

CONCLUSION

For prone breast irradiation, even based on DIR, the spatial correspondence of the target volumes between preoperative and postoperative MRI images were still poor. Therefore, it is not reasonable to delineate postoperative LC refer to preoperative diagnostic MRI based on DIR. Preoperative MRI also cannot provide individualized guidance for LC delineation according to tailored patient.

Mismatch Repair Status is an Effective Prognostic Factor for Early-Stage Endometrial Carcinoma

PURPOSE/OBJECTIVE(S)

This study is to evaluate the impact of mismatch repair (MMR) status on prognosis among patients with stage I to II (FIGO 2009) endometrial carcinoma (EC) treated with hysterectomy and adjuvant RT.

MATERIALS/METHODS

Between Oct. 2017 and Dec. 2020, patients with stage I to II (FIGO 2009) EC who had undergone hysterectomy followed by adjuvant RT in our institution were retrospectively reviewed. Clinical characteristics were compared between patients with proficient and deficient mismatch repair (pMMR and dMMR) using Pearson Chi-Square test for categorical variables. Kaplan-Meier method and log-rank test were used to compared overall survival (OS), disease-free survival (DFS), local-regional recurrence free survival (LRFS) and distant metastasis free survival (DMFS). Statistically significant difference was set as p<0.05.

RESULTS

Totally 276 stage I to II EC patients with known MMR status were included in this study. Among them, 211 patients were classified as pMMR while 65 patients were classified as dMMR. When compared to pMMR, patients with dMMR were more likely to have grade 3 and non-endometrioid type(37.8% vs. 20.8%, p = 0.014), lympho-vascular invasion (36.7% vs. 16.3%, p = 0.000), young age (<60) (28.6% vs. 17.2%, p = 0.027), HIR to HR classification(30.9% vs. 16.1%, p = 0.004). Of all the 276 patients, the median follow-up time was 31 months. Two-year DMFS was superior for pMMR compared to dMMR patients (96.3% vs. 95.0%, p = 0.048). Two-year DFS tended to be better for pMMR than dMMR patients with survival curves not crossed over each other (93.0% vs. 86.8%, p = 0.074). Two-year OS (98.9% vs. 98.4%, p = 0.716) and LRFS (96.3% vs. 95.0%, p = 0.815) were not different between pMMR/dMMR patients. For HIR to HR group, we reached the similar conclusion while for LR to IR group, survival statistics were not different between pMMR/dMMR patients. As to failure pattern, dMMR were more likely to have distant failure while local and regional failure were not different between the two groups.

CONCLUSION

For stage I to II EC, patients with dMMR have poorer DMFS and DFS compared to pMMR patients especially in HIR to HR risk classification. The combination of MMR status and other clinical and pathological factors may establish a new prognostic model and form a new risk stratification system.

[Robotic-assisted laparoscopic modified ventral onlay lingual mucosal graft in complex ureteral stricture construction: experience of eight cases]

Objective: To examine the efficacy of robot-assisted laparoscopic modified ventral onlay lingual mucosal graft for complex ureteral stricture. Methods: The clinical data of 8 patients with ureteral stricture admitted to the Department of Urology, General Hospital of Southern Theater Command from May to October 2022 were retrospectively analyzed. There were 6 males and 2 females, aged (45.1±10.2) years (range: 34 to 64 years), body mass index (24.6±2.0) kg/m2 (range: 20.7 to 26.6 kg/m2). Five cases on the left side, 3 cases on the right side, the length of the ureteral structure was (3.1±0.7) cm (range: 2.2 to 4.5 cm). The value of preoperative serum creatinine was (113.8±22.3) μmol/L (range: 96 to 15 μmol/L). Before excising the structure segment, the titched anastomosed part of the dorsal wall of the ureter, and then the posteriorly augmented anastomotic, the remaining ventral side was augmented with a onlay lingual mucosa graft, then the omentum flap was used to wrap the reconstructed ureteral segment. The lingual mucosa graft with a length of 2.5 to 5.0 cm and a width of 1.0 to 1.5 cm was cut according to the actual structure. The surgery information of the patient, complications, and recent follow-up were recorded. Results: The operation under robot-assisted laparoscopy was performed successfully in the 8 patients without conversion to open surgery. The duration of the operation was (226.9±22.8) minutes (range: 210 to 255 minutes), estimated blood loss was (93.8±25.9) ml (range: 75 to 150 ml), the retention time of the postoperative drainage tube was (4.8±1.3) days (range: 3 to 7 days), and the duration of postoperative hospitalization was (11.1±3.6) days (range: 9 to 14 days). One week after the operation, the patient could pronounce correctly, enunciate clearly, and eat normally. Double J tubes were removed 4 to 8 weeks after the operation. The follow-up time in this group was 3 to 9 months, the follow-up patients underwent imaging and other examinations, which showed a significant improvement in hydronephrosis on the affected side, and the value of renal pelvic separation on the affected side was (1.4±0.8) cm (range: 0 to 2.3 cm). The serum creatinine value was (100.1±24.9) μmol/L (range: 76 to 155 μmol/L). Three months after the operation, the ureteroscopy showed that the ureter was smooth and the mucosa was normal. Conclusions: Robot-assisted laparoscopic ureteroplasty with a lingual mucosal graft is a safe and feasible operation for complex ureteral stricture without serious complications, which provides a surgical option for repairing ureteral stricture.

