The Role and Mechanism of Ferroptosis Mediated by METTL3-m6A Modification in Regulating Radioresistance of Esophageal Cancer

PURPOSE/OBJECTIVE(S)

Radioresistance remains the major cause of recurrence within two years after radical radiotherapy in approximately 50% of patients with esophageal cancer (ESCC). Recently, it has been reported that enhancing ferroptosis can reverse tumor radioresistance. However, the underlying mechanisms remain elusive. The aim of this study was to elucidate the role and mechanism of ferroptosis mediated by METTL3 N6-methyladenosine (m6A) modification in regulating radioresistance of Esophageal Cancer. We hypothesize that inhibition of ferroptosis confers radioresistance in Esophageal Cancer by METTL3-induced m6A modification which increase the expression of m6A in the 3'UTR region of SOCS6 and inhibits its expression.

MATERIALS/METHODS

To explore the relationship between radioresistance and ferroptosis. Firstly, ferroptosis was analyzed by 4-HNE staining in ESCC specimens; Furthermore, cell death was detected by propidium iodide (PI) or SYTOX Green staining combined with microscopy or flow cytometry in ESCC radioresistance cells and parental cells, and Iron Assay Kit,C11-BODIPY were used to examine whether ferroptosis were inhibited in radioresistance cells. Subsequently, MeRIP-seq and MeRIP-PCR were performed for discussing the relationship between ferroptosis and m6A. Finally, Mettl3 depleted cells were generated with CRISPR/Cas9-mediated knockout system. Then, m6A methylation level, sensitivity to radiation and ferroptosis of Mettl3 depleted cells by EpiQuik m6A RNA methylation quantification kit, colony formation, C11-BODIPY and Western Blot.

RESULTS

Firstly, we found that the level of lipid peroxide 4-HNE in ESCC samples that recurred after radical radiotherapy was significantly lower than that in radiotherapy (40Gy), and the ferroptosis of radioresistance cells was inhibited. MeRIP-seq found that the level of m6A in radioresistance cells increased significantly, and then the KEGG pathway analysis of MeRIP-seq results showed that hypermethylation of m6A was closely related to ferroptosis signal pathway. and we also found that the level of m6A was significantly decreased by adding agonist (Erastin), whereas the modification level was significantly increased by adding inhibitor Fer-1. Meanwhile, we found that the level of m6A was significantly decreased in radioresistance cells silencing METTL3, while the ferroptosis was activated, which caused the radiosensitivity of ESCC. Lastly, MeRIP-PCR data showed that METTLT3 induced a significant increase in m6A level in 3' UTR region of SOCS6 mRNA and inhibited its expression, which eventually led to radioresistance of ESCC.

CONCLUSION

m6A-regulated ferroptosis inhibition confers radioresistance of ESCC. METTL3 up-regulated m6A in SOCS6 3' UTR and inhibited the expression of SOCS6, which caused the inhibition of ferroptosis.

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.

Induction Immunotherapy vs. Consolidation Immunotherapy for Unresectable Stage III NSCLC

PURPOSE/OBJECTIVE(S)

Consolidation immunotherapy after chemoradiotherapy (CRT) is the standard of care for unresectable stage III non-small cell lung cancer (NSCLC). However, whether upfront immunotherapy before CRT has similar benefits has not been addressed. This study aimed at exploring the efficacy and safety of induction immunotherapy for unresectable stage III NSCLC through real-world data.

MATERIALS/METHODS

Patients diagnosed with stage III NSCLC who received immunotherapy in combination with sequential (sCRT) or concurrent CRT (cCRT) between November 2018 and December 2021 were retrospectively identified. Patients were divided into induction (Ind), consolidation (Con) and induction plus consolidation (Ind+Con) immunotherapy groups. Progression-free survival (PFS) and overall survival (OS) were assessed from the initiation of treatment and estimated by Kaplan‒Meier method. The potential factors affecting PFS and OS were analyzed by univariate and multivariate Cox regression models.

RESULTS

One hundred and two patients were included, with 52 (51.0%) patients in the Ind group, 35 (34.3%) in the Con group and 15 (14.7%) in the Ind+Con group. Median PFS was 24.0 months vs. 36.0 months vs. 19.0 months in the three groups, and 2-year PFS were 43.0% vs 51.1% vs 44.4% (p = 0.940). Median OS was not reached (NR) vs. 44.0 months vs. NR, with a 2-year OS rate of 80.5% vs. 84.4% vs. 86.2% (p = 0.861). In the cCRT setting, 2-year PFS rates were 56.7% vs. 71.6% vs. 100.0% (p = 0.439), 2-year OS rates were 92.3% vs. 89.3% vs. 100.0% in the three groups (p = 0.827). In multivariate analysis, elder (HR = 0.487, p = 0.037) and cCRT (HR = 0.282, p = 0.001) were the independent factors favoring PFS, while only elder (HR = 0.088, p = 0.021) was the independent factors favoring OS. Adverse events were similar in the three arms. Further analysis found the objective response rate (ORR) and disease control rate (DCR) in the Ind and Ind+Con group after induction immunotherapy were 59.7% and 98.5%, respectively. Only 1 (1.5%) patient developed progression. Subgroup analysis showed no significant difference in PFS (p = 0.520) and OS (p = 0.116) between patients who responded to induction immunotherapy (PR+CR) and those who did not (SD+PD). Patients with <4 cycles of induction immunotherapy exhibited numerically better PFS than those with ≥4 cycles of induction immunotherapy (p = 0.113) and improved OS (p = 0.021).

CONCLUSION

Induction immunotherapy may achieve similar survival benefits to consolidation immunotherapy, and the combination of induction and consolidation immunotherapy with cCRT appears to achieve better outcomes. It seems feasible and safe to upfront immunotherapy before CRT, and further investigations on the combination of induction immunotherapy and CRT are warranted.

A Retrospective Analysis of Immediate Postoperative Electron Radiotherapy for Keloids

PURPOSE/OBJECTIVE(S)

The increasing incidence of keloid has seriously affected people's physical and mental health, and the postoperative recurrence rate is as high as 50-80%. Postoperative radiotherapy has been shown to significantly reduce the recurrence of keloid. Given the different treatment patterns in different institutions, we tried to analyze the data of patients in our center.

