Advancements and future directions in positron emission tomography-guided radiotherapy: a narrative review

BACKGROUND AND OBJECTIVE

Positron emission tomography (PET) imaging has been useful in delineating tumor volumes and allowing for improved radiation treatment. The field of PET-guided radiotherapy is rapidly growing and will have significant impact on radiotherapy delivery in the future. This narrative review provides an overview of the current state of PET-guided radiotherapy as well as the future directions of the field.

METHODS

For this narrative review, PubMed was searched for articles from 2010-2023. A total of 18 keywords or phrases were searched to provide an overview of PET-guided radiotherapy, radiotracers, the role of PET-guided radiotherapy in oligometastatic disease, and biology-guided radiotherapy (BgRT). The first 300 results for each keyword were searched and relevant articles were extracted. The references of these articles were also reviewed for relevant articles.

KEY CONTENT AND FINDINGS

In radiotherapy, 18F-2-fluoro-2-deoxy-D-glucose (F-FDG or FDG) is the major radiotracer for PET and when combined with computed tomography (CT) scan allows for anatomic visualization of metabolically active malignancy. Novel radiotracers are being explored to delineate certain cell types and numerous tumor metrics including metabolism, hypoxia, vascularity, and cellular proliferation. This molecular and functional imaging will provide improved tumor characterization. Through these radiotracers, radiation plans can employ dose painting by creating different dose levels based upon specific risk factors of the target volume. Additionally, biologic imaging during radiotherapy can allow for adaptation of the radiation plan based on response to treatment. Dose painting and adaptive radiotherapy should improve the therapeutic ratio through more selective dose delivery. The novel PET-linear accelerator hopes to combine these techniques and more by using radiotracers to deliver BgRT. The areas of radiotracer uptake will serve as fiducials to guide radiotherapy to themselves. This technique may prove promising in the growing area of oligometastatic radiation treatment.

CONCLUSIONS

Significant challenges exist for the future of PET-guided radiotherapy. However, with the advancements being made, PET imaging is set to change the delivery of radiotherapy.

A repository of grade 1 and 2 meningioma MRIs in a public dataset for radiomics reproducibility tests

PURPOSE

Meningiomas are the most common primary brain tumors in adults with management varying widely based on World Health Organization (WHO) grade. However, there are limited datasets available for researchers to develop and validate radiomic models. The purpose of our manuscript is to report on the first dataset of meningiomas in The Cancer Imaging Archive (TCIA).

ACQUISITION AND VALIDATION METHODS

The dataset consists of pre-operative MRIs from 96 patients with meningiomas who underwent resection from 2010-2019 and include axial T1post and T2-FLAIR sequences-55 grade 1 and 41 grade 2. Meningioma grade was confirmed based on the 2016 WHO Bluebook classification guideline by two neuropathologists and one neuropathology fellow. The hyperintense T1post tumor and hyperintense T2-FLAIR regions were manually contoured on both sequences and resampled to an isotropic resolution of 1 × 1 × 1 mm3 . The entire dataset was reviewed by a certified medical physicist.

DATA FORMAT AND USAGE NOTES

The data was imported into TCIA for storage and can be accessed at https://doi.org/10.7937/0TKV-1A36. The total size of the dataset is 8.8GB, with 47 519 individual Digital Imaging and Communications in Medicine (DICOM) files consisting of 384 image series, and 192 structures.

POTENTIAL APPLICATIONS

Grade 1 and 2 meningiomas have different treatment paradigms and are often treated based on radiologic diagnosis alone. Therefore, predicting grade prior to treatment is essential in clinical decision-making. This dataset will allow researchers to create models to auto-differentiate grade 1 and 2 meningiomas as well as evaluate for other pathologic features including mitotic index, brain invasion, and atypical features. Limitations of this study are the small sample size and inclusion of only two MRI sequences. However, there are no meningioma datasets on TCIA and limited datasets elsewhere although meningiomas are the most common intracranial tumor in adults.

StrataXRT for the prevention and treatment of radiation dermatitis: a critical review

PURPOSE

The primary objective is to systematically review primary studies, such as randomized control trials (RCTs), feasibility, exploratory, and case studies; and the secondary objective is to evaluate all secondary articles, such as reviews, guidelines, and editorials, relevant to the use of StrataXRT for the prevention and/or management of radiation dermatitis (RD) in cancer patients.

METHODS

A literature search was conducted up to February 26, 2023, for articles investigating the use of StrataXRT for the prevention and treatment of RD, in the following databases: Ovid MEDLINE, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), and Google Scholar. The keywords "StrataXRT", "dermatitis", "radiotherapy", and "radiation" were used to identify relevant articles.

RESULTS

Twenty-seven articles from 2018 to 2022 were identified to fulfill the inclusion criteria of this review, of which nine are primary studies and 18 are secondary papers. Significant heterogeneity was observed in the current literature studying the effects of StrataXRT, making it difficult to make cross-trial comparisons. There is a suggestion of the efficacy of StrataXRT in the prevention and treatment of RD.

CONCLUSION

The findings of this review recommend further adequately powered RCTs with robust methodology including patient and clinician assessments to determine the efficacy of StrataXRT in preventing and treating RD. This is essential to improve the quality of life of patients and identify which groups of patients would benefit most from StrataXRT.

Mepitel film for the prevention and treatment of acute radiation dermatitis in breast cancer: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

This systematic review and meta-analysis aimed to evaluate the efficacy of Mepitel film in preventing or treating acute radiation dermatitis (RD) in patients with breast cancer in randomized controlled trials (RCTs).

METHODS

Embase, APA PsychInfo, Journals@Ovid Full Text, Ovid MEDLINE, PubMed, and Cochrane Trials were searched until December 12, 2022, to identify RCTs on the use of Mepitel film for preventing or treating acute RD from breast cancer radiotherapy. Per-protocol analysis was used to compare outcomes, calculate pooled effect sizes, odds ratio (OR), and 95% confidence intervals (CI), and to create forest plots using random effects analysis in RevMan 5.4.

