Stereotactic body radiotherapy for primary renal cell carcinoma: a systematic review and practice guideline from the International Society of Stereotactic Radiosurgery (ISRS).

Surgery is the standard of care for patients with primary renal cell carcinoma. Stereotactic body radiotherapy (SBRT) is a novel alternative for patients who are medically inoperable, technically high risk, or who decline surgery. Evidence for using SBRT in the primary renal cell carcinoma setting is growing, including several rigorously conducted prospective clinical trials. This systematic review was performed to assess the safety and efficacy of SBRT for primary renal cell carcinoma. Review results then formed the basis for the practice guidelines described, on behalf of the International Stereotactic Radiosurgery Society. 3972 publications were screened and 36 studies (822 patients) were included in the analysis. Median local control rate was 94·1% (range 70·0-100), 5-year progression-free survival was 80·5% (95% CI 72-92), and 5-year overall survival was 77·2% (95% CI 65-89). These practice guidelines addressed four key clinical questions. First, the optimal dose fractionation was 25-26 Gy in one fraction, or 42-48 Gy in three fractions for larger tumours. Second, routine post-treatment biopsy is not recommended as it is not predictive of patient outcome. Third, SBRT for primary renal cell carcinoma in a solitary kidney is safe and effective. Finally, guidelines for post-treatment follow-up are described, which include cross-axial imaging of the abdomen including both kidneys, adrenals, and surveillance of the chest initially every 6 months. This systematic review and practice guideline support the practice of SBRT for primary renal cell carcinoma as a safe and effective standard treatment option. Randomised trials with surgery and invasive ablative therapies are needed to further define best practice.

Radiotherapy concepts for spinal metastases-results from an online survey among radiation oncologists of the German Society for Radiation Oncology.

PURPOSE: Spinal metastases (SM) are a common radiotherapy (RT) indication. There is limited level I data to drive decision making regarding dose regimen (DR) and target volume definition (TVD). We aim to depict the patterns of care for RT of SM among German Society for Radiation Oncology (DEGRO) members. METHODS: An online survey on conventional RT and Stereotactic Body Radiation Therapy (SBRT) for SM, distributed via e­mail to all DEGRO members, was completed by 80 radiation oncologists between February 24 and April 29, 2022. Participation was voluntary and anonymous. RESULTS: A variety of DR was frequently used for conventional RT (primary: n = 15, adjuvant: n = 14). 30 Gy/10 fractions was reported most frequently. TVD in adjuvant RT was heterogenous, with a trend towards larger volumes. SBRT was offered in 65% (primary) and 21% (adjuvant) of participants' institutions. A variety of DR was reported (primary: n = 40, adjuvant: n = 27), most commonly 27 Gy/3 fractions and 30 Gy/5 fractions. 59% followed International Consensus Guidelines (ICG) for TVD. CONCLUSION: We provide a representative depiction of RT practice for SM among DEGRO members. DR and TVD are heterogeneous. SBRT is not comprehensively practiced, especially in the adjuvant setting. Further research is needed to provide a solid data basis for detailed recommendations.

Prognostic value of cerebrospinal fluid tumor cell count in leptomeningeal disease from solid tumors.

PURPOSE: Treatment decisions for leptomeningeal disease (LMD) rely on patient risk stratification, since clinicians lack objective prognostic tools. The introduction of rare cell capture technology for identification of cerebrospinal fluid tumor cells (CSF-TCs), such as CNSide assay, improved the sensitivity of LMD diagnosis, but prognostic value is unknown. This study assesses the prognostic value of CSF-TC density in patients with LMD from solid tumors. METHODS: We conducted a retrospective cohort study of patients with newly diagnosed or previously treated LMD from a single institution who had CNSide assay testing for CSF-TCs from 2020 to 2023. Univariable and multivariable survival analyses were conducted with Cox proportional-hazards modeling. Maximally-selected rank statistics were used to determine an optimal cutpoint for CSF-TC density and survival. RESULTS: Of 31 patients, 29 had CSF-TCs detected on CNSide. Median (interquartile range [IQR]) CSF-TC density was 67.8 (4.7-639) TCs/mL. CSF cytology was positive in 16 of 29 patients with positive CNSide (CNSide diagnostic sensitivity = 93.5%, negative predictive value = 85.7%). Median (IQR) survival from time of CSF-TC detection was 176 (89-481) days. On univariable and multivariable analysis, CSF-TC density was significantly associated with survival. An optimal cutpoint for dichotomizing survival by CSF-TC density was 19.34 TCs/mL. The time-dependent sensitivity and specificity for survival using this stratification were 76% and 67% at 6 months and 65% and 67% at 1 year, respectively. CONCLUSIONS: CSF-TC density may carry prognostic value in patients with LMD from solid tumors. Integrating CSF-TC density into LMD patient risk-stratification may help guide treatment decisions.

