Stereotactic Ablative Radiotherapy for ≥T1b Primary Renal Cell Carcinoma: A Report From the International Radiosurgery Oncology Consortium for Kidney (IROCK)

Stereotactic Body Radiotherapy for Primary Renal Cell Carcinoma: A Case-Based Radiosurgery Society Practice Guide

Traditionally, renal cell carcinoma (RCC) was considered a radioresistant tumor, thereby limiting definitive radiation therapy management options. However, several recent studies have demonstrated that stereotactic body radiotherapy (SBRT) can achieve high rates of local control for the treatment of primary RCC. In the setting of an expanding use of SBRT for primary RCC, it is crucial to provide guidance on practical considerations such as patient selection, fractionation, target delineation, and response assessment. This is particularly important in challenging scenarios where a paucity of evidence exists, such as in patients with a solitary kidney, bulky tumors, or tumor thrombus. The Radiosurgery Society endorses this case-based guide to provide a practical framework for delivering SBRT to primary RCC, exemplified by three cases. This article explores topics of tumor size and dose fractionation, impact on renal function and treatment in the setting of a solitary kidney, and radiation's role in the management of inferior vena cava tumor thrombus. Additionally, we review existing evidence and expert opinion on target delineation, advanced techniques like MRI-guided SBRT, and SBRT response assessment.

Stereotactic body radiation therapy for primary renal cell carcinoma: A review on behalf of the CC-AFU

INTRODUCTION

The incidence of localized renal cell carcinoma (RCC) is on the rise among individuals aged 70 and older. While the gold standard for treatment remains surgical resection, some elderly and frail patients with comorbidities are not eligible for this procedure. In selected cases, percutaneous thermal ablation, such as cryotherapy, microwave and radiofrequency, offers less invasive options. General anesthesia is sometimes necessary for such treatments, but most of the procedures can be conducted using mild or deep conscious sedation. This approach is preferably recommended for small cT1a tumors situated at a distance from the renal hilum and/or ureter. Active surveillance remains an alternative in the case of small low grade RCC although it may induce anxiety in certain patients. Recent research has highlighted the potentials of stereotactic ablative body radiotherapy (SABR) as a noninvasive, well-tolerated, and effective treatment for small renal tumors. This narrative review aims to explore recent advances in SABR for localized RCC, including appropriate patient selection, treatment modalities and administration, as well as efficacy and tolerance assessment.

MATERIAL AND METHODS

We conducted a literature review using the terms [kidney cancer], [renal cell carcinoma], [stereotactic radiotherapy], [SBRT], and [SABR] in the Medline, PubMed, and Embase databases, focusing on prospective and relevant retrospective studies published in English.

RESULTS

Studies report local control rates ranging from 70% to 100% with SABR, highlighting its efficacy in treating RCC. The decline in glomerular filtration rate (GFR) is approximately -5 to -17mL/min over the years following SABR. Common toxicities are rare, primarily CTCAE grade 1, include fatigue, nausea, chest or back pain, diarrhea, or gastritis.

CONCLUSION

Stereotactic ablative body radiotherapy (SABR) may be considered as a viable option for patients with localized RCC who are not suitable candidates for surgery with a high local control rate and a favorable safety profile. This approach should be discussed in a multidisciplinary meeting and results from ongoing clinical trials are awaited.

LEVEL OF EVIDENCE: 5

Evaluation of Volumetric Response Assessment From SABR for Renal Cell Carcinoma

PURPOSE

SABR is increasingly used to treat renal cell carcinoma (RCC). However, the optimal method to assess treatment response is unclear. We aimed to quantify changes in both volume and maximum linear size of tumors after SABR and evaluate the utility of the 2 approaches in treatment response assessment.

METHODS AND MATERIALS

We retrospectively studied patients with RCC treated with SABR at our institution between 2013 and 2020. All available follow-up computed tomography scans were aligned, and tumors were contoured on all scans. Volume and maximum linear size were measured at each follow-up, relative to these measurements at the time of computed tomography simulation.

RESULTS

Twenty-four patients with 25 tumors were included. Median follow-up was 32 months (range, 16-67). Nineteen tumors (76%) had 30% volumetric response at a median time of 7 months after SABR, and 12 tumors (48%) had 30% decrease in maximum linear size at a median time of 16 months. Eighteen tumors (72%) decreased in volume on first follow-up scan and continued to shrink, and 5 tumors (20%) displayed transient growth after SABR (average 24% increase in volume). Compared with T1a tumors, T1b or larger tumors were more likely to have transient growth (8% vs 33%; P = .16) and had higher average relative volume 24 months after SABR (0.47 vs 0.8; P = .022).

CONCLUSIONS

Volume measurement results in more pronounced and earlier change compared with linear size measurement when assessing response to SABR. These findings may provide guidance when assessing treatment response for patients with RCC treated with SABR.

[Nephron sparing in the management of localized solid renal mass]

Managing a malignant renal tumor requires, first of all, a reflection on the necessity of its treatment. It must consider the renal function, altered at the time of diagnosis in 50% of cases. The treatment method chosen depends on many factors, in particular, the predicted residual renal function, the risk of chronic kidney disease, the need for temporary or long-term dialysis, and overall long-term survival. Other factors include the size, position, and number of tumors and a hereditary tumor background. When a renal-sparing management alternative is available, total nephrectomy should no longer be performed in patients with small malignant renal masses (cT1a). This may consist of surgery (partial nephrectomy or lumpectomy), percutaneous thermo-ablation (by radiofrequency, microwave, or cryotherapy). In patients with limited life expectancy, imaging-based surveillance may be proposed to suggest treatment in case of local progression. Good coordination between urologist, radiologist, nephrologist, and sometimes radiotherapist should allow optimal management of patients with a malignant renal tumor with or without underlying renal failure.

Immunotherapy and stereotactic body radiotherapy for older patients with non-metastatic renal cancer unfit for surgery or decline nephrectomy: practical proposal by the International Geriatric Radiotherapy Group

The standard of care for non-metastatic renal cancer is surgical resection followed by adjuvant therapy for those at high risk for recurrences. However, for older patients, surgery may not be an option due to the high risk of complications which may result in death. In the past renal cancer was considered to be radio-resistant, and required a higher dose of radiation leading to excessive complications secondary to damage of the normal organs surrounding the cancer. Advances in radiotherapy technique such as stereotactic body radiotherapy (SBRT) has led to the delivery of a tumoricidal dose of radiation with minimal damage to the normal tissue. Excellent local control and survival have been reported for selective patients with small tumors following SBRT. However, for patients with poor prognostic factors such as large tumor size and aggressive histology, there was a higher rate of loco-regional recurrences and distant metastases. Those tumors frequently carry program death ligand 1 (PD-L1) which makes them an ideal target for immunotherapy with check point inhibitors (CPI). Given the synergy between radiotherapy and immunotherapy, we propose an algorithm combining CPI and SBRT for older patients with non-metastatic renal cancer who are not candidates for surgical resection or decline nephrectomy.

