Organ sparing treatment for penile cancer using a 3D-printed high-dose-rate brachytherapy applicator

PURPOSE

We present a case study of the treatment of localized squamous cell carcinoma on the glans penis with a custom-fabricated high-dose-rate (HDR) brachytherapy applicator.

METHODS AND MATERIALS

A cylindrically shaped applicator was fabricated with eight embedded channels suitable for standard plastic brachytherapy catheters. An additional custom silicone bolus/sleeve was designed to be used with the 3D-printed applicator to provide an additional offset from the source to skin to reduce the surface dose and for patient comfort.

RESULTS

The patient (recurrent cT1a penile cancer) underwent CT simulation, and the brachytherapy plan was created with a nominal prescription dose of 40 Gy in 10 fractions given bidaily to the surface, and 35 Gy at 5 mm depth. Dose coverage to the clinical target volume was 94% (D90). Most fractions were treated with only 5-10 min of setup time. Follow up visits up to 1 year showed no evidence of disease with no significant changes in urinary and sexual function and limited cosmetic detriment to the patient.

CONCLUSIONS

Patient-specific organ-sparing HDR plesiotherapy using 3D printing technology can provide reliable and reproducible patient setup and may be effective in achieving disease control for superficial penile cancer, although preserving patient quality of life.

Thermal ablation compared to stereotactic body radiation therapy for hepatocellular carcinoma: A multicenter retrospective comparative study

BACKGROUND AIMS

Early-stage HCC can be treated with thermal ablation or stereotactic body radiation therapy (SBRT). We retrospectively compared local progression, mortality, and toxicity among patients with HCC treated with ablation or SBRT in a multicenter, US cohort.

APPROACH RESULTS

We included adult patients with treatment-naïve HCC lesions without vascular invasion treated with thermal ablation or SBRT per individual physician or institutional preference from January 2012 to December 2018. Outcomes included local progression after a 3-month landmark period assessed at the lesion level and overall survival at the patient level. Inverse probability of treatment weighting was used to account for imbalances in treatment groups. The Cox proportional hazard modeling was used to compare progression and overall survival, and logistic regression was used for toxicity. There were 642 patients with 786 lesions (median size: 2.1 cm) treated with ablation or SBRT. In adjusted analyses, SBRT was associated with a reduced risk of local progression compared to ablation (aHR 0.30, 95% CI: 0.15-0.60). However, SBRT-treated patients had an increased risk of liver dysfunction at 3 months (absolute difference 5.5%, aOR 2.31, 95% CI: 1.13-4.73) and death (aHR 2.04, 95% CI: 1.44-2.88, p < 0.0001).

CONCLUSIONS

In this multicenter study of patients with HCC, SBRT was associated with a lower risk of local progression compared to thermal ablation but higher all-cause mortality. Survival differences may be attributable to residual confounding, patient selection, or downstream treatments. These retrospective real-world data help guide treatment decisions while demonstrating the need for a prospective clinical trial.

Ablative radiotherapy in oligometastatic pancreatic cancer to delay polyprogression, limit chemotherapy, and improve outcomes

PURPOSE

The oligometastatic state is observed in patients across many malignancies, with increased recognition regarding improved outcomes after local therapies. However, there is limited data specifically regarding pancreatic ductal adenocarcinoma (PDAC). We hypothesized that an oligometastatic pancreatic ductal adenocarcinoma (OPanc) phenotype would benefit from stereotactic ablative radiotherapy (SABR) to all active metastatic sites. Here, we report our institutional experience of SABR-treated OPanc to evaluate the feasibility of the approach.

METHODS AND MATERIALS

A retrospective review of patients with synchronous or metachronous OPanc (one to five metastases) who received SABR to all active metastatic sites was performed. We identified a comparable group of patients with similar metastatic burden, range of CA19-9 levels, and no progression for at least five months who did not receive SABR. We compared overall survival as the primary outcome, and polyprogression-free survival and time off chemotherapy as the secondary exploratory assessments. A third group presenting with stage IV PDAC and more than five distant lesions (polymetastatic) was identified to help define expected outcomes after polyprogression.

RESULTS

Our study included 20 patients with OPanc receiving SABR and 21 who did not. SABR was delivered to 38 metastatic tumors. Out of the 20 SABR-treated OPanc patients, 17 (85%) had six or more months of time off chemotherapy, compared to seven patients (33.3%) among the chemotherapy-treated group. Median polyprogression-free survival was 40 and 14 months (hazard ratio= 0.2, 95% confidence interval 0.07-0.54, p-value= 0.0009), and overall survival was 42 and 18 months (hazard ratio= 0.21, 95% confidence interval 0.08-0.53, p-value= 0.0003), for SABR and chemotherapy-treated cohorts, respectively.

CONCLUSIONS

Management of OPanc with SABR as local regional therapy could improve outcomes in a selected population and warrants prospective evaluation.

Dose-Intensified Stereotactic Ablative Radiation for Localized Prostate Cancer

Purpose

Stereotactic ablative radiation (SAbR) has been increasingly used in prostate cancer (PCa) given its convenience and cost efficacy. Optimal doses remain poorly defined with limited prospective comparative trials and long-term safety/efficacy data at higher dose levels. We analyzed toxicity and outcomes for SAbR in men with localized PCa at escalated 45 Gy in 5 fractions.

Methods and Materials

This study retrospectively analyzed men from 2015 to 2019 with PCa who received linear-accelerator-based SAbR to 45 Gy in 5 fractions, along with perirectal hydrogel spacer, fiducial placement, and MRI-based planning. Disease control outcomes were calculated from end of treatment. Minimally important difference (MID) assessing patient-reported quality of life was defined as greater than a one-half standard deviation increase in American Urological Association (AUA) symptom score after SAbR.

Results

Two-hundred and forty-nine (249) low-, intermediate-, and high-risk PCa patients with median follow-up of 14.9 months for clinical toxicity were included. Acute urinary grade II toxicity occurred in 20.4% of patients. Acute grade II GI toxicity occurred in 7.3% of patients. For follow-up > 2 years (n = 69), late GU and GI grade ≥III toxicity occurred in 5.8% and 1.5% of patients, respectively. MID was evident in 31.8%, 23.4%, 35.8%, 37.0%, 33.3%, and 26.7% of patients at 3, 6, 12, 24, 36, and 48 months, respectively. The median follow-up for biochemical recurrence was 22.6 months with biochemical failure-free survival of 100% at 1 year (n = 226) and 98.7% for years 2 (n = 113) and 3 (n = 54).

Conclusions

SAbR for PCa at 45 Gy in 5 fractions shows an encouraging safety profile. Prospective studies with longer follow-up are warranted to establish this dose regimen as standard of care for PCa.

Exploratory ensemble interpretable model for predicting local failure in head and neck cancer: the additive benefit of CT and intra-treatment cone-beam computed tomography features

BACKGROUND

Local failure (LF) following chemoradiation (CRT) for head and neck cancer is associated with poor overall survival. If machine learning techniques could stratify patients at risk of treatment failure based on baseline and intra-treatment imaging, such a model could facilitate response-adapted approaches to escalate, de-escalate, or switch therapy.

