Description and evaluation of a new volumetric-modulated arc therapy plan complexity metric

This study describes a new plan complexity metric for volumetric-modulated arc therapy (VMAT) and evaluates the relationship of this metric with the VMAT dosimetric accuracy. The new modulation complexity score for VMAT (NMCSv) that is based on the aperture shape and multi-leaf collimator (MLC) leaf travel is described. Its performance is evaluated through correlation and receiver operating characteristic (ROC) analyses with patient-specific gamma passing rates using 2 3-dimensional diode arrays. For comparison, the following metrics are evaluated using the same correlation analyses: average field width, average leaf travel, modulation complexity score, and leaf travel modulation complexity score. Spearman's rank correlation analysis is performed to examine any relationships between the complexity metrics and the patient-specific gamma passing rates. ROC curves are used to assess the performance of the plan metrics using a gamma passing rate of 3%/3 mm criterion with a 95% tolerance level. In both the diode arrays, the gamma passing rates (3%/3 mm and 2%/2 mm) for patient-specific dosimetric verification of VMAT plans are moderately or weakly correlated to all the complexity metrics. NMCSv demonstrates the highest correlation with the passing rates (r = 0.652, p < 0.001 for Delta4 and r = 0.499, p < 0.001 for ArcCheck) and the highest area under the curve value (0.809, p < 0.01 for Delta4 and 0.734, p < 0.01 for ArcCheck). While using the Delta4 system, NMCSv exhibits an excellent classification performance with area under the curves of 0.926 (sensitivity: 0.913; specificity: 0.860; p < 0.01) and 0.918 (sensitivity: 0.943; specificity: 0.720; p < 0.01) for rectal and cervical cancer plans, respectively. NMCSv as a novel potential clinical plan complexity metric is moderately correlated with the gamma passing rate. It demonstrates the best performance with respect to distinguishing the dosimetric accuracy of VMAT plans among the evaluated metrics. The classification performance of complexity metrics can be affected by various dosimetry verification devices and treatment sites.

Design of a new breast vacuum bag to reduce the global and local setup errors and to reduce PTV margin in post-mastectomy radiation therapy

To design a new breast vacuum bag to reduce global and local setup errors in post-mastectomy radiation therapy (PMRT). A total of 24 PMRT patients were immobilized with an old vacuum bag and 26 PMRT patients were immobilized with a new vacuum bag. The registration results were analysed using four regions of interest (ROI): the global ROI [including the whole region of the planning target volume (PTV), G_ROI], the supraclavicular area (S_ROI), the ipsilateral chest wall region (C_ROI) and the ipsilateral arm region (A_ROI). The global and local setup errors of the two groups were compared. The global setup errors of the new vacuum group were significantly smaller than those in the old vacuum group with the exception of yaw axes (P < 0.05). The systematic error (Σ) and random error (σ) ranged from 1.21 to 2.13 mm. In the new vacuum group, the local setup errors in the medial-lateral (ML) direction and roll axes for C_ROI (the Σ and σ ranged from 0.65 to 1.35 mm), and the local setup errors in ML and superior-inferior (SI) directions for S_ROI were significantly smaller than those in the old vacuum group. The total required PTV margins for the chest wall in ML, SI, and anterior-posterior (AP) were 4.40, 3.12 and 3.77 mm respectively. The new vacuum bag can significantly reduce the global setup errors and local setup errors in PMRT. The respiratory motion of the chest wall was negligible, and the 5 mm PTV margin could cover the local setup errors in PMRT using the new vacuum bag with cone beam CT (CBCT) correction.

Gen-editing to model Short QT syndrome type 5 using human-induced pluripotent stem cell-derived cardiomyocytes

Aims

Short QT syndrome (SQTS), a disorder associated with characteristic electrocardiogram QT-segment abbreviation, predisposes afflicted patients to sudden cardiac death. Despite some progress in assessing the organ level pathophysiology and genetic changes of the disorder, the understanding of the human cellular phenotype and discovering of an optimal therapy has lagged due to a lack of appropriate human cellular models of the disorder. The aim of this study was to establish a cellular model of SQTS type 5 using human-induced pluripotent stem cell–derived cardiomyocytes (hiPSC-CMs) and gene-edited cell line using CRISPR/CAS9.

Methods and results

This study recruited one patient with short QT syndrome type 5 carrying a mutation in CACNb2 gene as well as one healthy control subject. We generated hiPSCs from their skin fibroblasts, and differentiated hiPSCs into cardiomyocytes (hiPSC-CMs) for physiological. Isogenic control hiPSC-CMs generated by the CRISPR/CAS9 technique were also used for the study.

