Artificial intelligence-assisted quantitative CT analysis of airway changes following SABR for central lung tumors.

INTRODUCTION: Use of stereotactic ablative radiotherapy (SABR) for central lung tumors can result in up to a 35% incidence of late pulmonary toxicity. We evaluated an automated scoring method to quantify post-SABR bronchial changes by using artificial intelligence (AI)-based airway segmentation. MATERIALS AND METHODS: Central lung SABR patients treated at Amsterdam UMC (AUMC, internal reference dataset) and Peter MacCallum Cancer Centre (PMCC, external validation dataset) were identified. Patients were eligible if they had pre- and post-SABR CT scans with ≤ 1 mm resolution. The first step of the automated scoring method involved AI-based airway auto-segmentation using MEDPSeg, an end-to-end deep learning-based model. The Vascular Modeling Toolkit in 3D Slicer was then used to extract a centerline curve through the auto-segmented airway lumen, and cross-sectional measurements were computed along each bronchus for all CT scans. For AUMC patients, airway stenosis/occlusion was evaluated by both visual assessment and automated scoring. Only the automated method was applied to the PMCC dataset. RESULTS: Study patients comprised 26 from AUMC, and 33 from PMCC. Visual scoring identified stenosis/occlusion in 8 AUMC patients (31 %), most frequently in the segmental bronchi. After airway auto-segmentation, minor manual edits were needed in 9 % of patients. Segmentation for a single scan averaged 83sec (range 73-136). Automated scoring nearly doubled detected airway stenosis/occlusion (n = 15, 58 %), and allowed for earlier detection in 5/8 patients who had also visually scored changes. Estimated rates were 48 % and 66 % at 1- and 2-years, respectively, for the internal dataset. The automated detection rate was 52 % in the external dataset, with 1- and 2-year risks of 56 % and 61 %, respectively. CONCLUSION: An AI-based automated scoring method allows for detection of more bronchial stenosis/occlusion after lung SABR, and at an earlier time-point. This tool can facilitate studies to determine early airway changes and establish more reliable airway tolerance doses.

Emerging Novel Functional Imaging and Immunotherapy in Renal Cell Carcinoma and Current Treatment Sequencing Strategies After Immunotherapy.

The management of renal cell carcinoma (RCC) has advanced significantly in the past two decades. Many promising functional imaging modalities such as radiolabeled tracer targeting carbonic anhydrase IX and prostate-specific membrane antigen are under development to detect primary kidney tumors, stage systemic disease, and assess treatment response in RCC. Immune checkpoint inhibitors targeting PD-1 and cytotoxic T-cell lymphocyte-4 have changed the treatment paradigm in advanced RCC. Trials investigating novel mechanisms such as LAG-3 immune checkpoint inhibition, chimeric antigen receptor T-cell therapies, and T-cell engagers targeting RCC-associated antigens are currently ongoing. With the rapidly changing treatment landscape of RCC, the treatment sequence strategies will continue to evolve. Familiarity with the toxicities associated with the therapeutic agents and how to manage them are essential to achieve optimal patient outcomes. This review summarizes the recent developments of functional imaging and immunotherapy strategies in RCC, and the evidence supports treatment sequencing.

Optimal management of radiation pneumonitis: Findings of an international Delphi consensus study.