RESULTS

Three RCTs were included in this review. Mepitel film significantly reduced the incidence of grade 3 RD (OR 0.15 95% CI 0.06, 0.37, p<0.0001) and grade 2 or 3 RD (OR 0.16 95% CI 0.04, 0.65, p=0.01) as scored on either the CTCAE or the RTOG scale. Additionally, Mepitel film significantly reduced RISRAS mean scores assessed by patients and combined researcher and patient (standardized mean difference (SMD) -7.59, 95% CI -14.42, -0.76, p=0.03; SMD -15.36, 95% CI -30.01, -0.71 p=0.04) but not the researcher component of the assessment tool (SMD -17.55, 95% CI -36.94, 1.84, p=0.08).

CONCLUSION

Mepitel film reduced the incidence of acute RD and improved patient-reported outcomes with minimal side effects, the main one being itchiness. Future research should assess the feasibility of Mepitel film with respect to specific patient-reported outcomes such as health-related quality of life issues associated with its use.

StrataXRT for the prevention of acute radiation dermatitis in breast cancer: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

To evaluate the overall efficacy of StrataXRT, a topical gel dressing, in preventing acute radiation dermatitis (RD) in breast cancer patients undergoing radiotherapy (RT).

METHODS

A systematic search was conducted on April 25, 2023 in Ovid MEDLINE, Embase, and Cochrane Central Register of Controlled Trials. Randomized controlled trials (RCTs) assessing the effectiveness of StrataXRT in preventing acute RD in breast cancer patients undergoing adjuvant RT to the breast or chest wall with or without regional nodes were included. Pooled incidence odds ratio (OR) and 95% confidence interval (CI) were calculated using a random-effects model, with analysis and forest plots generated in RevMan v5.4.

RESULTS

The analysis included three RCTs with a total of 189 patients assessed using per-protocol analysis. Two RCTs compared StrataXRT to standard of care, while the third compared it with Mepitel film and was reported separately. In the former RCTs, the odds ratio (OR) for developing acute grade 3 RD favored StrataXRT at 0.05 (95% CI, 0.01-0.22; P < 0.0001). The OR for developing acute grades 2-3 RD was 0.32 (95% CI, 0.03-3.18; P = 0.33). The RCT comparing StrataXRT with Mepitel film showed insignificant ORs for grade 3 and grades 2-3 RD. One RCT reported significantly lower erythema index (P = 0.008) and melanin index (P = 0.015) in StrataXRT patients. The use of StrataXRT did not raise additional safety concerns.

CONCLUSION

StrataXRT may help prevent severe acute RD in breast cancer RT patients. Further high quality, large-scale studies are needed to confirm these findings.

Comparison of preoperative versus postoperative treatment dosimetry plans of single-fraction stereotactic radiosurgery for surgically resected brain metastases

OBJECTIVE

Stereotactic radiosurgery (SRS) for operative brain metastasis (BrM) is usually administered 1 to 6 weeks after resection. Preoperative versus postoperative timing of SRS delivery related to surgery remains a critical question, as a pattern of failure is the development of leptomeningeal disease (LMD) in as many as 35% of patients who undergo postoperative SRS or the occurrence of radiation necrosis. As they await level I clinical data from ongoing trials, the authors aimed to bridge the gap by comparing postoperative with simulated preoperative single-fraction SRS dosimetry plans for patients with surgically resected BrM.

METHODS

The authors queried their institutional database to retrospectively identify patients who underwent postoperative Gamma Knife SRS (GKSRS) after resection of BrM between January 2014 and January 2021. Exclusion criteria were prior radiation delivered to the lesion, age < 18 years, and prior diagnosis of LMD. Once identified, a simulated preoperative SRS plan was designed to treat the unresected BrM and compared with the standard postoperative treatment delivered to the resection cavity per Radiation Therapy Oncology Group (RTOG) 90-05 guidelines. Numerous comparisons between preoperative and postoperative GKSRS treatment parameters were then made using paired statistical analyses.

RESULTS

The authors' cohort included 45 patients with a median age of 59 years who were treated with GKSRS after resection of a BrM. Primary cancer origins included colorectal cancer (27%), non-small cell lung cancer (22%), breast cancer (11%), melanoma (11%), and others (29%). The mean tumor and cavity volumes were 15.06 cm3 and 12.61 cm3, respectively. In a paired comparison, there was no significant difference in the planned treatment volumes between the two groups. When the authors compared the volume of surrounding brain that received 12 Gy or more (V12Gy), an important predictor of radiation necrosis, 64% of patient plans in the postoperative SRS group (29/45, p = 0.008) recorded greater V12 volumes. Preoperative plans were more conformal (p < 0.001) and exhibited sharper dose drop-off at the lesion margins (p = 0.0018) when compared with postoperative plans.

CONCLUSIONS

Comparison of simulated preoperative and delivered postoperative SRS plans administered to the BrM or resection cavity suggested that preoperative SRS allows for more highly conformal lesional coverage and sharper dose drop-off compared with postoperative plans. Furthermore, V12Gy was lower in the presurgical GKSRS plans, which may account for the decreased incidence of radiation necrosis seen in prior retrospective studies.

Adjuvant chemotherapy, not radiotherapy, prolongs survival for node-negative non-small cell lung cancer with positive surgical margins

Objective

The study objective was to determine differences in survival depending on adjuvant therapy type, timing, and sequence in node-negative disease with positive margins after non-small cell lung cancer resection.

Methods

The National Cancer Database was queried for patients with positive margins after surgical resection of treatment-naïve cT1-4N0M0 pN0 non-small cell lung cancer who underwent adjuvant radiotherapy or chemotherapy from 2010 to 2016. Adjuvant treatment groups were defined as surgery alone, chemotherapy alone, radiotherapy alone, concurrent chemoradiotherapy, sequential chemotherapy then radiotherapy, and sequential radiotherapy then chemotherapy. The impact of adjuvant radiotherapy initiation timing on survival was evaluated using multivariable Cox regression. Kaplan-Meier curves were generated to compare 5-year survival.