METHODS

A 1:2 retrospective case control cohort of patients treated at a single institution with definitive radiotherapy for head and neck cancer who failed locally, in-field at a primary or nodal structure were included. Radiomic features were extracted from baseline CT and CBCT scans at fractions 1 and 21 (delta) of radiotherapy with PyRadiomics and were selected for by: reproducibility (intra-class correlation coefficients ≥0.95), redundancy [maximum relevance and minimum redundancy (mRMR)], and informativeness [recursive feature elimination (RFE)]. Separate models predicting LF of primaries or nodes were created using the explainable boosting machine (EBM) classifier with 5-fold cross-validation for (I) clinical only, (II) radiomic only (CT1 and delta features), and (III) fused models (clinical + radiomic). Twenty-five iterations were performed, and predicted scores were averaged with a parallel ensemble design. Receiver operating characteristic curves were compared between models with paired-samples t-tests.

RESULTS

The fused ensemble model for primaries (using clinical, CT1, and delta features) achieved an AUC of 0.871 with a sensitivity of 78.3% and specificity of 90.9% at the maximum Youden J statistic. The fused ensemble model trended towards improvement when compared to the clinical only ensemble model (AUC =0.788, P=0.134) but reached significance when compared to the radiomic ensemble model (AUC =0.770, P=0.017). The fused ensemble model for nodes achieved an AUC of 0.910 with a sensitivity of 100.0% and specificity of 68.0%, which also trended towards improvement when compared to the clinical model (AUC =0.865, P=0.080).

CONCLUSIONS

The fused ensemble EBM model achieved high discriminatory ability at predicting LF for head and neck cancer in independent primary and nodal structures. Although an additive benefit of delta radiomics over clinical factors could not be proven, the results trended towards improvement with the fused ensemble model, which are promising and worthy of prospective investigation in a larger cohort.

SAbR for High-Risk Prostate Cancer-A Prospective Multilevel MRI-Based Dose Escalation Trial

PURPOSE

Radiation dose intensification improves outcome in men with high-risk prostate cancer (HR-PCa). A prospective trial was conducted to determine safety, feasibility, and maximal tolerated dose of multilevel magnetic resonance imaging (MRI)-based 5-fraction SAbR in patients with HR-PCa.

METHODS AND MATERIALS

This phase I clinical trial enrolled patients with HR-PCa with grade group ≥4, prostate-specific antigen (PSA) ≥20 ng/mL, or radiographic ≥T3, and well-defined prostatic lesions on multiparametric MRI (mpMRI) into 4 dose-escalation cohorts. The initial cohort received 47.5 Gy to the prostate, 50 Gy to mpMRI-defined intraprostatic lesion(s), and 22.5 Gy to pelvic lymph nodes in 5 fractions. Radiation doses were escalated for pelvic nodes to 25 Gy and mpMRI lesion(s) to 52.5 Gy and then 55 Gy. Escalation was performed sequentially according to rule-based trial design with 7 to 15 patients per cohort and a 90-day observation period. All men received peri-rectal hydrogel spacer, intraprostatic fiducial placement, and 2 years of androgen deprivation. The primary endpoint was maximal tolerated dose according to a 90-day acute dose-limiting toxicity (DLT) rate <33%. DLT was defined as National Cancer Institute Common Toxicity Criteria for Adverse Events ≥grade 3 treatment-related toxicity. Secondary outcomes included acute and delayed gastrointestinal (GI)/genitourinary (GU) toxicity graded with Common Toxicity Criteria for Adverse Events.

RESULTS

Fifty-five of the 62 enrolled patients were included in the analysis. Dose was escalated through all 4 cohorts without observing any DLTs. Median overall follow-up was 18 months, with a median follow-up of 42, 24, 12, and 7.5 months for cohorts 1 to 4 respectively. Acute and late grade 2 GU toxicities were 25% and 20%, while GI were 13% and 7%, respectively. Late grade 3 GU and GI toxicities were 2% and 0%, respectively.

CONCLUSIONS

SAbR dose for HR-PCa was safely escalated with multilevel dose painting of 47.5 Gy to prostate, 55 Gy to mpMRI-defined intraprostatic lesions, and 25 Gy to pelvic nodal region in 5 fractions. Longer and ongoing follow-up will be required to assess late toxicity.

A systematic review of intraluminal high dose rate brachytherapy in the management of malignant biliary tract obstruction and cholangiocarcinoma

PURPOSE

To conduct a systematic review evaluating the impact of high dose rate (HDR) intraluminal brachytherapy (ILBT) in the management of malignant biliary obstruction and cholangiocarcinoma with specific focus on stent patency, clinical outcomes and toxicities.

METHODS AND MATERIALS

A review of published articles was conducted using Medline, Embase and Cochrane databases using the search terms "bile duct carcinoma" or "cholangiocarcinoma" or "bile duct neoplasms" in combination with "brachytherapy" or "high dose rate brachytherapy" or "HDR brachytherapy". Studies published in English and reporting outcomes of ≥10 patients were included in the review. Only the most recent experience was included if same patients were included in sequential publications.

RESULTS

Seventeen studies were identified that met the inclusion criteria. Significant heterogeneity was observed in treatment regimens, which included use of surgery, external beam radiation (EBRT), and/or intra-arterial and intravenous chemotherapy in conjunction with ILBT. Nevertheless, among the included studies, use of ILBT appeared to result in longer duration of stent patency: 10 months with ILBT compared to 4-6 months without ILBT. A trend was observed towards prolonged local control and improved complete and partial response rates in patients treated with ILBT with or without EBRT. Weighted mean overall survival of patients treated with ILBT alone was 11.8 months compared to 10.5 months for those that received EBRT +/- chemotherapy in addition to ILBT. The included studies reported low complication rates and toxicity related to ILBT.

CONCLUSION

Brachytherapy can be an effective and safe tool in the management of malignant biliary tract obstruction in combination with stenting. Both retrospective and prospective studies have suggested improved outcomes when HDR ILBT is combined with percutaneous stenting.

Automatic liver tumor localization using deep learning-based liver boundary motion estimation and biomechanical modeling (DL-Bio)

PURPOSE

Recently, two-dimensional-to-three-dimensional (2D-3D) deformable registration has been applied to deform liver tumor contours from prior reference images onto estimated cone-beam computed tomography (CBCT) target images to automate on-board tumor localizations. Biomechanical modeling has also been introduced to fine-tune the intra-liver deformation-vector-fields (DVFs) solved by 2D-3D deformable registration, especially at low-contrast regions, using tissue elasticity information and liver boundary DVFs. However, the caudal liver boundary shows low contrast from surrounding tissues in the cone-beam projections, which degrades the accuracy of the intensity-based 2D-3D deformable registration there and results in less accurate boundary conditions for biomechanical modeling. We developed a deep-learning (DL)-based method to optimize the liver boundary DVFs after 2D-3D deformable registration to further improve the accuracy of subsequent biomechanical modeling and liver tumor localization.

METHODS

The DL-based network was built based on the U-Net architecture. The network was trained in a supervised fashion to learn motion correlation between cranial and caudal liver boundaries to optimize the liver boundary DVFs. Inputs of the network had three channels, and each channel featured the 3D DVFs estimated by the 2D-3D deformable registration along one Cartesian direction (x, y, z). To incorporate patient-specific liver boundary information into the DVFs, the DVFs were masked by a liver boundary ring structure generated from the liver contour of the prior reference image. The network outputs were the optimized DVFs along the liver boundary with higher accuracy. From these optimized DVFs, boundary conditions were extracted for biomechanical modeling to further optimize the solution of intra-liver tumor motion. We evaluated the method using 34 liver cancer patient cases, with 24 for training and 10 for testing. We evaluated and compared the performance of three methods: 2D-3D deformable registration, 2D-3D-Bio (2D-3D deformable registration with biomechanical modeling), and DL-Bio (DL model prediction with biomechanical modeling). The tumor localization errors were quantified through calculating the center-of-mass-errors (COMEs), DICE coefficients, and Hausdorff distance between deformed liver tumor contours and manually segmented "gold-standard" contours.