Dose-Effect Relationship of Kidney Function After SABR for Primary Renal Cell Carcinoma: TROG 15.03 FASTRACK II

PURPOSE

Stereotactic ablative body radiotherapy (SABR) is a novel option to treat primary renal cell carcinoma. However, a high radiation dose may be received by the treated kidney, which may affect its function posttreatment. This study investigates the dose-effect relationship of kidney SABR with posttreatment renal function.

METHODS AND MATERIALS

This was a prespecified secondary endpoint of the multicenter FASTRACK II (Focal Ablative STereotactic RAdiotherapy for Cancers of the Kidney phase II) clinical trial (National Clinical Trial 02613819). Patients received either 26 Gy in a single fraction (SF) for tumors with a maximal diameter of 4 cm or less or 42 Gy in 3 fractions (multifraction [MF]) for larger tumors. To determine renal function change, 99mTc-dimercaptosuccinic acid (DMSA) single-photon emission computed tomography/computed tomography (SPECT/CT) scans were acquired, and the glomerular filtration rate was estimated at baseline, 12, and 24 months posttreatment. Imaging data sets were rigidly registered to the planning CT where kidneys were segmented to calculate dose-response curves.

RESULTS

From 71 enrolled patients, 36 (51%) and 26 (37%) patients were included in this study based on availability of posttreatment data at 12 and 24 months, respectively. The ipsilateral kidney glomerular filtration rate decreased from baseline by 42% and 39% in the SF cohort and by 45% and 62% in the MF cohort, at 12 and 24 months, respectively (P < .03). The loss in renal function was 3.6%/Gy ± 0.8%/Gy and 4.5%/Gy ± 1.0%/Gy in the SF cohort and 1.7%/Gy ± 0.1%/Gy and 1.7%/Gy ± 0.2%/Gy in the MF cohort at 12 and 24 months, respectively. The major loss in renal function occurred in high-dose regions, where dose-response curves converged to a plateau.

CONCLUSIONS

For the first time in a multicenter study, the dose-effect relationship at 12 and 24 months post-SABR treatment for primary renal cell carcinoma was quantified. Kidney function reduces linearly with dose up to 100 Gy BED3.

Cancer-specific mortality in non-metastatic T1a renal cell carcinoma treated with radiotherapy versus partial nephrectomy

PURPOSE

Radiotherapy (RT) represents a treatment option for small renal masses with proven feasibility and tolerability. However, it has never been directly compared to partial nephrectomy (PN) with cancer-specific mortality (CSM) as an endpoint.

METHODS

Within the Surveillance, Epidemiology, and End Results database (2004-2020), we identified T1aN0M0 renal cell carcinoma (RCC) patients treated with RT or PN. We relied on 1:1 propensity score matching (PSM) for age, tumor size and histology. Subsequently, cumulative incidence plots and multivariable competing risks regression (CRR) models were fitted. The same methodology was then re-applied to a subset of patients with tumor size 21-40 mm.

RESULTS

Of 40,355 patients with T1aN0M0 RCC, 40,262 underwent PN (99.8%) vs 93 underwent RT (0.2%). RT patients were older (median age 72 vs 60 years, p < 0.001) and harbored larger tumor size (median size 28 vs 25 mm, p < 0.001) and a higher proportion of non-clear cell RCC (49% vs 22%, p < 0.001). After 1:1 PSM (92 RT versus 92 PN patients), cumulative incidence plots' derived CSM was 21.3 vs 4%, respectively. In multivariable CRR models, RT independently predicted higher CSM (hazard ratio (HR) 4.3, p < 0.001). In the subgroup with tumor size 21-40 mm, after 1:1 PSM (72 RT versus 72 PN patients), cumulative incidence plots derived CSM was 21.3% vs 4%, respectively. In multivariable CRR models, RT also independently predicted higher CSM (HR 4.7, p = 0.001).

CONCLUSIONS

In T1aN0M0 RCC patients, relative to PN, RT is associated with significantly higher absolute and relative CSM, even in patients with tumor size 21-40 mm.

A review of stereotactic ablative radiotherapy for nonmetastatic renal cell carcinoma

Renal cell carcinoma (RCC) is an uncommon malignancy whose incidence has been increasing over the past few decades, posing treatment challenges for elderly or infirm patients who are not surgical candidates. Stereotactic ablative radiotherapy (SABR) has emerged as a promising non-invasive treatment modality for RCC. The high dose-per-fraction used in SABR overcomes some of the mechanisms of radioresistance that has hindered the effective treatment of RCC with conventional radiotherapy. For primary RCC, local control rates for SABR exceed 90%, with typically minimal grade 3 or higher toxicities, offering a viable alternative for inoperable patients and those not eligible for or unable to tolerate radiofrequency or cryotherapy ablation. SABR can also be used in patients with a solitary kidney as a strategy for renal preservation to avoid need for dialysis. Given its excellent local control rates, low toxicity and preservation of renal function, SABR offers an attractive alternative to more invasive modalities for treatment of localized RCC.

MR-LINAC, a New Partner in Radiation Oncology: Current Landscape

Technological advances in radiation oncology are oriented towards improving treatment precision and tumor control. Among these advances, magnetic-resonance-image-guided radiation therapy (MRgRT) stands out, with technological advances to deliver targeted treatments adapted to a tumor's anatomy on the day while minimizing incidental exposure to organs at risk, offering an unprecedented therapeutic advantage compared to X-ray-based IGRT delivery systems. This new technology changes the traditional workflow in radiation oncology and requires an evolution in team coordination to administer more precise treatments. Once implemented, it paves the way for newer indication for radiation therapy to safely deliver higher doses than ever before, with better preservation of healthy tissues to optimize patient outcomes. In this narrative review, we assess the technical aspects of the novel linear accelerators that can deliver MRgRT and summarize the available published experience to date, focusing on oncological results and future challenges.

Stereotactic ablative radiotherapy for primary renal cell carcinoma

Stereotactic ablative radiotherapy (SAbR) is an emerging non-invasive definitive treatment option for primary renal cell carcinoma (RCC), particularly when surgery is not ideal. Employing ablative doses, SAbR delivered in one to five fractions to the primary tumor has been shown to achieve high local control rates with favorable toxicity profile in multiple retrospective and prospective series, and has dispelled previous notions of RCC radio-resistance. Moreover, emerging evidence suggests possible immunomodulatory effects, leading to clinical investigations of SAbR in combination with systemic and surgical management in patients with metastatic disease. In this review, we summarize key evidence supporting SAbR delivered to the primary tumor including preclinical rationale, dose escalation studies, recent prospective trials, and outcomes from ongoing multi-institutional registries. We also discuss areas of active clinical investigation including the use of primary SAbR in combination with systemic therapies in patients with metastatic disease. The accumulated body of evidence supports SAbR as promising indication being increasingly incorporated into the multi-disciplinary management of primary RCC.