Results

A total of 1713 patients met inclusion criteria. Five-year survival estimates differed significantly between cohorts: surgery alone, 40.7%; chemotherapy alone, 47.0%; radiotherapy alone, 35.1%; concurrent chemoradiotherapy, 45.7%; sequential chemotherapy then radiotherapy, 36.6%; and sequential radiotherapy then chemotherapy, 32.2% (P = .033). Compared with surgery alone, adjuvant radiotherapy alone had a lower estimated survival at 5 years, although overall survival did not differ significantly (P = .8). Chemotherapy alone improved 5-year survival compared with surgery alone (P = .0016) and provided a statistically significant survival advantage over adjuvant radiotherapy (P = .002). Compared with radiotherapy-inclusive multimodal therapies, chemotherapy alone yielded similar 5-year survival (P = .066). Multivariable Cox regression showed an inverse linear association between time to adjuvant radiotherapy initiation and survival, but with an insignificant trend (10-day hazard ratio, 1.004; P = .90).

Conclusions

In treatment-naïve cT1-4N0M0 pN0 non-small cell lung cancer with positive surgical margins, only adjuvant chemotherapy was associated with a survival improvement compared with surgery alone, with no radiotherapy-inclusive treatment providing additional survival benefit. Delayed timing of radiotherapy initiation was not associated with a survival reduction.

Pilot Study Demonstrating the Value of Interdisciplinary Education on the Integration of Radiation Therapy in Lung Cancer Management

This study aimed to understand baseline knowledge of basic principles of radiation therapy for lung cancer among medical oncology, thoracic surgery, and pulmonology trainees and practicing physicians and also assess whether a didactic lecture will improve objective knowledge and perceived comfort level in making appropriate referrals to radiation oncology (RO). Radiation oncologists at 8 academic institutions offered a presentation covering indications, logistics, efficacy, and toxicity of thoracic radiation. Participants completed a survey to assess their prior exposures to RO and perceived value of the lecture, and objective knowledge gained based on pre/post-lecture questions. Among 121 attendees, 76 completed the pre-test, and 25 the post-test (response rates 62.8% and 20.7%, respectively). Fifty-seven (75.0%) had never previously experienced a RO didactic about lung cancer, 62 (81.6%) had never seen a linear accelerator, and 65 (85.5%) had never rotated in a RO department. The mean pre-test score was 53.5% (SD 17.6%), with a trend (p = 0.066) towards thoracic surgeons (61.5%) performing better than medical oncologists (55.5%) or pulmonologists (48.3%). Level of training (p = 0.130), and prior RO exposures (p = 0.240), did not significantly impact pre-test scores. The mean post-test score of 75.1% (SD 3.6%) was significantly higher than mean pre-test score (p < 0.001). After the lecture, 25 participants (100%) felt more knowledgeable about RO, and 24 (96%) felt more comfortable making appropriate referrals to RO. A didactic lecture about RO for trainees and physicians who treat lung cancer at 8 academic institutions was feasible, filled a gap in exposure, and improved knowledge.

Integration of Universal Germline Genetic Testing for All New Breast Cancer Patients

BACKGROUND

The American Society of Breast Surgeons recommends genetic testing (GT) for all women with breast cancer (BC), but implementation and uptake of GT has not been well-described.

METHODS

A retrospective chart review was performed for newly diagnosed BC patients or patients with a newly identified recurrence of BC seen in a multidisciplinary clinic (MDBC) who were offered genetic counseling (GC) and GT.

RESULTS

The 138 women attending the MDBC had a median age of 54 years and comprised non-Hispanic whites (46%), Asians (28%), Hispanics (17%), blacks (4%), and other (5%). Of the 105 (76%) patients without prior GT, 100 (95%) accepted GC, with 93 (93%) of these 100 patients undergoing GT. The patients meeting the National Comprehensive Cancer Network (NCCN) guidelines for GT were more likely to undergo GT. Testing was performed with a 67- to 84-gene panel, together with an 8- to 9-gene STAT panel if needed. Among 120 patients with reports available, including 33 patients previously tested, 15 (12%) were positive (1 BLM, 1 BRCA1, 3 BRCA2, 1 BRIP1, 1 CFTR, 1 CHEK2, 1 MUTYH, 1 PALB2, 1 PRSS1, 1 RAD50, 1 RET, and 2 TP53), 44 (37%) were negative, and 61 (51%) had an uncertain variant. The median time to STAT results (n = 50) was 8 days. The STAT results were available before surgery for 47 (98%) of the 48 STAT patients undergoing surgery.

CONCLUSIONS

New BC patients attending the MDBC demonstrated high rates of acceptance of GC and GT. The combination of GC and GT can offer timely information critical to patient risk assessment and treatment planning.

Diagnosis of coronary layered plaque by deep learning

Background/Introduction

Healed coronary plaques, morphologically characterized by a layered pattern, are signatures of previous plaque disruption and healing. Recent optical coherence tomography (OCT) studies showed that layered plaque is associated with vascular vulnerability and rapid plaque progression. However, the diagnosis of layered plaque requires expertise in OCT image interpretation and is susceptible to interobserver variability.

Purpose

We aimed to develop a deep learning (DL) model for an accurate diagnosis of layered plaque.

Methods

We developed a Visual Transformer (ViT)-based DL model emulating the cardiologists who review consecutive OCT frames to make a diagnosis (Figure 1), and compared it to the standard convolutional neural network (CNN) model. We used 302,415 cross-sectional OCT images from 873 patients collected from 9 sites: 237,021 images from 581 patients for training and internal validation from 8 sites, and 65394 images from 292 patients collected from another site for external validation.

Results

Model performances were evaluated using the area under the receiver operating characteristics (AUC). In the five-fold cross validation, the ViT-based model showed better performance than the standard CNN-based model with AUC of 0.886 (95% confidence interval [CI], 0.882–0.891) compared with 0.797 (95% CI, 0.790–0.804). The ViT-based model also outperformed the standard CNN-based model in the external validation, with an AUC of 0.857 (95% CI, 0.849–0.864) compared to 0.806 (95% CI, 0.797–0.815) (Figure 2).

