Definitive, High-Dose-Per-Fraction, Conformal, Stereotactic External Radiation for Renal Cell Carcinoma

Dose-response of localized renal cell carcinoma after stereotactic body radiation therapy: A meta-analysis

BACKGROUND

Stereotactic ablative radiation therapy (SBRT) is an emerging treatment option for primary renal cell carcinoma (RCC), particularly in patients who are unsuitable for surgery. The aim of this review is to assess the effect of increasing the biologically equivalent dose (BED) via various radiation fractionation regimens on clinical outcomes.

METHODS

A literature search was conducted in PubMed (Medline), EMBASE, and the Cochrane Library for studies published up to October 2023. Studies reporting on patients with localized RCC receiving SBRT were included to determine its effectiveness on local control, progression-free survival, and overall survival. A random effects model was used to meta-regress clinical outcomes relative to the BED for each study and heterogeneity was assessed by I2.

RESULTS

A total of 724 patients with RCC from 22 studies were included, with a mean age of 72.7 years (range: 44.0-81.0). Local control was excellent with an estimate of 99 % (95 %CI: 97-100 %, I2 = 19 %), 98 % (95 %CI: 96-99 %, I2 = 8 %), and 94 % (95 %CI: 90-97 %, I2 = 11 %) at one year, two years, and five years respectively. No definitive association between increasing BED and local control, progression-free survival and overall survival was observed. No publication bias was observed.

CONCLUSIONS

A significant dose response relationship between oncological outcomes and was not identified, and excellent local control outcomes were observed at the full range of doses. Until new evidence points otherwise, we support current recommendations against routine dose escalation beyond 25-26 Gy in one fraction or 42-48 Gy in three fractions, and to consider de-escalation or compromising target coverage if required to achieve safe organ at risk doses.

Stereotactic body radiotherapy for inoperable patients with renal carcinoma

INTRODUCTION

The objective of this study was to analyze the dose-dependent safety profiles of stereotactic body radiation therapy (SBRT) in patients with inoperable small renal cell carcinoma (RCC).

MATERIAL

This is a retrospective study from a single institution including patients with RCC treated between 2011 and 2020 with SBRT on the primary tumor or on a local recurrence after surgery. All patients had been declared inoperable or refused surgery. The patients were divided into two dose level groups: group 1 (BED10<60Gy) and group 2 (BED10≥60Gy). Acute and late toxicities, renal function and local control (LC) were compared between the two groups.

RESULTS

A total of 24 patients were analyzed with an average follow-up of 25.1 months. Nine patients (37%) and three patients (14%) reported grade 1-2 acute and late toxicities, respectively. No grade≥3 acute and late toxicities were observed. There was no significant difference in acute and late toxicities between the two groups (P=0.21 and P=0.27, respectively). There was no significant difference in estimated glomerular filtration rate in the 15 patients, eligible for renal toxicity analysis between the pre-radiation and the 12-month follow-up (P=0.1) and the last follow-up (P=0.06). LC at the last follow-up was noted in 19 out of 23 patients (83%) and was based on imaging acquisition. LC was 77.8% for group 1 and 85.7% for group 2 (P=1.95).

CONCLUSION

Dose escalation was not associated with an increase in acute and late grade≥2 toxicities. There appears to be a trend towards increased LC at higher doses.

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.

Stereotactic Body Radiotherapy for Kidney Cancer: Ready for Prime Time?

The standard treatment for renal cell carcinoma (RCC) is surgery. However, a number of patients will not be candidates for surgical treatment or will reject this therapeutic approach. Therefore, alternative approaches are required. Historically, radiotherapy has been considered an ineffective treatment for RCC due to the radioresistance of renal tumour cells to conventional fractionation and the increased rate of toxicity. Stereotactic body radiotherapy (SBRT) is a radiotherapy technique that provides a non-invasive ablative treatment with remarkable rates of local control in both primary tumours and metastases in several locations, with a low associated morbidity due to the highly conformal dose and the use of image-guided techniques. Current evidence shows that a higher dose per fraction, achieving a higher biological effective dose, can overcome the radioresistance of RCC cells. Therefore, SBRT, as well as the combination of SBRT and new emerging immune therapies, has a potential role in the local treatment of primary RCC and oligometastatic RCC patients.

The Emerging Role of Radiation Therapy in Renal Cell Carcinoma

Simple Summary

Stereotactic ablative radiation therapy (SAbR) is a safe and effective local therapy for renal cell cancer (RCC) with emerging and evolving indications. In this review we provide an overview of the evidence to support SAbR for RCC in a variety of clinical settings.

Abstract

Advancements in radiation delivery technology have made it feasible to treat tumors with ablative radiation doses via stereotactic ablative radiation therapy (SAbR) at locations that were previously not possible. Renal cell cancer (RCC) was initially thought to be radioresistant, even considered toxic, in the era of conventional protracted course radiation. However, SAbR has been demonstrated to be safe and effective in providing local control to both primary and metastatic RCC by using ablative radiation doses. SAbR can be integrated with other local and systemic therapies to provide optimal management of RCC patients. We will discuss the rationale and available evidence for the integration and sequencing of SAbR with local and systemic therapies for RCC.