MATERIALS/METHODS

We retrospectively analyzed the clinical data of 455 patients with 498 keloids treated in our institution from 2010 to 2017. All patients received a four-fraction electron radiotherapy with single dose of 4 Gy within 24 hours of surgery. The recurrence and adverse reaction of immediate adjuvant radiotherapy in these patients was evaluated.

RESULTS

At the last follow-up date, 130 (26.5%) keloids had recurred after a middle follow-up of 68.1 months (42.6-129.9 months). The recurrence rates of 1 year, 3 years and 5 years were respectively14.5%, 18.7% and 21%. Recurrence rates vary depending on the keloid location. Among them, the recurrence rate of ear was low with 14% (43/298). Face, head neck and limbs was moderate with 38.8% (17/44) and 33.3% (8/24). Chest and Suprapubic region had a high recurrence rate of 50.8% (32/64) and 47.8% (33/69). Among the patients with recurrence, 16.9% (22/130) felt that their symptoms were better than before treatment, and 37.7% (49/130) were not worsen, which was acceptable. Multivariate analysis showed that age and duration of postoperative pruritus pain were correlated with recurrence (P = 0.036; P = 0.02). Radiotherapy combined with steroid and silicone reduced the recurrence rate compared with radiotherapy alone (P = 0.015). During treatment and follow-up, Infection occurred in 2 patients and cutaneous fibroblastoma in 1 patient.

CONCLUSION

Our radiotherapy regimen can effectively reduce the recurrence rate and improve the symptoms of patients with keloids, especially ear keloids. High recurrence sites need further improvement of radiotherapy dose and fraction. Combination of multiple treatments is better than single treatment.

High Dose Hyperfractionated Thoracic Radiotherapy vs. Standard Dose for Limited Stage Small-Cell Lung Cancer: A Multicenter, Open-Label Randomized, Phase 3 Trial

PURPOSE/OBJECTIVE(S)

Limited stage small-cell lung cancer (LS-SCLC) is associated with poor prognosis. We aimed to assess the efficacy and safety of high-dose, hyperfractionated thoracic radiotherapy of 54 Gy in 30 fractions compared with standard dose (45 Gy in 30 fractions) as a first-line treatment for LS-SCLC.

MATERIALS/METHODS

The study was an open-label, randomized, phase 3 trial, done at 16 public hospitals in China. Key inclusion criteria were patients aged 18-70 years, with previously histologically or cytologically confirmed LS-SCLC, previously untreated or received 1-2 courses of intravenous cisplatin (75 mg/m²of body-surface area, on day 1 or divided into two days of each cycle) or carboplatin (area under the curve of 5 mg/mL per min, day 1 of each cycle)and intravenous etoposide (100 mg/m²of body-surface area, on days 1-3 of each cycle), and an Eastern Cooperative Oncology Group (ECOG) performance status of 0-1.Eligible patients were randomly assigned (1:1) to receive volumetric-modulated arc radiotherapy (VMAT) of 45 Gy in 30 fractions or the simultaneous integrated boost VMAT (SIB-VMAT) of 54 Gy in 30 fractions to the primary lung tumor and lymph node metastases starting 0-42 days after the first chemotherapy course. Both groups of patients received thoracic radiotherapy twice per day and 10 fractions per week. Prophylactic cranial radiation (PCI, 25 Gy in 10 fractions) was implemented to patients with responsive disease. The primary endpoint was overall survival. Safety was analyzed in the as-treated population.

RESULTS

Between June 30, 2017, and April 6, 2021, 224 eligible patients were enrolled and randomly assigned to 54 Gy (n = 108) or 45 Gy (n = 116). Median follow-up for the primary analysis was 45 months (IQR 41-48). Median overall survival was significantly improved in the 54 Gy group (62.4 months) compared with the 45 Gy group (43.1 months; p = 0.001). Median progression-free survival was significantly improved in the 54 Gy group (30.5 months) compared with the 45 Gy group (16.7 months; p = 0.044). The most common grade 3-4 adverse events were neutropenia (30 [28%] of 108 patients in the 54 Gy group vs 27 [23%] of 116 patients in the 45 Gy group), neutropenic infections (6 [6%] vs 2 [2%]), thrombocytopenia (13 [12%] vs 12 [10%]), anemia (6 [6%] vs 4 [3%]), and esophagitis (1 [1%] vs 3 [3%]). Treatment-related serious adverse events occurred in 9 [8%] patients in the 54 Gy group and 16 [14%] patients in the 45 Gy group. There were one treatment-related deaths in 54 Gy group (myocardial infarction).

CONCLUSION

Compared with standard thoracic radiotherapy dose of 45 Gy, the high dose of 54 Gy improved overall survival and progression-free survival without increasing toxicities in patients with LS-SCLC, supporting twice-daily hyperfractionated thoracic radiotherapy of 54 Gy with concurrent chemotherapy is an alternative treatment option for LS-SCLC. This study is complete and registered with ClinicalTrials.gov, NCT03214003.

Long-Term Results of Induction Chemotherapy for Esophageal Squamous Cell Carcinoma Receiving Concurrent Chemoradiotherapy

PURPOSE/OBJECTIVE(S)

This study aimed to investigate the long-term clinical outcomes and toxicities of induction chemotherapy (IC) followed by concurrent chemoradiotherapy (CCRT) versus CCRT alone in patients with esophageal squamous cell carcinoma (ESCC).

MATERIALS/METHODS

Between 2008 and 2022, 271 ESCC patients who received definitive CCRT (IC followed by CCRT, n = 72; CCRT alone, n = 199) were enrolled. Radiotherapy technique included intensity modulated radiation therapy (IMRT) or volumetric modulated arc therapy (VMAT). Through a propensity score matched (PSM) method, 71 patients receiving IC and CCRT were matched 1:1 to patients who received CCRT alone, according to age, gender, performance status, tumor length, and pre-treatment TN stage. The Kaplan-Meier method and Cox proportional hazards model were applied to analyze survival and prognosis.