PURPOSE: Radiation pneumonitis (RP) is a dose-limiting toxicity for patients undergoing radiotherapy (RT) for lung cancer, however, the optimal practice for diagnosis, management, and follow-up for RP remains unclear. We thus sought to establish expert consensus recommendations through a Delphi Consensus study. METHODS: In Round 1, open questions were distributed to 31 expert clinicians treating thoracic malignancies. In Round 2, participants rated agreement/disagreement with statements derived from Round 1 answers using a 5-point Likert scale. Consensus was defined as ≥ 75 % agreement. Statements that did not achieve consensus were modified and re-tested in Round 3. RESULTS: Response rate was 74 % in Round 1 (n = 23/31; 17 oncologists, 6 pulmonologists); 82 % in Round 2 (n = 19/23; 15 oncologists, 4 pulmonologists); and 100 % in Round 3 (n = 19/19). Thirty-nine of 65 Round 2 statements achieved consensus; a further 10 of 26 statements achieved consensus in Round 3. In Round 2, there was agreement that risk stratification/mitigation includes patient factors; optimal treatment planning; the basis for diagnosis of RP; and that oncologists and pulmonologists should be involved in treatment. For uncomplicated radiation pneumonitis, an equivalent to 60 mg oral prednisone per day, with consideration of gastroprotection, is a typical initial regimen. However, in this study, no consensus was achieved for dosing recommendation. Initial steroid dose should be administered for a duration of 2 weeks, followed by a gradual, weekly taper (equivalent to 10 mg prednisone decrease per week). For severe pneumonitis, IV methylprednisolone is recommended for 3 days prior to initiating oral corticosteroids. Final consensus statements included that the treatment of RP should be multidisciplinary, the uncertainty of whether pneumonitis is drug versus radiation-induced, and the importance risk stratification, especially in the scenario of interstitial lung disease. CONCLUSIONS: This Delphi study achieved consensus recommendations and provides practical guidance on diagnosis and management of RP.

Characterization of FOLH1 Expression in Renal Cell Carcinoma.

PURPOSE: Given the emergence of PSMA-targeted diagnostic agents and therapeutics, we sought to investigate patterns of FOLH1 expression in RCC and their impacts on RCC outcomes. METHODS: We conducted a pooled multi-institutional analysis of patients with RCC having undergone DNA and RNA next-generation sequencing. FOLH1-high/low expression was defined as the ≥75th/<25th percentile of RNA transcripts per million (TPM). Angiogenic, T-effector, and myeloid expression signatures were calculated using previously defined gene sets. Kaplan-Meier estimates were calculated from the time of tissue collection or therapy start. RESULTS: We included 1,724 patients in the analysis. FOLH1 expression was significantly higher in clear cell (71%) compared to non-clear cell RCC tumors (19.0 versus 3.3 TPM, p < 0.001) and varied by specimen site (45% primary kidney/55% metastasis, 13.6 versus 9.9 TPM, p < 0.001). FOLH1 expression was correlated with angiogenic gene expression (Spearman = 0.76, p < 0.001) and endothelial cell abundance (Spearman = 0.76, p < 0.001). While OS was similar in patients with FOLH1-high versus -low ccRCC, patients with FOLH1-high clear cell tumors experienced a longer time on cabozantinib treatment (9.7 versus 4.6 months, respectively, HR 0.57, 95% CI 0.35-0.93, p < 0.05). CONCLUSIONS: We observed differential patterns of FOLH1 expression based on histology and tumor site in RCC. FOLH1 was correlated with angiogenic gene expression, increased OS, and a longer duration of cabozantinib treatment.

Functional Lung Avoidance Planning Using Multicriteria Optimization.

PURPOSE: Functional lung avoidance (FLA) radiation therapy is an evolving field. The aim of FLA planning is to reduce dose to areas of functioning lung, with comparable target coverage and dose to organs at risk. Multicriteria optimization (MCO) is a planning tool that may assist with FLA planning. This study assessed the feasibility of using MCO to adapt radiation therapy plans to avoid functional regions of lung that were identified using a 68Ga-4D-V/Q positron emission tomography/computed tomography. METHODS AND MATERIALS: A prospective clinical trial U1111-1138-4421 was performed in which patients had a 68Ga-4D-V/Q positron emission tomography/computed tomography before radiation treatment. Of the 72 patients enrolled in this trial, 38 patients had stage III non-small cell lung cancer and were eligible for selection into this planning study. Functional lung target volumes HF lung (highly functioning lung) and F lung (functional lung) were defined using the ventilated and perfused lung. Using knowledge-based planning, a baseline anatomic plan was created, and then a functional adapted plan was generated using multicriteria optimization. The primary aim was to spare dose to HF lung. Using the MCO tools, a clinician selected the final FLA plan. Dose to functional lung, target volumes, organs at risk and measures of plan quality were compared using standard statistical methods. RESULTS: The HF lung volume was successfully spared in all patients. The F lung volume was successfully spared in 36 of the 38 patients. There were no clinically significant differences in dose to anatomically defined organs at risk. There were differences in the planning target volume near maximum and minimum doses. Across the entire population, there was a statistically significant reduction in the functional mean lung dose but not in the functional volume receiving 20 Gy. All trade-off decisions were made by the clinician. CONCLUSIONS: Using MCO for FLA was achievable but did result in changes to planning target volume coverage. A distinct advantage in using MCO was that all decisions regarding the cost and benefits of FLA could be made in real time.