Immunotherapy and Radiation Therapy in Renal Cell Carcinoma

BACKGROUND

The management of renal cell carcinoma is rapidly evolving and immunotherapy, mostly consisting of immune checkpoint inhibitors, is revolutionizing the treatment scenario of metastatic patients. Novel fractionation schedules of radiotherapy, consisting of high doses in few fractions, can overcome the radioresistance of this tumor. Localized radiotherapy is associated with a systemic effect, known as the abscopal effect. This effect mediated by the immune system can be enhanced associating radiotherapy with immunotherapy.

OBJECTIVE

In this review, we explore the role of radiotherapy and immunotherapy in RCC, the rationale of combining these strategies and the on-going clinical trials investigating combinations of these two treatment modalities.

CONCLUSION

Combining immunotherapy and radiotherapy has a strong rationale and pre-clinical studies support their association because it can overcome the immunosuppression of the tumor microenvironment and increase the anti-tumor immune response. More clinical evidence, deriving from onclinical trials, are needed to prove the efficacy and safety of these treatments combined.

The Role of Daily Adaptive Stereotactic MR-Guided Radiotherapy for Renal Cell Cancer

Simple Summary

Standard treatment for localized renal cell carcinoma (RCC) is surgery. Stereotactic radiotherapy given in a few high dose fractions is a promising treatment for this indication and could be an alternative option for patients unsuitable for surgery. Stereotactic MR-guided radiotherapy (MRgRT) is clinically implemented as a new technique for precise treatment delivery of abdominal tumors, like RCC. In this study, we evaluated the clinical impact of stereotactic MRgRT given in five fractions of 8 Gy and routine plan re-optimization for 36 patients with large primary RCCs. Our evaluation showed good oncological results with minimal side-effects. Even in this group with large tumors, daily plan re-optimization was only needed in a minority of patients who can be identified upfront. This is a favorable result since online MRgRT plan adaptation is a time-consuming procedure. In these patients, MRgRT delivery will be faster, and these patients could be candidates for even less fractions per treatment.

Abstract

Novel magnetic-resonance-guided radiotherapy (MRgRT) permits real-time soft-tissue visualization, respiratory-gated delivery with minimal safety margins, and time-consuming daily plan re-optimisation. We report on early clinical outcomes of MRgRT and routine plan re-optimization for large primary renal cell cancer (RCC). Thirty-six patients were treated with MRgRT in 40 Gy/5 fractions. Prior to each fraction, re-contouring of tumor and normal organs on a pretreatment MR-scan allowed daily plan re-optimization. Treatment-induced toxicity and radiological responses were scored, which was followed by an offline analysis to evaluate the need for such daily re-optimization in 180 fractions. Mean age and tumor diameter were 78.1 years and 5.6 cm, respectively. All patients completed MRgRT with an average fraction duration of 45 min. Local control (LC) and overall survival rates at one year were 95.2% and 91.2%. No grade ≥3 toxicity was reported. Plans without re-optimization met institutional radiotherapy constraints in 83.9% of 180 fractions. Thus, daily plan re-optimization was required for only a minority of patients, who can be identified upfront by a higher volume of normal organs receiving 25 Gy in baseline plans. In conclusion, stereotactic MRgRT for large primary RCC showed low toxicity and high LC, while daily plan re-optimization was required only in a minority of patients.

The Reintroduction of Radiotherapy Into the Integrated Management of Kidney Cancer

The incidence of renal cell carcinoma (RCC) has been increasing, with a moderate subgroup of individuals who later develop metastatic disease. Historically, metastatic RCC has been managed with systemic therapy because RCC was believed to be radioresistant. Local therapies, such as stereotactic body radiation therapy, also known as stereotactic ablative radiotherapy, which utilize focused high-dose-rate radiation delivered over a limited number of treatments, have been successful in controlling local disease and, in some cases, extending survival in patients with intracranial and extracranial metastatic RCC. Stereotactic ablative radiotherapy is highly effective in treating intact disease when patients are not surgical candidates. Stereotactic ablative radiotherapy is well tolerated when used in conjunction with systemic therapy such as tyrosine kinase inhibitors and immune checkpoint inhibitors. These successes have prompted investigators to evaluate the efficacy of stereotactic body radiation therapy in novel settings such as neoadjuvant treatment of advanced RCC with tumor thrombus and oligometastatic/oligoprogressive disease states.

Radiation induces dynamic changes to the T cell repertoire in renal cell carcinoma patients

Clinical studies combining radiation and immunotherapy have shown promising response rates, strengthening efforts to sensitize tumors to immune-mediated attack. Thus, there is an ongoing surge in trials using preconditioning regimens with immunotherapy. Yet, due to the scarcity of resected tumors treated in situ with radiotherapy, there has been little investigation of radiation's sole contributions to local and systemic antitumor immunity in patients. Without this access, translational studies have been limited to evaluating circulating immune subsets and systemic remodeling of peripheral T cell receptor repertoires. This constraint has left gaps in how radiation impacts intratumoral responses and whether tumor-resident T cell clones are amplified following treatment. Therefore, to interrogate the immune impact of radiation on the tumor microenvironment and test the hypothesis that radiation initiates local and systemic expansion of tumor-resident clones, we analyzed renal cell carcinomas from patients treated with stereotactic body radiation therapy. Transcriptomic comparisons were evaluated by bulk RNA sequencing. T cell receptor sequencing monitored repertoires during treatment. Pathway analysis showed radiation-specific enrichment of immune-related processes, and T cell receptor sequencing revealed increased clonality in radiation-treated tumors. The frequency of identified, tumor-enriched clonotypes was tracked across serial blood samples. We observed increased abundance of tumor-enriched clonotypes at 2 wk postradiation compared with pretreatment levels; however, this expansion was not sustained, and levels contracted toward baseline by 4 wk posttreatment. Taken together, these results indicate robust intratumoral immune remodeling and a window of tumor-resident T cell expansion following radiation that may be leveraged for the rational design of combinatorial strategies.

