Local Control Rates of Metastatic Renal Cell Carcinoma (RCC) to Thoracic, Abdominal, and Soft Tissue Lesions Using Stereotactic Body Radiotherapy (SBRT)

Stereotactic body irradiation for metastasis from renal carcinoma: A retrospective study

Background

Renal cell carcinoma (RCC) has traditionally been considered to be radioresistant. Response rates are believed to be improved by a high dose of stereotactic body radiotherapy (SBRT). A retrospective analysis was conducted of patients treated with SBRT for metastatic disease from RCC.

Material and methods

We reviewed records from 20 patients who underwent SBRT for a total of 30 RCC metastases from 2015 to 2020. Patients were included who had a confirmed primary RCC and radiographic evidence of metastasis, either synchronous or metachronous. The most common SBRT fractionation was 30 Gy in 3 fractions.

Results

Median age was 60 years (range, 40-77 years) and 60% were male. After a median follow-up of 18 months (range, 3-36 months), overall survival was estimated to be 85% and 70%, at 1 and 2 years, respectively, and local control at 2 years was 83.33%. Only 5 patients had documented progression of disease, all of whom received biologically effective dose inferior to 100 Gy, and no patients treated with a higher biologically effective dose had disease, which progressed. The most common acute toxicity was grade 1 fatigue (20%). No grade 3 or higher acute toxicity occurred.

Conclusions

Treatment with SBRT in patients with RCC metastases yielded a high local control rate, promising survival rate, and low toxicity.

Comparative efficacy and safety of ablative therapies in the management of primary localised renal cell carcinoma: a systematic review and meta-analysis

BACKGROUND

Non-invasive and minimally invasive ablative treatments, including stereotactic body radiotherapy (SBRT), radiofrequency ablation, microwave ablation, and cryoablation, have emerged as key treatment options for managing renal cell carcinoma, especially for patients who are unsuitable for surgery. We aimed to compare the clinical efficacy and safety of these emerging treatment methods in patients with localised renal cell carcinoma.

METHODS

In this systematic review and meta-analysis, we searched PubMed (MEDLINE), Embase, and the Cochrane Library for publications between Jan 1, 2000, and March 1, 2024. Eligible articles were observational studies and randomised controlled trials including at least five adult patients (age ≥18 years) with primary and localised renal cell carcinoma treated with SBRT, radiofrequency ablation, microwave ablation, or cryoablation and that reported on local control outcomes. Two reviewers independently screened titles and abstracts and then full texts of eligible studies were independently evaluated by the same reviewers, with disagreements resolved via discussion or consultation with a third reviewer. Summary estimates were extracted from published reports manually using a standardised data extraction form. The primary endpoint was local control rate at 1 year, 2 years, and 5 years after start of treatment. A meta-analysis was conducted using a DerSimonian and Laird model to summarise local control rates. Publication bias was evaluated using funnel plots and Egger's test. We also recorded the frequency and severity of adverse events after treatment on the basis of the Common Terminology Criteria for Adverse Events (version 5.0) and Clavien-Dindo complication index. The study protocol was prospectively registered with PROSPERO, CRD42024511840.

FINDINGS

We identified 6668 records, of which 330 were assessed via full-text review, and 133 were included in our systematic review and meta-analysis. The eligible studies included data for 8910 patients (mean age 67·9 years [SD 7·3], 2518 [31·4%] of 8018 patients with available data were female and 5500 [68·6%] were male). Local control rates for SBRT were 99% (95% CI 97-100; I2=6%) at 1 year, 97% (95-99; I2=0%) at 2 years, and 95% (89-98; I2=42%) at 5 years; for radiofrequency ablation were 96% (94-98; I2=73%) at 1 year, 95% (92-98; I2=77%) at 2 years, and 92% (88-96; I2=78%) at 5 years; for microwave ablation were 97% (95-99; I2=74%) at 1 year, 95% (92-98; I2=77%) at 2 years, and 86% (75-94; I2=66%) at 5 years; and for cryoablation were 95% (93-96; I2=61%) at 1 year, 94% (91-96; I2=69%) at 2 years, and 90% (87-93; I2=74%) at 5 years. The proportion of patients who reported grade 3-4 adverse events was 3% (121 of 3726) after cryoablation, 2% (39 of 2503) after radiofrequency ablation, 1% (22 of 2069) after microwave ablation, and 2% (11 of 612) after SBRT. Risk of bias was moderate in most studies (70 [53%] of 133) and no publication bias was observed.