RESULTS

The IC + CCRT group had no improvement in 5-year overall survival (OS) rate (39.0% vs 29.3%, p = 0.360), recurrence-free survival (RFS) rate (39.0% vs 26.9%, p = 0.142), and distant metastasis-free survival (DMFS) rate (33.6% vs 27.2%, p = 0.515) compared with the CCRT group. The overall clinical response rate was 45.1% after IC in the IC + CCRT group. The IC responders (CR + PR + SD) group showed more favorable 5-year OS (41.7% vs. 14.3% vs. 29.3%, p < 0.001), RFS (41.7% vs. 14.3% vs. 26.9%, p < 0.001) and DMFS (37.3% vs. 0% vs. 27.2%, p < 0.001) compared with the IC non-responders (PD) group and the CCRT group. Besides, the 5-year OS rate (65.6% vs. 17.6% vs. 29.3%, p < 0.001), RFS rate (65.6% vs. 17.6% vs. 26.9%, p < 0.001), and DMFS rate (62.5% vs. 10.3% vs. 27.2%, p < 0.001) of the IC good responders (CR + PR) were significantly higher than that of the IC poor responders (SD + PD) and CCRT group. Multivariate analysis revealed that total radiotherapy time (≥ 49 days) and AJCC stage (Ⅲ/Ⅳ) were independent predictive factors of OS, RFS and DMFS. Besides, age was an independent predictive factor of DMFS. No significant difference was observed in the rates of grades 3-4 toxicities between both groups.

CONCLUSION

Our results showed the addition of IC to CCRT was not superior to CCRT in unselected ESCC patients, while IC responders could benefit from this regime without increase in toxicities.

Pseudo CT Images Synthesized from CBCT Based on Unsupervised DDPM in Cervical Cancer Radiotherapy

PURPOSE/OBJECTIVE(S)

The low image quality and inaccurate HU value of cone beam computed tomography (CBCT) restrict its further application in cervical cancer radiotherapy. A new unsupervised based denoising diffusion probabilistic model (DDPM) was proposed to synthesize pseudo-CT images from CBCT.

MATERIALS/METHODS

CBCT and CT images of 120 patients with cervical cancer were selected. The proposed DDPM network with condition and iterative mechanism was used for data training and testing between two image domains. In the training process, the model first obtained coarse pseudo-CT images with Gaussian noise through a diffusion process. Then, with the real CT images as the training target, the noise images were nonlinearly mapped to the domain of the CT images through the inverse diffusion process, and the fine pseudo-CT images were obtained. We repeated the above steps and gradually increased the number of noise diffusion. When the image difference value is less than the threshold, the training of the model is terminated and the pseudo-CT images are output. In the testing stage, each pseudo-CT generated was compared against the real CT image of the same patient based on the metrics of peak signal-to-noise ratio (PSNR), structural similarity index (SSIM) and normalized mean absolute error (NMAE).

RESULTS

In terms of anatomical verification, the PSNR (dB), SSIM (%) and NCC values between the pseudo-CT images obtained based on DDPM and the real CT images were presented as mean (standard deviation), which were 31.92(0.46), 86.69(4.55) and 0.0106(0.002) respectively. Compared with CBCT, the accuracy of the three metric values has been improved 15.6%, 14.2% and 23.3% respectively. For the metric values of the pseudo-CT images obtained based on the U-Net and CycleGAN models, the results synthesized based on the proposed model were paired with T-tests, the p values were all less than 0.05, and the differences were statistically significant.

CONCLUSION

The pseudo-CT images obtained based on the DDPM were close to the real CT images in anatomy. The pseudo-CT images synthesized by the proposed DDPM network have good application prospects in cervical cancer radiotherapy.

Deep Learning-Based Dose Prediction Model for Automated Spot-Scanning Proton Arc Planning

PURPOSE/OBJECTIVE(S)

Spot-scanning proton arc (SPArc) is a novel technique that employs a planning optimization algorithm to select the energies and positions of spots along a dynamic rotational arc trajectory. The SPArc technique has the potential to achieve superior dose conformality and treatment delivery efficiency over intensity-modulated proton therapy. However, creating such a SPArc plan using existing approaches is time-consuming and computationally extensively. This study investigated the feasibility of using the deep learning (DL) technique to predict the 3D dose distribution of the SPArc treatment plan, leveraging the prior knowledge acquired from conventional intensity-modulated radiation therapy (IMRT) plans.

MATERIALS/METHODS

A DL model, 3D-Unet with residual connections and attention gates, was trained using an open-source database of CT images, critical structures, and IMRT plans from 340 head and neck cancer patients (HNC) as the base model. Transfer learning technique was applied to fine-tune the model parameters using the SPArc treatment plans created on the HNC patients from an in-house dataset, where the SPArc treatment plans (including control point sampling, energy layer distribution, arc trajectory, etc.,) were optimized using a previously developed iterative approach. The performance of the DL model was evaluated by comparing predicted and planned doses over 17 SPArc treatment plans by using 4-fold cross-validation.

RESULTS

The SPArc planning time per patient was 8∼12 hours, while the dose prediction time was reduced to 2∼3 minutes using the proposed DL model. The deviation of D95 in the target was (-1.8±1.6) %. The deviation of the mean dose in the parotids, cord, mandible, and brainstem were (2.5±6.5) %, (-0.5±4.3) %, (1.4±3.9) %, and (3.4±8) % of the prescription, respectively. The dice similarity coefficients of the 80%, 70%, and 60% isodose lines were (0.9±0.09), (0.93±0.01), and (0.94±0.01), respectively.

CONCLUSION

Our results demonstrate that a DL-based dose prediction model can be created with a limited number of SPArc treatment plans through transfer learning. The DL model can directly predict the 3D dose distribution in minutes for automated planning. This study paves the roadmap to develop a quick clinical decision platform for the optimal selection among the multi-treatment modalities.

Introducing an Experimental Approach to Predict Spot Scanning Time Parameters for a Superconducting Cyclotron Proton Therapy Machine

PURPOSE/OBJECTIVE(S)

Proton pencil beam scanning (PBS) delivery sequence varies a lot among institutions due to the differences in vendors, machine types, and beamline configurations, which impacts PBS interplay effects and treatment delivery time estimation. This study aims to develop an independent experimental approach to predict the spot scanning time parameters for a clinical superconducting cyclotron proton therapy machine.

MATERIALS/METHODS

This independent experimental approach employed an open-air parallel-plate detector with a temporal resolution of 0.05ms. A series of spot, energy, and dose rate patterns were designed and delivered, including (1) Spot switching time (SSWT) under different spot spacing for IEC-X, IEC-Y directions and diagonal direction (traveling in both X and Y direction) for three energy layers (110, 170 and 230 MeV); The Wilcoxon test is used to validate the prediction of SSWT along the diagonal direction. (2) Energy layer switching time (ELST) with different descending energy gaps for a fixed initial energy and different initial energies for a fixed descending energy gap. (3) Dose rate (MU/min) are measured for different minimum-MU-per-energy-layer (MMPEL), which are compared with the previous publication.