Incorporating Stereotactic Ablative Radiotherapy into the Multidisciplinary Management of Renal Cell Carcinoma

Stereotactic ablative radiotherapy (SABR) has challenged the conventional wisdom surrounding the radioresistance of renal cell carcinoma (RCC). In the past decade, there has been a significant accumulation of clinical data to support the safety and efficacy of SABR in RCC. Herein, we review the use of SABR across the spectrum of RCC. We performed an online search of the Pubmed database from January 1990 through April 2023. Studies of SABR/stereotactic radiosurgery targeting primary, extracranial, and intracranial metastatic RCC were included. For SABR in non-metastatic RCC, this includes its use in small renal masses, larger renal masses, and inferior vena cava tumor thrombi. In the metastatic setting, SABR can be used at diagnosis, for oligometastatic and oligoprogressive disease, and for symptomatic reasons. Notably, SABR can be used for both the primary renal tumor and metastasis-directed therapy. Management of RCC is evolving rapidly, and the role that SABR will have in this landscape is being assessed in a number of ongoing prospective clinical trials. The objective of this narrative review is to summarize the evidence corroborating the use of SABR in RCC.

[Stereotactic body radiation therapy for primary kidney cancer]

The incidence of primary renal cancer is increasing, particularly in elderly patients who may have comorbidities and/or a surgical contraindications. Stereotactic body radiotherapy has primarily been evaluated retrospectively to date. The most commonly used dose schedules are 40Gy in five fractions, 42Gy in three fractions, and 26Gy in one fraction. The results in terms of local control and toxicity are very encouraging. The advantages of stereotactic body radiotherapy compared to thermal ablative treatments are its non-invasive nature, absence of general anesthesia, ability to treat larger lesions, and those close to the renal hilum. Prospective evaluations are still necessary.

Phase 2 Trial of Stereotactic Ablative Radiotherapy for Patients with Primary Renal Cancer

BACKGROUND

Most renal cell carcinomas (RCCs) are localized and managed by active surveillance, surgery, or minimally invasive techniques. Stereotactic ablative radiation (SAbR) may provide an innovative non-invasive alternative although prospective data are limited.

OBJECTIVE

To investigate whether SAbR is effective in the management of primary RCCs.

DESIGN, SETTING, AND PARTICIPANTS

Patients with biopsy-confirmed radiographically enlarging primary RCC (≤5 cm) were enrolled. SAbR was delivered in either three (12 Gy) or five (8 Gy) fractions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was local control (LC) defined as a reduction in tumor growth rate (compared with a benchmark of 4 mm/yr on active surveillance) and pathologic evidence of tumor response at 1 yr. Secondary endpoints included LC by the Response Evaluation Criteria in Solid Tumors (RECIST 1.1), safety, and preservation of kidney function. Exploratory tumor cell-enriched spatial protein and gene expression analysis were conducted on pre- and post-treatment biopsy samples.

RESULTS AND LIMITATIONS

Target accrual was reached with the enrollment of 16 ethnically diverse patients. Radiographic LC at 1 yr was observed in 94% of patients (15/16; 95% confidence interval: 70, 100), and this was accompanied by pathologic evidence of tumor response (hyalinization, necrosis, and reduced tumor cellularity) in all patients. By RECIST, 100% of the sites remained without progression at 1 yr. The median pretreatment growth rate was 0.8 cm/yr (interquartile range [IQR]: 0.3, 1.4), and the median post-treatment growth rate was 0.0 cm/yr (IQR: -0.4, 0.1, p < 0.002). Tumor cell viability decreased from 4.6% to 0.7% at 1 yr (p = 0.004). With a median follow-up of 36 mo for censored patients, the disease control rate was 94%. SAbR was well tolerated with no grade ≥2 (acute or late) toxicities. The average glomerular filtration rate declined from a baseline of 65.6 to 55.4 ml/min at 1 yr (p = 0.003). Spatial protein and gene expression analyses were consistent with the induction of cellular senescence by radiation.

CONCLUSIONS

This clinical trial adds to the growing body of evidence suggesting that SAbR is effective for primary RCC supporting its evaluation in comparative phase 3 clinical trials.

PATIENT SUMMARY

In this clinical trial, we investigated a noninvasive treatment option of stereotactic radiation therapy for the treatment of primary kidney cancer and found that it was safe and effective.

The Judicious Use of Stereotactic Ablative Radiotherapy in the Primary Management of Localized Renal Cell Carcinoma

Localized renal cell carcinoma is primarily managed surgically, but this disease commonly presents in highly comorbid patients who are poor operative candidates. Less invasive techniques, such as cryoablation and radiofrequency ablation, are effective, but require percutaneous or laparoscopic access, while generally being limited to cT1a tumors without proximity to the renal pelvis or ureter. Active surveillance is another management option for small renal masses, but many patients desire treatment or are poor candidates for active surveillance. For poor surgical candidates, a growing body of evidence supports stereotactic ablative radiotherapy (SABR) as a safe and effective non-invasive treatment modality. For example, a recent multi-institution individual patient data meta-analysis of 190 patients managed with SABR estimated a 5.5% five-year cumulative incidence of local failure with one patient experiencing grade 4 toxicity, and no other grade ≥3 toxic events. Here, we discuss the recent developments in SABR for the management of localized renal cell carcinoma, highlighting key concepts of appropriate patient selection, treatment design, treatment delivery, and response assessment.

NeoAdjuvant pembrolizumab and STEreotactic radiotherapy prior to nephrectomy for renal cell carcinoma (NAPSTER): A phase II randomised clinical trial

Background

Surgery remains the standard of care for localised renal cell carcinoma (RCC). Nevertheless, nearly 50% of patients with high-risk disease experience relapse after surgery, with distant sites being common. Considering improved outcomes in terms of disease-free survival with adjuvant immunotherapy with pembrolizumab, we hypothesise that neoadjuvant SABR with or without the addition of pembrolizumab before nephrectomy will lead to improved disease outcomes by evoking better immune response in the presence of an extensive reserve of tumor-associated antigens.