The hiPSC-CMs from the patient showed a reduced calcium current (ICa-L) density and shortened action potential duration (APD) compared with healthy control hiPSC-CMs and isogenic hiPSC-CMs. Furthermore, they demonstrated abnormal rhythmic activities. Carbachol increased the arrhythmic events in SQTS significantly but not in healthy and isogenic control cells. Gene and protein expression profiling showed a decreased CACNb2 expression in SQTS cells. Quinidine prolonged the APD and abolished arrhythmic activity.

Conclusions

Patient-specific hiPSC-CMs are able to recapitulate single-cell phenotype features of SQTS type 5 and provide novel opportunities to further elucidate the cellular disease mechanism and test drug effects.

Funding Acknowledgement

Type of funding source: None

Long-Term Results of Partial Breast Irradiation After Breast-Conserving Surgery for Early Stage Breast Cancer: A Prospective Phase II Trial in China

Background

Partial breast radiotherapy (PBI) has emerged as an option after breast-conserving surgery for early stage breast cancer patients.

Methods

A total of 55 patients with early stage breast cancer between 2009 and 2013 were enrolled in this single-institutional phase II prospective clinical trial. All patients received adjuvant PBI-IMRT after lumpectomy, with the prescription of 48 Gy in 12 fractions at 4 Gy per fraction, 5 days a week. The primary endpoint was ipsilateral breast tumor recurrence (IBTR), the other endpoints were a regional nodal failure (RNF), distant metastasis (DM) rate, disease-free survival (DFS), and overall survival (OS). These endpoints were used to evaluate clinical outcomes. The cosmetic effects and the late toxicity were assessed according to Harvard standard scale and CTCAE 3.0, respectively.

Results

In our cohorts, the median age was 45.60 years old (range 31-65 years) and 29.09% of these patients were post-menopause (n = 16). Most patients were T1 stage (65.45%) or N0 stage (70.91%). 80% of patients were ER-positive, 67.27% PR positive, and 61.82% HER2 negative. At the median follow-up of 9.25 years, RNF was 0% and IBTR occurred in only one patient (1.82%) to the chest wall. Except for one patient (1.82%) had DM to lung and pleura and died from disease progression, the remaining patients were alive at the end of the 10-year follow-up. The 10-year DFS and OS were 94.55 and 98.18%. One patient (1.82%) was diagnosed with endometrial cancer after PBI. Except for 9 patients who declined the cosmetic assessment, the rest of the 46 patients (83.64%) were all rated as good and well-satisfied with the appearance of the irradiated breast. No breast retraction and fibrosis were observed in any of the patients. Additionally, only 4 patients experienced grade 1 late toxicity (7.28%). None had grade 3 or higher late toxicity.

Conclusion

This is the first study to report the 10-year results of PBI after breast-conserving surgery in Chinese patients. Our study suggested that PBI had durable local control and maintained good cosmetic outcomes with minimal late toxicity at long term follow up for the early stage breast cancer patients.

Application of 3D-print silica bolus for nasal NK/T-cell lymphoma radiation therapy

The aim of the study was to evaluate the clinical feasibility of a 3D-print silica bolus for nasal NK/T-cell lymphoma radiation therapy. Intensity modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT) plans were designed using an anthropomorphic head phantom with a 3D-print silica bolus and other kinds of bolus used clinically, and the surface dose was measured by a metal oxide semiconductor field-effect transistor (MOSFET) dosimeter. Four nasal NK/T patients with or without 3D-print silica bolus were treated and the nose surface dose was measured using a MOSFET dosimeter during the first treatment. Plans for the anthropomorphic head phantom with 3D-print bolus have more uniform dose and higher conformity of the planning target volume (PTV) compared to other boluses; the homogeneity index (HI) and conformity index (CI) of the VMAT plan were 0.0589 and 0.7022, respectively, and the HI and CI of the IMRT plan were 0.0550 and 0.7324, respectively. The MOSFET measurement results showed that the surface dose of the phantom with 3D-print bolus was >180 cGy, and that of patients with 3D-print bolus was higher than patients without bolus. The air gap volume between the 3D-print bolus and the surface of patients was <0.3 cc. The 3D-print silica bolus fitted well on the patient’s skin, effectively reducing air gaps between bolus and patient surface. Meanwhile, the 3D-print silica bolus provided patients with higher individuation, and improved the conformity and uniformity of the PTV compared to other kinds of boluses.