Craniospinal irradiation for CNS leukemia: rates of response and durability of CNS control.

PURPOSE: Management of CNS involvement in leukemia may include craniospinal irradiation (CSI), though data on CSI efficacy are limited. METHODS: We retrospectively reviewed leukemia patients who underwent CSI at our institution between 2009 and 2021 for CNS involvement. CNS local recurrence (CNS-LR), any recurrence, progression-free survival (PFS), CNS PFS, and overall survival (OS) were estimated. RESULTS: Of thirty-nine eligible patients treated with CSI, most were male (59%) and treated as young adults (median 31 years). The median dose was 18 Gy to the brain and 12 Gy to the spine. Twenty-five (64%) patients received CSI immediately prior to allogeneic hematopoietic cell transplant, of which 21 (84%) underwent total body irradiation conditioning (median 12 Gy). Among 15 patients with CSF-positive disease immediately prior to CSI, all 14 assessed patients had pathologic clearance of blasts (CNS-response rate 100%) at a median of 23 days from CSI start. With a median follow-up of 48 months among survivors, 2-year PFS and OS were 32% (95% CI 18-48%) and 43% (95% CI 27-58%), respectively. Only 5 CNS relapses were noted (2-year CNS-LR 14% (95% CI 5-28%)), which occurred either concurrently or after a systemic relapse. Only systemic relapse after CSI was associated with higher risk of CNS-LR on univariate analysis. No grade 3 or higher acute toxicity was seen during CSI. CONCLUSION: CSI is a well-tolerated and effective treatment option for patients with CNS leukemia. Control of systemic disease after CSI may be important for CNS local control. CNS recurrence may reflect reseeding from the systemic space.

Focal therapy for oligometastatic and oligoprogressive renal cell carcinoma: a narrative review.

Metastatic renal cell carcinoma (RCC) can present with oligometastatic disease and/or develop oligoprogression following systemic therapy. Cytoreductive and focal metastasis-directed therapy options include resection, stereotactic ablative radiation and thermal ablation. Aggressive focal therapy may allow delay in initiation of or modification to systemic therapy and improve clinical outcomes. In this narrative review we synthesize current practice guidelines and prospective data on focal therapy management options and highlight future research. Patient selection and the choice of focal treatment techniques are controversial due to limited and heterogeneous data and patients may benefit from multidisciplinary evaluation. Prospective comparative trials with clearly defined inclusion criteria and relevant end points are needed to clarify the risks and benefits of different approaches.

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Radiation necrosis or tumor progression? A review of the radiographic modalities used in the diagnosis of cerebral radiation necrosis.

PURPOSE: Cerebral radiation necrosis is a complication of radiation therapy that can be seen months to years following radiation treatment. Differentiating radiation necrosis from tumor progression on standard magnetic resonance imaging (MRI) is often difficult and advanced imaging techniques may be needed to make an accurate diagnosis. The purpose of this article is to review the imaging modalities used in differentiating radiation necrosis from tumor progression following radiation therapy for brain metastases. METHODS: We performed a review of the literature addressing the radiographic modalities used in the diagnosis of radiation necrosis. RESULTS: Differentiating radiation necrosis from tumor progression remains a diagnostic challenge and advanced imaging modalities are often required to make a definitive diagnosis. If diagnostic uncertainty remains following conventional imaging, a multi-modality diagnostic approach with perfusion MRI, magnetic resonance spectroscopy (MRS), positron emission tomography (PET), single photon emission spectroscopy (SPECT), and radiomics may be used to improve diagnosis. CONCLUSION: Several imaging modalities exist to aid in the diagnosis of radiation necrosis. Future studies developing advanced imaging techniques are needed.

Intracranial Germ Cell Tumors.