Methods and analysis

This prospective, open-label, phase II, randomised, non-comparative, clinical trial will investigate the use of neoadjuvant stereotactic ablative body radiotherapy (SABR) with or without pembrolizumab prior to nephrectomy. The trial will be conducted at two centres in Australia that are well established for delivering SABR to primary RCC patients. Twenty-six patients with biopsy-proven clear cell RCC will be recruited over two years. Patients will be randomised to either SABR or SABR/pembrolizumab. Patients in both arms will undergo surgery at 9 weeks after completion of experimental treatment. The primary objectives are to describe major pathological response and changes in tumour-responsive T-cells from baseline pre-treatment biopsy in each arm. Patients will be followed for sixty days post-surgery.

Outcomes and significance

We hypothesize that SABR alone or SABR plus pembrolizumab will induce significant tumor-specific immune response and major pathological response. In that case, either one or both arms could justifiably be used as a neoadjuvant treatment approach in future randomized trials in the high-risk patient population.

Stereotactic Magnetic Resonance-Guided Adaptive and Non-Adaptive Radiotherapy on Combination MR-Linear Accelerators: Current Practice and Future Directions

Stereotactic body radiotherapy (SBRT) is an effective radiation therapy technique that has allowed for shorter treatment courses, as compared to conventionally dosed radiation therapy. As its name implies, SBRT relies on daily image guidance to ensure that each fraction targets a tumor, instead of healthy tissue. Magnetic resonance imaging (MRI) offers improved soft-tissue visualization, allowing for better tumor and normal tissue delineation. MR-guided RT (MRgRT) has traditionally been defined by the use of offline MRI to aid in defining the RT volumes during the initial planning stages in order to ensure accurate tumor targeting while sparing critical normal tissues. However, the ViewRay MRIdian and Elekta Unity have improved upon and revolutionized the MRgRT by creating a combined MRI and linear accelerator (MRL), allowing MRgRT to incorporate online MRI in RT. MRL-based MR-guided SBRT (MRgSBRT) represents a novel solution to deliver higher doses to larger volumes of gross disease, regardless of the proximity of at-risk organs due to the (1) superior soft-tissue visualization for patient positioning, (2) real-time continuous intrafraction assessment of internal structures, and (3) daily online adaptive replanning. Stereotactic MR-guided adaptive radiation therapy (SMART) has enabled the safe delivery of ablative doses to tumors adjacent to radiosensitive tissues throughout the body. Although it is still a relatively new RT technique, SMART has demonstrated significant opportunities to improve disease control and reduce toxicity. In this review, we included the current clinical applications and the active prospective trials related to SMART. We highlighted the most impactful clinical studies at various tumor sites. In addition, we explored how MRL-based multiparametric MRI could potentially synergize with SMART to significantly change the current treatment paradigm and to improve personalized cancer care.

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.

Stereotactic body radiation therapy to the kidney for metastatic renal cell carcinoma: A narrative review of an emerging concept

This narrative review provides a historical overview of cytoreductive nephrectomy for metastatic renal cell carcinoma (mRCC) and examines the safety and therapeutic potential of cytoreductive stereotactic body radiation therapy (SBRT) for mRCC in the modern immunotherapy era. In the last five years, the introduction of immune checkpoint inhibitors for the treatment of mRCC has improved outcomes for patients. This has brought forth new exploration of the role of CN in combination with immunotherapy. Early retrospective evidence suggests that there may be a benefit of deferred CN after immunotherapy (IOT) for de novo mRCC patients. However, there has also been concern regarding the feasibility of surgery after IOT due to inflammation. SBRT may be an appropriate alternative in these circumstances. Since 1999, cytoreductive SBRT has been used for inoperable primary RCC. Several prospective and retrospective studies treating the kidney tumor for localized RCC have shown that this technique is safe and produces favorable and durable local control. SBRT has also exhibited similar effectiveness to CN, while providing additional benefits including noninvasiveness and the ability to treat tumors that can't be treated with nephrectomy or ablation due to size or location. Furthermore, SBRT confers immunostimulatory effects, which are hypothesized to work synergistically with immunotherapy. Clinicians should consider SBRT a safe and reliable alternative to CN for RCC patients. Ongoing studies are exploring the utility of SBRT for treatment of the primary tumor in mRCC patients receiving standard of care immunotherapy.

Adjuvant Therapy for High-Risk Localized Renal Cell Carcinoma: Current Landscape and Future Direction

Locally and regionally advanced renal cell carcinoma (RCC) can recur at high rates even after visually complete resection of primary disease. Both targeted therapies and immunotherapies represent potential agents that might help reduce recurrence of RCC in these patients. This paper reviews the current body of evidence defining their potential impact and examines the large Phase III randomized clinical trials that have been performed to assess the safety and efficacy of these systemic therapies in the adjuvant setting. Given that the findings from these trials have been predominantly negative, this paper also explores the role of other potential adjuvant agents, including single and combination agent targeted therapies and immunotherapies, whose use is currently limited to metastatic RCC. Finally, the use of radiation therapy and the use of advanced imaging modalities in RCC are also considered.

Stereotactic Body Radiotherapy for Renal Cell Carcinoma: Oncological and Renal Function Outcomes

AIMS

To evaluate oncological and renal function outcomes of stereotactic body radiotherapy (SBRT) for medically inoperable patients with localised renal cell carcinoma.

MATERIALS AND METHODS

Consecutive patients treated with curative intent SBRT (30-45 Gy in five fractions or 42 Gy in three fractions) were included. Data on local control (Response Evaluation Criteria in Solid Tumors [RECIST] v1.1), distant metastasis, impact on estimated glomerular filtration rate (eGFR) and proportional ipsilateral and contralateral renal functions (measured through renal scans) were collected. Univariate and multivariable analyses were conducted to determine association of variables with oncological and renal function outcomes.

RESULTS

Seventy-four patients were analysed. The median follow-up was 27.8 months (interquartile range 17.6-41.7). Fifty-seven per cent had tumours ≥ T1b. One-, 2- and 4-year cumulative incidence of local failure was 5.85, 7.77 and 7.77%, respectively. The cumulative incidence of distant metastasis at 2 years was 4.24%. On multivariable analysis, a lower planning target volume (PTV) mean dose (P = 0.019) and a larger PTV (P = 0.005) were significantly associated with the risk of developing local failure. A lower PTV maximum dose (P = 0.039) was significantly associated with the risk of developing distant metastasis. The median change in global eGFR (ml/min) from pre-SBRT levels was -7.0 (interquartile range -14.5 to -1.0) at 1 year and -11.5 (interquartile range -19.5 to -4.0) at 2 years. The proportion of ipsilateral (differential) renal function decreased over time from 47% of overall renal function pre-SBRT to 36% at 2 years, whereas the proportion of contralateral renal function correspondingly improved. On multivariable analysis, a higher volume of uninvolved renal cortex (P < 0.0001) was significantly associated with a smaller decrease in eGFR over time.