RESULTS

The predicted DVFs by the DL model showed improved accuracy at the liver boundary, which translated into more accurate liver tumor localizations through biomechanical modeling. On a total of 90 evaluated images and tumor contours, the average (± sd) liver tumor COMEs of the 2D-3D, 2D-3D-Bio, and DL-Bio techniques were 4.7 ± 1.9 mm, 2.9 ± 1.0 mm, and 1.7 ± 0.4 mm. The corresponding average (± sd) DICE coefficients were 0.60 ± 0.12, 0.71 ± 0.07, and 0.78 ± 0.03; and the average (± sd) Hausdorff distances were 7.0 ± 2.6 mm, 5.4 ± 1.5 mm, and 4.5 ± 1.3 mm, respectively.

CONCLUSION

DL-Bio solves a general correlation model to improve the accuracy of the DVFs at the liver boundary. With improved boundary conditions, the accuracy of biomechanical modeling can be further increased for accurate intra-liver low-contrast tumor localization.

Brachial Plexus Tolerance to Single-Session SAbR in a Pig Model

PURPOSE

The single-session dose tolerance of the spinal nerves has been observed to be similar to that of the spinal cord in pigs, counter to the perception that peripheral nerves are more tolerant to radiation. This pilot study aims to obtain a first impression of the single-session dose-response of the brachial plexus using pigs as a model.

METHODS AND MATERIALS

Ten Yucatan minipigs underwent computed tomography and magnetic resonance imaging for treatment planning, followed by single-session stereotactic ablative radiotherapy. A 2.5-cm length of the left-sided brachial plexus cords was irradiated. Pigs were distributed in 3 groups with prescription doses of 16 (n = 3), 19 (n = 4), and 22 Gy (n = 3). Neurologic status was assessed by observation for changes in gait and electrodiagnostic examination. Histopathologic examination was performed with light microscopy of paraffin-embedded sections stained with Luxol fast blue/periodic acid-Schiff and Masson's trichrome.

RESULTS

Seven of the 10 pigs developed motor deficit to the front limb of the irradiated side, with a latency from 5 to 8 weeks after irradiation. Probit analysis of the maximum nerve dose yields an estimated ED₅₀ of 19.3 Gy for neurologic deficit, but the number of animals was insufficient to estimate 95% confidence intervals. No motor deficits were observed at a maximum dose of 17.6 Gy for any pig. Nerve conduction studies showed an absence of sensory response in all responders and absent or low motor response in most of the responders (71%). All symptomatic pigs showed histologic lesions to the left-sided plexus consistent with radiation-induced neuropathy.

CONCLUSIONS

The single-session ED₅₀ for symptomatic plexopathy in Yucatan minipigs after irradiation of a 2.5-cm length of the brachial plexus cords was determined to be 19.3 Gy. The dose-response curve overlaps that of the spinal nerves and the spinal cord in the same animal model. The relationship between the brachial plexus tolerance in pigs and humans is unknown, and caution is warranted when extrapolating for clinical use.

A Multi-Institutional Phase 2 Trial of High-Dose SAbR for Prostate Cancer Using Rectal Spacer

PURPOSE

High-dose SABR for prostate cancer offers the radiobiologic potency of the most intensified radiation therapy regimens but was associated with >90% rates of ulceration of the anterior rectal wall on endoscopic assessment; this infrequently progressed to severe rectal toxicity in prior prospective series. A multi-institutional phase 2 prospective trial was conducted to assess whether placement of a perirectal hydrogel spacer would reduce acute periprostatic rectal ulcer events after high-dose (>40 Gy) SABR.

METHODS AND MATERIALS

Eligible patients included men with stage ≤T2c localized grade group 1 to 3 prostate cancer, a prostate-specific antigen (PSA) level ≤15 ng/mL, American Urological Association Symptom Index = AUA-SI scores ≤18, and a gland volume ≤80 cm³. Patients underwent perirectal hydrogel spacer placement, followed by SABR of 45 Gy in 5 fractions every other day to the prostate only. Androgen deprivation was not allowed except for cytoreduction. The rectal wall was directly assessed by serial anoscopy during follow-up to determine whether the spacer would reduce acute periprostatic rectal ulcer events from >90% to <70% within 9 months of treatment.

RESULTS

Forty-four men were enrolled and 43 were eligible for protocol analysis. The median follow-up for surviving patients was 48 months. Acute periprostatic ulcers were observed in 6 of 42 patients (14.3%; 95% confidence interval, 6.0%-27%; P < .001) at a median of 2.9 months posttreatment (range, 1.7-5.6 months). All ulcers (grade 1, 5 ulcers; grade 2, 1 ulcer) resolved on repeat anoscopy within 8 months of incidence. There were no grade ≥3 late gastrointestinal toxicities; the incidence of late grade-2 gastrointestinal toxicities was 14.3%, with a prevalence at 3 years of 0%. No toxicities greater than grade 3 occurred in any domain. Four-year freedom from biochemical failure was 93.8% (95% CI, 85.2%-100.0%).

CONCLUSIONS

Temporary hydrogel spacer placement before high-dose SABR treatment for localized prostate cancer and use of strict dose constraints are associated with a significant reduction in the incidence of rectal ulcer events compared with prior phase 1/2 trial results.

Hydrogel Spacer Rectal Wall Infiltration Associated With Severe Rectal Injury and Related Complications After Dose Intensified Prostate Cancer Stereotactic Ablative Radiation Therapy

The risk of rectal toxicity during and after prostate cancer radiation therapy is common to all treatment regimens. Hydrogel rectal spacers are increasingly being used to mitigate this risk and to facilitate dose-escalation, but also may infiltrate the rectal wall, with unclear clinical implication. We present a case of significant infiltration associated with severe late rectal injury (grade 4) and further grade 3 to 4 sequelae (recto-urethral fistula and associated osteomyelitis requiring exenteration) after high-dose stereotactic body radiation therapy for localized prostate cancer. The injury's temporal pattern associated with the expected timing of gel dissolution and displacement of infiltrated rectal layers potentially toward high dose regions together suggest a contributing role of the infiltration to the injury. In light of the rapid increase of hydrogel rectal spacer utilization, we review the case's evolution, concerning imaging findings, and associated literature and make suggestions regarding treatment planning and endoscopic assessment in the setting of infiltration or expected injury.

Trends and Factors Associated With Receipt of Upfront Surgery for Stage II to III Rectal Adenocarcinoma in the United States, 2006 to 2016

INTRODUCTION

The German rectal study published in 2004 established neoadjuvant chemoradiation as a standard of care for locally advanced rectal cancer and current National Comprehensive Cancer Network guidelines endorse several preoperative regimens. Upfront surgery, however, is considered substandard care. In the era of evolving treatment paradigms for locally advanced rectal cancer, we sought to assess trends and predictors of receipt of upfront surgery for stage II to III rectal cancer.

METHODS

The National Cancer Database was used to identify patients diagnosed with clinical stage II to III rectal adenocarcinoma between 2006 and 2016. Multivariable logistic regression defined adjusted odds ratios and associated 95% confidence intervals of receipt of upfront definitive surgery. The timing of upfront surgery relative to day of diagnosis and rate of receipt of adjuvant therapy were also estimated.