Delphi consensus on stereotactic ablative radiotherapy for oligometastatic and oligoprogressive renal cell carcinoma-a European Society for Radiotherapy and Oncology study endorsed by the European Association of Urology.

The purpose of this European Society for Radiotherapy and Oncology (ESTRO) project, endorsed by the European Association of Urology, is to explore expert opinion on the management of patients with oligometastatic and oligoprogressive renal cell carcinoma by means of stereotactic ablative radiotherapy (SABR) on extracranial metastases, with the aim of developing consensus recommendations for patient selection, treatment doses, and concurrent systemic therapy. A questionnaire on SABR in oligometastatic renal cell carcinoma was prepared by a core group and reviewed by a panel of ten prominent experts in the field. The Delphi consensus methodology was applied, sending three rounds of questionnaires to clinicians identified as key opinion leaders in the field. At the end of the third round, participants were able to find consensus on eight of the 37 questions. Specifically, panellists agreed to apply no restrictions regarding age (25 [100%) of 25) and primary renal cell carcinoma histology (23 [92%] of 25) for SABR candidates, on the upper threshold of three lesions to offer ablative treatment in patients with oligoprogression, and on the concomitant administration of immune checkpoint inhibitor. SABR was indicated as the treatment modality of choice for renal cell carcinoma bone oligometatasis (20 [80%] of 25) and for adrenal oligometastases 22 (88%). No consensus or major agreement was reached regarding the appropriate schedule, but the majority of the poll (54%-58%) retained the every-other-day schedule as the optimal choice for all the investigated sites. The current ESTRO Delphi consensus might provide useful direction for the application of SABR in oligometastatic renal cell carcinoma and highlight the key areas of ongoing debate, perhaps directing future research efforts to close knowledge gaps.

Dose-Effect Relationship of Kidney Function After SABR for Primary Renal Cell Carcinoma.

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.

Multi-institutional Analysis of Metastasis-directed Therapy with or Without Androgen Deprivation Therapy in Oligometastatic Castration-sensitive Prostate Cancer.

BACKGROUND: Metastasis-directed therapy (MDT) is increasingly being used in oligometastatic castration-sensitive prostate cancer (omCSPC). However, it is currently unclear how to optimally integrate MDT with the standard of care of systemic hormonal therapy. OBJECTIVE: To report long-term outcomes of MDT alone versus MDT and a defined course of androgen deprivation therapy (ADT) in omCSPC. DESIGN, SETTING, AND PARTICIPANTS: Here, a multicenter, international retrospective cohort of omCSPC as defined by conventional imaging was reported. OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS: Biochemical progression-free survival (bPFS), distant progression-free survival (dPFS), and combined biochemical or distant progression-free survival (cPFS) were evaluated with Kaplan-Meier and multivariable Cox proportional hazard regression models. RESULTS AND LIMITATIONS: A total of 263 patients were included, 105 with MDT + ADT and 158 with MDT alone. The majority of patients had metachronous disease (90.5%). Five-year bPFS, dPFS, and cPFS were, respectively, 24%, 41%, and 19% in patients treated with MDT + ADT and 11% (hazard ratio [HR] 0.48, 95% confidence interval [CI] 0.36-0.64), 29% (HR 0.56, 95% CI 0.40-0.78), and 9% (HR 0.50, 95% CI 0.38-0.67) in patients treated with MDT alone. On a multivariable analysis adjusting for pretreatment variables, the use of ADT was associated with improved bPFS (HR 0.43, p < 0.001), dPFS (HR 0.45, p = 0.002), and cPFS (HR 0.44, p < 0.001). CONCLUSIONS: In this large multi-institutional report, the addition of concurrent ADT to MDT appears to improve time to prostate-specific antigen progression and distant recurrence, noting that about 10% patients had durable control with MDT alone. Ongoing phase 3 studies will help further define treatment options for omCSPC. PATIENT SUMMARY: Here, we report a large retrospective review evaluating the outcomes of metastasis-directed therapy with or without a limited course of androgen deprivation for patients with oligometastatic castration-sensitive prostate cancer. This international multi-institutional review demonstrates that the addition of androgen deprivation therapy to metastasis-directed therapy (MDT) improves progression-free survival. While a proportion of patients appear to have long-term disease control with MDT alone, further work in biomarker discovery is required to better identify which patients would be appropriate for de-escalated therapy.