Conclusion(s)

The ViT-based DL model will help cardiologists to make an accurate diagnosis of layered plaque, which might help to stratify the risk of future adverse cardiac events.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Mrs. Gillian Gray through the Allan Gray Fellowship Fund in Cardiology

Patterns of Use of Stereotactic Body Radiation Therapy Compared With Surgery for Definitive Treatment of Primary Early-stage Non-small Cell Lung Cancer

OBJECTIVE

As stereotactic body radiation therapy (SBRT) becomes widely available for early-stage non-small cell lung cancer (NSCLC), there may be concerns in the surgical community that SBRT is being offered for patients with operable tumors, even though surgery is standard of care. We evaluated the trends in SBRT and surgery over time for patients with NSCLC.

MATERIALS AND METHODS

The National Cancer Database was queried for patients with node-negative NSCLC ≤5 cm from 2004 to 2016. The relationships between definitive local treatment modalities and year were analyzed using a multinomial regression model while controlling for other covariates.

RESULTS

Among the 202,367 patients who met the inclusion criteria, there was a steady decrease in mean tumor size in all treatment modalities, from 2.44 cm (SD=1.08) to 2.25 cm (SD=1.00) over the study period. In the multinomial model, the probability of receiving lobectomy demonstrated a slight decline from 58% (2004) to 53% (2016). The use of SBRT increased from 1% to 20%, while patients receiving no therapy declined from 27% to 16%. The likelihood of SBRT increased with year of diagnosis (P<0.0001) and decreasing tumor size (P<0.0001), compared with lobectomy. Age, race, income, facility, and Charlson-Deyo score were also associated with treatment modality.

CONCLUSIONS

The mean tumor size of early-stage NSCLC decreased over the study period for all treatment modalities. SBRT use has increased, mostly among older patients with smaller tumors and Charlson-Deyo scores ≥3. The increase in SBRT contributed to the significant decline in patients who had no therapy.

Voxelwise Prediction of Recurrent High-Grade Glioma via Proximity Estimation-Coupled Multidimensional Support Vector Machine

PURPOSE

To provide early and localized glioblastoma (GBM) recurrence prediction, we introduce a novel postsurgery multiparametric magnetic resonance-based support vector machine (SVM) method coupling with stem cell niche (SCN) proximity estimation.

METHODS AND MATERIALS

This study used postsurgery magnetic resonance imaging (MRI) scans from 50 patients with recurrent GBM, obtained approximately 2 months before clinically diagnosed recurrence. The main prediction pipeline consisted of a proximity-based estimator to identify regions with high risk of recurrence (HRRs) and an SVM classifier to provide voxelwise prediction in HRRs. The HRRs were estimated using the weighted sum of inverse distances to 2 possible origins of recurrence-the SCN and the tumor cavity. Subsequently, multiparametric voxels (from T1, T1 contrast-enhanced, fluid-attenuated inversion recovery, T2, and apparent diffusion coefficient) within the HRR were grouped into recurrent (warped from the clinical diagnosis) and nonrecurrent subregions and fed into the proximity estimation-coupled SVM classifier (SVM_PE). The cohort was randomly divided into 40% and 60% for training and testing, respectively. The trained SVM_PE was then extrapolated to an earlier time point for earlier recurrence prediction. As an exploratory analysis, the SVM_PE predictive cluster sizes and the image intensities from the 5 magnetic resonance sequences were compared across time to assess the progressive subclinical traces.

RESULTS

On 2-month prerecurrence MRI scans from 30 test cohort patients, the SVM_PE classifier achieved a recall of 0.80, a precision of 0.69, an F1-score of 0.73, and a mean boundary distance of 7.49 mm. Exploratory analysis at early time points showed spatially consistent but significantly smaller subclinical clusters and significantly increased T1 contrast-enhanced and apparent diffusion coefficient values over time.

CONCLUSIONS

We demonstrated a novel voxelwise early prediction method, SVM_PE, for GBM recurrence based on clinical follow-up MR scans. The SVM_PE is promising in localizing subclinical traces of recurrence 2 months ahead of clinical diagnosis and may be used to guide more effective personalized early salvage therapy.

Temporality and Patterns of Metastatic Recurrence in Node-Positive Breast Cancer Following Trimodality Therapy: Opportunity for Improved Oligometastases Detection and Salvage Local Therapy

OBJECTIVES

There is evidence that detection and treatment of oligometastases (≤5 lesions) may improve survival in breast cancer patients. However, there are no current national guidelines for screening of early, asymptomatic metastases. This study examined the patterns and timing of recurrence with respect to survival in node-positive breast cancer (NPBC) patients at higher risk for developing metastases.

METHODS

A single-institution retrospective review of NPBC patients treated with trimodality therapy was performed to collect patient and disease characteristics, recurrence location, method of detection, and survival outcome. Univariate and multivariate analyses were done to identify factors associated with recurrence.

RESULTS

Ninety-four NPBC patients treated at a safety-net hospital between 2008 and 2019 were identified. Twenty-one developed recurrence and were divided into oligometastatic (OM) (n=10) or diffusely metastatic (DM) (n=11) subgroups. Median recurrence-free survival in OM and DM was 18 and 36 months, respectively. Median overall survival (OS) for OM was not reached. Median OS for DM was 57 months. Four patients with OM progressed to diffuse disease in a median period of 17 months; median survival thereafter was 57 months. All patients with recurrence had distant metastases on initial detection, with the most common site being bone (14). Recurrence was most frequently detected by computed tomography (CT) (13), with the majority of disease located within the thorax region.

CONCLUSIONS

All NPBC patients had distant metastasis at time of recurrence. Patients with OM had shorter interval to recurrence yet longer OS compared with DM. This study highlights improved surveillance imaging for timely detection of OM breast cancer that may yet be amenable to aggressive local salvage therapy to prevent progression to diffuse disease.