RESULTS

Among 51,562 patients, 6411 (12.4%) were treated with upfront surgery, which decreased from 16.7% in 2006 to 7.1% in 2016 (P<0.001). The majority of patients (5737 [89.5%]) had definitive surgery after initial diagnostic biopsy. Variables associated with receipt of upfront surgery included female sex, older age, higher comorbidity score, and treatment at a community cancer center (P<0.001). Among those receiving upfront surgery, 2904 (45.3%) received adjuvant radiation therapy, 3218 (50.2%) received adjuvant chemotherapy, and 2559 (39.9%) received no further treatment.

CONCLUSIONS

The proportion of patients with clinical stage II to III rectal cancer treated with upfront surgery has steadily declined since 2006, however, certain subgroups appear to remain at greater risk. Further research is needed to better elucidate patient and systems-level factors contributing to these disparities in care.

Disparities in Characteristics, Access to Care, and Oncologic Outcomes in Young-Onset Colorectal Cancer at a Safety-Net Hospital

PURPOSE

Young-onset colorectal cancer is an emerging cause of significant morbidity and mortality globally. Despite this, limited data exist regarding clinical characteristics and outcomes, particularly in safety-net populations where access to care is limited. We aimed to study disparities in clinical characteristics and outcomes in patients with young-onset colorectal cancer in the safety-net setting.

METHODS

We performed a retrospective review of patients < 50 years old diagnosed and/or treated for colorectal cancer between 2001 and 2017 at a safety-net hospital. Kaplan-Meier and Cox regression models were constructed to compare overall survival (OS), progression-free survival (PFS), and relapse-free survival (RFS) by race and ethnicity, stratifying for relevant clinical and pathologic factors.

RESULTS

A total of 395 young-onset patients diagnosed at a safety-net hospital were identified and 270 were included in the analysis (49.6% Hispanic, 25.9% non-Hispanic Black, 20.0% non-Hispanic White, and 4.4% other). Non-Hispanic White race was independently associated with worse OS (hazzard ratio [HR], 0.53; 95% CI, 0.29 to 0.97), as were lack of insurance, higher clinical stage, and mismatch repair proficiency. There was no significant difference seen in PFS or RFS between racial and ethnic groups.

CONCLUSION

Non-Hispanic White race or ethnicity was found to be independently associated with worse OS in a safety-net population of patients with young-onset colorectal cancer. Other independent predictors of worse OS include higher stage, lack of insurance, and mismatch repair proficiency.

Patterns of Dose Escalation Among Patients With Esophageal Cancer Undergoing Definitive Radiation Therapy: 2006-2016

PURPOSE

Although single-institution series suggest potential benefit to dose escalation in definitive radiation therapy for esophageal cancer, randomized trials including intergroup-0123 and the recently presented A Randomized Trial of Dose Escalation in definitive Chemoradiotherapy for patients with Oesophageal cancer (ARTDECO) trial showed no improvement in outcomes with higher radiation therapy dose. As such, there may be significant variation in radiation dose for definitive treatment of esophageal cancer.

METHODS AND MATERIALS

The National Cancer Database was used to identify patients who received a diagnosis of nonmetastatic T2+ esophageal cancer between 2006 and 2016 who did not receive definitive surgery and were treated with chemotherapy and radiation therapy doses between 41.4 and 74 Gy. Multivariable logistic regression defined adjusted odds ratios (AORs) of receipt of >50.4 Gy, including year of diagnosis (2006-2013 vs 2014-2016) ∗ histology (squamous cell carcinoma [SCC] vs adenocarcinoma) and year of diagnosis (2006-2013 vs 2014-2016) ∗ disease site (cervical esophagus vs noncervical esophagus) interaction terms, to assess whether the effect of diagnosis year on dose varied by histology and disease site, respectively.

RESULTS

Among 14,517 patients, the most common dose was 50.4 Gy, used for 6955 (47.9%) patients. Dose escalation above 50.4 Gy was observed in 4440 (30.6%) patients and declined by year, from 42.2% in 2006 to 23.5% in 2016. Patients with SCC versus adenocarcinoma had higher odds of dose escalation (39.3% vs 23.8%; AOR 1.46; P < .001), as did those with cervical esophageal primaries versus other primary sites (54.9% vs 27.4%; AOR 2.51; P < .001). The effect of later diagnosis year was greater for adenocarcinoma than for SCC (pint = 0.001, AOR 0.54, P < .001 vs AOR 0.71, P < .001) and significant for noncervical esophagus but not cervical esophagus (pint <0.001, AOR 0.56, P < .001 vs AOR 0.95, P = .616).

CONCLUSIONS

Dose escalation in definitive chemoradiotherapy for esophageal cancer declined over time, particularly for adenocarcinoma histology and noncervical primary site. Given the recent results of ARTDECO, our findings can serve as a benchmark from which to measure future shifts in practice patterns.

Quantitative PET Imaging and Clinical Parameters as Predictive Factors for Patients With Cervical Carcinoma: Implications of a Prediction Model Generated Using Multi-Objective Support Vector Machine Learning

Purpose:

Quantitative features from pre-treatment positron emission tomography (PET) have been used to predict treatment outcomes for patients with cervical carcinoma. The purpose of this study is to use quantitative PET imaging features and clinical parameters to construct a multi-objective machine learning predictive model.

Materials/Methods:

Seventy-five patients with stage IB2-IVA disease treated at our institution from 2009–2012 were analyzed. Models predicting locoregional and distant failure were generated using clinical parameters (age, race, stage, histology, tumor size, nodal status) and imaging features (12 textural, 9 intensity, 8 geometric features, 2 additional imaging features) from pre-treatment PET. Model features were selected based on a multi-objective evolutionary algorithm to maximize specificity given a fixed moderately high sensitivity using support vector machine learning methods. Model 1 used clinical parameters only (C), Model 2 used imaging features only (I), and Model 3 used clinical and imaging features (C+I). Sensitivity, specificity, area under a receiver-operating characteristic curve (AUC), and p-values were compared to assess ability to predict locoregional and distant failure.

Results:

C+I had the highest performance for both locoregional failure (AUC 0.84, p < 0.01; specificity: 0.86; sensitivity: 0.79) and distant failure (AUC 0.75, p < 0.01; specificity: 0.75; sensitivity: 0.75).

Conclusions:

Based on a moderately high fixed sensitivity and optimized for specificity, the model using both clinical parameters and imaging features (C+I) had the best performance in predicting both locoregional failure and distant failure.

Review of brachytherapy complications - Upper gastrointestinal tract

While brachytherapy applications are not widely used for cancer diagnoses in the upper GI tract (including the esophagus, liver, stomach, and pancreas), they have a clear role in palliation and symptom management and occasionally definitive locoregional treatment. With the increasing use of image-guided techniques, the incidence of side effects and complications has shown to be lower than many other alternative treatment modalities, making brachytherapy approaches a preferred treatment option. This review examines procedural complications and acute and chronic adverse effects from radiation associated with esophageal, hepatobiliary, and pancreatic brachytherapy and their management.

Stage-specific Conditional Survival Among Young (Age Below 50 y) Versus Older (Age 50 y and Above) Adults With Colorectal Cancer in the United States

BACKGROUND

Conditional survival (CS) is a relevant prognostic measure and may be particularly important for young adult patients with colorectal cancer (CRC), whose incidence is rising. We sought to compare CS among young versus older adults with CRC.

METHODS

Patients diagnosed with CRC between 2004 and 2010 were identified from the Surveillance, Epidemiology, and End Results registry. Smoothed yearly hazards of death due to CRC, other causes and any cause were estimated, stratified by age at diagnosis (below 50 vs. 50 y and above) and stage (I-III vs. IV). Stage-specific conditional 5-year overall survival and cancer-specific survival given that patients had already survived 1 to 5 years after diagnosis was calculated.

