Newton Hurst, MD, PhD

PURPOSE: Magnetic resonance (MR)-guided radiation therapy enables online adaptation to address intra- and interfractional changes. To address the need of high-fidelity synthetic computed tomography (synCT) required for dose calculation, we developed a conditional generative adversarial network for synCT generation from low-field MR imaging in the brain.

METHODS AND MATERIALS: Simulation MR-CT pairs from 12 patients with glioma imaged with a head and neck surface coil and treated on a 0.35T MR-linac were prospectively included to train the model consisting of a 9-block residual network generator and a PatchGAN discriminator. Four-fold cross-validation was implemented. SynCT was quantitatively evaluated against real CT using mean absolute error (MAE), peak signal-to-noise ratio (PSNR), and structural similarity index measure (SSIM). Dose was calculated on synCT applying original treatment plan. Dosimetric performance was evaluated by dose-volume histogram metric comparison and local 3-dimensional gamma analysis. To demonstrate utilization in treatment adaptation, longitudinal synCTs were generated for qualitative evaluation, and 1 offline adaptation case underwent 2 comparative plan evaluations. Secondary validation was conducted with 9 patients on a different MR-linac using a high-resolution brain coil.

RESULTS: Our model generated high-quality synCTs with MAE, PSNR, and SSIM of 70.9 ± 10.4 HU, 28.4 ± 1.5 dB, and 0.87 ± 0.02 within the field of view, respectively. Underrepresented postsurgical anomalies challenged model performance. Nevertheless, excellent dosimetric agreement was observed with the mean difference between real and synCT dose-volume histogram metrics of -0.07 ± 0.29 Gy for target D95 and within [-0.14, 0.02] Gy for organs at risk. Significant differences were only observed in the right lens D0.01cc with negligible overall difference (<0.13 Gy). Mean gamma analysis pass rates were 92.2% ± 3.0%, 99.2% ± 0.7%, and 99.9% ± 0.1% at 1%/1 mm, 2%/2 mm, and 3%/3 mm, respectively. Secondary validation yielded no significant differences in synCT performance for whole-brain MAE, PSNR, and SSIM with comparable dosimetric results.

CONCLUSIONS: Our conditional generative adversarial network model generated high-fidelity brain synCTs from low-field MR imaging with excellent dosimetric performance. Secondary validation suggests great promise of implementing synCTs to facilitate robust dose calculation for online adaptive brain MR-guided radiation therapy.

PMID:39357787 | DOI:10.1016/j.ijrobp.2024.09.046

For MR-guided radiation therapy treatment planning, an MRI and CT of the intended treatment site are typically acquired. Patients' prior treatments or procedures can cause image artifacts in one or both scans, which may impact treatment planning or the radiation dose calculation. In this case report, a patient with several previous transcatheter arterial chemoembolization (TACE) procedures was planned for radiation therapy on a low-field MR-linac, and the impact of residual iodinated oil on the radiation dose calculation and MR-guided adaptive workflow was evaluated.

PMID:38222202 | PMC:PMC10784766 | DOI:10.7759/cureus.50459

Oligometastatic state is believed to potentially represent a transitional stage between early, locoregional state disease and widely metastatic disease. Historically, locoregional approaches, particularly in advanced colorectal cancers, have demonstrated efficacy in select patients with limited burden of metastatic disease. Recent strides in systemic therapies, including biomarker-based treatments and immunotherapy, alongside innovations in surgical techniques and novel locoregional approaches such as stereotactic radiotherapy and ablation, have ushered in a new era of therapeutic possibilities across all oligometastatic GI cancers. Despite these advancements, there remains a significant gap in high-quality prospective evidence guiding patient selection and treatment decisions across various disease types. Ongoing clinical trials are anticipated to provide crucial insights into oligometastatic states, fostering the refinement of disease-specific oligometastatic state definitions and treatment algorithms. This article reviews existing data on the management of oligometastatic GI cancer, summarizes current state of knowledge for each disease state, and provides updates on ongoing studies in this space.

PMID:38190577 | DOI:10.1200/EDBK_430152

PURPOSE: In this prospective phase 2 trial, we investigated the toxicity and patient-reported quality-of-life outcomes in patients treated with stereotactic body radiation therapy (SBRT) to the prostate gland and a simultaneous focal boost to magnetic resonance imaging (MRI)-identified intraprostatic lesions while also de-escalating dose to the adjacent organs at risk.