Surviving Over a Decade With Glioblastoma: A Clinical Course Characterized by Multiple Recurrences, Numerous Salvage Treatments, and Novel Use of Cesium-131 Tiles

The prognosis for patients diagnosed with recurrent glioblastoma (GBM) remains poor, with no clear standard of care regarding salvage therapy. Common approaches include chemotherapy, re-resection, tumor treating fields, and reirradiation. However, most studies have shown these to have limited benefits. Reirradiation is particularly difficult due to concern for increased risk of toxicity to surrounding normal brain tissue. A novel intracranial brachytherapy system called GammaTile® (GT Medical Technologies, Tempe, Arizona) involves the placement of Cesium-131 radioactive tiles in the tumor cavity following maximal safe resection. This allows for a highly conformal dose distribution with rapid fall-off to minimize overlap with prior radiation fields and for the application of radiation directly to the high-risk tumor bed. This case report highlights a patient with GBM who survived 11.5 years through multiple recurrences and discusses the many salvage treatments he received, including bevacizumab, irinotecan, and stereotactic radiosurgery (SRS). This case exemplifies that aggressive systemic and local therapies can work well in select patients allowing for long-term survival with a good quality of life. Further efforts should be made to identify which patients may benefit from these therapies. The case study additionally reports on the use of GammaTile therapy. Due to prior external beam radiation therapy and SRS to the treatment site, further external beam radiation options were limited, and the patient was offered GammaTile as local therapy. Although it did not provide a survival benefit in this case due to progressive disease outside of the field of treatment, GammaTile serves as a valuable option in providing local therapy to patients who can no longer receive further radiation. It should be used with careful consideration in lesions characterized by aggressive local invasion.

Automatic detection and segmentation of multiple brain metastases on magnetic resonance image using asymmetric UNet architecture

Detection of brain metastases is a paramount task in cancer management due both to the number of high-risk patients and the difficulty of achieving consistent detection. In this study, we aim to improve the accuracy of automated brain metastasis (BM) detection methods using a novel asymmetric UNet (asym-UNet) architecture. An end-to-end asymmetric 3D-UNet architecture, with two down-sampling arms and one up-sampling arm, was constructed to capture the imaging features. The two down-sampling arms were trained using two different kernels (3 × 3 × 3 and 1 × 1 × 3, respectively) with the kernel (1 × 1 × 3) dominating the learning. As a comparison, vanilla single 3D UNets were trained with different kernels and evaluated using the same datasets. Voxel-based Dice similarity coefficient (DSC_v), sensitivity (S _v), precision (P _v), BM-based sensitivity (S _BM), and false detection rate (F _BM) were used to evaluate model performance. Contrast-enhanced T1 MR images from 195 patients with a total of 1034 BMs were solicited from our institutional stereotactic radiosurgery database. The patient cohort was split into training (160 patients, 809 lesions), validation (20 patients, 136 lesions), and testing (15 patients, 89 lesions) datasets. The lesions in the testing dataset were further divided into two subgroups based on the diameters (small S = 1-10 mm, large L = 11-26 mm). In the testing dataset, there were 72 and 17 BMs in the S and L sub-groups, respectively. Among all trained networks, asym-UNet achieved the highest DSC_v of 0.84 and lowest F _BM of 0.24. Although vanilla 3D-UNet with a single 1 × 1 × 3 kernel achieved the highest sensitivities for the S group, it resulted in the lowest precision and highest false detection rate. Asym-UNet was shown to balance sensitivity and false detection rate as well as keep the segmentation accuracy high. The novel asym-UNet segmentation network showed overall competitive segmentation performance and more pronounced improvement in hard-to-detect small BMs comparing to the vanilla single 3D UNet.

Use of Salvage Surgery or Stereotactic Radiosurgery for Multiply Recurrent Skull Base Chordomas: A Single-Institution Experience and Review of the Literature

Introduction  Chordomas are locally destructive neoplasms characterized by appreciable recurrence rates after initial multimodality treatment. We examined the outcome of salvage treatment in recurrent/progressive skull base chordomas. Methods  This is a retrospective review of recurrent/progressive skull base chordomas at a tertiary urban academic medical center. The outcomes evaluated were overall survival, progression-free survival (PFS), and incidence of new toxicity. Results  Eighteen consecutive patients who underwent ≥1 course of treatment (35.3% salvage surgery, 23.5% salvage radiation, and 41.2% both) were included. The median follow-up was 98.6 months (range 16-215 months). After initial treatment, the median PFS was 17.7 months (95% confidence interval [CI]: 4.9-22.6 months). Following initial therapy, age ≥ 40 had improved PFS on univariate analysis ( p  = 0.03). All patients had local recurrence, with 15 undergoing salvage surgical resections and 16 undergoing salvage radiation treatments (mostly stereotactic radiosurgery [SRS]). The median PFS was 59.2 months (95% CI: 4.0-99.3 months) after salvage surgery, 58.4 months (95% CI: 25.9-195 months) after salvage radiation, and 58.4 months (95% CI: 25.9.0-98.4 months) combined. Overall survival for the total cohort was 98.7% ± 1.7% at 2 years and 92.8% ± 5.5% at 5 years. Salvage treatments were well-tolerated with two patients (11%) reporting tinnitus and one patient each (6%) reporting headaches, visual field deficits, hearing loss, anosmia, dysphagia, or memory loss. Conclusion  Refractory skull base chordomas present a challenging treatment dilemma. Repeat surgical resection or SRS seems to provide adequate salvage therapy that is well-tolerated when treated at a tertiary center offering multimodality care.

Trimodality vs Chemoradiation and Salvage Resection in cN2 Stage IIIA Non-Small Cell Lung Cancer

To determine the overall survival (OS) in patients who underwent planned trimodality therapy (TMT) and those who underwent definitive concurrent chemoradiation (CRT), but later received salvage resection (SR) for stage IIIA (cN2) (AJCC 7th ed.) non-small cell lung cancer. National Cancer Database data set from 2004 to 2014 was queried. TMT was defined as multiagent CRT with dose >45 Gy, followed by lobectomy or pneumonectomy ≤90 days from end of CRT. SR was defined as multiagent CRT with dose >59 Gy and lobectomy or pneumonectomy performed >90 days from CRT completion. Propensity score weighting and propensity score matching methods were used to balance patient and tumor characteristics and to calculate hazard ratios. A total of 2025 (1899 TMT and 126 SR) patients were analyzed. TMT and SR groups shared similar characteristics. Surgery occurred at a median of 41 days (range 1-90) after CRT in the TMT group and 114 days (91-440) in the SR group. The 90-day mortality after surgery was 6.5% for TMT and 5% for SR (P = 0.43). The 3- and 5-year OS were 55.1% and 35.7% for TMT and 51.6% and 45.0% for SR (P = 0.92, 0.68), with no difference across unadjusted cohort and propensity-adjusted cohort. Patients with cN2 stage IIIA non-small cell lung cancer treated in the United States with definitive CRT followed by SR had similar OS as upfront TMT with similar postoperative mortality despite SR occurring >90 days after >59 Gy CRT. SR remains an option for medically appropriate patients after definitive dose CRT.