CONCLUSION

In this large institutional cohort, oncological outcomes of renal cell carcinoma treated with SBRT were favourable and a longitudinal decline in renal function in the ipsilateral kidney and compensatory increase in the contralateral kidney were observed. Clinical and dosimetric factors were significantly associated with oncological and renal function outcomes.

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.

Stereotactic Body Radiotherapy for Localized Kidney Cancer

PURPOSE OF REVIEW

Stereotactic body radiation therapy (SBRT) is increasingly utilized in the management of localized kidney cancers, particularly for patients who are not surgical candidates. Herein, we provide a narrative review of SBRT in the management of localized kidney cancers.

RECENT FINDINGS

Recent prospective studies and multi-institutional retrospective studies highlight the safety and efficacy of SBRT in the management of renal tumors, a disease previously thought to be radioresistant. Studies have shown that local control is greater than 90% with rare grade 3 or 4 toxicity and no grade 5 toxicity. SBRT can be utilized successfully in the treatment of large kidney tumors (> 5 cm). New techniques such as MRI-guided radiation therapy may further improve the therapeutic ratio. However, randomized clinical trials are necessary to confirm the optimal dosing schedule and compare outcomes with nephrectomy, which remains the standard of care in suitable patients. Advances in SBRT have made this modality a safe and effective treatment option in the management of localized kidney cancers.

Cryoablation for the Treatment of Kidney Cancer: Comparison With Other Treatment Modalities and Review of Current Treatment

With cancer among the leading causes of death worldwide and kidney cancer among the more common cancers in the United States, it has become increasingly important to ensure that first-line treatments remain validated and supported in recent literature. Surgical intervention has long remained the gold standard for intervention but with newer techniques and technology on the horizon, there must be a constant review of other options that may provide improved outcomes and reduction of associated risks. Ablative techniques have gained traction and are becoming a valuable intervention for multiple different types of cancers, kidney cancer included. Cryoablation, a newer ablative technique taking advantage of extreme cold to freeze and destroy abnormal tissue, provides a promising option for treatment. Currently, no review article, to our knowledge, compares all the different treatment options for kidney cancer. Additionally, while some literature has addressed cryoablation in comparison to other methods of management, there has not been an extensive review to combine our current understanding of these comparisons. In this review article, we provide an overview of each of the commonly used treatments for kidney cancer and summarize the current literature regarding the advantages and disadvantages of each intervention. Finally, we seek to compare cryoablation, a newer option for treatment, to each of the approaches with the goal of evaluating the best methods for management and determining cryoablation's role alongside these current interventions.

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.

The multispeciality approach to the management of localised kidney cancer

Historically, kidney cancer was approached in a siloed single-speciality way, with urological surgeons managing the localised stages of the disease and medical oncologists caring for patients if metastases developed. However, improvements in the management of localised kidney cancer have occurred rapidly over the past two decades with greater understanding of the disease biology, diagnostic options, and innovations in curative treatments. These developments are favourable for patients but provide a substantially more complex landscape for patients and clinicians to navigate, with associated challenging decisions about who to treat, how, and when. As such, the skill sets needed to manage the various aspects of the disease and guide patients appropriately outstrips the capabilities of one particular specialist, and the evolution of a multispeciality approach to the management of kidney cancer is now essential. In this Review, we summarise the current best multispeciality practice for the management of localised kidney cancer and the areas in need of further research and development.

The Role of Stereotactic Ablative Body Radiotherapy in Renal Cell Carcinoma

CONTEXT

Stereotactic ablative body radiotherapy (SABR) is an emerging treatment modality for primary and metastatic renal cell carcinoma (RCC).

OBJECTIVE

To review and summarise the evidence on the use of SABR in RCC in a narrative review.

EVIDENCE ACQUISITION

We performed an online search of the PubMed database from January 2000 through December 2021. Studies of SABR/stereotactic radiosurgery (SRS) targeting primary, extracranial, or intracranial metastatic RCC were included.

EVIDENCE SYNTHESIS

Two meta-analyses (including 54 studies), and 13 prospective and 20 retrospective studies were included in this review. In aggregate, SABR for 589 primary RCCs in 575 patients resulted in a local control rate of above 90% with grade 3-4 toxicity of 0-9%. Similarly, the local control rate ranged between 90% and 97% with SRS in 1225 patients with intracranial metastatic RCC. SABR was able to delay systemic therapy for at least 1 yr in 70-90% of oligometastatic RCC patients with grade 3-4 toxicity of <10%. As per the early data, the combination of SABR with systemic therapy for metastatic RCC, such as targeted therapy or immunotherapy, appears safe, feasible, and tolerable.

CONCLUSIONS

We outlined data supporting SABR in the key clinical scenarios of primary and metastatic, including oligometastatic, RCC in lieu of systemic therapy, in combination with systemic therapy, and palliation of brain and spinal metastases.

PATIENT SUMMARY

Stereotactic ablative body radiotherapy (SABR) is a relatively new treatment option in kidney cancer. Here, we review the published literature on the experience of using SABR in kidney cancer. The accumulated evidence demonstrates that SABR can be used safely and effectively to treat selected cases of primary or secondary kidney cancer.

Synergistic Effect of Stereotactic Radiotherapy Combined with Karelizumab on Patients with Advanced NSCLC

In this paper, synergistic effects of stereotactic radiotherapy (SRS) combined with karelizumab on the patients with advanced NSCLC have been analyzed through extensive experiments. For this purpose, 100 patients with advanced NSCLC in our hospital from December 2018 to December 2020 were selected and divided into control group and observation group. The control group was treated with SRS, while the observation group was treated with karelizumab at the same time. The data of age, gender, BMI, pathological type, and clinical stage were collected and recorded. After 3 months of treatment, the short-term efficacy of the two groups was evaluated according to RECIST solid tumor efficacy evaluation standard. Fasting venous blood of all patients before and 3 months after treatment was collected. The serum levels of matrix metalloproteinase-9 (MMP-9), cytokeratin 19 fragment (CY211), carcinoembryonic antigen (CEA), and vascular endothelial growth factor (VEGF) were detected by the enzyme-linked immunosorbent assay. The KPS score was used to evaluate the quality of life before and after treatment. The incidence of fatigue, diarrhea, and other adverse reactions were compared between the two groups. The patients were followed up for 3 years, and the survival of all patients was recorded. The total effective rate of the observation group was 50.00% (23/46), which was evidently higher than that (27.78% (15/54)) of the control group (P < 0.05). After treatment, the parameters of CY211, MMP-9, VEGF, and CEA in the two groups were evidently lower than those before treatment, and the parameters of CY211, MMP-9, VEGF, and CEA in the observation group were evidently lower than those in the control group after treatment (P < 0.05). After treatment, KPS parameters of the two groups were evidently higher than those before treatment, and KPS parameters of the observation group were evidently higher than those of the control group after treatment (P < 0.05). The 1-year, 2-year, and 3-year survival rates of the observation group were 95.64% (44/46), 89.13% (41/46), and 80.43% (37/46), respectively, and the 2-year and 3-year survival rates of the observation group were evidently higher than those of the control group (P < 0.05). SRS combined with karelizumab in the treatment of patients with advanced NSCLC has good curative effect, can evidently inhibit the angiogenesis and tumor growth and metastasis, can evidently improve the quality of life of patients, has a good synergistic effect, and can be widely used in clinic.