Visualization of laser-induced breakdown spectroscopy data of mouse organs based on the feature extraction method

At present, there is no comprehensive and systematic research on laser-induced breakdown spectroscopy (LIBS) data visualization. In particular, the LIBS spectra of biological samples have large noise and weak signals, which seriously affect the feature visualization. Here, three commonly used sample visualization methods were compared, and a new method was applied for tissue sample visualization. We used the LIBS mapping technique to obtain LIBS spectra of different organ slice samples from mice. LIBS spectral distribution was visualized after extracting the region of interest. The three spectral visualization methods are compared, and the performance of visualization algorithms is quantitatively analyzed. The potential of heat-diffusion for the affinity-based transition embedding (PHATE) method highlights the details of the LIBS spectral distribution while maintaining the overall structure of the data. The correlation coefficient between dimensionality reduction data and raw data is 0.97, and the average distance between samples of different categories is 0.64, which are superior to those of traditional principal component analysis (PCA), multidimensional scaling (MDS), and t-distributed stochastic neighbor embedding (t-SNE). The results show that the PHATE method can serve as a very promising LIBS spectral visualization tool.

Optimized quantification of intra-host viral diversity in SARS-CoV-2 and influenza virus sequence data

High error rates of viral RNA-dependent RNA polymerases lead to diverse intra-host viral populations during infection. Errors made during replication that are not strongly deleterious to the virus can lead to the generation of minority variants. However, accurate detection of minority variants in viral sequence data is complicated by errors introduced during sample preparation and data analysis. We used synthetic RNA controls and simulated data to test seven variant-calling tools across a range of allele frequencies and simulated coverages. We show that choice of variant caller and use of replicate sequencing have the most significant impact on single-nucleotide variant (SNV) discovery and demonstrate how both allele frequency and coverage thresholds impact both false discovery and false-negative rates. When replicates are not available, using a combination of multiple callers with more stringent cutoffs is recommended. We use these parameters to find minority variants in sequencing data from SARS-CoV-2 clinical specimens and provide guidance for studies of intra-host viral diversity using either single replicate data or data from technical replicates. Our study provides a framework for rigorous assessment of technical factors that impact SNV identification in viral samples and establishes heuristics that will inform and improve future studies of intra-host variation, viral diversity, and viral evolution. IMPORTANCE When viruses replicate inside a host cell, the virus replication machinery makes mistakes. Over time, these mistakes create mutations that result in a diverse population of viruses inside the host. Mutations that are neither lethal to the virus nor strongly beneficial can lead to minority variants that are minor members of the virus population. However, preparing samples for sequencing can also introduce errors that resemble minority variants, resulting in the inclusion of false-positive data if not filtered correctly. In this study, we aimed to determine the best methods for identification and quantification of these minority variants by testing the performance of seven commonly used variant-calling tools. We used simulated and synthetic data to test their performance against a true set of variants and then used these studies to inform variant identification in data from SARS-CoV-2 clinical specimens. Together, analyses of our data provide extensive guidance for future studies of viral diversity and evolution.