RESULTS

A SSWT jump at 10mm (can be customized) spot spacing is observed because of triggering the machine's "raster mode" threshold. Discontinuous two variable piecewise linear functions were used to fit the SSWT in X/Y for spot spacing and energy. SSWT in X/Y is increasing as spot spacing and energy increase. SSWT in the diagonal direction is determined by the time either in the x-direction or y-direction, whichever takes longer (see Table 1 for one example of validations). ELST is linear depending on descending energy gap. The dose rate dependence on MMPEL is confirmed with previous publications of a similar type of machine.

CONCLUSION

The study provided the first independent quantitative experimental modeling of the beam delivery time parameters without any information from vendors. Such machine-specific delivery sequence models could pave the foundation of precise interplay effect evaluation for clinical decision-making.

A Novel Planning and Delivery Technology: Dose, Dose Rate and Linear Energy Transfer (LET) Optimization Based on Spot-Scanning Proton Arc Therapy FLASH (SPLASHLET)

PURPOSE/OBJECTIVE(S)

To achieve a high conformal dose with Linear Energy Transfer (LET) optimized FLASH proton therapy, we introduced a new planning and delivery technique concept, the voxel-wised optimization of LET distribution and dose rate based on scanning arc therapy (SPLASHLET) MATERIALS/METHODS: The algorithm optimizes (1) the clinical dose-volume constraint based on dose distribution and (2) the clinical LET-volume constraint based on LET distribution using Alternating Direction Method of Multipliers (ADMM) with Limited-memory BFGS solver by minimizing the monitor unit (MU) constraint on spot weight and (3) the effective dose-average dose rate by minimizing the accelerator's beam current sequentially. Such optimization framework enables the high dose conformal dynamic arc therapy with the capability of LET painting with voxel-based FLASH dose rate in an open-source proton planning platform (MatRad, Department of Medical Physics in Radiation Oncology, German Cancer Research Center-DKFZ). It aiming to minimize the overall cost function value combined with plan quality and voxel-based LET and dose rate constraints. Three representative cases (brain, liver and prostate cancer) were used for testing purposes. Dose-volume histogram (DVH), LET volume histogram (LVH) dose rate volume histogram (DRVH) and dose rate map were assessed compared to the original SPArc plan (SPArcoriginal).

RESULTS

SPLASHLET plan could offer comparable plan quality compared to SPArcoriginal plan. The DRVH results indicated that SPArcoriginal could not achieve FLASH using the clinic beam current configuration, while SPLASHLET could significantly not only improve V40Gy/s in target and region of interest (ROI) but also improve the mean LET in the target and reduce the high LET in organ at risk (OAR) in comparison with SPArcoriginal (Table 1).

CONCLUSION

SPLASHLET offers the first LET painting with voxel-based ultra-dose-rate and high-dose conformity treatment using proton beam therapy. Such technique has the potential to take full vantage of LET painting, FLASH and SPArc.

Re-Irradiation for Locally Primary Recurrence in Esophageal Squamous Cell Carcinoma Treated with IMRT/VMAT

PURPOSE/OBJECTIVE(S)

Locally primary recurrence of esophageal squamous cell carcinoma (ESCC) after definitive treatment has the potential for increasing overall survival with re-irradiation (Re-RT), especially with advanced technique. This study aimed to evaluate the efficacy and toxicities of Re-RT using intensity-modulated radiotherapy (IMRT)/volumetric modulated arc therapy (VMAT) for local primary-recurrence of ESCC.

MATERIALS/METHODS

A total of 130 ESCC patients with local primary-recurrence from Xijing hospital between 2008 and 2021 were enrolled and 30 patients underwent IMRT/VMAT based salvage Re-RT. Cox regression analysis was used to analyze the prognostic factors for overall survival (OS) and after recurrence survival (ARS). The toxicities of 30 patients receiving Re-RT were also assessed.

RESULTS

The median OS and ARS of the 130 recurrent patients were 21 months (1-164 months) and 6 months (1-142 months). The 1-, 2-, and 3-year OS rates were 81.5%, 39.2%, and 23.8%, respectively. Besides, the 1-, 2-, and 3-year ARS rates were 30.0%, 10%, and 6.2%. Multivariate analysis showed that Re-RT ± chemotherapy (p = 0.043) and chemotherapy alone (p < 0.001) and esophageal stents (p = 0.004) were independent prognostic factors for OS. The median OS of 30 patients treated with Re-RT were significantly better than that of 29 patients treated with chemotherapy (34.5 months vs. 22 months, p = 0.030). Among 30 ESCC patients treated with Re-RT, the median OS and ARS were 34.5 months (range 12-163 months) and 6 months (range 1-132 months), respectively. The recurrence-free interval (RFI) (> 12 months) and initial radiation dose (> 60 Gy) were significantly associated with improved OS. Radiation esophagitis (Grade 1-2) occurred in 16 patients and myelosuppression (Grade1-2) occurred in 10 patients. Grade 3 toxicities (radiation esophagitis and myelosuppression) were only 13.3%. There were no grade 4 toxicities.

CONCLUSION

Our results demonstrated that IMRT/VMAT-based Re-RT was an effective therapeutic option for ESCC patients with local primary-recurrence compared with chemotherapy alone or without any treatment. Re-RT had improved OS but unfavorable ARS.

Mitigation of Dosimetric Uncertainty in MRI-Based Proton Planning Using Spot-Scanning Proton Arc (SPArc) Technique

PURPOSE/OBJECTIVE(S)

MRI-based synthetic CT (SCT) images created using generative adversarial network (GAN) have been demonstrated to be feasible for intensity-modulated proton therapy (IMPT) planning. However, dose calculation accuracy can be uncertain in some regions within/near the target of head and neck patients due to the local CT number estimation error or sharp dose fall-off. This study investigated the feasibility of using the SPArc technique to mitigate such dosimetric uncertainty.