The Role of Conventionally Fractionated Radiotherapy and Stereotactic Radiotherapy in the Treatment of Carcinoid Tumors and Large-Cell Neuroendocrine Cancer of the Lung

The occurrence of neuroendocrine tumors among the diagnosed neoplasms is extremely rare and is associated with difficulties in undertaking effective therapy due to the histopathological differentiation of individual subtypes and the scarce clinical data and recommendations found in the literature. The choice of treatment largely depends not only on its type, but also on the location and production of excess hormones by the tumor itself. Common therapeutic approaches include surgical removal of the tumor, the use of chemotherapy, targeted drug therapy, peptide receptor radionuclide therapy, and the use of radiation therapy. This article reviews the current knowledge on the classification and application of radiotherapy in the treatment of lung NETs. Case reports were presented in which treatment with conventional radiotherapy, radical and palliative radiochemotherapy, as well as stereotactic fractionated radiotherapy in the treatment of typical (TC) and atypical (AT) lung carcinoids and large cell neuroendocrine carcinoma (LCNC) were used. We hope that the solutions presented in the literature will allow many radiation oncologists to make the best, often personalized decisions about the therapeutic qualifications of patients.

Imaging considerations for thermal and radiotherapy ablation of primary and metastatic renal cell carcinoma

Ablative (percutaneous and stereotactic) thermal and radiotherapy procedures for management of both primary and metastatic renal cell carcinoma are increasing in popularity in clinical practice. Data suggest comparable efficacy with lower cost and morbidity compared to nephrectomy. Ablative therapies may be used alone or in conjunction with surgery or chemotherapy for treatment of primary tumor and metastatic disease. Imaging plays a crucial role in pre-treatment selection and planning of ablation, intra-procedural guidance, evaluation for complications, short- and long-term post-procedural surveillance of disease, and treatment response. Treatment response and disease recurrence may differ considerably after ablation, particularly for stereotactic radiotherapy, when compared to conventional surgical and chemotherapies. This article reviews the current and emerging role of imaging for ablative therapy of renal cell carcinoma.

DMSA-SPECT: A Novel Approach to Nephron Sparing SBRT for Renal Cell Carcinoma

PURPOSE

Stereotactic body radiation therapy (SBRT) treatment planning for renal cell carcinoma requires accurate delineation of tumor from normal tissue due to the radiosensitivity of normal renal cortical tissue. Tc-99m dimercapto succinic acid (DMSA) renal imaging is a functional imaging technique that precisely differentiates normal renal cortical tissue from tumor. There are no prior publications reporting using this imaging modality for SBRT treatment planning.

METHODS AND MATERIALS

A 59-year-old female with stage IV renal cell carcinoma progressed on systemic therapy and was dispositioned to primary cytoreduction with SBRT. She had baseline renal dysfunction and her tumor was 9 cm without clear delineation from normal tissue on conventional imaging. DMSA-single-photon emission computerized tomography (SPECT)/computed tomography (CT) was used for treatment planning.

RESULTS

DMSA-SPECT/CT precisely delineated normal renal cortical tissue from tumor. Three months after treatment, labs were stable and DMSA-SPECT/CT was unchanged. The treated lesion had markedly decreased positron emission tomography avidity.

CONCLUSIONS

DMSA-SPECT or SPECT/CT can be incorporated into radiation therapy planning for renal lesions to improve target delineation and better preserve renal function.

Focal Prostate Stereotactic Body Radiation Therapy With Correlative Pathological and Radiographic-Based Treatment Planning

Introduction

Advances in multiparametric MRI (mpMRI) combining anatomic and functional imaging can accurately identify foci of adenocarcinoma within the prostate, offering the possibility of partial gland therapy. We performed tandem prospective pilot trials to investigate the feasibility of focal prostate SBRT (f-SBRT) based on correlating diagnostic mpMRI and biopsies with confirmatory pathology in treatment planning.

Materials and Methods

Patients with pathologic focal Gleason 6–7 disease and a corresponding PIRADS 4–5 lesion on mpMRI underwent targeted and comprehensive biopsies using MRI/ultrasound fusion under electromagnetic sensor navigation. After rigorous analysis for imaging biopsy concordance, five of 18 patients were eligible to proceed to f-SBRT. Chi-squared test was used for differences from expected outcomes, and concordance was estimated with binomial distribution theory and Wilson’s method.

Results

Six patients had Gleason 6 and 12 had Gleason 3 + 4 disease (mean PSA: 5.8 ng/ml, range: 2.2–8.4). Absolute concordance was 43.8% (95% CI: 0.20, 0.64). Patterns of discordance included additional sites of ipsilateral disease, bilateral disease, and negative target. Five were upstaged to a new NCCN risk category necessitating treatment escalation. The five patients with concordant pathology completed three-fraction f-SBRT with sparing of the surrounding normal structures (including contralateral neurovascular bundle), with no reported grade 2+ toxicities and favorable PSA responses (mean: 41% decrease).

Conclusions

On our pilot trials of f-SBRT planning using rigorous imaging and pathology concordance, image-guided confirmatory biopsies frequently revealed additional disease, suggesting the need for caution in partial-gland therapy. For truly focal disease, f-SBRT provided excellent dosimetry, minimal toxicity, and encouraging biochemical response. Clinical Trial Registration: www.clinicaltrials.gov, NCT02681614; NCT02163317.

Nivolumab in Combination with Stereotactic Body Radiotherapy in Pretreated Patients with Metastatic Renal Cell Carcinoma. Results of the Phase II NIVES Study

BACKGROUND

Nivolumab showed an overall survival (OS) benefit in pretreated metastatic renal cell carcinoma (mRCC). The role of stereotactic body radiotherapy (SBRT) in mRCC remains to be defined.

OBJECTIVE

Our aim was to evaluate the efficacy and safety of SBRT in combination with nivolumab in second- and third-line mRCC patients.

DESIGN, SETTING, AND PARTICIPANTS

The NIVES study was a phase II, single-arm, multicenter trial in patients with mRCC with measurable metastatic sites who progressed after antiangiogenic therapy, of whom at least one was suitable for SBRT.