RESULTS

Among 161,859 patients with median follow-up of 54 months, 35,411 (21.9%) were aged below 50 years. For older adults with nonmetastatic CRC, hazards of death due to noncancer causes exceeded that of rectal and colon cancer ∼6.1 and 3.8 years after diagnosis, respectively. Patients experienced improved CS over time with greater improvement seen for more advanced stages. However, young adults had less CS improvement over time than older adults. For example, the 5-year cancer-specific survival for stage IV colon cancer improved from 15.6% to 77.2% (change=61.6%) 0 to 5 years after diagnosis for older adults but only 20.3% to 67.7% (change=47.4%) for young adults.

CONCLUSIONS

Prognosis for CRC improves over time for all patients, although the increase in survival appears to be less for young than older adults. Up to 10 years after diagnosis, the primary cause of death in young adults with CRC remains their incident cancer.

Sociodemographic Disparities in the Receipt of Adjuvant Chemotherapy Among Patients With Resected Stage I-III Pancreatic Adenocarcinoma

BACKGROUND

Adjuvant therapy for resected pancreatic adenocarcinoma was given a category 1 NCCN recommendation in 2000, yet many patients do not receive chemotherapy after definitive surgery. Whether sociodemographic disparities exist for receipt of adjuvant chemotherapy is poorly understood.

METHODS

The National Cancer Database was used to identify patients diagnosed with nonmetastatic pancreatic adenocarcinoma who underwent definitive surgery from 2004 through 2015. Multivariable logistic regression defined the adjusted odds ratio (aOR) and associated 95% CI of receipt of adjuvant chemotherapy. Among patients receiving chemotherapy, multivariable logistic regression assessed the odds of treatment with multiagent chemotherapy.

RESULTS

Among 18,463 patients, 11,288 (61.1%) received any adjuvant chemotherapy. Sociodemographic factors inversely associated with receipt of any adjuvant chemotherapy included uninsured status (aOR, 0.61; 95% CI, 0.50-0.74), Medicaid insurance (aOR, 0.66; 95% CI, 0.57-0.77), and lower income (P<.001 for all income levels compared with ≥$46,000). Black race (aOR, 0.72; 95% CI, 0.57-0.90) and female sex (aOR, 0.75; 95% CI, 0.65-0.86) were associated with lower odds of receiving multiagent chemotherapy. There was a statistically significant interaction term between black race and age/comorbidity status (P=.03), such that 26.4% of black versus 35.8% of nonblack young (aged ≤65 years) and healthy (Charlson-Deyo comorbidity score 0) patients received multiagent adjuvant chemotherapy (P=.006), whereas multiagent adjuvant chemotherapy rates were similar among patients who were not young and healthy (P=.15).

CONCLUSIONS

In this nationally representative study, receipt of adjuvant chemotherapy appeared to be associated with sociodemographic characteristics, independent of clinical factors. Sociodemographic differences in receipt of adjuvant chemotherapy may represent a missed opportunity for improving outcomes and a driver of oncologic disparities.

Enhancing liver tumor localization accuracy by prior-knowledge-guided motion modeling and a biomechanical model

BACKGROUND

Pre-treatment liver tumor localization remains a challenging task for radiation therapy, mostly due to the limited tumor contrast against normal liver tissues, and the respiration-induced liver tumor motion. Recently, we developed a biomechanical modeling-based, deformation-driven cone-beam CT estimation technique (Bio-CBCT), which achieved substantially improved accuracy on low-contrast liver tumor localization. However, the accuracy of Bio-CBCT is still affected by the limited tissue contrast around the caudal liver boundary, which reduces the accuracy of the boundary condition that is fed into the biomechanical modeling process. In this study, we developed a motion modeling and biomechanical modeling-guided CBCT estimation technique (MM-Bio-CBCT), to further improve the liver tumor localization accuracy by incorporating a motion model into the CBCT estimation process.

METHODS

MM-Bio-CBCT estimates new CBCT images through deforming a prior high-quality CT or CBCT volume. The deformation vector field (DVF) is solved by iteratively matching the digitally-reconstructed-radiographs (DRRs) of the deformed prior image to the acquired 2D cone-beam projections. Using the same solved DVF, the liver tumor volume contoured on the prior image can be transferred onto the new CBCT image for automatic tumor localization. To maximize the accuracy of the solved DVF, MM-Bio-CBCT employs two strategies for additional DVF optimization: (I) prior-knowledge-guided liver boundary motion modeling with motion patterns extracted from a prior 4D imaging set like 4D-CTs/4D-CBCTs, to improve the liver boundary DVF accuracy; and (II) finite-element-analysis-based biomechanical modeling of the liver volume to improve the intra-liver DVF accuracy. We evaluated the accuracy of MM-Bio-CBCT on both the digital extended-cardiac-torso (XCAT) phantom images and real liver patient images. The liver tumor localization accuracy of MM-Bio-CBCT was evaluated and compared with that of the purely intensity-driven 2D-3D deformation technique, the 2D-3D deformation technique with motion modeling, and the Bio-CBCT technique. Metrics including the DICE coefficient and the center-of-mass-error (COME) were assessed for quantitative evaluation.

RESULTS

Using limited-view 20 projections for CBCT estimation, the average (± SD) DICE coefficients between the estimated and the 'gold-standard' liver tumors of the XCAT study were 0.57±0.31, 0.78±0.26, 0.83±0.21, and 0.89±0.11 for 2D-3D deformation, 2D-3D deformation with motion modeling, Bio-CBCT and MM-Bio-CBCT techniques, respectively. Using 20 projections for estimation, the patient study yielded average DICE results of 0.63±0.21, 0.73±0.13 and 0.78±0.12, and 0.83±0.09, correspondingly. The MM-Bio-CBCT localized the liver tumor to an average COME of ~2 mm for both the XCAT and the liver patient studies.

CONCLUSIONS

Compared to Bio-CBCT, MM-Bio-CBCT further improves the accuracy of liver tumor localization. MM-Bio-CBCT can potentially be used towards pre-treatment liver tumor localization and intra-treatment liver tumor location verification to achieve substantial radiotherapy margin reduction.

Automatic PET cervical tumor segmentation by combining deep learning and anatomic prior

Cervical tumor segmentation on 3D ¹⁸FDG PET images is a challenging task because of the proximity between cervix and bladder, both of which can uptake ¹⁸FDG tracers. This problem makes traditional segmentation based on intensity variation methods ineffective and reduces overall accuracy. Based on anatomy knowledge, including 'roundness' of the cervical tumor and relative positioning between the bladder and cervix, we propose a supervised machine learning method that integrates convolutional neural network (CNN) with this prior information to segment cervical tumors. First, we constructed a spatial information embedded CNN model (S-CNN) that maps the PET image to its corresponding label map, in which bladder, other normal tissue, and cervical tumor pixels are labeled as  -1, 0, and 1, respectively. Then, we obtained the final segmentation from the output of the network by a prior information constrained (PIC) thresholding method. We evaluated the performance of the PIC-S-CNN method on PET images from 50 cervical cancer patients. The PIC-S-CNN method achieved a mean Dice similarity coefficient (DSC) of 0.84 while region-growing, Chan-Vese, graph-cut, fully convolutional neural networks (FCN) based FCN-8 stride, and FCN-2 stride, and U-net achieved 0.55, 0.64, 0.67, 0.71, 0.77, and 0.80 mean DSC, respectively. The proposed PIC-S-CNN provides a more accurate way for segmenting cervical tumors on 3D PET images. Our results suggest that combining deep learning and anatomic prior information may improve segmentation accuracy for cervical tumors.