METHODS AND MATERIALS: Eligible patients included low- or intermediate-risk prostate cancer (Gleason score ≤7, prostate specific antigen ≤20, T stage ≤2b). SBRT was prescribed to 40 Gy in 5 fractions delivered every other day to the prostate, with any areas of high disease burden (MRI-identified prostate imaging reporting and data system 4 or 5 lesions) simultaneously escalated to 42.5 to 45 Gy and areas overlapping organs at risk (within 2 mm of urethra, rectum, and bladder) constrained to 36.25 Gy (n = 100). Patients without a pretreatment MRI or without MRI-identified lesions were treated to dose of 37.5 Gy with no focal boost (n = 14).

RESULTS: From 2015 to 2022, a total of 114 patients were enrolled with a median follow-up of 42 months. No acute or late grade 3+ gastrointestinal (GI) toxicity was observed. One patient developed late grade 3 genitourinary (GU) toxicity at 16 months. In patients treated with focal boost (n = 100), acute grade 2 GU and GI toxicity was seen in 38% and 4% of patients, respectively. Cumulative late grade 2+ GU and GI toxicities at 24 months were 13% and 5% respectively. Patient-reported outcomes showed no significant long-term change from baseline in urinary, bowel, hormonal, or sexual quality-of-life scores after treatment.

CONCLUSIONS: SBRT to a dose of 40 Gy to the prostate gland with a simultaneous focal boost up to 45 Gy is well tolerated with similar rates of acute and late grade 2+ GI and GU toxicity as seen in other SBRT regimens without intraprostatic boost. Moreover, no significant long-term changes were seen in patient-reported urinary, bowel, or sexual outcomes from pretreatment baseline.

PMID:37179035 | DOI:10.1016/j.ijrobp.2023.05.004

PURPOSE: The acquisition of multiparametric quantitative magnetic resonance imaging (qMRI) is becoming increasingly important for functional characterization of cancer prior to- and throughout the course of radiation therapy. The feasibility of a qMRI method known as magnetic resonance fingerprinting (MRF) for rapid T1 and T2 mapping was assessed on a low-field MR-linac system.

METHODS: A three-dimensional MRF sequence was implemented on a 0.35T MR-guided radiotherapy system. MRF-derived measurements of T1 and T2 were compared to those obtained with gold standard single spin echo methods, and the impacts of the radiofrequency field homogeneity and scan times ranging between 6 and 48 min were analyzed by acquiring between 1 and 8 spokes per time point in a standard quantitative system phantom. The short-term repeatability of MRF was assessed over three measurements taken over a 10-h period. To evaluate transferability, MRF measurements were acquired on two additional MR-guided radiotherapy systems. Preliminary human volunteer studies were performed.

RESULTS: The phantom benchmarking studies showed that MRF is capable of mapping T1 and T2 values within 8% and 10% of gold standard measures, respectively, at 0.35T. The coefficient of variation of T1 and T2 estimates over three repeated scans was < 5% over a broad range of relaxation times. The T1 and T2 times derived using a single-spoke MRF acquisition across three scanners were near unity and mean percent errors in T1 and T2 estimates using the same phantom were < 3%. The mean percent differences in T1 and T2 as a result of truncating the scan time to 6 min over the large range of relaxation times in the system phantom were 0.65% and 4.05%, respectively.

CONCLUSIONS: The technical feasibility and accuracy of MRF on a low-field MR-guided radiation therapy device has been demonstrated. MRF can be used to measure accurate T1 and T2 maps in three dimensions from a brief 6-min scan, offering strong potential for efficient and reproducible qMRI for future clinical trials in functional plan adaptation and tumor/normal tissue response assessment.

PMID:34487357 | PMC:PMC8733901 | DOI:10.1002/mp.15202

Traditionally, clinicians have assumed the primary responsibility for evaluating disease- and treatment-related outcomes. In the past few decades, however, a series of recommendations and standards promulgated by professional societies and regulatory agencies have resulted in increased use of patient-reported outcome (PRO) measures in cancer clinical trials. PROs, such as quality of life (QOL) measures, are important in establishing overall treatment effectiveness in cancer clinical trials, and they can inform clinical decision making. This article discusses the current state of the science in PRO research for patients with lung cancer, the cancer type with the highest incidence rate and the lowest survival rate worldwide. The discussion focuses on (1) PRO and survival; (2) electronic PRO reporting and interventions; (3) PROs and immunotherapy; (4) PRO, biomarkers, and precision health; (5) key issues in applying PROs in clinical trials; and (6) future directions for research.