Proton Therapy for Primary Renal Cell Carcinoma: The First Nationwide Retrospective Study in Japan

BACKGROUND/AIM

This multi-institutional study aimed to investigate the efficacy and feasibility of proton beam therapy (PBT) for renal cell carcinoma (RCC) in Japan.

PATIENTS AND METHODS

The survival, local control, and toxicities in 22 RCC patients treated between 2001 and 2016 at 6 Japanese PBT institutes were analyzed.

RESULTS

The 22 patients comprised 20 men and had a median age of 67 (range=42-88) years. The total irradiation dose was 60-79.6 Gy (relative biological effectiveness). Over a median follow-up of 37 months, the 3-year overall and disease-specific survival rates were 95% and 100%, respectively, and no recurrence occurred. No patient experienced grade 3 or higher adverse events. The serum blood urea nitrogen (p=0.25) and creatinine levels (p=0.95) were not significantly affected, although the mean estimated glomerular filtration rate was reduced by 7.1±11.2 ml/min/1.73 m² Conclusion: Despite the small number of patients, high-dose PBT can control RCC while maintaining their renal function with high probability, and could be and alternative curative therapy especially for inoperable patients.

Nephron-Sparing Robotic Radiosurgical Therapy for Primary Renal Cell Carcinoma: Single-Institution Experience and Review of the Literature

PURPOSE

We report our single-institution stereotactic body radiation therapy (SBRT) experience on stage I renal cancer with prospectively collected toxicity and efficacy data.

METHODS AND MATERIALS

A total of 21 patients with solitary renal tumors, including 14 surgical candidates who refused surgery (66%), were treated with SBRT. Histologic confirmation was obtained on all patients before treatment; 2 had transitional cell carcinoma and 19 had renal cell carcinoma. The median age was 71 years (range, 58-88). Nearly all patients received 48 Gy in 3 fractions.

RESULTS

The median follow-up was 78 months (range, 5-107). At 5 years post treatment, the local tumor control rate was 100%. Tumor size decreased by a median value of 5.3% at 1 year post treatment, 15.6% at 2 years post treatment, and 15.4% at 5 years post treatment. Glomerular filtration rate had decreased by a median value of 1.5% at 1 year post treatment, 7.0% at 2 years post treatment, and 14.2% at 5 years post treatment. Three patients experienced grade 1 toxicity; no other treatment-related adverse effects were reported.

CONCLUSIONS

SBRT is a promising noninvasive treatment in the management of primary renal cell carcinoma, with evolving clinical evidence demonstrating encouraging results with respect to local control and toxicity.

Is there a role for stereotactic radiotherapy in the treatment of renal cell carcinoma?

Renal cell carcinoma (RCC) has traditionally been regarded as radioresistant tumor based on preclinical data and negative clinical trials using conventional fractionated radiotherapy. However, there is emerging evidence that radiotherapy delivered in few fractions with high single-fraction and total doses may overcome RCC s radioresistance. Stereotactic radiotherapy (SRT) has been successfully used in the treatment of intra- and extracranial RCC metastases showing high local control rates accompanied by low toxicity. Although surgery is standard of care for non-metastasized RCC, a significant number of patients is medically inoperable or refuse surgery. Alternative local approaches such as radiofrequency ablation or cryoablation are invasive and often restricted to small RCC, so that there is a need for alternative local therapies such as stereotactic body radiotherapy (SBRT). Recently, both retrospective and prospective trials demonstrated that SBRT is an attractive treatment alternative for localized RCC. Here, we present a comprehensive review of the published data regarding SBRT for primary RCC. The radiobiological rationale to use higher radiation doses in few fractions is discussed, and technical aspects enabling the safe delivery of SBRT despite intra- and inter-fraction motion and the proximity to organs at risk are outlined.

Renal Cancer is Not Radioresistant: Slowly but Continuing Shrinkage of the Tumor After Stereotactic Body Radiation Therapy

Purpose:

To evaluate the safety and efficacy of stereotactic body radiation therapy for primary lesion of renal cell carcinoma with long-term and regular follow-up of tumor size and renal function.

Methods:

This prospective study included 13 patients treated with stereotactic body radiation therapy for primary lesion of stage I renal cell carcinoma between August 2007 and June 2016 in our institution. Diagnosis of renal cell carcinoma was made by 2 radiologists using computed tomography or magnetic resonance imaging. A dosage of 60 Gy in 10 fractions or 70 Gy in 10 fractions was prescribed. The higher dose was selected if dose constraints were satisfied. Tumor response on imaging examination, local progression-free rate, overall survival, and toxicity were assessed.

Results:

The mean follow-up period was 48.3 months (range: 11-108 months). The tumors showed very slow but continuous response during long-term follow-up. Three cases (23.1%) showed transient progression during the short follow-up. The mean duration until the day on which partial response was confirmed among the partial or complete response cases was 22.6 months (95% confidence interval, 15.3-30.0 months). Local progression-free rate was 92.3% for 3 years and overall survival rate 91.7% for 2 years and 71.3% for 3 years. Twelve cases (92.3%) had impaired renal function at baseline. Renal function decreased slowly and mildly in most of the cases, but 2 cases of solitary kidney showed grade 4 or 5 renal dysfunction.