Systematic endoscopic staging of mediastinum to guide radiotherapy planning in patients with locally advanced non-small-cell lung cancer (SEISMIC): an international, multicentre, single-arm, clinical trial.

BACKGROUND: Systematic mediastinal lymph node staging by endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) improves accuracy of staging in patients with early-stage non-small-cell lung cancer (NSCLC). However, patients with locally advanced NSCLC commonly undergo only selective lymph node sampling. This study aimed to determine the proportion of patients with locally advanced NSCLC in whom systematic endoscopic mediastinal staging identified PET-occult lymph node metastases, and to describe the consequences of PET-occult disease on radiotherapy planning. METHODS: This prospective, international, multicentre, single-arm, international study was conducted at seven tertiary lung cancer centres in four countries (Australia, Canada, the Netherlands, and the USA). Patients aged 18 years or older with suspected or known locally advanced NSCLC underwent systematic endoscopic mediastinal lymph node staging before combination chemoradiotherapy or high-dose palliative radiotherapy. The primary endpoint was the proportion of participants with PET-occult mediastinal lymph node metastases shown following systematic endoscopic staging. The study was prospectively registered with Australian New Zealand Clinical Trials Registry, ACTRN12617000333314. FINDINGS: From Jan 30, 2018, to March 23, 2022, 155 patients underwent systematic endoscopic mediastinal lymph node staging and were eligible for analysis. 58 (37%) of patients were female and 97 (63%) were male. Discrepancy in extent of mediastinal disease identified by PET and EBUS-TBNA was observed in 57 (37% [95% CI 29-44]) patients. PET-occult lymph node metastases were identified in 18 (12% [7-17]) participants, including 16 (13% [7-19]) of 123 participants with clinical stage IIIA or cN2 NSCLC. Contralateral PET-occult N3 disease was identified in nine (7% [2-12]) of 128 participants staged cN0, cN1, or cN2. Identification of PET-occult disease resulted in clinically significant changes to treatment in all 18 patients. In silico dosimetry studies showed the median volume of PET-occult lymph nodes receiving the prescription dose of 60 Gy was only 10·1% (IQR 0·1-52·3). No serious adverse events following endoscopic staging were reported. INTERPRETATION: Our findings suggests that systematic endoscopic mediastinal staging in patients with locally advanced or unresectable NSCLC is more accurate than PET alone in defining extent of mediastinal involvement. Standard guideline-recommended PET-based radiotherapy planning results in suboptimal tumour coverage. Our findings indicate that systematic endoscopic staging should be routinely performed in patients with locally advanced NSCLC being considered for radiotherapy to accurately inform radiation planning and treatment decision making in patients with locally advanced NSCLC. FUNDING: None.

The impact of pre-treatment smoking status on survival after chemoradiotherapy for locally advanced non-small-cell lung cancer.

INTRODUCTION: Smoking is a risk factor for the development of lung cancer and reduces life expectancy within the general population. Retrospective studies suggest that non-smokers have better outcomes after treatment for lung cancer. We used a prospective database to investigate relationships between pre-treatment smoking status and survival for a cohort of patients with stage III non-small-cell lung cancer (NSCLC) treated with curative-intent concurrent chemoradiotherapy (CRT). METHODS: All patients treated with CRT for stage III NSCLC at a major metropolitan cancer centre were prospectively registered to a database. A detailed smoking history was routinely obtained at baseline. Kaplan-Meier statistics were used to assess overall survival and progression-free survival in never versus former versus current smokers. RESULTS: Median overall survival for 265 eligible patients was 2.21 years (95 % Confidence Interval 1.78, 2.84). It was 5.5 years (95 % CI 2.1, not reached) for 25 never-smokers versus 1.9 years (95 % CI 1.5, 2.7) for 182 former smokers and 2.2 years (95 % CI 1.3, 2.7) for 58 current smokers. Hazard ratio for death was 2.43 (95 % CI 1.32-4.50) for former smokers and 2.75 (95 % CI 1.40, 5.40) for current smokers, p = 0.006. Actionable tumour mutations (EGFR, ALK, ROS1) were present in more never smokers (14/25) than former (9/182) or current (3/58) smokers. TKI use was also higher in never smokers but this was not significantly associated with superior survival (Hazard ratio 0.71, 95 % CI 0.41, 1.26). CONCLUSIONS: Never smokers have substantially better overall survival than former or current smokers after undergoing CRT for NSCLC.