Low-dose cone-beam CT (LD-CBCT) reconstruction for image-guided radiation therapy (IGRT) by three-dimensional dual-dictionary learning

BACKGROUND

To develop a low-dose cone beam CT (LD-CBCT) reconstruction method named simultaneous algebraic reconstruction technique and dual-dictionary learning (SART-DDL) joint algorithm for image guided radiation therapy (IGRT) and evaluate its imaging quality and clinical application ability.

METHODS

In this retrospective study, 62 CBCT image sets from February 2018 to July 2018 at west china hospital were randomly collected from 42 head and neck patients (mean [standard deviation] age, 49.7 [11.4] years, 12 females and 30 males). All image sets were retrospectively reconstructed by SART-DDL (resultant D-CBCT image sets) with 18% less clinical raw projections. Reconstruction quality was evaluated by quantitative parameters compared with SART and Total Variation minimization (SART-TV) joint reconstruction algorithm with paired t test. Five-grade subjective grading evaluations were done by two oncologists in a blind manner compared with clinically used Feldkamp-Davis-Kress algorithm CBCT images (resultant F-CBCT image sets) and the grading results were compared by paired Wilcoxon rank test. Registration results between D-CBCT and F-CBCT were compared. D-CBCT image geometry fidelity was tested.

RESULTS

The mean peak signal to noise ratio of D-CBCT was 1.7 dB higher than SART-TV reconstructions (P < .001, SART-DDL vs SART-TV, 36.36 ± 0.55 dB vs 34.68 ± 0.28 dB). All D-CBCT images were recognized as clinically acceptable without significant difference with F-CBCT in subjective grading (P > .05). In clinical registration, the maximum translational and rotational difference was 1.8 mm and 1.7 degree respectively. The horizontal, vertical and sagittal geometry fidelity of D-CBCT were acceptable.

CONCLUSIONS

The image quality, geometry fidelity and clinical application ability of D-CBCT are comparable to that of the F-CBCT for head-and-neck patients with 18% less projections by SART-DDL.

Immune cell infiltration features and related marker genes in lung cancer based on single-cell RNA-seq

PURPOSE

Immune cells in the immune microenvironment of lung cancer have a great impact on the development of lung cancer. Our purpose was to analyze the immune cell infiltration features and related marker genes for lung cancer.

METHODS

Single cell RNA sequencing data of 11,485 lung cancer cells were retrieved from the Gene Expression Omnibus. After quality control and data normalization, cell clustering was performed using the Seurat package. Based on the marker genes of each cell type from the CellMarker database, each cell was divided into G1, G2M, and S phases. Then, differential expression and functional enrichment analyses were performed. CIBERSORT was used to reconstruct immune cell types.

RESULTS

Following cell filtering, highly variable genes were identified for all cells. 14 cell types were clustered. Among them, CD4 + T cell, B cell, plasma cell, natural killer cell and cancer stem cell were the top five cell types. Up-regulated genes were mainly enriched in immune-related biological processes and pathways. Using CIBERSORT, we identified the significantly higher fractions of naïve B cell, memory CD4 + T cell, T follicular helper cell, T regulatory helper cell and M1 macrophage in lung cancer tissues compared to normal tissues. Furthermore, the fractions of resting NK cell, monocyte, M0 macrophage, resting mast cell, eosinophil and neutrophil were significantly lower in tumor tissues than normal tissues.

CONCLUSION

Our findings dissected the immune cell infiltration features and related marker genes for lung cancer, which might provide novel insights for the immunotherapy of lung cancer.

Home enteral nutrition may prevent myelosuppression of patients with nasopharyngeal carcinoma treated by concurrent chemoradiotherapy

BACKGROUND

The aim of this study is to assess the effect of home enteral nutrition (HEN) on the myelosuppression of patients with nasopharyngeal cancer (NPC) during the course of concurrent chemoradiotherapy (CCRT).

METHODS

A total of 18 outpatients with NPC administered oral nutritional supplementation intervention at home during the course of CCRT were designated as the HEN group, whereas 36 patients with NPC who had previously completed CCRT were retrospectively included as the control group. Patient Generated Subjective Global Assessment, body mass index (BMI), and blood test were evaluated prior to CCRT. During the course of CCRT, blood test was assessed every 2 weeks.