Stereotactic radiosurgery and ipilimumab for patients with melanoma brain metastases: clinical outcomes and toxicity

INTRODUCTION

There is evidence that the combination of ipilimumab and stereotactic radiosurgery (SRS) for brain metastases improves outcomes. We investigated clinical outcomes, radiation toxicity, and impact of ipilimumab timing in patients treated with SRS for melanoma brain metastases.

METHODS

We retrospectively identified 91 patients treated with SRS at our institution for melanoma brain metastases from 2006 to 2015. Concurrent ipilimumab administration was defined as within ± 4 weeks of SRS procedure. Acute and late toxicities were graded with CTCAE v4.03. Overall survival (OS), local failure, distant brain failure, and failure-free survival were analyzed with the Kaplan-Meier method. OS was analyzed with Cox regression.

RESULTS

Twenty-three patients received ipilimumab concurrent with SRS, 28 patients non-concurrently, and 40 patients did not receive ipilimumab. The median age was 62 years and 91% had KPS ≥ 80. The median follow-up time was 7.4 months. Patients who received ipilimumab had a median OS of 15.1 months compared to 7.8 months in patients who did not (p = 0.02). In multivariate analysis, ipilimumab (p = 0.02) and diagnosis-specific graded prognostic assessment (p = 0.02) were associated with OS. There were no differences in intracranial control by ipilimumab administration or timing. The incidence of radiation necrosis was 5%, with most events occurring in patients who received ipilimumab.

CONCLUSIONS

Patients who received ipilimumab had improved OS even after adjusting for prognostic factors. Ipilimumab did not appear to increase risk for acute toxicity. The majority of radiation necrosis events, however, occurred in patients who received ipilimumab. Our results support the continued use of SRS and ipilimumab as clinically appropriate.

Integration of radiation and immunotherapy in breast cancer - Treatment implications

Radiation therapy (RT) has been successfully used in the treatment of breast cancer (BC) for over a century. While historically thought to be immunosuppressive, new data have shown that RT can work together with the immune system to eliminate cancer. It can cause immunogenic cell death and facilitate tumor neoantigen presentation and cross-priming of tumor-specific T-lymphocytes, turning irradiated tumor into an in-situ vaccine. Unfortunately, due to various immune escape mechanism put in place by the tumor, RT alone rarely results in a systemic response of metastatic disease sites (known as the abscopal effect). Immunotherapy, a series of agents designed to stimulate the immune system in order to generate tumor-specific immune response, is showing promise in treatment of various cancers, including BC, and can be an ideal complement to RT in stimulating a systemic immune response to reject the tumor cells. This review discusses the mechanisms in which RT can trigger an immune response for tumor rejection, and provide emerging preclinical and clinical data of combination immunoradiotherapy, and its potential in treating BC.

Safety-net versus private hospital setting for brain metastasis patients treated with radiosurgery alone: Disparities in follow-up care and outcomes

BACKGROUND

Stereotactic radiosurgery (SRS) alone is an increasingly accepted treatment for brain metastases, but it requires adherence to frequently scheduled follow-up neuroimaging because of the risk of distant brain metastasis. The effect of disparities in access to follow-up care on outcomes after SRS alone is unknown.

METHODS

This retrospective study included 153 brain metastasis patients treated consecutively with SRS alone from 2010 through 2016 at an academic medical center and a safety-net hospital (SNH) located in Los Angeles, California. Outcomes included neurologic symptoms, hospitalization, steroid use and dependency, salvage SRS, salvage whole-brain radiotherapy, salvage neurosurgery, and overall survival.

RESULTS

Ninety-three of the 153 patients were private hospital (PH) patients, and 60 were SNH patients. The median follow-up time was 7.7 months. SNH patients received fewer follow-up neuroimaging studies (1.5 vs 3; P = .008). In a multivariate analysis, the SNH setting was a significant risk factor for salvage neurosurgery (hazard ratio [HR], 13.65; P < .001), neurologic symptoms (HR, 3.74; P = .002), and hospitalization due to brain metastases (HR, 6.25; P < .001). More clinical visits were protective against hospitalizations due to brain metastases (HR, 0.75; P = .002), whereas more neuroimaging studies were protective against death (HR, 0.65; P < .001).

CONCLUSIONS

SNH patients with brain metastases treated with SRS alone had fewer follow-up neuroimaging studies and were at higher risk for neurologic symptoms, hospitalization for brain metastases, and salvage neurosurgery in comparison with PH patients. Clinicians should consider the practice setting and patient access to follow-up care when they are deciding on the optimal strategy for the treatment of brain metastases. Cancer 2018;124:167-75. © 2017 American Cancer Society.

Daily patient setup error in prostate image guided radiation therapy with fiducial-based kilovoltage onboard imaging and conebeam computed tomography

BACKGROUND

This study examined the interfraction setup error in patients undergoing prostate radiotherapy using fiducial markers and on-board imaging.

METHODS

Patients (n=53) were aligned to the treatment isocenter by laser followed by orthogonal kilovoltage (kV) radiographs to visualize bony anatomy and implanted fiducial markers. The magnitude and direction of couch shifts for isocenter correction required was determined by image registration for bony anatomy and fiducial markers. Twice weekly, 25 of the 53 patients also underwent conebeam computed tomography (CBCT) to measure any residual error in patient positioning. Based on individual coordinate shifts from CBCT, a net three-dimensional (3D) residual shift magnitude vector R was calculated.

RESULTS

The average couch shifts were 0.26 and 0.40 cm in inferior direction and 0.25 and 0.33 cm in superior direction for alignments made with bony anatomy and fiducial markers, respectively (P<0.0001). There were no significant differences noted in the vertical or lateral planes between the two image registration methods. In subset of 25 patients, no residual shift from fiducial plain film set up was required with CBCT matching in 66.5%, 52.4% and 57.9% of fractions for longitudinal, vertical and lateral planes, respectively, with majority (79%) of patients having a net residual 3D shifts of <0.3 cm. The use of CBCT increased average treatment time by approximately 6 min compared to kV radiographs alone.