[Exploration of the clinical application of combined endoscopic and laparoscopic surgery in early gastric cancer: 15 cases]

Objective: To investigate the application of combined gastroscopy and laparoscopy (dual scope) in the treatment of early gastric cancer. Methods: In this descriptive case series study, we retrospectively collected data on 15 patients with cT1b stage gastric cancer who had undergone combined laparoscopic and endoscopic surgery in the 900th Hospital of the People's Liberation Army of China from May 2020 to October 2022. The study cohort comprised nine men and six women of median age 59 (range: 47-76) years and median body mass index 20.9 (range: 18.3-26.2) kg/m2. Seven of the lesions were located on the lesser curvature of the gastric antrum and eight in the gastric angle. All lesions were biopsied for pathological examination and evaluated by endoscopic ultrasonography, followed by endoscopic submucosal dissection (ESD) and laparoscopic regional lymph node dissection. Studied variables included surgical and pathological features, postoperative factors, and outcomes. Results: In this group of patients, the median (range) operative time for ESD was 45 (30-82) minutes, the duration of laparoscopic lymph node dissection (45.1±8.6) minutes, and the median (range) intraoperative blood loss during lymph node dissection 30 (10-80) mL. Of the 13 patients with negative postoperative horizontal margins, four were stage SM1 and had no lymph node metastases (Stage SM1) and nine were Stage SM2, of which had one positive regional lymph node and two received additional standard distal gastrectomy with D2 lymphadenectomy concurrently because of positive ESD specimens (lymph node negative). No lymph node metastases were found in the surgical specimens of these patients. The remaining two patients had positive vertical margins; both had undergone concurrent standard distal gastrectomy with D2 lymphadenectomy. One of them was found to be lymph node positive (No. 3, one node). Four patients had impaired gastric emptying after dual-scope treatment, all of whom recovered well with symptomatic management; one patient with a suspected lymphatic leak was also managed conservatively. There were no cases of postoperative bleeding, abdominal infection, or incisional infection. At a median follow-up of 14 (6-26) months, no tumor recurrence or metastasis had been identified in any of the patients. Three patients had a grade B nutrition score 3 to 6 months after surgery, all of whom had undergone major gastrectomy, and two patients who had undergone dual-scope surgery reported an increase in acid reflux and belching after surgery compared with the preoperative period. Conclusion: A combined technique is safe and feasible for the treatment of early gastric cancer and is worthy of further exploration.

[Clinical characteristics of children with IgE-mediated cow's milk protein allergy]

Objective: To analyze the clinical characteristics of children with IgE-mediated cow's milk protein allergy (CMPA) and provide a basis for disease management and prevention. Methods: A cross-sectional study was conducted to analyze 142 children aged 0-12 years who were diagnosed with IgE-mediated CMPA in Capital Institute of Pediatrics Affiliated Children's Hospital from 2020 to 2022. There were 79 males (55.6%) and 63 females (44.4%), with an average age of 14 (8, 27) months. 61 cases (43.0%) were in the <1-year-old group, 54 cases (38.0%) in the 1-3-year-old group, and 27 cases (19.0%) in the >3-year-old group. Data on demographic data, clinical manifestations, mean wheel diameter of skin prick test and serum specific IgE level were collected. The serum cow's milk protein sIgE and component sIgE were measured by ImmunoCAP fully automated system of fluorescence enzyme-linked immunosorbent assay, and statistically analyzed using chi-square test, nonparametric tests, correlation. Results: Cutaneous symptoms were the first and most frequent in 142 children (97.9%, 139/142 cases), followed by digestive (29.6%, 42/142 cases) and respiratory symptoms (27.5%, 39/142 cases).The proportion of children with respiratory symptoms after consuming cow's milk was significantly higher in the>3 years age group than those in the infant and toddler groups(66.7% vs 19.7%,χ2=18.396,P<0.01;66.7% vs 16.7%,χ2=20.250,P<0.01), and the symptoms involving ≥3 systems were also significantly higher than those in the other two groups(37.0% vs 13.1%,χ2=6.597,P<0.05;37.0% vs 7.4%,χ2=12.120,P<0.01). The average cow's milk SPT diameter and serum sIgE levels in the>3 years age group were significantly higher than those in the infant and toddler groups (Z=-4.682, P<0.01; Z=-3.498, P<0.01); (Z=-4.463, P<0.01; Z=-6.463, P<0.01). The most common cow's milk component protein were β-lactoglobulin(65.1%,56/86 cases) and casein (57.0%, 49/86 cases). Multiple-sensitization rate of the patients were 54.9%. Egg white (43.7%, 62/142 cases) was the most common co-sensitization food allergen while mold (12.7%, 18/142 cases) and weed pollen (12.7%, 18/142 cases) were the main co-sensitization aeroallergens. The proportion of multiple-sensitization to aeroallergens in the children group was the highest (51.9%, 14/27 cases), followed by the toddler group (29.6%, 16/54 cases), and the infant group was the least (3.3%, 2/61 cases). There was a significant difference among these three groups (χ2=7.476, P<0.05). Conclusion: Skin and mucosal symptoms are the most common in CMPA patients. The proportion of respiratory symptoms and multisystem involvement increased with age as well as the wheal diameter in skin test and serum sIgE level elevated. CMPA patients older than 3 years had the highest proportion of aeroallergen sensitization and airway allergic diseases.