Stereotactic ablative body radiotherapy for primary kidney cancer (TROG 15.03 FASTRACK II): a non-randomised phase 2 trial.

BACKGROUND: Stereotactic ablative body radiotherapy (SABR) is a novel non-invasive alternative for patients with primary renal cell cancer who do not undergo surgical resection. The FASTRACK II clinical trial investigated the efficacy of SABR for primary renal cell cancer in a phase 2 trial. METHODS: This international, non-randomised, phase 2 study was conducted in seven centres in Australia and one centre in the Netherlands. Eligible patients aged 18 years or older had biopsy-confirmed diagnosis of primary renal cell cancer, with only a single lesion; were medically inoperable, were at high risk of complications from surgery, or declined surgery; and had an Eastern Cooperative Oncology Group performance status of 0-2. A multidisciplinary decision that active treatment was warranted was required. Key exclusion criteria were a pre-treatment estimated glomerular filtration rate of less than 30 mL/min per 1·73 m2, previous systemic therapies for renal cell cancer, previous high-dose radiotherapy to an overlapping region, tumours larger than 10 cm, and direct contact of the renal cell cancer with the bowel. Patients received either a single fraction SABR of 26 Gy for tumours 4 cm or less in maximum diameter, or 42 Gy in three fractions for tumours more than 4 cm to 10 cm in maximum diameter. The primary endpoint was local control, defined as no progression of the primary renal cell cancer, as evaluated by the investigator per Response Evaluation Criteria in Solid Tumours (version 1.1). Assuming a 1-year local control of 90%, the null hypothesis of 80% or less was considered not to be worthy of proceeding to a future randomised controlled trial. All patients who commenced trial treatment were included in the primary outcome analysis. This trial is registered with ClinicalTrials.gov, NCT02613819, and has completed accrual. FINDINGS: Between July 28, 2016, and Feb 27, 2020, 70 patients were enrolled and initiated treatment. Median age was 77 years (IQR 70-82). Before enrolment, 49 (70%) of 70 patients had documented serial growth on initial surveillance imaging. 49 (70%) of 70 patients were male and 21 (30%) were female. Median tumour size was 4·6 cm (IQR 3·7-5·5). All patients enrolled had T1-T2a and N0-N1 disease. 23 patients received single-fraction SABR of 26 Gy and 47 received 42 Gy in three fractions. Median follow-up was 43 months (IQR 38-60). Local control at 12 months from treatment commencement was 100% (p<0·0001). Seven (10%) patients had grade 3 treatment-related adverse events, with no grade 4 adverse events observed. Grade 3 treatment-related adverse events were nausea and vomiting (three [4%] patients), abdominal, flank, or tumour pain (four [6%]), colonic obstruction (two [3%]), and diarrhoea (one [1%]). No treatment-related or cancer-related deaths occurred. INTERPRETATION: To our knowledge, this is the first multicentre prospective clinical trial of non-surgical definitive therapy in patients with primary renal cell cancer. In a cohort with predominantly T1b or larger disease, SABR was an effective treatment strategy with no observed local failures or cancer-related deaths. We observed an acceptable side-effect profile and renal function after SABR. These outcomes support the design of a future randomised trial of SABR versus surgery for primary renal cell cancer. FUNDING: Cancer Australia Priority-driven Collaborative Cancer Research Scheme.

Partially Ablative Body Radiotherapy (PABR): A novel approach for palliative radiotherapy of locally advanced bulky unresectable sarcomas.