CONCLUSIONS

The residual setup errors following daily kV image guided localization, as determined by CBCT, were small, which demonstrates high accuracy of kV localization when fiducial markers are present.

Multi-Institutional Implementation and Evaluation of a Curriculum for the Medical Student Clerkship in Radiation Oncology

PURPOSE

Radiation oncology curriculum development is challenging because of limited numbers of trainees at any single institution. The goal of this project is to implement and evaluate a standardized medical student clerkship curriculum following the multi-institutional cooperative group research model.

METHODS

During the 2013 academic year, a standardized curriculum was implemented at 11 academic medical centers consisting of three 1-hour lectures and a hands-on radiation treatment planning workshop. After the curriculum, students completed anonymous evaluations using Likert-type scales (1 = "not at all" to 5 = "extremely") and free responses. Evaluations asked students to rate their comfort, before and after the curriculum, with radiation oncology as a specialty, knowledge of radiotherapy planning methods, and ability to function as a radiation oncology resident. Nonparametric statistical tests were used in the analysis.

RESULTS

Eighty-eight students at 11 academic medical centers completed the curriculum de novo, with a 72.7% (64 of 88) survey response rate. Fifty-seven students (89.1%) reported intent to pursue radiation oncology as their specialty. Median (interquartile range) student ratings of the importance of curricular content were as follows: overview, 4 (4-5); radiation biology/physics, 5 (4-5); practical aspects/emergencies, 5 (4-5); and planning workshop, 4 (4-5). Students reported that the curriculum helped them better understand radiation oncology as a specialty (5 [4-5]), increased specialty decision comfort (4 [3-5]), and would help the transition to radiation oncology residency (4 [4-5]). Students rated their specialty decision comfort significantly higher after completing the curriculum (4 [4-5] versus 5 [5-5]; P < .001).

CONCLUSIONS

A national standardized curriculum was successfully implemented at 11 academic medical centers, providing proof of principle that curriculum development can follow the multi-institutional cooperative group research model.

Equivalent Survival With Mastectomy or Breast-conserving Surgery Plus Radiation in Young Women Aged < 40 Years With Early-Stage Breast Cancer: A National Registry-based Stage-by-Stage Comparison

BACKGROUND

Studies have shown that young patients with early-stage breast cancer (BC) are increasingly undergoing mastectomy instead of breast-conserving therapy (BCT) consisting of lumpectomy and radiation. We examined the difference in outcomes in young women (aged < 40 years) who had undergone BCT versus mastectomy.

MATERIALS AND METHODS

The Surveillance, Epidemiology, and End Results database was queried for women aged < 40 years with stage I or II invasive BC treated with surgery from 1998 to 2003. Breast cancer-specific survival (BCSS) and overall survival (OS) were evaluated using Kaplan-Meier survival analysis and the log-rank test between treatment types.

RESULTS

Of the 7665 women, 3249 received BCT and 2627 underwent mastectomy without radiation. When separated by stage (I, IIA, and IIB), with a median follow-up duration of 111 months, the BCT and mastectomy-only groups showed no statistically significant differences in BCSS and OS. Overall, the age group of 35 to 39 years (66% of total) was associated with better 10-year BCSS (88%) and OS (86.1%) compared with the younger patients aged 20 to 34 years (34% of total). The latter group had a 10-year BCSS and OS of 84.1% and 82.3%, respectively (P < .001 for both BCSS and OS). However, when the patients of each age group were further subdivided by stage, the BCT group continued to show noninferior BCSS and OS compared with the mastectomy group in all subgroups.

CONCLUSION

The results of our study suggest that although young age might be a poor prognostic factor for BC, no evidence has shown that these patients will have better outcomes after mastectomy than after BCT.

Second cancer, breast cancer, and cardiac mortality in stage T1aN0 breast cancer patients with or without external beam radiation therapy: a national registry study

INTRODUCTION/BACKGROUND

With improved BC screening and treatment, the risk for long-term toxicities of treatments must be considered, especially in good prognosis patients. In this study we examined the outcome, risks of second cancers, and cardiac mortality with RT for early-stage BC from recent years.

MATERIALS AND METHODS

Analysis of the SEER database was conducted for women who had stage T1aN0 BC as their first primary malignancy between 1990 and 1997 and were treated with partial or complete mastectomy with or without external beam RT. The overall survival (OS), BC-specific survival (BCSS), cardiac cause-specific survival (CCS), and deaths from second cancers in the chest area were compared between the RT and no-RT groups.

RESULTS

Of the 6515 women identified, 2796 received RT and 3719 did not. The median age group (60-64 years) and follow-up lengths (approximately 15 years) were similar. Compared with the RT group, the no-RT group was associated with lower 10-year OS (85.5% vs. 79.3%; P < .0001), BCSS (97.3% vs. 96.4%; P = .04), and CCS (97.0% vs. 93.8%; P < .0001). In the RT group, left-sided BC was not associated with higher cardiac mortality. There were no statistically significant incidences in mortality due to subsequent cancers. The most common second cancer mortality included 114 (2%) lung, 25 (0.4%) lymphoma, 19 (0.3%) leukemia, 3 (0.05%) soft tissue, and 2 (0.03%) esophagus.

CONCLUSION

This review of SEER data suggests that secondary malignancy in the chest area and cardiac mortality are rare after RT in the 1990s for T1aN0 BC.

Detection of interleukin-33 in serum and carcinoma tissue from patients with hepatocellular carcinoma and its clinical implications

OBJECTIVE

To study the clinical significance of intercellular interleukin (IL)-33 in hepatocellular carcinoma (HCC).

METHODS

Using immunohistochemistry, this prospective study compared IL-33 protein levels in samples of HCC tissue and normal tissue adjacent to the tumour in 60 patients with HCC, and in normal liver tissue from six healthy controls. Interferon (IFN)-α, IFN-γ and IL-33 serum levels were also analysed by enzyme-linked immunosorbent assay in HCC 30 patients and 10 healthy controls. The level of IL-33 immunohistochemical staining was compared with the rate of lymph node metastasis in HCC patients.