Femoral Fracture in Primary Soft-Tissue Sarcoma of the Thigh and Groin Treated with Intensity-Modulated Radiation Therapy: Observed versus Expected Risk

PURPOSE

This study was designed to compare the observed risk of femoral fracture in primary soft-tissue sarcoma (STS) of the thigh/groin treated with intensity-modulated radiation therapy (IMRT) to expected risk calculated using the Princess Margaret Hospital (PMH) nomogram.

METHODS

Expected femoral fracture risk was calculated by using the PMH nomogram. Cumulative risk of fracture was estimated by using Kaplan-Meier statistics. Prognostic factors were assessed with univariate and multivariate analysis using Cox's stepwise regression.

RESULTS

Between February 2002 and December 2010, 92 consecutive eligible patients were assessed. Median follow-up was 73 months (106 months in surviving patients). IMRT was delivered preoperatively (50 Gy) in 13 (14%) patients and postoperatively in 79 (86%) patients (median dose, 63 Gy; range, 59.4-66.6 Gy). The observed crude risk of fractures was 6.5% compared with 25.6% expected risk from the nomogram; the cumulative risk of fracture using IMRT at 5 years was 6.7% (95% CI 2.8-16.0%). The median time to fracture was 23 months (range, 6.9-88.6). Significant predictors of fracture on univariate analysis were age ≥ 60 years (p = 0.03), tumor location in the anterior thigh (p = 0.008), and periosteal stripping to > 20 cm (p < 0.0001). On multivariate analysis, age ≥ 60 years and periosteal stripping > 20 cm retained significance (p = 0.04 and p = 0.009, respectively).

CONCLUSIONS

In this study, the cumulative risk of femur fracture in patients treated with IMRT (6.7%) is less than the expected risk using the PMH nomogram (25.6%). Established predictors of femur fracture, such as gender, tumor size, and dose of RT, seem to have less impact on fracture risk when using IMRT.

A pilot study using kernelled support tensor machine for distant failure prediction in lung SBRT

We developed a kernelled support tensor machine (KSTM)-based model with tumor tensors derived from pre-treatment PET and CT imaging as input to predict distant failure in early stage non-small cell lung cancer (NSCLC) treated with stereotactic body radiation therapy (SBRT). The patient cohort included 110 early stage NSCLC patients treated with SBRT, 25 of whom experienced failure at distant sites. Three-dimensional tumor tensors were constructed and used as input for the KSTM-based classifier. A KSTM iterative algorithm with a convergent proof was developed to train the weight vectors for every mode of the tensor for the classifier. In contrast to conventional radiomics approaches that rely on handcrafted imaging features, the KSTM-based classifier uses 3D imaging as input, taking full advantage of the imaging information. The KSTM-based classifier preserves the intrinsic 3D geometry structure of the medical images and the correlation in the original images and trains the classification hyper-plane in an adaptive feature tensor space. The KSTM-based predictive algorithm was compared with three conventional machine learning models and three radiomics approaches. For PET and CT, the KSTM-based predictive method achieved the highest prediction results among the seven methods investigated in this study based on 10-fold cross validation and independent testing.

4D liver tumor localization using cone-beam projections and a biomechanical model

PURPOSE

To improve the accuracy of liver tumor localization, this study tests a biomechanical modeling-guided liver cone-beam CT (CBCT) estimation (Bio-CBCT-est) technique, which generates new CBCTs by deforming a prior high-quality CT or CBCT image using deformation vector fields (DVFs). The DVFs can be used to propagate tumor contours from the prior image to new CBCTs for automatic 4D tumor localization.

METHODS/MATERIALS

To solve the DVFs, the Bio-CBCT-est technique employs an iterative scheme that alternates between intensity-driven 2D-3D deformation and biomechanical modeling-guided DVF regularization and optimization. The 2D-3D deformation step solves DVFs by matching digitally reconstructed radiographs of the 3D deformed prior image to 2D phase-sorted on-board projections according to imaging intensities. This step's accuracy is limited at low-contrast intra-liver regions without sufficient intensity variations. To boost the DVF accuracy in these regions, we use the intensity-driven DVFs solved at higher-contrast liver boundaries to fine-tune the intra-liver DVFs by finite element analysis-based biomechanical modeling. We evaluated Bio-CBCT-est's accuracy with seven liver cancer patient cases. For each patient, we simulated 4D cone-beam projections from 4D-CT images, and used these projections for Bio-CBCT-est based image estimations. After Bio-CBCT-est, the DVF-propagated liver tumor/cyst contours were quantitatively compared with the manual contours on the original 4D-CT 'reference' images, using the DICE similarity index, the center-of-mass-error (COME), the Hausdorff distance (HD) and the voxel-wise cross-correlation (CC) metrics. In addition to simulation, we also performed a preliminary study to qualitatively evaluate the Bio-CBCT-est technique via clinically acquired cone beam projections. A quantitative study using an in-house deformable liver phantom was also performed.

RESULTS

Using 20 projections for image estimation, the average (±s.d.) DICE index increased from 0.48 ± 0.13 (by 2D-3D deformation) to 0.77 ± 0.08 (by Bio-CBCT-est), the average COME decreased from 7.7 ± 1.5 mm to 2.2 ± 1.2 mm, the average HD decreased from 10.6 ± 2.2 mm to 5.9 ± 2.0 mm, and the average CC increased from -0.004 ± 0.216 to 0.422 ± 0.206. The tumor/cyst trajectory solved by Bio-CBCT-est matched well with that manually obtained from 4D-CT reference images.

CONCLUSIONS

Bio-CBCT-est substantially improves the accuracy of 4D liver tumor localization via cone-beam projections and a biomechanical model.

Rectal radiation dose-reduction techniques in prostate cancer: a focus on the rectal spacer

Prostate cancer is the most common cancer in men. External beam radiotherapy by a variety of methods is a standard treatment option with excellent disease control. However, acute and late rectal side effects remain a limiting concern in intensification of therapy in higher-risk patients and in efforts to reduce treatment burden in others. A number of techniques have emerged that allow for high-radiation dose delivery to the prostate with reduced risk of rectal toxicity, including image-guided intensity-modulated radiation therapy, endorectal balloons and various forms of rectal spacers. Image-guided radiation therapy, either intensity-modulated radiation therapy or stereotactic ablative radiation therapy, in conjunction with a rectal spacer, is an efficacious means to reduce acute and long-term rectal toxicity.

Shell feature: a new radiomics descriptor for predicting distant failure after radiotherapy in non-small cell lung cancer and cervix cancer

Distant failure is the main cause of human cancer-related mortalities. To develop a model for predicting distant failure in non-small cell lung cancer (NSCLC) and cervix cancer (CC) patients, a shell feature, consisting of outer voxels around the tumor boundary, was constructed using pre-treatment positron emission tomography (PET) images from 48 NSCLC patients received stereotactic body radiation therapy and 52 CC patients underwent external beam radiation therapy and concurrent chemotherapy followed with high-dose-rate intracavitary brachytherapy. The hypothesis behind this feature is that non-invasive and invasive tumors may have different morphologic patterns in the tumor periphery, in turn reflecting the differences in radiological presentations in the PET images. The utility of the shell was evaluated by the support vector machine classifier in comparison with intensity, geometry, gray level co-occurrence matrix-based texture, neighborhood gray tone difference matrix-based texture, and a combination of these four features. The results were assessed in terms of accuracy, sensitivity, specificity, and AUC. Collectively, the shell feature showed better predictive performance than all the other features for distant failure prediction in both NSCLC and CC cohorts.