Intracranial germ cell tumors are rare tumors occurring in adolescents and young adults, which include germinomas and non-germinomatous type germ cell tumors (NGGCT). In the past few decades, cooperative trial groups in Europe and North America have developed successful strategies to improve survival outcomes and decrease treatment-related toxicities. New approaches to establishing diagnosis have deferred the need for radical surgery. The 5-year event-free survival (EFS) is above 90% and even patients who present with metastatic germinoma can still be cured with chemotherapy and craniospinal irradiation. The combination of surgery, chemotherapy, and radiation therapy is tailored to patients based on grouping and staging. For NGGCT, neoadjuvant chemotherapy followed by delayed surgery for residual disease and radiotherapy can yield a 5-year EFS of 70%. Further strategies should focus on reducing long-term complications while preserving high cure rates.

5-year outcomes after stereotactic ablative body radiotherapy for primary renal cell carcinoma: an individual patient data meta-analysis from IROCK (the International Radiosurgery Consortium of the Kidney).

BACKGROUND: Stereotactic ablative body radiotherapy (SABR) is a non-invasive treatment option for primary renal cell carcinoma, for which long-term data are awaited. The primary aim of this study was to report on long-term efficacy and safety of SABR for localised renal cell carcinoma. METHODS: This study was an individual patient data meta-analysis, for which patients undergoing SABR for primary renal cell carcinoma across 12 institutions in five countries (Australia, Canada, Germany, Japan, and the USA) were eligible. Eligible patients had at least 2 years of follow-up, were aged 18 years or older, had any performance status, and had no previous local therapy. Patients with metastatic renal cell carcinoma or upper-tract urothelial carcinoma were excluded. SABR was delivered as a single or multiple fractions of greater than 5 Gy. The primary endpoint was investigator-assessed local failure per the Response Evaluation Criteria in Solid Tumours version 1.1, and was evaluated using cumulative incidence functions. FINDINGS: 190 patients received SABR between March 23, 2007, and Sept 20, 2018. Single-fraction SABR was delivered in 81 (43%) patients and multifraction SABR was delivered in 109 (57%) patients. Median follow-up was 5·0 years (IQR 3·4-6·8). 139 (73%) patients were men, and 51 (27%) were women. Median age was 73·6 years (IQR 66·2-82·0). Median tumour diameter was 4·0 cm (IQR 2·8-4·9). 96 (75%) of 128 patients with available operability details were deemed inoperable by the referring urologist. 56 (29%) of 190 patients had a solitary kidney. Median baseline estimated glomerular filtration rate (eGFR) was 60·0 mL/min per 1·73 m2 (IQR 42·0-76·0) and decreased by 14·2 mL/min per 1·73 m2 (IQR 5·4-22·5) by 5 years post-SABR. Seven (4%) patients required dialysis post-SABR. The cumulative incidence of local failure at 5 years was 5·5% (95% CI 2·8-9·5) overall, with single-fraction SABR yielding fewer local failures than multifraction (Gray's p=0·020). There were no grade 3 toxic effects or treatment-related deaths. One (1%) patient developed an acute grade 4 duodenal ulcer and late grade 4 gastritis. INTERPRETATION: SABR is effective and safe in the long term for patients with primary renal cell carcinoma. Single-fraction SABR might yield less local failure than multifraction, but further evidence from randomised trials is needed to elucidate optimal treatment schedules. These mature data lend further support for renal SABR as a treatment option for patients unwilling or unfit to undergo surgery. FUNDING: None.

Radiation myelopathy following stereotactic body radiation therapy for spine metastases.

PURPOSE: Stereotactic body radiation therapy (SBRT) is now considered a standard of care treatment option in the management of spine metastases. One of the most feared complications of spine SBRT is radiation myelopathy (RM). METHODS: We provided a narrative review of RM following spine SBRT based on review of the published literature, including data on spinal cord dose constraints associated with the risk of RM, strategies to mitigate the risk, and management options for RM. RESULTS: There are limited published data of cases of RM following spine SBRT with detailed spinal cord dosimetry. The HyTEC report provided recommendations for the point maximal dose (Dmax) for the spinal cord that is associated with a < 5% risk of RM for 1-5 fractions spine SBRT. In the setting of spine SBRT reirradiation after previous conventional external beam radiation therapy (cEBRT), factors associated with RM are: SBRT spinal cord Dmax, cumulative spinal cord Dmax, and the time interval between previous RT and SBRT reirradiation. There are various strategies to mitigate the risk of RM, including accurate delineation of the spinal cord (or thecal sac), strict adherence to the recommended spinal cord dose constraints, and robust treatment immobilisation set-up and delivery. Limited effective treatment options are available for patients who develop RM, and these include corticosteroids, hyperbaric oxygen, and bevacizumab; however, none have been supported by high quality evidence. CONCLUSION: RM is a rare but devastating complication following SBRT for spine metastases. There are strategies to minimise the risk of RM to ensure safe delivery of spine SBRT.