BACKGROUND: Locally advanced, bulky, unresectable sarcomas cause significant tumour mass effects, leading to burdensome symptoms. We have developed a novel Partially Ablative Body Radiotherapy (PABR) technique that delivers a high, ablative dose to the tumour core and a low, palliative dose to its periphery aiming to increase overall tumour response without significantly increasing treatment toxicity. AIM: This study aims to report the safety and oncologic outcomes of PABR in patients with bulky, unresectable sarcomas. METHODS AND MATERIALS: A total of 18 patients with histologically proven sarcoma treated with PABR from January 2020 to October 2023 were retrospectively reviewed. The primary endpoints were symptomatic and structural response rates. Secondary endpoints were overall survival, freedom from local progression, freedom from distant progression, and acute and late toxicity rates. RESULTS: All patients had tumours ≥5 cm with a median tumour volume of 985 cc, and the most common symptom was pain. The median age is 72.5 years and 44.5 % were ECOG 2-3. The most common regimen used was 20 Gy in 5 fractions with an intratumoral boost dose of 50 Gy (83.3 %). After a median follow-up of 11 months, 88.9 % of patients exhibited a partial response with a mean absolute tumour volume reduction of 49.5 %. All symptomatic patients experienced symptom improvement. One-year OS, FFLP and FFDP were 61 %, 83.3 % and 34.8 %, respectively. There were no grade 3 or higher toxicities. CONCLUSION: PABR for bulky, unresectable sarcomas appears to be safe and may provide good symptomatic response, tumour debulking, and local control. Further study is underway.

The Potential Contribution of Radiopharmaceutical Therapies in Managing Oligometastatic Disease.

There is a growing understanding of the oligometastatic disease state, characterized by the presence of 5 or fewer lesions. Advanced molecular imaging techniques, such as prostate-specific membrane antigen PET, refines the ability to detect oligometastatic recurrences (oligorecurrences) early. These developments have led to the exploration of metastasis-directed therapy (MDT) in oligorecurrent disease as an alternative to or as a means of delaying systemic therapy. Unfortunately, MDT often does not provide a durable cure, and progression-particularly progression in multiple new areas-remains a concern. Simultaneously, developments in radioligand therapy (RLT) have led to studies showing overall survival benefits with α-emitting and ß-emitting RLT in advanced, high-volume, metastatic castration-resistant prostate cancer. The success of RLT in late-stage disease suggests that earlier use in the disease spectrum may be impactful. Specifically, integration of RLT with MDT might reduce progression, including polymetastatic progression, in the setting of oligorecurrent disease.

Low rate of severe-end-stage kidney disease after SABR for localised primary kidney cancer.

BACKGROUND: Stereotactic ablative body radiotherapy (SABR) is an emerging treatment for patients with primary renal cell carcinoma (RCC). However, its impact on renal function is unclear. This study aimed to evaluate incidence and clinical factors predictive of severe to end-stage chronic kidney disease (CKD) after SABR for RCC. METHODS AND MATERIALS: This was a Single institutional retrospective analysis of patients with diagnosed primary RCC receiving SABR between 2012-2020. Adult patients with no metastatic disease, baseline estimated glomerular filtration rate (eGFR) of ≥ 30 ml/min/1.73 m2, and at least one post-SABR eGFR at six months or later were included in this analysis. Patients with upper tract urothelial carcinoma were excluded. Primary outcome was freedom from severe to end-stage CKD, determined using the Kaplan-Meier estimator. The impact of baseline CKD, age, hypertension, diabetes, tumor size and fractionation schedule were assessed by Cox proportional hazard models. RESULTS: Seventy-eight consecutive patients were included, with median age of 77.8 years (IQR 70-83), tumor size of 4.5 cm (IQR 3.9-5.8) and follow-up of 42.2 months (IQR 23-60). Baseline median eGFR was 58 mls/min; 55% (n = 43) of patients had baseline CKD stage 3 and the remainder stage 1-2. By last follow-up, 1/35 (2.8%) of baseline CKD 1-2, 7/27 (25.9%) CKD 3a and 11/16 (68.8%) CKD 3b had developed CKD stage 4-5. The estimated probability of freedom from CKD stage 4-5 at 1 and 5 years was 89.6% (CI 83.0-97.6) and 65% (CI 51.4-81.7) respectively. On univariable analysis, worse baseline CKD (p < 0.0001) and multi-fraction SABR (p = 0.005) were predictive for development of stage 4-5 CKD though only the former remained significant in multivariable model. CONCLUSION: In this elderly cohort with pre-existing renal dysfunction, SABR achieved satisfactory nephron sparing with acceptable rates of severe to end-stage CKD. It can be an attractive option in patients who are medically inoperable.