MATERIALS/METHODS

A GAN using a 3D U-net as the generator and a 6-layer 3D convolutional neural network as the discriminator was trained with T1-weighted MR-CT image pairs from 162 nasopharyngeal carcinoma patients (14 for validation). The generator was used to generate SCT images from MR images for 7 test patients. For each test patient, the CT image was used to create a SPArc plan and an IMPT plan with the same clinical objectives. The SPArc plans (control point frequency sampling, arc trajectory, etc.) were optimized using a previously developed iterative approach. The dose distributions of both SPArc plans and IMPT plans were re-calculated on the SCT images and compared to the one calculated on the CT images. The dosimetric uncertainty was quantified using the gamma index.

RESULTS

The 2%/2mm and 3%/3mm passing rates for SPArc plans were (96.9¡À2.7) % and (98.6¡À1.5) %, while the passing rates for IMPT plans were (94.0¡À3.9) % and (96.4+2.9) %. A significant reduction in dosimetric uncertainty was identified for SPArc plans (p ¡Ü0.021). Table 1 shows the passing rates for the 7 test individuals.

CONCLUSION

SPArc can mitigate the uncertainty of dose calculation in MRI-based proton planning. Further research needs to validate these findings on a larger patient cohort. The study paves the road map for using MRI for SPArc planning.

30 Gy vs. 45 Gy Consolidative Thoracic Radiation (cTRT) for Extensive Stage Small Cell Lung Cancer (ES-SCLC): A Multicenter, Randomized, Phase 3 Trial

PURPOSE/OBJECTIVE(S)

Consolidative thoracic radiotherapy (cTRT) showed potential benefit to extensive stage small cell lung cancer (ES-SCLC). However, the optimum dose of cTRT is unknown. The purpose of this randomized trial was to compare the effect of 45 Gy in 15 fractions with 30 Gy in 10 fractions cTRT in ES-SCLC.

MATERIALS/METHODS

This phase III, randomized trial was conducted in 12 public hospitals in China. Eligible patients with pathologically confirmed ES-SCLC who responded to 4-6 cycles of etoposide plus cisplatin (EP) or carboplatin (EC) chemotherapy were randomized 1:1 to receive either 30 Gy in 10 fractions or 45 Gy in 15 fractions cTRT. The primary outcome was 2-year overall survival (OS). Secondary outcomes included 2-year progression-free survival (PFS), 2-year local control (LC) and radiation treatment related toxicity. The primary objective was to detect an OS improvement in 45 Gy cTRT group at 2 years from 13% to 26% assuming a two-sided a = 0.05 and power of 85%, with a planned sample size of 186 patients. This trial was registered with Clinical Trials.gov, number NCT02675088.

RESULTS

Between January 15, 2016, and September 20, 2022, 90 patients were randomly assigned either 30 Gy in 10 fractions (n = 50) or 45 Gy in 15 fractions (n = 40) cTRT group. Recruitment to the trial closed early due to slow accrual since first-line chemoimmunotherapy has become the new standard of care for ES-SCLC. The median age of patients was 58 years, 87.8% were male, 76.7% had a smoking history, 95.6% received IMRT, and 58.9% received prophylactic cranial irradiation. At a median follow-up of 39.9 months (IQR 27.2-59.2), there was no significant difference in the 2-year OS between the 45 Gy group and the 30 Gy group, at 43.4% (95% CI 29.3%-64.3%) and 40.0% (95% CI 27.9%-59.1%), respectively (log-rank p = 0.62; HR 1.13 [95% CI 0.69-1.84]). The 2-year PFS was 12.1% (95% CI 4.3%-33.8%) in the 45 Gy group and 9.0% (95% CI 3.2%-25.2%) in the 30 Gy group (log-rank p = 0.25, HR 0.76(95% CI [0.478-1.22]). There were also no significant differences in locoregional recurrence free survival (log-rank p = 0.75; HR 0.888 [95% CI 0.423-1.863]) and distant metastasis free survival (log-rank p = 0.95; HR 1.015 [95% CI 0.624-1.651]) between two groups. No grade 5 toxicity was observed in both groups. Patients treated with higher cTRT dose presented with increased incidence of grade 3+ radiation pneumonitis (10% vs 2%) and hematological toxicity (20% vs 12.5%).

CONCLUSION

This randomized trial did not find a higher probability of survival improvement in patients with ES-SCLC receiving cTRT of 45 Gy in 15 fractions compared with 30 Gy in 10 fractions. In contrast, there was an increase in toxicity, especially radiation pneumonitis. Additional randomized studies investigating the role of cTRT in ES-SCLC after a response to chemoimmunotherapy are warranted.

Primary Small Cell Carcinoma of the Esophagus in a Large Multicenter Cohort: Prognostic Factors and Treatment Strategies in the Modern Era

PURPOSE/OBJECTIVE(S)

Primary small cell carcinoma of esophageal (PSCCE) is a rare malignancy with aggressive behavior associated with a perceived poor prognosis. Due to its rarity, the clinical characteristics and the optimal clinical management have not yet been defined, therefore, we designed a multicenter retrospective study to analyze the prognostic factors and the impact of treatment on the prognosis of PSCCE patients.

MATERIALS/METHODS

We retrospectively evaluated 704 consecutive patients with PSCCE from five participating centers between April 2008 and July 2021. The PSCCE was diagnosed based on the World Health Organization classification. Treatment strategies included surgery, radiotherapy (RT), or chemotherapy only, and combination of 2-3 treatment modalities (surgery, RT and chemotherapy). The estimated hazard rates provide the trajectory of progression and death overtime. Univariate survival analysis was conducted by using Kaplan-Meier plots, and the log-rank test was used to compare survival differences. Cox regression analysis was used to determine the independent prognostic factors in multivariate analysis.

RESULTS

Overall, 69.0% (486/704) of the patients were male, with a median age of 63 years (range 38-96). Most of the patients were regional lymph node positive (N+, 64.0%), and nearly half with advanced stage (M+, 47.2%). With a median follow-up time of 16 months, 472 patients (67.0%) exhibited disease progression and 429 patients (60.9%) died. Following initial treatment, 85.1% (402/472) of progression/death and 80.1% (344/429) of mortalities occurred within 24 months. Consistently, the maximum annual death and progression/death hazards are highest in the 15.6 months and 9.6 months. The overall survival (OS) rates at 1, 3 and 5 years for all patients were 65.1%, 26.5% and 18.3%, respectively. Univariate survival analysis showed that ECOG score, alcohol abuse, TNM stage, N stage, and M stage were correlated with OS (P <0.05). Multivariate analysis showed that the N stage (HR: 1.378, P = 0.018) and M stage (HR: 1.945, P <0.001) carried independent prognostic factors for OS. In the term of treatment, the OS rates for M- patients treated with combined modality therapy (CMT, surgery±radiotherapy/chemotherapy) were better than those treated with surgery alone or radiotherapy/chemotherapy (3-year OS: 36.7% VS 25.6% VS 32.2%; P = 0.045). The OS rates for M+ patients treated with chemotherapy alone, radiotherapy alone, or radiotherapy combined with chemotherapy were no significant differences (3-year OS: 12.2% VS 19.4% VS 11.1%; P = 0.400).