Conclusion:

All renal tumors decreased in size slowly but continuously for years after stereotactic body radiation therapy. Renal cancer can be treated radically with stereotactic body radiation therapy as a radiosensitive tumor, but careful attention should be given in cases with solitary kidney.

Stereotactic body radiation therapy (SBRT) on renal cell carcinoma, an overview of technical aspects, biological rationale and current literature

BACKGROUND

Stereotactic body radiotherapy (SBRT) is characterized by the delivery of high doses of ionizing radiation in few fractions. It is highly effective in achieving local control, and, due to the high biological effective dose administered, it seems to overcome the radioresistance of renal cell carcinoma (RCC). Thus, SBRT could constitute a treatment option for the management of localized RCC in patients who are not surgical candidates. In this paper, we report an overview about data from the current evidence about SBRT in patients affected by localized RCC.

MATERIALS AND METHODS

A non-systematic review was performed, including data from both retrospective and prospective studies focusing on the use of SBRT for localized RCC and its biological rationale. Furthermore, ongoing trials on this issue are reported.

CONCLUSION

Currently, SBRT might be considered a treatment alternative in inoperable patients affected by primary RCC. Currently, dose-escalation to 48 Gy in 3-4 fractions are effective and well tolerated. Emerging role of immune therapies in RCC patients warrant further studies to explore interactions between SBRT and immune response.

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.

Renal Cell Carcinoma in von Hippel-Lindau Disease-From Tumor Genetics to Novel Therapeutic Strategies

von Hippel-Lindau (VHL) disease is an autosomal dominant syndrome caused by mutations in the VHL tumor-suppressor gene, leading to the dysregulation of many hypoxia-induced genes. Affected individuals are at increased risk of developing recurrent and bilateral kidney cysts and dysplastic lesions which may progress to clear cell renal cell carcinoma (ccRCC). Following the eponymous VHL gene inactivation, ccRCCs evolve through additional genetic alterations, resulting in both intratumor and intertumor heterogeneity. Genomic studies have identified frequent mutations in genes involved in epigenetic regulation and phosphoinositide 3-kinase-AKT-mechanistic target of rapamycin (mTOR) pathway activation. Currently, local therapeutic options include nephron-sparing surgery and alternative ablative procedures. For advanced metastatic disease, systemic treatment, including inhibition of vascular endothelial growth factor pathways and mTOR pathways, as well as immunotherapy are available. Multimodal therapy, targeting multiple signaling pathways and/or enhancing the immune response, is currently being investigated. A deeper understanding of the fundamental biology of ccRCC development and progression, as well as the development of novel and targeted therapies will be accelerated by new preclinical models, which will greatly inform the search for clinical biomarkers for diagnosis, prognosis, and response to treatment.

Stereotactic ablative radiation therapy in renal cell carcinoma: From oligometastatic to localized disease

Renal Cell Carcinoma (RCC) has historically been considered a radioresistant cancer, and radiotherapy was usually delivered with a palliative goal. Stereotactic ablative radiotherapy (SABR) allows the delivery of high doses on small treatment volumes in a safe and effective way, thus opening the doors to new applicationsof radiotherapy both in the treatment of the primary and oligometastasic disease. Aim of the current review is to explore the state of art of SABR in the therapeutic approach to RCC.

Stereotactic body radiotherapy for renal cell cancer and pancreatic cancer : Literature review and practice recommendations of the DEGRO Working Group on Stereotactic Radiotherapy

PURPOSE

This report of the Working Group on Stereotactic Radiotherapy of the German Society of Radiation Oncology (DEGRO) aims to provide a literature review and practice recommendations for stereotactic body radiotherapy (SBRT) of primary renal cell cancer and primary pancreatic cancer.

METHODS

A literature search on SBRT for both renal cancer and pancreatic cancer was performed with focus on prospective trials and technical aspects for clinical implementation.

RESULTS

Data on renal and pancreatic SBRT are limited, but show promising rates of local control for both treatment sites. For pancreatic cancer, fractionated SBRT should be preferred to single-dose treatment to reduce the risk of gastrointestinal toxicity. Motion-compensation strategies and image guidance are paramount for safe SBRT delivery in both tumor entities.

CONCLUSION

SBRT for renal cancer and pancreatic cancer have been successfully evaluated in phase I and phase II trials. Pancreatic SBRT should be practiced carefully and only within prospective protocols due to the risk of severe gastrointestinal toxicity. SBRT for primary renal cell cancer appears a viable option for medically inoperable patients but future research needs to better define patient selection criteria and the detailed practice of SBRT.