RESULTS

In male patients, hemoglobin (HB) and red blood cell were decreased (P < .05) in both HEN and control group after CCRT, whereas white blood cell (WBC) started to decrease since week 2 of CCRT in the control group but maintained in the HEN group which was significantly higher than the control (5.05 ± 1.29 vs 3.77 ± 1.5, P < .05). In female patients, HB and WBC were reduced in control group during CCRT, whereas these indicators also maintained in the HEN group. Surprisingly, all patients with lower BMI (<24 kg/m² ) had a significant increase in platelet (PLT) after CCRT (200.78 ± 58.03 vs 253.00 ± 69.82, P < .05), while had steady HB and WBC values in the HEN group. At the end of CCRT, WBC and PLT of the HEN group were both higher than those in the control group (5.21 ± 1.07 vs 3.37 ± 1.52), (253.00 ± 69.82 vs 165.57 ± 59.56) (P < .05 for both). Our findings suggest that HEN is effective in preventing myelosuppression during CCRT for patients with NPC.

CONCLUSION

Our findings suggest that HEN is effective in preventing myelosuppression during CCRT for patients with NPC.

A polymorphic MYC response element in KBTBD11 influences colorectal cancer risk, especially in interaction with an MYC-regulated SNP rs6983267

Background

MYC is a well-established cancer driver gene regulating the expression of numerous genes, indicating that polymorphisms in MYC response elements could affect tumorigenesis through altering MYC regulation. We performed integrative multistage study to evaluate the effects of variants in MYC response elements and colorectal cancer (CRC) risk.

Patients and methods

We systematically integrated ChIP-Seq, DNase-Seq and transcription factor motif data to screen variants with potential ability to affect the MYC binding affinity. Then, we conducted a two-stage case-control study, totally consisting of 4830 CRC cases and 4759 controls in Chinese population to identify risk polymorphisms and interactions. The effects of risk variants were confirmed by functional assays in CRC LoVo, SW480 and HCT15 cells.

Results

We identified a novel polymorphism rs11777210 in KBTBD11 significantly associated with CRC susceptibility (P = 2.43 × 10-12). Notably, we observed a significant interaction between rs11777210 and MYC nearby rs6983267 (P-multi = 0.003, P-add = 0.005), subjects carrying rs6983267 GG and rs11777210 CC genotypes showing higher susceptibility to CRC (2.83-fold) than those carrying rs6983267 TT and rs11777210 TT genotypes. We further demonstrated that rs6983267 T > G increased MYC expression, and MYC bound to and negatively regulated KBTBD11 expression when the rs11777210 C risk allele was present. KBTBD11 was downregulated in tumor tissues, and KBTBD11 knockdown promoted cell proliferation and inhibited cell apoptosis.

Conclusion

The rs11777210 is a potential predictive biomarker of CRC susceptibility, and KBTBD11 functions as a putative tumor suppressor in tumorigenesis. Our study highlighted the high CRC risk of people carrying rs6983267 G and rs11777210 C alleles, and provided possible biological mechanism of the interaction.

Analysis of which local set-up errors can be covered by a 5-mm margin for cone beam CT-guided radiotherapy for nasopharyngeal carcinoma

Objective:

To analyse which local set-up errors can be covered by a 5-mm margin for cone beam computed tomography (CBCT)-guided radiotherapy in nasopharyngeal carcinoma (NPC).

Methods:

11 regions of interest (ROIs) were registered for 24 NPC patients, with a total of 323 CBCT scans. According to the registration results, clinical target volume–planning target volume (CTV–PTV)/organs at risk-planning risk volume (OAR-PRV) margin analysis; Pearson correlation analysis; Bland–Altman plots; and a receiver operating characteristic (ROC) analysis were used to investigate which local set-up errors of substructure can be represented by the PTV_ROI.

Results:

The clinical target volume-PTV/OAR-planning risk volume margins were less than 5 mm for C1_ROI-C4_ROI, mandible (M_ROI), and sphenoid sinus (S_ROI) with respect to PTV_ROI. C1_ROI-C4_ROI, M_ROI, and S_ROI exhibited significant correlations and consistencies in the mediolateral, superior–inferior, and anteroposterior (AP) directions and significant receiver operating characteristic analysis results in the anteroposterior direction.

Conclusion:

Only the upper local set-up error of C1_ROI-C4_ROI, M_ROI, and S_ROI can be covered by a 5-mm margin for CBCT-guided NPC radiotherapy with a large ROI. Using these ROIs as an integral reference ROI is better than individual bony landmark.

Advances in knowledge:

This report is helpful to CBCT registration for NPC radiotherapy in clinical practice.