PMID:32450592 | DOI:10.1055/s-0040-1712099

PURPOSE: Magnetic resonance-guided radiation therapy (MRgRT) has shown great promise for localization and real-time tumor monitoring. However, to date, quantitative imaging has been limited for low field MRgRT. This work benchmarks quantitative T1, R2*, and Proton Density (PD)mapping in a phantom on a 0.35 T MR-linac and implements a novel acquisition method, STrategically Acquired Gradient Echo (STAGE). To further validate STAGE in a clinical setting, a pilot study was undertaken in a cohort of brain tumor patients to elucidate opportunities for longitudinal functional imaging with an MR-linac in the brain.

METHODS: STAGE (two triple-echo gradient echo (GRE) acquisitions) was optimized for a 0.35T low-field MR-linac. Simulations were performed to choose two flip angles to optimize signal-to-noise ratio (SNR) and T1-mapping precision. Tradeoffs between SNR, scan time, and spatial resolution for whole-brain coverage were evaluated in healthy volunteers. Data were inputted into a STAGE processing pipeline to yield four qualitative images (T1-weighted, enhanced T1-weighted, proton-density (PD) weighted, and simulated FLuid-Attenuated Inversion Recovery (sFLAIR)), and three quantitative datasets (T1, PD, and R2*). A benchmarking ISMRM/NIST phantom consisting of vials with variable NiCl2 and MnCl2 concentrations was scanned using variable flip angles (VFA) (2-60 degrees) and inversion recovery (IR) methods at 0.35 T. STAGE and VFA T1 values of vials were compared to IR T1 values. As measures of agreement with reference values and repeatability, relative error (RE) and coefficient of variability (CV) were calculated, respectively, for quantitative MR values within the phantom vials (spheres). To demonstrate feasibility, longitudinal STAGE data (pretreatment, weekly, and ~ 2 months post-treatment) were acquired in an IRB-approved pilot study of brain tumor cases via the generation of temporal and differential quantitative MRI maps.

RESULTS: In the phantom, RE of measured VFA T1 and STAGE relative to IR reference values were 7.0 ± 2.5% and 9.5 ± 2.2% respectively. RE for the PD vials was 8.1 ± 6.8% and CV for phantom R2* measurements was 10.1 ± 9.9%. Simulations and volunteer experiments yielded final STAGE parameters of FA = 50°/10°, 1 × 1 × 3 mm3 resolution, TR = 40 ms, TE = 5/20/34 ms in 10 min (64 slices). In the pilot study of brain tumor patients, differential maps for R2* and T1 maps were sensitive to local tumor changes and appeared similar to 3 T follow-up MRI datasets.

CONCLUSION: Quantitative T1, R2*, and PD mapping are promising at 0.35 T agreeing well with reference data. STAGE phantom data offer quantitative representations comparable to traditional methods in a fraction of the acquisition time. Initial feasibility of implementing STAGE at 0.35 T in a patient brain tumor cohort suggests that detectable changes can be observed over time. With confirmation in a larger cohort, results may be implemented to identify areas of recurrence and facilitate adaptive radiation therapy.

PMID:32434276 | PMC:PMC7677202 | DOI:10.1002/mp.14251

Despite strong evidence for the involvement of PDGF signaling in breast cancer, little is known about the PDGF ligand responsible for PDGFR activation during breast cancer progression. Here, we found PDGF-C to be highly expressed in breast carcinoma cell lines. Immunohistochemical analysis of invasive breast cancer revealed an association between increased PDGF-C expression and lymph node metastases, Ki-67 proliferation index, and poor disease-free survival. We also identified a PDGF-C splice variant encoding truncated PDGF-C (t-PDGF-C) isoform lacking the signal peptide and the N-terminal CUB domain. While t-PDGF C homodimer is retained intracellularly, it can be secreted as a heterodimer with full-length PDGF-C (FL-PDGF-C). PDGF-C downregulation reduced anchorage-independent growth and matrigel invasion of MDA-MB-231 cells. Conversely, ectopic expression of t-PDGF-C enhanced phenotypic transformation and invasion in BT-549 cells expressing endogenous FL-PDGF-C. The present study provides new insights into the functional significance of PDGF-C and its splice variant in human breast cancer.