The Impact of COVID-19 on US Radiation Oncology Residents.

The purpose of our study is to assess the impact of COVID-19 on the clinical responsibilities, training, and wellness of US radiation oncology residents. An anonymous cross-sectional survey was sent to all 91 radiation oncology residency programs in the USA. The survey included questions related to demographics, changes in clinical duties and training, job prospects, and wellness indicators. Univariate and multivariate logistic regression analyses were used to evaluate factors associated with residents endorsing high satisfaction with their departments' response to COVID-19. A total of 96 residents completed the survey from 67 US radiation oncology programs. In the multivariate logistic regression model, remote contouring (OR: 3.91 (95% CI: 1.11, 13.80), p = 0.03) and belief that one will be adequately trained to independently practice after completing residency (OR: 4.68 (1.12, 19.47), p = 0.03) were significantly associated with high resident satisfaction with their department's response to COVID-19. Most residents indicated that hypofractionation was encouraged to a greater extent (n = 79, 82.3%), patients were triaged by disease risk (n = 67, 69.8%), and most agreed/strongly agreed that they have been provided with adequate personal protective equipment (PPE) (n = 85, 88.5%). The COVID-19 pandemic has affected the training and wellness of radiation oncology residents. Our analysis suggests that radiation oncology programs might increase resident satisfaction with their department's response to COVID-19 by enabling remote contouring and working with residents to identity and remedy possible concerns regarding their ability to independently practice post residency.

Role of Imaging in Renal Cell Carcinoma: A Multidisciplinary Perspective.

With the expansion in cross-sectional imaging over the past few decades, there has been an increase in the number of incidentally detected renal masses and an increase in the incidence of renal cell carcinomas (RCCs). The complete characterization of an indeterminate renal mass on CT or MR images is challenging, and the authors provide a critical review of the best imaging methods and essential, important, and optional reporting elements used to describe the indeterminate renal mass. While surgical staging remains the standard of care for RCC, the role of renal mass CT or MRI in staging RCC is reviewed, specifically with reference to areas that may be overlooked at imaging such as detection of invasion through the renal capsule or perirenal (Gerota) fascia. Treatment options for localized RCC are expanding, and a multidisciplinary group of experts presents an overview of the role of advanced medical imaging in surgery, percutaneous ablation, transarterial embolization, active surveillance, and stereotactic body radiation therapy. Finally, the arsenal of treatments for advanced renal cancer continues to grow to improve response to therapy while limiting treatment side effects. Imaging findings are important in deciding the best treatment options and to monitor response to therapy. However, evaluating response has increased in complexity. The unique imaging findings associated with antiangiogenic targeted therapy and immunotherapy are discussed. An invited commentary by Remer is available online. Online supplemental material is available for this article. ©RSNA, 2021.

Radiation Necrosis from Stereotactic Radiosurgery-How Do We Mitigate?

OPINION STATEMENT: Intracranial stereotactic radiosurgery (SRS) is an effective and convenient treatment for many brain conditions. Data regarding safety come mostly from retrospective single institutional studies and a small number of prospective studies. Variations in target delineation, treatment delivery, imaging follow-up protocols and dose prescription limit the interpretation of this data. There has been much clinical focus on radiation necrosis (RN) in particular, as it is being increasingly recognized on follow-up imaging. Symptomatic RN may be treated with medical therapy (such as corticosteroids and bevacizumab) with surgical resection being reserved for refractory patients. Nevertheless, RN remains a challenging condition to manage, and therefore upfront patient selection for SRS remains critical to provide complication-free control. Mitigation strategies need to be considered in situations where the baseline risk of RN is expected to be high-such as large target volume or re-irradiation. These may involve reduction in the prescribed dose or hypofractionated stereotactic radiation therapy (HSRT). Recently published guidelines and international meta-analysis report the benefit of HSRT in larger lesions, without compromising control rates. However, careful attention to planning parameters and SRS techniques still need to be adhered, even with HSRT. In cases where the risk is deemed to be high despite mitigation, a combination approach of surgery with or without post-operative radiation should be considered.

Stereotactic Radiotherapy as a Treatment Option for Renal Tumors in the Solitary Kidney: A Multicenter Analysis from the IROCK.