INTERVENTION

The patients received SBRT to a lesion at a dose of 10 Gy in three fractions for 7 d from the first infusion of nivolumab. Nivolumab was given at an initial dose of 240 mg every 14 d for 6 mo and then 480 mg q4-weekly in responding patients.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

We hypothesized that nivolumab plus SBRT improves the objective response rate (ORR) compared with nivolumab alone from 25% (derived from historical controls) to 40%. Secondary endpoints were progression-free survival (PFS), OS, disease control rate (DCR) of irradiated and nonirradiated metastases, and safety.

RESULTS AND LIMITATIONS

Sixty-nine patients were enrolled from July 2017 to March 2019. The ORR was 17% and the DCR was 55%. The median PFS was 5.6 mo (95% confidence interval [CI], 2.9-7.1) and median OS 20 mo (95% CI, 17-not reached). After 1.5 yr of follow-up, 23 patients died. The median time to treatment response was 2.8 mo and median duration of response was 14 mo. No new safety concerns arose.

CONCLUSIONS

We did not find sufficient evidence to suggest that nivolumab in combination with SBRT provides an added benefit in pretreated mRCC patients; it should however be evaluated in patients with oligometastatic or oligoprogressive disease.

PATIENT SUMMARY

Nivolumab in combination with stereotactic body radiotherapy does not provide evidence of increased outcomes in metastatic renal cell carcinoma patients. However this approach was safe and showed a good response of the irradiated lesions.

Stereotactic Ablative Radiation Therapy for the Treatment of Upper Urinary Tract Urothelial Carcinoma

PURPOSE

Urothelial carcinomas (UCs), also known as transitional cell carcinomas, account for the majority of upper urinary tract tumors. The gold-standard therapy for operable patients with localized disease is radical nephroureterectomy. However, some patients are not surgical candidates. Data on the use of modern radiation therapy for upper urinary tract UC (UTUC) are scarce. The purpose of this study was to assess the safety and efficacy of SABR in UTUC.

METHODS AND MATERIALS

This retrospective study included all patients with UTUC treated with SABR at one institution. Charts were reviewed to evaluate renal function and the development of toxicity using Common Terminology Criteria for Adverse Events, version 3.0. Tumor response on follow-up imaging with computed tomography or magnetic resonance imaging scans was assessed using the Response Evaluation Criteria in Solid Tumors, version 1.1.

RESULTS

A total of 16 patients (7 patients with UC at the ureter and 9 at the renal pelvis) were identified as treated with SABR. Of the 9 patients with renal pelvis UC, 4 had a previous history of bladder cancer. At the time of treatment, the median age was 85 years (range, 67-95 years). Most patients received 40 Gy in 8 fractions every second day. The median followup was 21 months (range, 3-110 months). Most patients maintained stable renal function, and only 2 patients developed worsening chronic kidney disease, but none required dialysis. Acutely, 4 patients developed grade 1 diarrhea, and 1 patient had new grade 1 hematuria. No chronic side effects were observed. One patient did not have follow-up imaging and was excluded from the tumor-response analysis. Two patients had a complete response of the treated lesion, 9 had a partial response, 2 had stable disease, and 2 had disease progression within the treatment field.

CONCLUSIONS

This small case series suggests that SABR for UTUC is safe and well-tolerated, with good radiographic tumor response to ablative doses of radiation therapy.

Personalising treatment plan quality review with knowledge-based planning in the TROG 15.03 trial for stereotactic ablative body radiotherapy in primary kidney cancer

INTRODUCTION

Quality assurance (QA) of treatment plans in clinical trials improves protocol compliance and patient outcomes. Retrospective use of knowledge-based-planning (KBP) in clinical trials has demonstrated improved treatment plan quality and consistency. We report the results of prospective use of KBP for real-time QA of treatment plan quality in the TROG 15.03 FASTRACK II trial, which evaluates efficacy of stereotactic ablative body radiotherapy (SABR) for kidney cancer.

METHODS

A KBP model was generated based on single institution data. For each patient in the KBP phase (open to the last 31 patients in the trial), the treating centre submitted treatment plans 7 days prior to treatment. A treatment plan was created by using the KBP model, which was compared with the submitted plan for each organ-at-risk (OAR) dose constraint. A report comparing each plan for each OAR constraint was provided to the submitting centre within 24 h of receiving the plan. The centre could then modify the plan based on the KBP report, or continue with the existing plan.

RESULTS

Real-time feedback using KBP was provided in 24/31 cases. Consistent plan quality was in general achieved between KBP and the submitted plan. KBP review resulted in replan and improvement of OAR dosimetry in two patients. All centres indicated that the feedback was a useful QA check of their treatment plan.

CONCLUSION

KBP for real-time treatment plan review was feasible for 24/31 cases, and demonstrated ability to improve treatment plan quality in two cases. Challenges include integration of KBP feedback into clinical timelines, interpretation of KBP results with respect to clinical trade-offs, and determination of appropriate plan quality improvement criteria.

Metastatic Renal Cell Carcinoma to the Spine: Outcomes and Morbidity: Single-Center Experience

BACKGROUND

Renal cell carcinoma with metastases to the spine (RCCMS) requires a multidisciplinary approach. We reviewed our institutional experience with RCCMS patients undergoing spinal surgery in order to identify factors that may affect clinical outcomes, survival, and complications.

METHODS

Patients with RCCMS who underwent operative intervention from 2007 to 2020 were reviewed retrospectively.

RESULTS

Forty-four patients with the diagnosis of RCCMS were identified. Pain was the most common symptom, and neurologic dysfunction was present in one third of cases. Thoracic spine was the most common location (N = 27), followed by the lumbar (N = 12) and cervical (N = 5) regions. The overall survival from diagnosis of renal cell carcinoma was 25 (2 - 194) months and 8 (0.3 - 92) months after spinal surgery. Gender, age, spinal level, postoperative radiation, and nephrectomy had no bearing on survival. Survival for patients with a Tokuhashi score of 0 - 8, 9 - 11, and 12 - 15 was 6.5 (1.5 - 23.5), 8.9 (0.3 - 91.6), and 23.4 (2.5 - 66) months, respectively (P = 0.03). The postoperative American Spinal Cord Injury Association score of E (hazard ratio 0.109 [95% confidence interval 0.022 - 0.534, P = 0.006) also bore a significant influence on survival. There was a total of 10 complications in 7 of 44 (16%) patients.

CONCLUSIONS

Median postoperative survival of patients with RCCMS was 8 (0.3 - 92) months. Higher Tokuhashi score and ASIA E score at follow-up correlated with improved overall survival. Complication rate was 16%. Spinal surgery in RCCMS is indicated for the preservation of function and prevention of neurologic deterioration. Multimodality therapy with improved chemotherapy and stereotactic spinal radiation is expected to impact quality and length of survival positively.