Curative Stereotactic Robotic Radiotherapy Treatment for Extracranial, Extrapulmonary, Extrahepatic, and Extraspinal Tumors: Technique, Early Results, and Toxicity

We investigated the technique, early results and toxicity of curative stereotactic radiotherapy with the CyberKnife® (Accuray Incorporated, Sunnyvale, California, USA) in 15 extracranial, extrapulmonary, extrahepatic, and extraspinal tumors. Fourteen tumors were located close to the bowel or esophagus. The PTV = GTV + 2–5 mm. The dose to the tumors varied from 10 fractions of 4 Gy up to 3 fractions of 20 Gy (median dose/fraction: 7 Gy; median number of fractions: 6), and depended on the proximity of the bowel. A small volume of the bowel was allowed to receive a dose of 6 Gy/fraction. The dose to the PTV was prescribed to the 75–85% isodose line. With a median follow up of 18 months, the 2-year local control and overall survival was 100%. Due to our flexible fractionation schedules, we were able to prescribe the dose to at least 90% of the PTV (median 95%) without increasing the dose to the bowel > 6 Gy/fraction. Five acute side effects were seen in four patients: two patients had transient grade 1 lymph edema in the leg, one patient complained of grade 1 pain in the abdomen and diarrhea, and one patient complained of grade 1 radiation dermatitis. Late toxicity such as grade 1 rectal bleeding, grade 1 diarrhea, grade 2 painful subcutaneous fibrosis, grade 2 pain in a surgical scar on the abdominal wall and an asymptomatic occlusion of the ureter was observed. Curative stereotactic radiotherapy treatment with the CyberKnife for extracranial, extrapulmonary, extrahepatic, and extraspinal, locally recurrent or solitary metastatic tumors is feasible and results in excellent local control and survival with low acute and late toxicity. A small volume of the bowel is able to tolerate a dose of 6 Gy per fraction for a maximum of 6 fractions.

Stereotactic Ablative Radiotherapy for the Treatment of Clinically Localized Renal Cell Carcinoma

Thermal ablation is currently the most studied treatment option for medically inoperable patients with clinically localized renal cell carcinoma (RCC). Recent evidence suggests that stereotactic ablative radiotherapy (SABR) may offer an effective noninvasive alternative for these patients. In this review, we explore the current literature on SABR for the primary treatment of RCC and make recommendations for future studies so that an accurate comparison between SABR and other ablative therapies may be conducted.

Contemporary Trends in the Utilization of Radiotherapy in Patients With Renal Cell Carcinoma

OBJECTIVE

To examine the utilization of radiation therapy (RT) in patients with renal cell carcinoma (RCC) using a large national tumor registry.

MATERIALS AND METHODS

Patients diagnosed with RCC were identified using the National Cancer Data Base. Our primary objective was to assess temporal trends in the utilization of RT. Our secondary objective was to identify patient and treatment factors associated with receipt of RT. The Cochran-Armitage test was used for trend analysis. Multivariable logistic regression was performed to identify factors associated with RT use.

RESULTS

A total of 279,427 patients were diagnosed with RCC from 1998 to 2010. A total of 233,572 (83.6%) had localized or locally advanced disease, whereas the remaining 45,855 (16.4%) had metastatic disease. There was a decrease in radiotherapy across all patients during this period (1.5%-0.6%, P <.001); as salvage or adjuvant therapy with surgery (1.3%-0.3%, P <.001), and in patients with metastatic disease (33.3%-28.5%, P <.001). Factors associated with increased RT use in patients with nonmetastatic RCC included male gender, receipt of systemic therapy, higher stage, higher grade, nonacademic treatment facility, facility location, and sarcomatoid or other histology.

CONCLUSION

In the National Cancer Data Base, we observed a decrease in the use of RT for patients with RCC from 1998 to 2010. Patients with more aggressive disease characteristics were more likely to receive RT. Well-designed clinical trials are needed to clarify the role of RT in the management of these patients.

Image guidance and stabilization for stereotactic ablative body radiation therapy (SABR) treatment of primary kidney cancer

PURPOSE

Stereotactic ablative body radiation therapy for primary kidney cancer treatment relies on motion management that can quantify both the trajectory of kidney motion and stabilize the patient. A prospective ethics-approved clinical trial of stereotactic treatment to primary kidney targets was conducted at our institution. Our aim was to report on specific kidney tumor motion and the inter- and intrafraction motion as seen on treatment.

METHODS AND MATERIALS

Patients with tumor size <5 cm received a dose of 26 Gy in 1 fraction and those with tumor size ≥5 cm received 42 Gy in 3 fractions. All patients underwent a 4-dimensional computed tomography planning scan, immobilized in a dual-vacuum system. A conventional linear accelerator cone beam computed tomography scan was used for pre-, mid-, and posttreatment imaging to verify target position.

RESULTS

Between July 2012 and October 2014, 33 targets from 32 consecutive patients (24 males/8 females) were treated. Seventeen targets were prescribed 26 Gy/1 fraction and the remaining 16 targets received 42 Gy/3 fractions. Kidney motion at each of the poles was not affected by the presence of tumor (P = .875), nor was the motion statistically different from the corresponding contralateral kidney pole (P = .909). The mean 3-dimensional displacement of the target at mid- and posttreatment was 1.3 mm (standard deviation ± 1.6) and 1.0 mm (standard deviation ± 1.3), respectively. The maximum displacement in any direction for 95% of the fractions at mid- and posttreatment was ≤3 mm.

CONCLUSION

In summary, stereotactic ablative body radiation therapy of primary kidney targets can be accurately delivered on a conventional linear accelerator with protocol that has minimal intrafractional target motion.

Emerging applications of stereotactic body radiotherapy

Stereotactic body radiotherapy (SBRT) has been used extensively in patients with lung, liver and spinal tumors, and the treatment outcomes are very favorable. For certain conditions such as medically inoperable stage I non-small-cell lung cancer, liver and lung oligometastases, primary liver cancer and spinal metastases, SBRT is regarded as one of the standard therapies. In the recent years, the use of SBRT has been extended to other disease conditions and sites such as recurrent head and neck cancer, renal cell carcinoma, prostate cancer, adrenal metastasis, pancreatic cancer, gynecological malignancies, spinal cord compression, breast cancer, and stage II-III non-small-cell lung cancer. Preliminary data in the literature show promising results but the follow-up intervals are short for most studies. This paper will provide an overview of these emerging applications.