Accurate segmenting of cervical tumors in PET imaging based on similarity between adjacent slices

Because in PET imaging cervical tumors are close to the bladder with high capacity for the secreted ¹⁸FDG tracer, conventional intensity-based segmentation methods often misclassify the bladder as a tumor. Based on the observation that tumor position and area do not change dramatically from slice to slice, we propose a two-stage scheme that facilitates segmentation. In the first stage, we used a graph-cut based algorithm to obtain initial contouring of the tumor based on local similarity information between voxels; this was achieved through manual contouring of the cervical tumor on one slice. In the second stage, initial tumor contours were fine-tuned to more accurate segmentation by incorporating similarity information on tumor shape and position among adjacent slices, according to an intensity-spatial-distance map. Experimental results illustrate that the proposed two-stage algorithm provides a more effective approach to segmenting cervical tumors in 3D¹⁸FDG PET images than the benchmarks used for comparison.

Value of combined adjuvant chemotherapy and radiation on survival for stage III uterine cancer: is less radiation equal to more?

Objective

Locally advanced endometrioid adenocarcinoma (LA-EAC) accounts for the majority of deaths for this cancer, yet there is no consensus on adjuvant treatment after surgery. Past studies suggest that combined modality treatment (CMT) may improve outcomes over treatment with chemotherapy (CT) or radiation therapy (RT, either external beam radiotherapy [EBRT] or vaginal brachytherapy [VBT]) alone. Using a large US-based population-based registry, we evaluated adjuvant CMT in LA-EAC and the relative benefit of regional EBRT compared to focused VBT.

Methods

We studied patients diagnosed with Stage III LA-EAC between 2004 and 2013 from the National Cancer Data Base (NCDB). We used Cox regression and a log-rank test to assess survival based on treatment with CT alone, EBRT alone, VBT alone, or CMT with EBRT and/or VBT. We used a χ² test to compare covariates between patients receiving CMT with EBRT or VBT.

Results

Patients who received CMT had better survival than those who received CT or EBRT/VBT alone. Compared to CMT with VBT, patients who received CMT with EBRT were slightly older and had more advanced-stage or positive nodes, and fewer had lymph node surgery. We found no survival difference between CMT with EBRT and CMT with VBT even when categorizing patients as high or low risk according to age, grade, and stage (low-risk p=0.3460; high-risk p=0.2158).

Conclusion

CMT was associated with superior survival outcomes compared to monotherapy. We observed no survival difference between radiation modalities in CMT, which highlights the effectiveness of a more focused treatment like brachytherapy.

Dosimetric comparison of rectal-sparing capabilities of rectal balloon vs injectable spacer gel in stereotactic body radiation therapy for prostate cancer: lessons learned from prospective trials

This study aimed to compare the rectal-sparing capabilities of rectal balloons vs absorbable injectable spacer gel in stereotactic body radiation therapy (SBRT) for prostate cancer. Patient samples included in this analysis were obtained from 2 multi-institutional prospective trials of SBRT for prostate cancer using a rectal balloon (n = 36 patients) and injectable spacer gel (n = 36). Treatment prescription dose was 45 Gy in 5 fractions in 42 patients; for equal comparison, the remaining 30 patients were rescaled to 45 Gy from 47.5 Gy prescription (n = 6) and 50 Gy prescription (n = 24). The median prostate volumes and body mass index in the 2 patient samples were not statistically significantly different (p= 0.67 and 0.45, respectively), supporting anatomic similarity between cohorts. The injectable spacer gel achieved dosimetric superiority over the rectal balloon with respect to the maximum dose to the rectum (42.3 vs 46.2 Gy, p < 0.001), dose delivered to 33% of the rectal circumference (28 vs 35.1 Gy, p < 0.001), and absolute volume of rectum receiving 45 Gy (V45_Gy), V40_Gy, and V30_Gy (0.3 vs 1.7 cc, 1 vs 5.4 cc, and 4.1 vs 9.6 cc, respectively; p < 0.001 in all cases). There was no difference between the 2 groups with respect to the V50_Gy of the rectum or the dose to 50% of the rectal circumference (p= 0.29 and 0.06, respectively). The V18.3_Gy of the bladder was significantly larger with the rectal balloon (19.9 vs 14.5 cc, p= 0.003). In this analysis of patients enrolled on 2 consecutive multi-institutional prospective trials of SBRT for prostate cancer, the injectable spacer gel outperformed the rectal balloon in the majority of the examined and relevant dosimetric rectal-sparing parameters. The rectal balloon did not outperform the injectable spacer gel in any measured rectal dose parameter.

Predictive modeling of outcomes following definitive chemoradiotherapy for oropharyngeal cancer based on FDG-PET image characteristics

In this study, we investigate the use of imaging feature-based outcomes research ('radiomics') combined with machine learning techniques to develop robust predictive models for the risk of all-cause mortality (ACM), local failure (LF), and distant metastasis (DM) following definitive chemoradiation therapy (CRT). One hundred seventy four patients with stage III-IV oropharyngeal cancer (OC) treated at our institution with CRT with retrievable pre- and post-treatment 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) scans were identified. From pre-treatment PET scans, 24 representative imaging features of FDG-avid disease regions were extracted. Using machine learning-based feature selection methods, multiparameter logistic regression models were built incorporating clinical factors and imaging features. All model building methods were tested by cross validation to avoid overfitting, and final outcome models were validated on an independent dataset from a collaborating institution. Multiparameter models were statistically significant on 5 fold cross validation with the area under the receiver operating characteristic curve (AUC)  =  0.65 (p  =  0.004), 0.73 (p  =  0.026), and 0.66 (p  =  0.015) for ACM, LF, and DM, respectively. The model for LF retained significance on the independent validation cohort with AUC  =  0.68 (p  =  0.029) whereas the models for ACM and DM did not reach statistical significance, but resulted in comparable predictive power to the 5 fold cross validation with AUC  =  0.60 (p  =  0.092) and 0.65 (p  =  0.062), respectively. In the largest study of its kind to date, predictive features including increasing metabolic tumor volume, increasing image heterogeneity, and increasing tumor surface irregularity significantly correlated to mortality, LF, and DM on 5 fold cross validation in a relatively uniform single-institution cohort. The LF model also retained significance in an independent population.

Stereotactic ablative body radiosurgery (SABR) or Stereotactic body radiation therapy (SBRT)

While conventional treatment relies on protracted courses of therapy using relatively small dose-per-fraction sizes of 1.8-2Gy, there is substantial evidence gathered over decades that this may not be the optimal approach for all targetable disease. Stereotactic ablative body radiosurgery (SABR) or stereotactic body radiation therapy (SBRT) is a technique which uses precise targeting to deliver high doses of radiation capable of ablating tumors directly. In this review, we will discuss the justification for and techniques used to deliver ablative doses to improve treatment outcomes, interactions with biological and immunologic therapy, and special procedures to spare normal tissue, which have facilitated the expanding role for these techniques in the management of a wide range of malignant histologies and disease states.