PMID:31542979 | PMC:PMC6872946 | DOI:10.1080/08977194.2019.1662415

BACKGROUND: We performed an analysis of the National Cancer Database (NCDB) to evaluate overall survival (OS) in patients with base of tongue (BOT) cancer treated with external beam radiation therapy (EBRT) combined with brachytherapy (BT).

METHODS: The tongue NCDB Participant User File was used to obtain demographic and clinical patient data. The Kaplan-Meier method was used to determine OS. Significance was determined using univariable and multivariable Cox proportional hazards models.

RESULTS: At 3 years, OS was 69.6%, 77.1%, and 63.7% for patients treated with EBRT (n = 27 954), EBRT + BT (n = 209), or BT alone (n = 154), respectively (P = .01). On multivariable analysis, the instantaneous hazard of death for patients receiving EBRT + BT was 25% (Hazard ratio [HR] = 0.75, 95% CI: 0.58-0.98) lower than patients receiving only EBRT (P = .03).

CONCLUSIONS: The addition of BT to EBRT in BOT cancer has an OS benefit.

PMID:30788877 | DOI:10.1002/hed.25497

Background. Acrokeratosis paraneoplastica, or Bazex syndrome, is a paraneoplastic syndrome characterized by cutaneous psoriasiform lesions with associated acral erythema and scale, as well as nail changes, including onycholysis and ungual dystrophy. Its most advanced, severe form involves the trunk, elbows, and knees. It is typically associated with upper aerodigestive tract malignancies in males. Rare cases associated with gynecological cancers have been reported, including uterine adenocarcinoma, as well as ovarian and vulvar squamous cell carcinomas. Cutaneous manifestations often precede cancer diagnosis. In most reported cases, skin changes resolve when the underlying malignancy is adequately treated. Main Observations. We present the case of a 56-year-old female diagnosed with acrokeratosis paraneoplastica following the discovery of FIGO stage IIB cervical squamous cell carcinoma (SCC). Scaling, hyperpigmentation, xerosis, and fissuring were noted on the patient's hands, feet, legs, arms, and lower back. Pitting was noted on her fingernails. Her cervical cancer was successfully treated with chemoradiotherapy, after which her cutaneous lesions persisted for two months before resolving. Conclusions. The presentation of acrokeratosis paraneoplastica in this context is atypical. Reports of associations with gynecological cancers, as in our patient's case, are exceedingly rare.

PMID:28101384 | PMC:PMC5215458 | DOI:10.1155/2016/7137691

BACKGROUND: Although larynx preservation affords patients improvements in laryngectomy-free survival, little has been reported regarding the functional outcomes after larynx preservation. The purpose of this study was to report the predictive value of pretreatment CT-gross tumor volume (GTV) for persistence of tracheostomy and percutaneous endoscopic gastrostomy (PEG) tube in larynx preservation patients.

METHODS: Each patient had a CT scan before initiation of therapy and the GTV was contoured.

RESULTS: Using recursive partitioning analysis (RPA), threshold GTVs of 27.16 cc and 12 cc were identified for association of time with tracheostomy and PEG tube, respectively. Median (95% confidence interval [CI]) times above and below these thresholds were 1.84 (1.06-not reached [NR]) and 0.75 (0.63-1.26) years, respectively (p = .03) for time with tracheostomy and 1.75 (1.34-NR) and 0.84 (0.46-NR) years, respectively (p = 0.10) for time with PEG tube.

CONCLUSION: This study demonstrates that pretreatment CT-GTV is predictive of an approximately 2.5-fold and approximately 2-fold, respectively, increase in time with tracheostomy and PEG tube. © 2016 Wiley Periodicals, Inc. Head Neck 38: First-1458, 2016.

PMID:27131223 | PMC:PMC6857528 | DOI:10.1002/hed.24458

BACKGROUND: Lymphatic vessel density (LVD) has been shown to be an important predictor of survival in head and neck cancers. We report the predictive value of LVD for progression-free survival (PFS) and overall survival (OS) in laryngeal/hypopharyngeal cancer.