PURPOSE: Stereotactic ablative radiotherapy is an emerging treatment for renal cell carcinoma. Our study objective was to evaluate this therapy in patients with a solitary kidney, focusing on oncologic and renal function outcomes. MATERIALS AND METHODS: We pooled individual patient data from 9 IROCK (International Radiosurgery Oncology Consortium for Kidney) institutions in Germany, Australia, the United States of America, Canada and Japan. Median followup was 2.6 years. Baseline characteristics and outcomes were compared between the solitary and bilateral kidney cohorts. Predictors of renal function after stereotactic ablative radiotherapy were assessed by logistic regression modeling. RESULTS: A total of 81 patients with a solitary kidney underwent stereotactic ablative radiotherapy. Mean age was 67.3 years and 97.5% of patients had good performance status, including ECOG (Eastern Cooperative Oncology Group) 0-1 or KPS (Karnofsky Performance Status) 70% or greater. Median tumor diameter was 3.7 cm (IQR 2.5-4.3) and 37% of tumors were 4 cm or greater. The 138 patients in the bilateral cohort harbored larger tumors and were older (p <0.001) with a lower baseline estimated glomerular filtration rate (p = 0.024). After stereotactic ablative radiotherapy in the solitary kidney cohort the mean ± SD estimated glomerular filtration rate decrease was -5.8 ± 10.8 ml per minute (-9%). No patient with a solitary kidney required dialysis. After stereotactic ablative radiotherapy a tumor size of 4 cm or greater was associated with an estimated glomerular filtration rate decrease of 15 ml per minute or greater (OR 4.2, p = 0.029). At 2 years the rates of local control, and progression-free, cancer specific and overall survival in the solitary cohort were 98.0%, 77.5%, 98.2% and 81.5%, respectively. There was no significant difference in renal function or oncologic outcomes between the cohorts (p >0.05). CONCLUSIONS: In this analysis of the IROCK database stereotactic ablative radiotherapy in patients with a solitary kidney had an acceptable impact on renal function and achieved excellent oncologic outcomes, similar to those in patients with bilateral kidneys. Thus, stereotactic ablative radiotherapy represents a viable treatment option in patients with renal cell carcinoma in a solitary kidney.

Trends in Management of Oligometastatic Hormone-Sensitive Prostate Cancer.

PURPOSE OF REVIEW: Systemic therapy for patients with hormone-sensitive oligometastatic prostate cancer is non-curative and associated with toxicities. Meanwhile, this population presents unique clinical opportunities to improve outcomes, including the demonstrated benefits of radiotherapy to the primary tumor or oligometastatic sites. RECENT FINDINGS: Recently published randomized studies have demonstrated benefits with the addition of radiotherapy to the primary disease or metastatic lesions in patients with synchronous or metachronous disease. The introduction of novel PET imaging has improved the sensitivity and specificity for detecting metastatic disease and provides an opportunity to better select patients who will benefit from local therapy. The data presented in this review supports revisiting practice guidelines for patients with hormone-sensitive metastatic prostate cancer, particularly in relation to the role of radiotherapy to the primary tumor and sites of oligometastatic disease. Future trials will aim to further establish the role of metastasis-directed therapies in metachronous, synchronous, and castrate-resistant disease.

Pooled analysis of stereotactic ablative radiotherapy for primary renal cell carcinoma: A report from the International Radiosurgery Oncology Consortium for Kidney (IROCK).