CONCLUSION

PSCCE is characterized by a high degree of malignancy with high risks of lymphatic and distant metastasis, N and M stages are the most important prognostic factor. In terms of treatment, comprehensive treatment is most likely to benefit patients without distant metastasis.

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.

Development and Validation of CT-Based Clinical-Radiomics Nomogram for Early Stage Extranodal Nasal-Type NK/T Cell Lymphoma: A Multicenter Study

PURPOSE/OBJECTIVE(S)

Most patients with extranodal nasal-type NK/T cell lymphoma (ENKTCL) had a localized disease with extensive primary tumor invasion at diagnosis (70-90%). Several clinical risk indexes, such as nomogram-revised risk index (NRI), international prognostic index (IPI), Korean Prognostic Index (KPI) and prognostic index of natural killer lymphoma (PINK), were used for ENKTCL patient stratification and providing information in clinical decision-making. However, they had low predictive power for early-stage patients with ENKTCL. This is the first study to construct a model with more predictive power through CT-based radiomics signature combined with traditional clinical risk indexes for overall survival (OS) of patients with early-stage ENKTCL.

MATERIALS/METHODS

A total of 196 early stage ENKTCL patients were randomly assigned into the training (n = 147) and interval validation set (n = 49) in a 3:1 ratio. And 83 and 19 early stage ENKTCL patients from other two centers were used for external validation set (n = 62). All patients received radiotherapy after 2-3 cycles of chemotherapy. 1316 CT radiomic features before radiotherapy were extracted and selected to construct the radiomics signature (RS). A CT-based nomogram was established by integrating clinical indexes and radiomics signature in training set and was tested in two validation sets.

RESULTS

With a median follow-up period of 59.9 months, 48 patients (24.1%) died. Compared with other prognostic index, NRI had better power to predict 5-year OS in the training cohort. The radiomics signature constructed by 11 selected radiomic features showed better prognostic performance than NRI for predicting 5-year OS in training set (C-index: 0.75 vs. 0.66), internal validation set (C-index: 0.71 vs. 0.62) and external validation set (C-index: 0.68 vs. 0.60). Patients were stratified into high- and low-risk groups by median radiomic signature. Patients in high-risk group had worse 5-year OS than patients in low-risk group (training set: 92% vs. 65%, P<0.001; internal validation set: 88% vs. 59%, P<0.05; external validation set 90% vs. 60%, P<0.05). The nomogram established by integrating radiomics signature with NRI showed optimal prognostic performance with C-index of 0.77 in training, 0.73 in internal and 0.71 in external validation set. Calibration curves showed good agreement.

CONCLUSION

The clinical-radiomics nomogram integrating CT-based radiomics signature combined with traditional clinical risk index provided an excellent prognostic tool for OS, which could be helpful for personalized risk stratification and treatment in early stage ENKTCL patients.

[Living-donor intestinal transplantation]

Due to advances in surgical techniques, perioperative care, and new immunosuppressive agents, intestinal transplantation has become a valid therapeutic choice for chronic intestinal failure. Intestinal transplantation has been performed most commonly using deceased donation, while less than 2% of which have been from living donation. Living donor intestinal transplantation obtaining a segmental intestinal graft, usually from close relatives. Preliminary results show that acute/chronic rejection rates, postoperative opportunistic infections, and graft versus host disease are significantly reduced after living donor intestinal transplantation, contributing to improved graft and patient survivals. Due to a severe shortage of organ donation, especially in children, living donor intestinal transplantation has increasingly become an important treatment option for patients with chronic intestinal failure in China.

Lymphocyte Count Kinetics and the Effect of Different Radiotherapy Techniques on Radiation-Induced Lymphopenia in Patients with Breast Cancer Receiving Hypofractionated Postmastectomy Radiotherapy

PURPOSE/OBJECTIVE(S)

Radiation-induced lymphopenia (RIL) is associated with poor prognosis in solid tumors. This study aimed to describe the lymphocyte kinetics in patients with breast cancer receiving hypofractionated postmastectomy radiotherapy (RT) and to investigate the association of different RT techniques with RIL.

MATERIALS/METHODS

We assessed 607 patients who received hypofractionated postmastectomy RT for breast cancer in our prospective clinical database from 8 hospitals. All patients received irradiation to the chest wall and supraclavicular fossa. RT techniques included integrated RT with the photon-based intensity modulated techniques to irradiate all target volumes (integrated RT) and a hybrid approach combining photon irradiation to supraclavicular nodes and electron irradiation to the chest wall (hybrid RT). Peripheral lymphocyte counts (PLC) were tested prior to RT (baseline), weekly during RT, at 1, 2 weeks, 3, 6 months after RT, and then every 6 months. Grade 3+ RIL was defined as PLC nadir during RT of <0.5 ×103/ml. Mean PLC was compared by the t test. Univariate, multivariate, and propensity score matching (PSM) analyses were used to evaluate the effect of different RT techniques on grade 3+ RIL.

RESULTS

During RT, 121 (19.9%) of patients had grade 3+ RIL. The PLC started to recover at 1 week and reached baseline levels 1 year after RT. A greater proportion of the patients treated with the integrated RT (90/269, 33.5%) developed grade 3+ PLC compared with those receiving hybrid RT (31/338, 9.2%, P < 0.001). After conducting PSM, multivariate analyses showed lower baseline PLC (HR = 0.15, P<0.001) and RT technique (the integrated RT vs. hybrid RT, HR = 4.76, P<0.001) were independent risk factors for grade 3+ RIL. The PLC in patients receiving the integrated RT after RT were higher than that in those receiving hybrid RT (p<0.05).

CONCLUSION

RT technique affect the risk of and recovery from RIL, which may impact survival. Choosing appropriate RT technique to minimize RIL might be considered to benefit their outcomes.