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.

An Economic Analysis of SC24 in Canada: A Randomized Study of SBRT Compared With Conventional Palliative RT for Spinal Metastases.

PURPOSE: The Canadian Cancer Trials Group (CCTG) Symptom Control 24 protocol (SC.24) was a multicenter randomized controlled phase 2/3 trial conducted in Canada and Australia. Patients with painful spinal metastases were randomized to either 24 Gy/2 stereotactic body radiation therapy (SBRT) or 20 Gy/5 conventional external beam radiation therapy (CRT). The study met its primary endpoint and demonstrated superior complete pain response rates at 3 months following SBRT (35%) versus CRT (14%). SBRT planning and delivery is resource intensive. Given its benefits in SC.24, we performed an economic analysis to determine the incremental cost-effectiveness of SBRT compared with CRT. METHODS AND MATERIALS: The trial recruited 229 patients. Cost-effectiveness was assessed using a Markov model taking into account observed survival, treatments costs, retreatment, and quality of life over the lifetime of the patient. The EORTC-QLU-C10D was used to determine quality of life values. Transition probabilities for outcomes were from available patient data. Health system costs were from the Canadian health care perspective and were based on 2021 Canadian dollars (CAD). The incremental cost-effectiveness ratio (ICER) was expressed as the ratio of incremental cost to quality-adjusted life years (QALY). The impact of parameter uncertainty was investigated using deterministic and probabilistic sensitivity analyses. RESULTS: The base case for SBRT compared with CRT had an ICER of $9,040CAD per QALY gained. Sensitivity analyses demonstrated that the ICER was most sensitive to variations in the utility assigned to "No local failure" ($5,457CAD to $241,051CAD per QALY), adopting low and high estimates of utility and the cost of the SBRT (ICERs ranging from $7345-$123,361CAD per QALY). It was more robust to variations in assumptions around survival and response rate. CONCLUSIONS: SBRT is associated with higher upfront costs than CRT. The ICER shows that, within the Canadian health care system, SBRT with 2 fractions is likely to be more cost-effective than CRT.

Stereotactic Body Radiation Therapy: A Radiosurgery Society Guide to the Treatment of Localized Prostate Cancer Illustrated by Challenging Cases.

Traditionally, external beam radiotherapy (EBRT) for localized prostate cancer (PCa) involved lengthy courses with low daily doses. However, advancements in radiation delivery and a better understanding of prostate radiobiology have enabled the development of shorter courses of EBRT. Ultrahypofractionated radiotherapy, administering doses greater than 5 Gy per fraction, is now considered a standard of care regimen for localized PCa, particularly for intermediate-risk disease. Stereotactic body radiotherapy (SBRT), a specific type of ultrahypofractionated radiotherapy employing advanced planning, imaging, and treatment technology to deliver in five or fewer fractions, is gaining prominence as a cost-effective, convenient, and safe alternative to longer radiotherapy courses. It is crucial to address practical considerations related to patient selection, fractionation scheme, target delineation, and planning objectives. This is especially important in challenging clinical situations where clear evidence for guidance may be lacking. The Radiosurgery Society endorses this case-based guide with the aim of providing a practical framework for delivering SBRT to the intact prostate, exemplified by two case studies. The article will explore common SBRT dose/fractionation schemes and dose constraints for organs-at-risk. Additionally, it will review existing evidence and expert opinions on topics such as SBRT dose escalation, the use of rectal spacers, the role of androgen deprivation therapy in the context of SBRT, SBRT in special patient populations (e.g., high-risk disease, large prostate, high baseline urinary symptom burdens, and inflammatory bowel disease), as well as new imaging-guidance techniques like Magnetic Resonance Imaging for SBRT delivery.