[Application of TIGIT combined with interleukin-6 detection in the evaluation of Crohn's disease status]

To explore the application of IL-6, PCT, T lymphocyte subsets and TIGIT expression on T lymphocytes in the evaluation of Crohn's disease status. Using a cross-sectional study, total of 119 confirmed patients with Crohn's disease who were treated in the Affiliated Hospital of Jiangxi University of Traditional Chinese Medicine from June 2020 to December 2022 were selected. The age range was 18-59 years old, and the median age (interquartile range) was 37 (29, 45) years old, including 57 cases in active disease group (30 males, 27 females), 62 cases in disease remission group (33 males, 29 females); 50 healthy control groups (27 males, 23 females), the age range was 19-60 years old, and the median age (interquartile range) was 38 (31, 46) years old. The level of IL-6 was detected by flow fluorescence microsphere method, the concentration of PCT was detected by immunochromatography, and the levels of T lymphocyte subsets and TIGIT were detected by flow cytometry. The differences and correlations between the detection indicators in each group were compared, logistic regression was used to analyze the factors influencing the progression of Crosne's disease and the clinical value of each detection indicator was analyzed by ROC curve. The results showed that there were no statistically significant differences in age and gender among the control group, the remission group, and the active group (H=1.422,χ2=0.020;P=0.491, P=0.990); in the active group, IL-6 was 17.55(9.67, 21.72)pg/ml, PCT was 0.38(0.14, 0.43)ng/ml, CD3+CD4+ was 35.47%±6.01%, CD3+CD8+ was 30.50%±5.20%, TIGIT was 25.08%±6.30%; in the remission group, IL-6 was 8.46(5.21, 10.04) pg/ml, PCT was 0.26(0.11, 0.35) ng/ml, CD3+CD4+ was 37.62%±4.86%, CD3+CD8+ was 28.30%±5.28%, TIGIT was 34.22%±5.45%; in the control group, IL-6 was 6.13(3.57, 8.12)pg/ml, PCT was 0.17(0.10, 0.21)ng/m, CD3+CD4+ was 39.74%±3.94%, CD3+CD8+ was 26.59%±4.50%, and TIGIT was 37.64%±6.22%.There were significant differences in IL-6, PCT, CD3+CD4+%, CD3+CD8+%, and TIGIT among the three groups(H=58.688, H=18.003, F=9.600, F=8.124, F=65.059;P<0.001, P<0.001, P<0.001, P<0.001, P<0.001), Among them, IL-6 and TIGIT in the active group were significantly different from those in the remission group (P<0.001, P<0.001), and only TIGIT was significantly different between the remission group and the control group (P=0.007);Spearman correlation analysis showed that the expression of TIGIT on T lymphocytes was negatively correlated with the levels of IL-6; the results of Logistic regression analysis showed that IL-6, PCT and TIGIT were independent factors affecting the progression of Crohn's disease;Comparing the ROC curves of the active group and the remission group, found that TIGIT was significantly different from PCT, CD3+CD4+, CD3+CD8+(Z=4.011, Z=4.091, Z=4.157; P<0.001, P<0.001, P<0.001), no statistical difference with IL-6 (Z=1.193, P=0.233). Selected the combined detection of IL-6 and TIGIT with the best AUC area and Youden index, which shows that the clinical value is improved, the AUC area of IL-6+TIGIT was significantly different from that of IL-6 (Z=2.674, P=0.008). In summary, TIGIT of T lymphocytes and IL-6 detection may be valuable in the diagnosis and treatment of Crohn's disease, and the combined detection of TIGIT and IL-6 may be meaningful for evaluating the status of Crohn's disease.