BACKGROUND: Stereotactic ablative radiotherapy (SABR) is an emerging therapy for primary renal cell carcinoma. The authors assessed safety, efficacy, and survival in a multi-institutional setting. Outcomes between single-fraction and multifraction SABR were compared. METHODS: Individual patient data sets from 9 International Radiosurgery Oncology Consortium for Kidney institutions across Germany, Australia, the United States, Canada, and Japan were pooled. Toxicities were recorded using Common Terminology Criteria for Adverse Events, version 4.0. Patient, tumor, and treatment characteristics were stratified according to the number of radiotherapy fractions (single vs multiple). Survival outcomes were examined using Kaplan-Meier estimates and Cox proportional-hazards regression. RESULTS: Of 223 patients, 118 received single-fraction SABR, and 105 received multifraction SABR. The mean patient age was 72 years, and 69.5% of patients were men. There were 83 patients with grade 1 and 2 toxicity (35.6%) and 3 with grade 3 and 4 toxicities (1.3%). The rates of local control, cancer-specific survival, and progression-free survival were 97.8%, 95.7%, and 77.4%, respectively, at 2 years; and they were 97.8%, 91.9%, and 65.4%, respectively, at 4 years. On multivariable analysis, tumors with a larger maximum dimension and the receipt of multifraction SABR were associated with poorer progression-free survival (hazard ratio, 1.16 [P < .01] and 1.13 [P = .02], respectively) and poorer cancer-specific survival (hazard ratio, 1.28 [P < .01] and 1.33 [P = .01], respectively). There were no differences in local failure between the single-fraction cohort (n = 1) and the multifraction cohort (n = 2; P = .60). The mean ( ± standard deviation) estimated glomerular filtration rate at baseline was 59.9 ± 21.9 mL per minute, and it decreased by 5.5 ± 13.3 mL per minute (P < .01). CONCLUSIONS: SABR is well tolerated and locally effective for treating patients who have primary renal cell carcinoma and has an acceptable impact on renal function. An interesting observation is that patients who receive single-fraction SABR appear to be less likely to progress distantly or to die of cancer. Cancer 2018;124:934-42. © 2017 American Cancer Society.

Tumor radiomic heterogeneity: Multiparametric functional imaging to characterize variability and predict response following cervical cancer radiation therapy.

BACKGROUND: Robust approaches to quantify tumor heterogeneity are needed to provide early decision support for precise individualized therapy. PURPOSE: To conduct a technical exploration of longitudinal changes in tumor heterogeneity patterns on dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI) and FDG positron emission tomography / computed tomography (PET/CT), and their association to radiation therapy (RT) response in cervical cancer. STUDY TYPE: Prospective observational study with longitudinal MRI and PET/CT pre-RT, early-RT (2 weeks), and mid-RT (5 weeks). POPULATION: Twenty-one FIGO IB2 -IVA cervical cancer patients receiving definitive external beam RT and brachytherapy. FIELD STRENGTH/SEQUENCE: 1.5T, precontrast axial T1 -weighted, axial and sagittal T2 -weighted, sagittal DWI (multi-b values), sagittal DCE MRI (<10 sec temporal resolution), postcontrast axial T1 -weighted. ASSESSMENT: Response assessment 1 month after completion of treatment by a board-certified radiation oncologist from manually delineated tumor volume changes. STATISTICAL TESTS: Intensity histogram (IH) quantiles (DCE SI10% and DWI ADC10% , FDG-PET SUVmax ) and distribution moments (mean, variance, skewness, kurtosis) were extracted. Differences in IH features between timepoints and modalities were evaluated by Skillings-Mack tests with Holm's correction. Area under receiver-operating characteristic curve (AUC) and Mann-Whitney testing was performed to discriminate treatment response using IH features. RESULTS: Tumor IH means and quantiles varied significantly during RT (SUVmean : ↓28-47%, SUVmax : ↓30-59%, SImean : ↑8-30%, SI10% : ↑8-19%, ADCmean : ↑16%, P < 0.02 for each). Among IH heterogeneity features, FDG-PET SUVCoV (↓16-30%, P = 0.011) and DW-MRI ADCskewness decreased (P = 0.001). FDG-PET SUVCoV was higher than DCE-MRI SICoV and DW-MRI ADCCoV at baseline (P < 0.001) and 2 weeks (P = 0.010). FDG-PET SUVkurtosis was lower than DCE-MRI SIkurtosis and DW-MRI ADCkurtosis at baseline (P = 0.001). Some IH features appeared to associate with favorable tumor response, including large early RT changes in DW-MRI ADCskewness (AUC = 0.86). DATA CONCLUSION: Preliminary findings show tumor heterogeneity was variable between patients, modalities, and timepoints. Radiomic assessment of changing tumor heterogeneity has the potential to personalize treatment and power outcome prediction. LEVEL OF EVIDENCE: 2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1388-1396.

Postoperative hypofractionated stereotactic brain radiation (HSRT) for resected brain metastases: improved local control with higher BED10.