Stereotactic radiation therapy of renal cancer inferior vena cava tumor thrombus

Renal Cell Carcinoma (RCC) is a common malignancy world-wide that is rising in incidence. Up to 10% of RCC patients present with inferior vena cava (IVC) tumor thrombus (IVC-TT). Although surgery is the only treatment with proven efficacy for IVC-TT, the surgical management of advanced (level III and IV) IVC-TT is difficult with high morbidity and mortality, and offers a poor survival outcome. Currently, there are no treatment options in the setting of recurrent or unresectable RCC IVC-TT. Even though RCC may be resistant to conventionally fractionated radiation therapy, hypofractionated radiation has shown excellent control rates for both primary and metastatic RCC. We report our experience treating 2 RCC patients with Level IV IVC-TT -one recurrent and the other unresectable-with stereotactic ablative radiation therapy (SABR). The first patient is a 75-year-old gentleman with a level IV RCC IVC-TT who presented 9 months after his radical nephrectomy and thrombectomy with a growing level IV IVC-TT that became refractory to 4 targeted agents. He received SABR of 50Gy in 5 fractions and at 2-year follow-up is doing well with a significant decrease in the enhancement and size of the IVC-TT. The second patient is an 83-year-old gentleman who presented with metastatic RCC and level IV IVC-TT but was not a surgical candidate. After progression on temsirolimus, he received SABR of 36Gy in 4 fractions to his IVC-TT and survived 18 months post-SABR. Both patients improved symptomatically and did not experience any acute or late treatment-related toxicity. Their survival of 24 months and 18 months are comparable to the reported median survival of 20 months in patients with level IV IVC-TT that underwent surgical resection. Therefore, SABR can be a potentially safe treatment option in the unresectable setting for RCC patients with IVC-TT and should be further evaluated in prospective trials.

Extracranial oligometastatic renal cell carcinoma: current management and future directions

The term 'oligometastases' was formulated to describe an intermediate state between widespread metastases and locally confined disease. The standard of care in metastatic renal cell carcinoma is systemic therapy; however, in patients with solitary or limited metastases, aggressive local therapies may potentially prolong survival. The literature suggests a survival benefit with surgical metastasectomy, with a reported 5-year survival as high as 45% in those who achieve complete resection. More recently, an expanding body of evidence supports the role of stereotactic ablative body radiation therapy for the treatment of oligometastatic renal cell carcinoma and early results demonstrate comparable local control rates with surgery. There is also increasing interest in the abscopal and immunologic effects of localized radiation. With the proliferation of newer targeted agents and immunomodulatory agents, current work is addressing the optimization of patient selection and avenues towards sequencing and combining the various treatment options.

A Review of Kidney Motion under Free, Deep and Forced-Shallow Breathing Conditions: Implications for Stereotactic Ablative Body Radiotherapy Treatment

Motion management strategies are important during stereotactic ablative body radiotherapy for abdominal targets. The kidney is a mobile retroperitoneal organ that moves with respiration. A review of the literature was performed to investigate the reported degree of kidney motion associated with various breathing conditions. A structured search was performed using Medline from January 1970 to May 2013 for all publications describing cranial-caudal kidney motion. Relevance to radiotherapy practice was reviewed based on any breathing instructions and/or immobilization equipment that could affect breathing pattern. Studies were categorized under three types of breathing conditions: Forced-shallow, breath-hold/deep and free. A total of 25 publications were identified describing cranial-caudal kidney motion with a combined total of 415 participants. Three publications described forced-shallow breathing using prone positioning or abdominal compression plates. Prone positioning, compared to supine positioning, did little to minimise kidney motion, however use of compression plates can result in kidney motion of less than 5 mm. Eight publications described deep breathing/breath hold techniques that showed average kidney motion ranging between 10 mm-40 mm. Fifteen publications investigated kidney motion under free breathing with the majority reporting mean motion of less than 10 mm. Kidney movement of up to 8.1 mm in the anterior posterior direction and 6.2 mm laterally were reported with no indications that breathing technique can influence the extent of this motion. In summary, kidney movement is complex and consideration should be made to ensure that motion management strategies provide the desired radiotherapy benefit. There are limited publications on the effectiveness of abdominal compression on reducing kidney motion which warrant further investigation in this area.

Role of radiation therapy for renal tumors

Renal cell carcinoma (RCC) is an aggressive malignancy that carries a poor prognosis, especially in patients presenting with advanced stage. Primary treatment for localized RCC is surgical resection however, a significant number of patients still develop locoregional and distant metastasis after curative resection. In metastatic disease, radiation therapy (RT) has been used for palliation routinely for brain and other extracranial lesions with respectable response rates. However, RT for primary RCC has questionable benefit. In this article, the authors discuss the evidence with regards to the role of RT in primary RCC either as a primary treatment, adjuvant treatment, or preoperatively to improve resection outcomes. In addition, novel RT techniques such as stereotactic body radiation therapy and its use in RCC management are also addressed. Finally, the authors discuss the techniques and doses of RT for primary RCC.