Quality Assurance in a Phase III, Multicenter, Randomized Trial of POstmastectomy radioThErapy in Node posiTive Breast Cancer with or without Internal mAmmary nodaL Irradiation (POTENTIAL): A Planning Dummy Run

PURPOSE/OBJECTIVE(S)

To report the planning dummy run results of the POstmastectomy radioThErapy in Node posiTive breast cancer with or without Internal mAmmary nodaL irradiation (POTENTIAL) trial-a multicenter, randomized, phase 3 trial-to evaluate postmastectomy radiotherapy, with or without internal mammary nodal irradiation, for patients with high-risk breast cancer.

MATERIALS/METHODS

All participating institutions were provided the contours of the dummy run case, and they generated radiotherapy (RT) plans per protocol guidelines. The plans were reviewed and feedback were provided by the quality assurance team, after which the institutions resubmitted revised plans. The information on beams arrangement, skin flash, inhomogeneity corrections, and protocol compliance was assessed both in the primary and final submission.

RESULTS

Theplans from 26 institutions were included in the analysis. A number of major deviations were found in the primary submission, such as less strict constraint on organs at risk (OARs) V5Gy, and no application of chest wall skin flash. The protocol compliance rates of the dose coverage for the planning target volume of the chest wall (PTVcw), PTV of supra/infraclavicular fossa plus axilla levels I, II, III (PTVsc+ax), and PTV of the IMN region (PTVim) were all significantly improved in the final submission compared with those in the primary submission, which were 96.2% vs. 69.2%, 100% vs. 76.9%, and 88.4% vs. 53.8, respectively. For OARs, the protocol compliance rates of heart Dmean, left anterior descending coronary artery V40Gy, ipsilateral lung V5Gy, and stomach V5Gy were significantly improved.

CONCLUSION

All major deviations were corrected and protocol compliance was significantly improved and of high level in the final submission. Moreover, the variations were reduced. Therefore, a planning dummy run was essential to guarantee good RT plan quality and inter-institutional consistency for multicenter trials.

Efficacy and Safety of Multifraction Stereotactic Radiation Therapy with Volumetric Modulated Arc Therapy Technique for Multiple Brain Metastases

PURPOSE/OBJECTIVE(S)

Multifraction stereotactic radiotherapy (MF-SRT) with volumetric modulated arc therapy (VMAT) is the standard treatment option for patients with multiple brain metastases. VMAT has superior physical accessibility and economic accessibility compared with advanced radiotherapy technologies such as Tomo or Proton radiotherapy. However, existing studies has mainly focused on comparing the dosimetric parameters between distinct radiotherapy techniques. Moreover, single fraction stereotactic radiosurgery is preferentially recommended for treatment of brain metastases with maximum diameter <2cm compared with MF-SRT. There is a lack of clinical results of its efficacy and subgroup analyses according to diameter. Thus, we first report the detailed analysis of clinical results of SRT using VMAT for brain metastases.

MATERIALS/METHODS

This study is a retrospective analysis of SRT for multiple brain metastasis using VMAT. The clinical efficacy of VMAT was evaluated by local control (LC) in 6-months, 1-year, and 2-year.

RESULTS

A total of 63 patients with 214 brain metastases were enrolled. The most common fractionation schemes were 40 Gy/8F and 48 Gy/12F. In all, LC rates at 6-month, 1-year, and 2-year were 95.5%, 90.6%, and 76.8%, respectively. Using univariate and multivariate analyses according to stratification factors including maximum diameter, GTV volume, dose per fraction, fractions, inner structure, and BED (α/β = 10), we found that no factors were associated with 6-month LC, 1-year LC, and 2-year LC. 1-year LC rates for maximum diameter ≥1 and <2, ≥2 and <3, and ≥3 cm were 89.2%, 90.7%, and 95.7%, respectively. The 1-year LC rates for tumors with GTV <3, ≥3 and <5, ≥5 and <10, and ≥10 cc were 87.0%, 91.7%, 94.7%, and 96.6%, respectively. Interestingly, 1year-LC in GTV ≥3 cc tends to higher than those in GTV <3 cc, but there was no significant difference (94.4% vs 87%, P = 0.162). Brain radionecrosis (RN) was the most significant toxicity occurring in 10 (4.7%) out of the 214 treated brain metastases. Among 6 patients with RN, 4 (66.7%) had been treated with tyrosine kinase inhibitors.

CONCLUSION

The use of MF-SRT with VMAT for multiple brain metastases showed a comparable clinical efficacy to other techniques described in the literature. And the LC rate for maximum diameter <2cm treated with MF-SRT VMAT was comparable to single fraction stereotactic radiosurgery as previously reported. The treatment-related toxicity was acceptable.

Metal-organic framework template-guided electrochemical lithography on substrates for SERS sensing applications

The templating method holds great promise for fabricating surface nanopatterns. To enhance the manufacturing capabilities of complex surface nanopatterns, it is important to explore new modes of the templates beyond their conventional masking and molding modes. Here, we employed the metal-organic framework (MOF) microparticles assembled monolayer films as templates for metal electrodeposition and revealed a previously unidentified guiding growth mode enabling the precise growth of metallic films exclusively underneath the MOF microparticles. The guiding growth mode was induced by the fast ion transportation within the nanochannels of the MOF templates. The MOF template could be repeatedly used, allowing for the creation of identical metallic surface nanopatterns for multiple times on different substrates. The MOF template-guided electrochemical growth mode provided a robust route towards cost-effective fabrication of complex metallic surface nanopatterns with promising applications in metamaterials, plasmonics, and surface-enhanced Raman spectroscopy (SERS) sensing fields.

Flavor-food ingredient interactions in fortified or reformulated novel food: Binding behaviors, manipulation strategies, sensory impacts, and future trends in delicious and healthy food design

With consumers gaining prominent awareness of health and well-being, a diverse range of fortified or reformulated novel food is developed to achieve personalized or tailored nutrition using protein, carbohydrates, or fat as building blocks. Flavor property is a critical factor in the acceptability and marketability of fortified or reformulated food. Major food ingredients are able to interact with flavor compounds, leading to a significant change in flavor release from the food matrix and, ultimately, altering flavor perception. Although many efforts have been made to elucidate how food matrix components change flavor binding capacities, the influences on flavor perception and their implications for the innovation of fortified or reformulated novel food have not been systematically summarized up to now. Thus, this review provides detailed knowledge about the binding behaviors of flavors to major food ingredients, as well as their influences on flavor retention, release, and perception. Practical approaches for manipulating these interactions and the resulting flavor quality are also reviewed, from the scope of their intrinsic and extrinsic influencing factors with technologies available, which is helpful for future food innovation. Evaluation of food-ingredient interactions using real food matrices while considering multisensory flavor perception is also prospected, to well motivate food industries to investigate new strategies for tasteful and healthy food design in response to consumers' unwillingness to compromise on flavor for health.