INTRODUCTION: HSRT directed to large surgical beds in patients with resected brain metastases improves local control while sparing patients the toxicity associated with whole brain radiation. We review our institutional series to determine factors predictive of local failure. METHODS: In a total of 39 consecutive patients with brain metastases treated from August 2011 to August 2016, 43 surgical beds were treated with HSRT in three or five fractions. All treatments were completed on a robotic radiosurgery platform using the 6D Skull tracking system. Volumetric MRIs from before and after surgery were used for radiation planning. A 2-mm PTV margin was used around the contoured surgical bed and resection margins; these were reviewed by the radiation oncologist and neurosurgeon. Lower total doses were prescribed based on proximity to critical structures or if prior radiation treatments were given. Local control in this study is defined as no volumetric MRI evidence of recurrence of tumor within the high dose radiation volume. Statistics were calculated using JMP Pro v13. RESULTS: Of the 43 surgical beds analyzed, 23 were from NSCLC, 5 were from breast, 4 from melanoma, 5 from esophagus, and 1 each from SCLC, sarcoma, colon, renal, rectal, and unknown primary. Ten were treated with three fractions with median dose 24 Gy and 33 were treated with five fractions with median dose 27.5 Gy using an every other day fractionation. There were no reported grade 3 or higher toxicities. Median follow up was 212 days after completion of radiation. 10 (23%) surgical beds developed local failure with a median time to failure of 148 days. All but three patients developed new brain metastases outside of the treated field and were treated with stereotactic radiosurgery, whole brain radiation and/or chemotherapy. Five patients (13%) developed leptomeningeal disease. With a median follow up of 226 days, 30 Gy/5 fx was associated with the best local control (93%) with only 1 local failure. A lower total dose in five fractions (ie 27.5 or 25 Gy) had a local control rate of 70%. For three fraction SBRT, local control was 100% using a dose of 27 Gy in three fractions (follow up was > 600 days) and 71% if 24 Gy in three fractions was used. A higher total biologically equivalent dose (BED10) was statistically significant for improved local control (p = 0.04) with a threshold BED10 ≥ 48 associated with better local control. CONCLUSIONS: HSRT after surgical resection for brain metastasis is well tolerated and has improved local control with BED10 ≥ 48 (30 Gy/5 fx and 27 Gy/3 fx). Additional study is warranted.

Utilization of radiotherapy and stereotactic body radiation therapy for renal cell cancer in the USA.

AIM: This study evaluated national practice patterns of cT1N0M0 renal cell cancer, with a focus on stereotactic body radiation therapy (SBRT) utilization. METHODS: The National Cancer Database was queried (2004-2013) for patients with newly-diagnosed cT1a/bN0M0 renal cell cancer that received definitive treatment. Temporal trends in utilization were tabulated. RESULTS: Altogether, 138,495 patients met inclusion criteria; 13,725 (9.9%) patients received ablative therapy, 57,924 (41.8%) partial nephrectomy, 67,168 (48.5%) radical nephrectomy and 308 (0.2%) external beam radiation therapy (EBRT). The proportion of EBRT that was SBRT increased substantially from 25% in 2004 to 95.4% in 2013, with a sharp inflection point from 2005 to 2006. CONCLUSION: SBRT utilization has sharply risen over time; in most recent years, the vast majority of EBRT is delivered in the form of SBRT.

Outcomes and toxicities in patients treated with definitive focal therapy for primary prostate cancer: systematic review.

AIM: This systematic review summarizes the clinical data on focal therapy (FT) when used alone as definitive therapy for primary prostate cancer (PCa). METHODS: The protocol is detailed in the online PROSPERO database, registration No. CRD42014014765. Articles evaluating any form of FT alone as a definitive treatment for PCa in adult male patients were included. RESULTS: Of 10,419 identified articles, 10,401 were excluded, and thus leaving 18 for analysis. In total, 2288 patients were treated using seven modalities. The outcomes of FT in PCa seem to be similar to those observed with whole gland therapy and with fewer side effects. CONCLUSION: Further research, including prospective randomized trials, is warranted to elucidate the potential advantages of focal radiation techniques for treating PCa. Prospero Registration Number: CRD42014014765.

Spinal metastases: multimodality imaging in diagnosis and stereotactic body radiation therapy planning.

Due to increased effectiveness of cancer treatments and increasing survival rates, metastatic disease has become more frequent compared to the past, with the spine being the most common site of bony metastases. Diagnostic imaging is an integral part of screening, diagnosis and follow-up of spinal metastases. In this article, we review the principles of multimodality imaging for tumor detection with respect to their value for diagnosis and stereotactic body radiation therapy planning for spinal metastases. We will also review the current international consensus agreement for stereotactic body radiation therapy planning, and the role of imaging in achieving the best possible treatment plan.