METHODS: Fifty-five untreated patients with T3/T4 laryngeal and T4 hypopharyngeal cancer underwent laryngectomy between 1999 and 2010. Surgical specimens were immunostained with D2-40, a specific lymphatic marker. LVDs were determined in tumor vessel "hot spots." Recursive partitioning analysis identified LVD thresholds for both peritumoral (LVDpt) and intratumoral (LVDit) vessels for association with PFS and OS.

RESULTS: Patients with mean LVDit of <11 vessels/mm(2) had 2-year PFS and OS rates of 58% and 65%, respectively, compared to 13% and 13% for those with LVDit ≥11 vessels/mm(2) (p = .06 and .04, respectively).

CONCLUSION: Intratumoral lymphatic vessel density is predictive of PFS and OS in locally advanced laryngeal/hypopharyngeal cancer. © 2015 Wiley Periodicals, Inc. Head Neck 38: E417-E420, 2016.

PMID:25641342 | DOI:10.1002/hed.24011

The PDGF (platelet-derived growth factor) family members are potent mitogens for cells of mesenchymal origin and serve as important regulators of cell migration, survival, apoptosis and transformation. Tumour-derived PDGF ligands are thought to function in both autocrine and paracrine manners, activating receptors on tumour and surrounding stromal cells. PDGF-C and -D are secreted as latent dimers, unlike PDGF-A and -B. Cleavage of the CUB domain from the PDGF-C and -D dimers is required for their biological activity. At present, little is known about the proteolytic processing of PDGF-C, the rate-limiting step in the regulation of PDGF-C activity. In the present study we show that the breast carcinoma cell line MCF7, engineered to overexpress PDGF-C, produces proteases capable of cleaving PDGF-C to its active form. Increased PDGF-C expression enhances cell proliferation, anchorage-independent cell growth and tumour cell motility by autocrine signalling. In addition, MCF7-produced PDGF-C induces fibroblast cell migration in a paracrine manner. Interestingly, PDGF-C enhances tumour cell invasion in the presence of fibroblasts, suggesting a role for tumour-derived PDGF-C in tumour-stromal interactions. In the present study, we identify tPA (tissue plasminogen activator) and matriptase as major proteases for processing of PDGF-C in MCF7 cells. In in vitro studies, we also show that uPA (urokinase-type plasminogen activator) is able to process PDGF-C. Furthermore, by site-directed mutagenesis, we identify the cleavage site for these proteases in PDGF-C. Lastly, we provide evidence suggesting a two-step proteolytic processing of PDGF-C involving creation of a hemidimer, followed by GFD-D (growth factor domain dimer) generation.

PMID:22035541 | PMC:PMC3342761 | DOI:10.1042/BJ20111020

The platelet-derived growth factor (PDGF) proteins are potent stimulators of cell proliferation/transformation and play a major role in cell-cell communication. For over two decades, PDGFs were thought to exist as three dimeric polypeptides (the homodimers AA and BB and the heterodimer AB). Recently, however, the PDGF C and D chains were discovered in a BLAST search of the expressed sequence tag databases. The PDGF CC and DD dimers have a unique two-domain structure with an NH(2)-terminal CUB (compliment subcomponents C1r/C1s, Uegf, and Bmp1) domain and a COOH-terminal PDGF/vascular endothelial growth factor domain. Whereas secreted PDGF AA, BB, and AB readily activate their cell surface receptors, it was suggested that extracellular proteolytic removal of the CUB domain is required for the PDGF/vascular endothelial growth factor domain of PDGF CC and DD to activate PDGF receptors. In the present study, we examined the processing of latent PDGF D into its active form and the effects of PDGF D expression on prostate cancer progression. We show that LNCaP cells auto-activate latent PDGF DD into the active PDGF domain, which can induce phosphorylation of the beta-PDGF receptor and stimulates LNCaP cell proliferation in an autocrine manner. Additionally, LNCaP-PDGF D-conditioned medium induces migration of the prostate fibroblast cell line 1532-FTX, indicating LNCaP-processed PDGF DD is active in a paracrine manner as well. In a severe combined immunodeficient mouse model, PDGF DD expression accelerates early onset of prostate tumor growth and drastically enhances prostate carcinoma cell interaction with surrounding stromal cells. These demonstrate a potential oncogenic activity of PDGF DD in the development and/or progression of prostate cancer.

PMID:14996732 | PMC:PMC4171134 | DOI:10.1158/0008-5472.can-03-3047