Novel application of stereotactic ablative radiotherapy using CyberKnife® for early-stage renal cell carcinoma in patients with pre-existing chronic kidney disease: Initial clinical experiences

The treatment of renal cell carcinoma (RCC) in patients diagnosed with chronic kidney disease (CKD) requires particular care in order to preserve the remaining renal function. The present study aimed to investigate the potential of a novel nephron-sparing treatment, which is capable of targeting tumors embedded deep within tissues. The present study analyzed three patients, with pre-existing CKD and multiple comorbidities, who were successfully treated for stage I RCC using the CyberKnife^® stereotactic ablative radiotherapy (SABR) system. The total prescribed dose was 40 Gy in five fractions administered over five consecutive days. Treatment efficiency was determined using computed tomography scans of the tumors and periodic measurements of the glomerular filtration rate over a period of 12–40 months. Local control, defined as a radiologically stable condition, was achieved in all patients. Lung metastasis was observed in one patient nine months after SABR; however, the side-effects were generally mild and self-limiting. One patient developed renal failure 26 months after SABR, while the severity of CKD was only marginally altered in the other two patients and renal failure did not occur. In conclusion, in the present study, SABR with CyberKnife^® was observed to be well tolerated in the patients, with an acceptable acute toxicity effect. Therefore, it may represent a potential therapeutic option for patients with early-stage RCC who have previously been diagnosed with CKD, but for whom other nephron-sparing treatments are contraindicated.

Renal cell carcinoma treated with stereotactic radiotherapy with histological change confirmed on autopsy: a case report

Background

Treatment of primary renal cell carcinoma using radiotherapy with curative intent is rare, because renal cell carcinoma is generally regarded as a radiation-resistant tumor. Recently, stereotactic body radiation therapy has been radically applied for cancers in various organs including renal cell carcinoma. However, there were few reports describing pathological changes of renal cell carcinoma post stereotactic body radiation therapy. This is the first report we are aware of documenting late histological effects of stereotactic body radiation therapy on renal cell carcinoma and surrounding normal tissue.

Case presentation

A right renal tumor was identified in a Japanese 70-year-old man on follow-up computed tomography for his chronic hepatitis. T1N0M0 renal cell carcinoma was clinically diagnosed as the tumor was 3 cm in diameter and well-enhanced with intravenously infused contrast material in the arterial phase on computed tomography. No metastases in regional lymph nodes or distant sites were evident. Stereotactic body radiation therapy was selected as an alternative therapy to surgery because of his poor liver function. A total dose of 60 Gy in 10 fractions over 12 days was delivered using a 10-megavolt X-ray. The renal tumor gradually decreased in size and partial response had been achieved at 2 years after completing stereotactic body radiation therapy. Hepatocellular carcinoma was identified during follow-up in the patient and he died of progression of hepatocellular carcinoma with hepatic failure 2.5 years after completing stereotactic body radiation therapy. Autopsy was done and it showed almost complete necrosis of tumor tissues with a small amount of viable renal carcinoma cells. These pathological findings suggested marked effects of stereotactic body radiation therapy on clear cell renal cell carcinoma.

Conclusion

Our case demonstrates a good pathological response with small foci of remnant viable cancer cells after stereotactic body radiation therapy of 60Gy in 10 fractions for small renal cell carcinoma. Although further experiences and longer follow-up are mandatory to conclude the optimal treatment schedule and efficacy of stereotactic body radiation therapy for renal cell carcinoma, stereotactic body radiation therapy may represent a novel less-invasive option for the treatment of primary renal cell carcinoma.

Individually wide range of renal motion evaluated by four-dimensional computed tomography

Objectives

Assessment of physiologic renal motion in order to optimize abdominal intensity-modulated radiation therapy and stereotactic body radiation therapy.

Methods and materials

Twenty patients with a median age of 47 years underwent computed tomography simulation and four-dimensional computed tomography acquisition. Thirty-nine kidneys were contoured during ten phases of respiration to estimate renal motion.

Results

Kidney motion was not related to age (p = 0.42), sex (p = 0.28), height (p = 0.75), or body weight (p = 0.63). The average +/- standard deviation (SD) of movement of the center of gravity for all subjects was 11.1 +/- 4.8 mm in the cranio-caudal (CC) direction (range, 2.5-20.5 mm), 3.6 +/- 2.1 mm in the anterior-posterior (AP) direction (range, 0.6-8.0 mm), and 1.7 +/- 1.4 mm in the right-left (RL) direction (range, 0.4-5.9 mm). Renal motion strongly correlated with the respiratory phases (r > 0.97 and p < 0.01 in all three directions).

Conclusions

Renal motion was independent of age, sex, height, or body weight. Renal motion in all directions was strongly respiration dependent, but motion in the cranio-caudal direction showed wide individual variation. In a clinical setting, it will be necessary to evaluate renal respiratory motion separately in each individual.

Salvage robot-assisted partial nephrectomy for the management of renal cell carcinoma following failed stereotactic radiotherapy

With proper patient selection, this study suggests a robot-assisted laparoscopic approach may be utilized in the salvage management of renal tumors following failed stereotactic radiosurgery.

Nephron-sparing surgery is currently the standard of care for the management of small renal masses. While both neoadjuvant and adjuvant conventional external beam radiotherapy have failed to demonstrate an oncologic benefit for the treatment of renal cell carcinoma, more recent work aims to explore the utility of stereotactic radiotherapy. We present the case of a 70-year-old woman who failed primary treatment of a small renal mass with the CyberKnife radiotherapy system and describe her successful salvage treatment with robot-assisted partial nephrectomy. This case demonstrates the safety of robotic surgery for the management of renal tumors following failed stereotactic radiotherapy.