Stereotactic Body Radiotherapy for Frail Patients with Primary Renal Cell Carcinoma: Preliminary Results after 4 Years of Experience

Simple Summary

Surgical therapy is currently the standard of care for the treatment of primary renal cell carcinoma (RCC). Alternative strategies such as stereotactic body radiotherapy (SBRT) have emerged as potentially curative treatment approaches. In this study, we show a promising short-term local control effect of SBRT in the management of primary RCC. The treatment was well tolerated with no high-grade side effects. The main advantages are the outpatient management without anesthesia and the non-invasive approach. Thus, SBRT appears to be a promising alternative to surgery, or ablative therapy, to treat primary RCC in patients with poor physical health. Future studies are needed to definitively assess the place of SBRT in the RCC treatment portfolio.

Abstract

Introduction: The aim of this study was to report the oncological outcomes and toxicity of stereotactic body radiotherapy (SBRT) to treat primary renal cell carcinoma (RCC) in frail patients unfit for surgery or standard alternative ablative therapies. Methods: We retrospectively enrolled 23 patients who had SBRT for primary, biopsy-proven RCC at our tertiary center between October 2016 and March 2020. Treatment-related toxicities were defined using CTCAE, version 4.0. The primary outcome was local control which was defined using the Response Evaluation Criteria in Solid Tumors. Results: The median age, Charlson score and tumor size were 81 (IQR 79–85) years, 7 (IQR 5–8) and 40 (IQR 28–48) mm, respectively. The most used dose fractionation schedule was 35 Gy (78.3%) in five or seven fractions. The median duration of follow-up for all living patients was 22 (IQR 10–39) months. Local recurrence-free survival, event-free survival, cancer-specific survival and overall survival were 96 (22/23), 74 (18/23), 96 (22/23) and 83% (19/23), respectively. There were no grade 3–4 side effects. No patients required dialysis during the study period. No treatment-related deaths or late complications were reported. Conclusion: SBRT appears to be a promising alternative to surgery or ablative therapy to treat primary RCC in frail patients.

Adaptive Magnetic Resonance-Guided Stereotactic Body Radiotherapy: The Next Step in the Treatment of Renal Cell Carcinoma

Adaptive MR-guided radiotherapy (MRgRT) is a new treatment paradigm and its role as a non-invasive treatment option for renal cell carcinoma is evolving. The early clinical experience to date shows that real-time plan adaptation based on the daily MRI anatomy can lead to improved target coverage and normal tissue sparing. Continued technological innovations will further mitigate the challenges of organ motion and enable more advanced treatment adaptation, and potentially lead to enhanced oncologic outcomes and preservation of renal function. Future applications look promising to make a positive clinical impact and further the personalization of radiotherapy in the management of renal cell carcinoma.

Combining Stereotactic Body Radiotherapy and Microwave Ablation Appears Safe and Feasible for Renal Cell Carcinoma in an Early Series

Microwave (MW) ablation and stereotactic body radiation therapy (SBRT) are both used in treating inoperable renal cell carcinoma (RCC). MW ablation and SBRT have potentially complementary advantages and limitations. Combining SBRT and MW ablation may optimize tumor control and toxicity for patients with larger (> 5 cm) RCCs or those with vascular involvement. Seven patients with RCC were treated at our institution with combination of SBRT and MW ablation, median tumor size of 6.4 cm. Local control was 100% with a median follow-up of 15 months. Four patients experienced grade 2 nausea during SBRT. Three patients experienced toxicities after MW ablation, 2 with grade 1 hematuria and 1 with grade 3 retroperitoneal bleed/collecting system injury. Median eGFR (estimated glomerular filtration rate) preceding and following SBRT and MW ablation was 69 mL/min/1.73 m² and 68 mL/min/1.73 m² (P = .19), respectively. In patients who are not surgical candidates, larger RCCs or those with vascular invasion are challenging to treat. Combination treatment with SBRT and MW ablation may balance the risks and benefits of both therapies and demonstrates high local control in our series. MW ablation and SBRT have potentially complementary advantages and limitations.

Daily online adaptive magnetic resonance image (MRI) guided stereotactic body radiation therapy for primary renal cell cancer

Stereotactic body radiotherapy (SBRT) has demonstrated promising outcomes for patients with early-stage, medically inoperable, primary renal cell carcinoma (RCC) in large multi-institutional studies and prospective clinical trials. The traditional approach used in these studies consisted of a CT-based planning approach for target and organ-at-risk (OAR) volume delineation, treatment planning, and daily treatment delivery. Alternatively, MRI-based approaches using daily online adaptive radiotherapy have multiple advantages to improve treatment outcomes: (1) more accurate delineation of the target volume and OAR volumes with improved soft tissue visualization; (2) gated beam delivery with biofeedback from the patient; and (3) potential for daily plan adaptation due to changes in anatomy to improve target coverage, reduce dose to OARs, or both. The workflow, treatment planning principles, and aspects of treatment delivery specific to this technology are outlined using a case example of a patient with an early-stage RCC of the right kidney treated with MRI-guided SBRT using daily adaptive treatment to a dose of 42 Gy in 3 fractions.

Patient-reported Quality of Life following Stereotactic Body Radiation Therapy for Primary Kidney Cancer - Results from a Prospective Cohort Study

AIMS

We report on the first prospective series of patient-reported quality of life (QoL) following stereotactic body radiation therapy (SBRT) for primary kidney cancer.

MATERIALS AND METHODS

Patients were treated on a multi-institutional prospective cohort study with 30-42 Gy SBRT in three or five fractions. QoL assessments were carried out using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core-15 Palliative (EORTC-QLQ-C15-PAL), the Functional Assessment of Cancer Therapy-Kidney Symptom Index-19 (FACT FKSI-19) and the EuroQol-5D-3L tools at baseline, 1 week, and 1, 3 and 6 months post-treatment. QoL over time was analysed using linear mixed modelling, pairwise and anchor-based analyses.

RESULTS

Twenty-eight patients were included. No significant reduction in any QoL metric was observed on repeated measures. However, a trend to reduced EORTC global QoL and fatigue was observed at 1 week, with improvement over time in other symptom scores such as pain, appetite and nausea. On pairwise analysis, there were statistically significant reductions in global QoL at 1 week (with subsequent recovery) and dyspnoea at 6 months post-SBRT. Trends to improved pain, appetite and nausea were observed following SBRT. Less than half of patients reported stable or better EORTC global QoL at 1 week. For all other QoL and symptom scales, most patients had reported stable or better scores at all times, with a slight proportional improvement in emotional functioning, nausea, fatigue, pain and appetite, and a slight worsening of physical functioning and dyspnoea over time.

CONCLUSIONS

SBRT results in well-preserved QoL in the weeks to months following treatment for primary kidney cancer.

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.