Atypical teratoid/rhabdoid tumour with CDK6 amplification in a child: a case report and literature review

Atypical teratoid/rhabdoid tumours (AT/RTs) are rare central nervous system neoplasms that frequently occur in infants and children and have a very poor prognosis. In recent years, molecular analysis of AT/RTs has shown that biallelic inactivation of SMARCB1 (INI1, SNF5, BAF47) or SMARCA4 (BRG1) frequently occurs. Here, we present a case of basal ganglia AT/RT with SMARCB1 gene deficiency and CDK6 gene amplification in a 5-year-old child. A 5-year-old boy was hospitalized due to a 1-week history of frontal and parietal headache. Magnetic resonance imaging (MRI) demonstrated a 3 cm × 2 cm × 1.5 cm heterogeneous enhanced mass located at the right basal ganglia that partially protruded into the right lateral ventricle. The lesion was successfully resected under electrophysiological monitoring and neuronavigation. The postoperative pathological examination implied an AT/RT diagnosis, with loss of SMARCB1 protein, SMARCB1 gene deficiency and CDK6 gene amplification. Unfortunately, the patient died due to respiratory and circulatory failure at 5 weeks after the operation. To date, standard regimens have not yet been established due to the lack of large-scale prospective studies for AT/RT. The p16-RB signalling pathway should be considered as a potential target for AT/RT treatment modalities. Apart from traditional regimens, targeted therapies, especially CDK4/6 inhibitors, are likely a promising therapeutic option for AT/RT treatment.

[Prevalence of obesity and its association with dietary patterns: a cohort study among Tibetan pastoralists in Qinghai Province]

Objectives: To explore obesity prevalence and its association with dietary patterns among Tibetan pastoralists during the urbanization transition in Qinghai Province. Methods: Using an open cohort study design, 1 003 subjects were enrolled at baseline in 2018, 599 were followed up, and 1 012 were newly recruited in 2022. A total of 1 913 adults over 18 years were included in the study, and a questionnaire survey and health examination were conducted. Factor analysis was used to identify dietary patterns, and a mixed-effects model was used to analyze the association between dietary patterns and obesity. Results: From 2018 to 2022, the prevalence rates of overweight, obesity, and central obesity were 27.6%, 33.8%, and 54.6%, respectively. Age-sex-standardized prevalence of obesity and central obesity increased. Three dietary patterns were identified: the modern pattern was characterized by frequent consumption of pork, poultry, processed meat, fresh fruits, sugary drinks, salty snacks, etcetera; the urban pattern was characterized by frequent consumption of refined carbohydrates, beef and mutton, vegetables and eggs, etcetera; and pastoral pattern featured frequent consumption of tsamba, Tibetan cheese, buttered/milk tea, and whole-fat dairy products. After adjusting for demographic characteristics, socioeconomic status, and lifestyle factors, compared with the T1, subjects in the T3 of urban pattern scores were more likely to be overweight (OR=2.09, 95%CI: 1.10-3.95) and overweight/obese (OR=1.23, 95%CI: 1.00-1.51), whereas those in the T3 of pastoral pattern scores had a lower risk of overweight (OR=0.45, 95%CI: 0.24-0.84), obesity (OR=0.81, 95%CI: 0.69-0.95), overweight/obesity (OR=0.75, 95%CI: 0.61-0.91) and central obesity (OR=0.58, 95%CI: 0.38-0.89). Conclusions: Prevalence of obesity and central obesity was high among Tibetan pastoralists during the urbanization transition. Urban dietary pattern was a risk factor for overweight and overweight/obesity, whereas pastoral dietary pattern was a protective factor for overweight, obesity, overweight/obesity, and central obesity. Tailored interventions are needed to improve local people's health.

Prevalence, drivers and surveillance of antibiotic resistance and antibiotic use in rural China: Interdisciplinary study

This study aimed to characterise antibiotic prescribing and dispensing patterns in rural health facilities in China and determine the community prevalence of antibiotic resistance. We investigated patterns and drivers of antibiotic use for common respiratory and urinary tract infections (RTI/UTI) in community settings, examined relationships between presenting symptoms, clinical diagnosis and microbiological results in rural outpatient clinics, and assessed potential for using patient records to monitor antibiotic use. This interdisciplinary mixed methods study included: (i) Observations and exit interviews in eight village clinics and township health centres and 15 retail pharmacies; (ii) Urine, throat swab and sputum samples from patients to identify potential pathogens and test susceptibility; (iii) 103 semi-structured interviews with doctors, patients, pharmacy workers and antibiotic-purchasing customers; (iv) Assessment of completeness and accuracy of electronic patient records through comparison with observational data. 87.9% of 1123 recruited clinic patients were prescribed antibiotics (of which 35.5% contained antibiotic combinations and >40% were for intravenous administration), most of whom had RTIs. Antibiotic prescribing for RTIs was not associated with presence of bacterial pathogens but was correlated with longer duration of infection (OR = 3.33) and presence of sore throat (OR = 1.64). Fever strongly predicted prescription of intravenous antibiotics (OR = 2.87). Resistance rates in bacterial pathogens isolated were low compared with national data. 25.8% of patients reported antibiotics use prior to their clinic visit, but only 56.2% of clinic patients and 53% of pharmacy customers could confirm their prescription or purchase included antibiotics. Diagnostic uncertainty, financial incentives, understanding of antibiotics as anti-inflammatory and limited doctor-patient communication were identified as key drivers of antibiotic use. Completion and accuracy of electronic patient records were highly variable. Prevalence of antibiotic resistance in this rural population is relatively low despite high levels of antibiotic prescribing and self-medication. More systematic use of e-records and in-service training could improve antibiotic surveillance and stewardship in rural facilities. Combining qualitative and observational anthropological methods and concepts with microbiological and epidemiological investigation of antibiotic resistance at both research design and analytic synthesis stages substantially increases the validity of research findings and their utility in informing future intervention development.