Role of radiation therapy in the management of renal cell cancer

Renal cell carcinoma (RCC) is traditionally considered to be radioresistant; therefore, conventional radiotherapy (RT) fraction sizes of 1.8 to 2 Gy are thought to have little role in the management of primary RCC, especially for curative disease. In the setting of metastatic RCC, conventionally fractionated RT has been an effective palliative treatment in 50% of patients. Recent technological advances in radiation oncology have led to the clinical implementation of image-guided radiotherapy, allowing biologically potent doses to the tumors intra- and extra-cranially. As predicted by radiobiologic modeling, favorable outcomes have been observed with highly hypofractionated schemes modeled after the experience with intracranial stereotactic radiosurgery (SRS) for RCC brain metastases with reported local control rates averaging 85%. At present, both primary and metastatic RCC tumors may be successfully treated using stereotactic approaches, which utilize steep dose gradients to maximally preserve function and avoid toxicity of adjacent organs including liver, uninvolved kidney, bowel, and spinal cord regions. Future endeavors will combine stereotactic body radiation therapy (SBRT) with novel targeted therapies, such as tyrosine kinase inhibitors and targeted rapamycin (mTOR) inhibitors, to maximize both local and systemic control.

A review of current management of brain metastases

BACKGROUND

The brain metastasis (BM) represents one of the most common and refractory malignancies worldwide with a rising incidence in all countries. It is generally believed that once a BM has developed, this disease cannot be cured and has a poor prognosis. The challenges of managing this tumor include diagnosis and selective treatment options. In addition, patients with BM frequently have greater expectations of the current therapy outcomes, which hope to get long-term survival and good quality of life.

METHODS

This is a review of current clinical practice based on an exhaustive literature search of PubMed, Embase, and Google Scholar. A series of case studies is presented to provide outcomes of the effective management in BMs that have required treatment for the terminal stage of patients with cancer, and makes recommendations for future practice.

RESULTS

Current technical advances have been made in the diagnosis and treatment of BM. After surgery, radiotherapy, or stereotactic radiosurgery, and for some cases additional systemic chemotherapy for the primary cancer, most patients experience meaningful symptom relief, improved quality of life and longer survival time. An evidence-based summary of recommendations has been produced to guide neurosurgeons and oncologists in managing this particular group of patients.

CONCLUSIONS

On the basis of the available data, this treatment approach for well-selected patients is currently not recommended in the treatment of BMs except in experienced medical centers. Clinical judgment is made balancing surgical, radiotherapy, chemotherapy and management principles to advocacy the best therapy outcome.

A survey of stereotactic body radiotherapy use in the United States

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a technique used to deliver high, ablative doses of radiation in a limited number of fractions to ≥ 1 extracranial target(s). To the authors' knowledge, the prevalence of SBRT use among radiation oncologists in the United States is unknown.

METHODS

A random sample of 1600 American radiation oncologists was surveyed via e-mail and facsimile (fax) regarding SBRT usage, including year of adoption, motivations, disease sites treated, and common prescriptions used.

RESULTS

Of 1373 contactable physicians, 551 responses (40.1%) were received. The percentage of physicians using SBRT was 63.9% (95% confidence interval, 60%-68%), of whom nearly half adopted it in 2008 or later. The most commonly cited reasons for adopting SBRT were to allow the delivery of higher than conventional radiation doses (90.3%) and to allow retreatment (73.9%) in select patients. Academic physicians were more likely to report research as a motivation for SBRT adoption, whereas physicians in private practice were more likely to list competitive reasons. Among SBRT users, the most common disease sites treated were lung (89.3%), spine (67.5%), and liver (54.5%) tumors. Overall, 76.0% of current SBRT users planned to increase their use, whereas 66.5% of nonusers planned to adopt the technology in the future.

CONCLUSIONS

SBRT has rapidly become a widely adopted treatment approach among American radiation oncologists. Further research and prospective trials are necessary to assess the benefits and risks of this novel technology.

Extracorporeal stereotactic radiosurgery for small renal masses

Over the past decade we have witnessed both a grade and stage migration for renal cell carcinoma. This shift in clinicopathology has been met with a paradigm shift in the treatment of these renal mass lesions. This trend has evolved from laparoscopic extirpation to needle-based and now extracorporeal ablation. At the forefront of the extracorporeal, minimally invasive treatment modalities is radiosurgical ablation. Still in its inaugural phase, renal radiosurgery is devoid of any long-term studies; however, short-term studies thus far show enormous potential. Herein we present the current status of radiosurgical ablation of small renal masses.

Radiation-associated kidney injury

The kidneys are the dose-limiting organs for radiotherapy to upper abdominal cancers and during total body irradiation. The incidence of radiotherapy-associated kidney injury is likely underreported owing to its long latency and because the toxicity is often attributed to more common causes of kidney injury. The pathophysiology of radiation injury is poorly understood. Its presentation can be acute and irreversible or subtle, with a gradual progressive dysfunction over years. A variety of dose and volume parameters have been associated with renal toxicity and are reviewed to provide treatment guidelines. The available predictive models are suboptimal and require validation. Mitigation of radiation nephropathy with angiotensin-converting enzyme inhibitors and other compounds has been shown in animal models and, more recently, in patients.