RESULTS

IL-33 was strongly positive in the cytoplasm of hepatocytes. The median percentage of IL-33-positive tissue was higher in HCC than in normal liver tissue samples (adjacent to the tumour or from controls). Serum IFN-α, IFN-γ and IL-33 levels were higher in pre- and postoperative samples from HCC patients than in control samples, and in patients with metastasis compared with those without metastasis.

CONCLUSIONS

Increased IL-33 protein levels were observed in serum and liver tissue from HCC patients; IL-33 may be a useful biological marker for monitoring HCC growth and metastasis.

UV light emitting transparent conducting tin-doped indium oxide (ITO) nanowires

Multifunctional single crystalline tin-doped indium oxide (ITO) nanowires with tuned Sn doping levels are synthesized via a vapor transport method. The Sn concentration in the nanowires can reach 6.4 at.% at a synthesis temperature of 840 °C, significantly exceeding the Sn solubility in ITO bulks grown at comparable temperatures, which we attribute to the unique feature of the vapor-liquid-solid growth. As a promising transparent conducting oxide nanomaterial, layers of these ITO nanowires exhibit a sheet resistance as low as 6.4 Ω/[Symbol: see text] and measurements on individual nanowires give a resistivity of 2.4 × 10(-4) Ω cm with an electron density up to 2.6 × 10(20) cm(-3), while the optical transmittance in the visible regime can reach ∼ 80%. Under the ultraviolet excitation the ITO nanowire samples emit blue light, which can be ascribed to transitions related to defect levels. Furthermore, a room temperature ultraviolet light emission is observed in these ITO nanowires for the first time, and the exciton-related radiative process is identified by using temperature-dependent photoluminescence measurements.

Influence of season on some skin properties: winter vs. summer, as experienced by 354 Shanghaiese women of various ages

The facial skin of 354 women, aged 18-80, living in Shanghai, was investigated over two successive 6-month periods, summer and winter. Results from clinical assessments indicate that aging signs, such as wrinkling and sagging, are unaffected over such period. However, physical measurements revealed alterations in some functional criteria of the skin, such as sebum output, skin colour, melanin content of pigmented spots, skin hydration, all being increased during summer. The relationships between all criteria, as well as technical or applied inferences/consequences from this study, are discussed.

PTEN, tau-AP-3, thymidylate synthase immunohistochemistry scoring expression in patients with uterine leiomyomas, uterine smooth muscle tumors of uncertain malignancy potential and uterine leiomyosarcomas

Uterine smooth muscle tumors are frequently classified as benign and malignant. However, an assortment of mitotic counts and nuclear atypia can be indecisive between uncertain malignant potential, and malignant uterine smooth muscle tumors. We applied three immunohistochemical parameters to distinguish between cases of benign, malignant, and those with uncertain malignant histology.

Atomistic free-volume zones and inelastic deformation of metallic glasses

The amorphous nature of metallic glasses and their mechanical properties make them interesting for structural applications. However, the interplay between the nature of atomic structures in metallic glasses and mechanical properties remains poorly understood. In this study, high-frequency dynamic micropillar tests have been used to probe both atomic clusters and flow defects in metallic glasses. We show that loosely bonded atomistic free-volume zones that are enveloped elastically by tightly bonded atomic clusters show a deformation character similar to supercooled liquids. At room temperature, the effective viscosity of these free-volume zones is of the order of 1 x 10(8) Pa s before the occurrence of shear banding. The confined liquid-like deformation of free-volume zones leads to significant mechanical hysteresis in micropillars under dynamic loading, providing important insight into how atomistic structural features affect the deformation behaviours in metallic glasses in the apparent elastic regime. The inelastic behaviour also serves as the basis for the superior damping resistance of metallic glasses.

Malignant transformation of extragonadal endometriosis: a case report

Though malignant transformation of endometriosis has been documented, malignancy arising from extragonadal endometriosis is rare. We present the case of a 39-year-old woman with abdominal pain and fullness after menstruation. Evaluation revealed a cul-de-sac mass and CA-125 level of 1048 U/ml. A hysterectomy, bilateral salpingo-oophorectomy, and omentectomy were performed. Endometrioid adenocarcinoma with a clearly defined transition zone from endometriosis to adenocarcinoma was noted histologically. Adjuvant chemotherapy and GnRH agonist treatment was administered. Serum CA-125 level was 1.51 U/ml 19 months after completion of treatment. Patients with endometriosis and elevated CA-125 levels should be managed aggressively and CA-125 levels monitored until they have normalized.

Importance of the (nabla) D term in frequency-resolved optical diffusion imaging

The effects of the approximation DD=0 that is often used in frequency-resolved optical diffusion imaging are examined. It is shown that this approximation can affect the performance of integral-equation-based approaches to optical diffusion imaging, such as the Born iterative method and the distorted Born iterative method. The approximation introduces errors into the calculation of data used in simulations, which can lead to misleading evaluations of reconstruction algorithms. Numerical calculations show the magnitude of these effects and the appearance of artifacts in reconstructed images when conventional inversion algorithms are applied to more accurately calculated data.

Pharmacokinetics of weekly transdermal estradiol controlled delivery system in postmenopausal Chinese

AIM

To study Pharmacokinetical profile of weekly transdermal estradiol controlled delivery system (E2-WTCDS) in 18 Chinese postmenopausal women.

METHODS

Single and multiple daily doses of E2-WTCDS were applied to an area of intact skin on the lower abdomen, using Estraderm TTS (E2-TTS) from Ciba-Geigy Company as control. E2 concentration in serum was measured by RIA.

RESULTS

Cmax 38 +/- 5 ng.L-1, Tmax 22 +/- 5 h, AUC 5651 +/- 386 ng.h.L-1, Cmax(SS) 44 +/- 7 ng.L-1, Cmax(SS) 35 +/- 4 ng.L-1, Fl 0.22 +/- 0.10. The relative bioavailability of E2-WTCDS was comparable to E2-TTS during the same period of system application.

CONCLUSION

E2-WTCDS maintained relatively constant and effective serum estradiol concentrations and is suitable for once-weekly application.