Stereotactic body radiotherapy for metastatic spinal sarcoma: a detailed patterns-of-failure study

OBJECTIVE The aim of this study was to report the first detailed analysis of patterns of failure within the spinal axis of patients treated with stereotactic body radiotherapy (SBRT) for sarcoma spine metastases. METHODS Between 2005 and 2012, 88 consecutive patients with metastatic sarcoma were treated with SBRT for 120 spinal lesions. Seventy-one percent of patients were enrolled on prospective institutional protocols. For patients who underwent routine posttreatment total-spine MRI (64 patients, 88 lesions), each site of progression within the entire spinal axis was mapped in relation to the treated lesion. Actuarial rates of local-, adjacent-, and distant-segment failure-free survival (FFS) were calculated using the Kaplan-Meier method. RESULTS The median follow-up for the cohort was 14.4 months, with 81.7% of patients followed up until death. The 12-month actuarial rate of local FFS was 85.9%; however, 83.3% of local failures occurred in conjunction with distant-segment failures. The 12-month actuarial rates of isolated local-, adjacent-, and distant-segment FFS were 98.0%, 97.8%, and 74.7%, respectively. Of patients with any spinal progression (n = 55), only 25.5% (n = 14) had progression at a single vertebral level, with 60.0% (n = 33) having progression at ≥ 3 sites within the spine simultaneously. Linear regression analysis revealed a relationship of decreasing risk of failure with increasing distance from the treated index lesion (R(2) = 0.87), and 54.1% of failures occurred ≥ 5 vertebral levels away. Treatment of the index lesion with a lower biological effective dose (OR 3.2, 95% CI 1.1-9.2) and presence of local failure (OR 18.0, 95% CI 2.1-152.9) independently predicted for distant spine failure. CONCLUSIONS Isolated local- and adjacent-segment failures are exceptionally rare for patients with metastatic sarcoma to the spine treated with SBRT, thereby affirming the treatment of the involved level only. The majority of progression within the spinal axis occurs ≥ 5 vertebral levels away. Thus, total-spine imaging is necessary for surveillance posttreatment.

Review of treatment options for oligometastatic non-small cell lung cancer

Our understanding of metastatic disease is constantly evolving. Although outcomes for patients with stage IV non-small cell lung cancer (NSCLC) are poor, aggressive/radical local intervention may be effective in a subset of patients with limited or "oligometastatic" disease. Here we review and compare the range of available treatment options that are specific to oligometastatic NSCLC, and discuss potential directions of future clinical research.

Outcomes and prognostic factors in women with 1 to 3 breast cancer brain metastases treated with definitive stereotactic radiosurgery

BACKGROUND

With the continuing increase in the use of definitive stereotactic radiosurgery (SRS) for patients with limited brain metastases (BM), clinicians need more specific prognostic tools. We investigated clinical predictors of outcomes in patients with limited breast cancer BM treated with SRS alone.

METHODS AND MATERIALS

We identified 136 patients with breast cancer and 1-3 BM who underwent definitive SRS for 186 BM between 2000 and 2012. The Kaplan-Meier method was used to assess overall survival (OS), regional failure (RF), and local failure (LF). Associations between clinical factors and outcomes were tested using Cox regression. A point scoring system was used to stratify patients based on OS, and the predictive power was tested with concordance probability estimate (CPE).

RESULTS

The median OS was 17.6 months. The 12-month RF and LF rates were 45% and 10%, respectively. On multivariate analysis, >1 lesion (hazard ratio [HR] = 1.6, P=.02), triple-negative (TN) disease (HR=2.0, P=.006), and active extracranial disease (ED) (HR=2.7, P<.0001) were significantly associated with worse OS. The point score system was defined using proportional simplification of the multivariate Cox proportional hazards regression function. The median OS for patients with 3.0-4.0 points (n=37), 4.5-5.5 points (n=28), 6.0-6.5 points (n=37), and 8-8.5 points (n=34) were 9.2, 15.6, 25.1, and 45.1 months, respectively (P<.0001, CPE = 0.72). Active ED (HR=2.4, P=.0007) was significantly associated with RF. Higher risk for LF was significantly associated with larger BM size (HR=3.1, P=.0001).

CONCLUSION

Patients with >1 BM, active ED, and TN had the highest risk of death after SRS. Active ED is an important prognostic factor for OS and intracranial control.

Comparison of local recurrence with conventional and intensity-modulated radiation therapy for primary soft-tissue sarcomas of the extremity

PURPOSE

The use of intensity-modulated radiation therapy (IMRT) in the treatment of soft tissue sarcoma (STS) of the extremity is increasing, but no large-scale direct comparison has been reported between conventional external-beam radiation therapy (EBRT) and IMRT.

METHODS

Between January 1996 and December 2010, 319 consecutive adult patients with primary nonmetastatic extremity STS were treated with limb-sparing surgery and adjuvant radiotherapy (RT) at a single institution. Conventional EBRT was used in 154 patients and IMRT in 165 with similar dosing schedules. Median follow-up time for the cohort was 58 months.

RESULTS

Treatment groups were comparable in terms of tumor location, histology, tumor size, depth, and use of chemotherapy. Patients treated with IMRT were older (P = .08), had more high-grade lesions (P = .05), close (< 1 mm) or positive margins (P = .04), preoperative radiation (P < .001), and nerve manipulation (P = .04). Median follow-up was 90 months for patients treated with conventional EBRT and 42 months for patients treated with IMRT. On multivariable analysis adjusting for patient age and tumor size, IMRT retained significance as an independent predictor of reduced LR (hazard ratio = 0.46; 95% CI, 0.24 to 0.89; P = .02).

CONCLUSION

Despite a preponderance of higher-risk features (especially close/positive margin) in the IMRT group, IMRT was associated with significantly reduced local recurrence compared with conventional EBRT for primary STS of the extremity.

Intraoperative phosphorus-32 brachytherapy plaque for multiply recurrent high-risk epidural neuroblastoma

Achieving local control is a crucial component in the management of neuroblastoma, but this may be complicated in the setting of prior radiation treatment, especially when the therapeutic target is in proximity to critical structures such as the spinal cord. The authors describe a pediatric patient with multiply recurrent neuroblastoma and prior high-dose radiation therapy to the spine who presented with progressive epidural disease. The patient was managed with resection and intraoperative high-dose-rate brachytherapy using a phosphorus-32 ((32)P) plaque previously developed for the treatment of brain and spine lesions.

Intraoperative and percutaneous iridium-192 high-dose-rate brachytherapy for previously irradiated lesions of the spine

PURPOSE

Advances in stereotactic radiosurgery have improved local control of spine metastases, but local failure is still a problem and repeat irradiation is limited by normal tissue tolerance. A novel high-dose-rate (HDR) brachytherapy technique has been developed to treat these previously irradiated lesions.

METHODS AND MATERIALS

Five patients with progressive disease at previously irradiated sites in the spine who were not amenable to further external beam radiation were treated. Catheters were placed intraoperatively in 2 patients and percutaneously implanted in 3 patients with image-guided techniques. Conformal plans were generated to deliver dose to target tissues and spare critical structures. Patients received single-fraction treatment using HDR iridium-192 brachytherapy.

RESULTS

Median dose was 14 Gy (range, 12-18 Gy) with a median gross total volume D90 of 75% (range, 31-94%); spinal cord/cauda equina dose constraints were met. At a median followup of 9 months, no local progression of disease has been observed. Four patients had reduction in pain 1-4 weeks after treatment. No brachytherapy-related complications have been observed.

CONCLUSIONS

Intraoperative and percutaneous iridium-192 HDR spine brachytherapy techniques were not associated with complications or acute toxicity. There has been no local progression at treated sites, and most patients experienced reduction in cancer-related pain.