INTERPRETATION

All investigated ablative methods continue to represent effective treatment choices in renal cell carcinoma, and these findings support multi-disciplinary discussions of these treatment methods, along with surgery and surveillance, to individualise treatment decisions in these patients. Future research should aim to conduct randomised controlled trials across larger patient populations to further elucidate the long-term oncological and survival outcomes associated with these treatments.

FUNDING

None.

Prognostic assessment of patients with bone metastatic renal cell cancer treated with palliative radiotherapy

The present study investigated the prognosis of patients who received palliative radiotherapy (RT) for bone metastases (BMs) from renal cell cancer (RCC), and assessed the prognostic factors specific to BMs from RCC. A total of 109 patients with RCC and BMs who underwent RT for the first time were included in the study. Prognostic factors were evaluated using multivariate analysis and a scoring system based on regression coefficients was devised. The median follow-up time was 9 months, and the 0.5-year overall survival (OS) rate was 73.0%. In the multivariate analysis, the significant prognostic factors were higher performance status (≥2), no control of the primary site, disseminated metastasis, lymph node metastasis and multiple BMs. A score of 1 point was assigned to each risk factor. The median OS times were 19.0 and 5.0 months in patients with a total score of ≤1 (n=49) and >1 (n=60), respectively (P<0.01). In conclusion, a comprehensive prognostic assessment using these factors may be useful for predicting the prognoses of patients with BMs from RCC. In addition, this scoring system may be useful in selecting the optimal RT dose.

The Role of Stereotactic Body Radiotherapy (SBRT) in Oligoprogressive Renal Cell Carcinoma (RCC) Treated with ICIs-TKIs: A Retrospective Multicentric Study

BACKGROUND

This multicentric, retrospective study investigated the use of stereotactic body radiotherapy (SBRT) in patients (pts) with metastatic renal cell carcinoma (mRCC) who experienced oligoprogression during a combination therapy with an immune checkpoint inhibitor (ICI) and a tyrosine-kinase inhibitor (TKI).

METHODS

We retrospectively evaluated 34 pts affected by oligoprogressive RCC treated with an ICI-TKI combination between January 2020 and December 2023. SBRT was delivered to each site of oligoprogressive metastatic disease. After SBRT, pts were given follow-up clinical evaluations. 6-12-18-month local control (LC) rates and median next-line treatment-free survival (NEST-FS) were the primary endpoints. The secondary endpoints were overall response rate (ORR), clinical benefits and safety.

RESULTS

After a median follow-up of 24 months, 6-12-18-month LC rates were 100%, 71% and 43%, respectively, and the median NEST-FS was 20 months. ORR was 90%, while clinical benefit was 100%. No > G2 adverse events related to SBRT were recorded.

CONCLUSIONS

In our study, SBRT for oligoprogressive mRCC turned out to be a safe and useful treatment which was able to preserve current treatment. Further prospective studies are necessary to explore the effects of the ICIs-TKIs combination and SBRT upon oligoprogressive sites in mRCC.

Predictive Factors for Long-Term Disease Control in Systemic Treatment-Naïve Oligorecurrent Renal Cell Carcinoma Treated with Up-Front Stereotactic Ablative Radiotherapy (SABR)

BACKGROUND

Stereotactic ablative radiotherapy (SABR) is emerging as a potential local treatment option for oligometastatic RCC. This study aims to evaluate the efficacy of SABR in patients with oligorecurrent RCC.

METHODS

A total of 50 patients with histologically confirmed RCC underwent SABR for oligorecurrence between 2006 and 2022. Eligible patients had up to five extracranial metastases and were systemic treatment-naïve at the time of irradiation. The primary endpoints of the analysis were overall survival (OS), local control (LC), distant metastasis-free survival (DMFS), and time to systemic therapy initiation.

RESULTS

The median OS was not reached, with 1- and 3-year OS rates of 93.8% and 77.5%, respectively. LC rates at one and three years were 95.8% and 86.5%, respectively. The median time to systemic therapy initiation was 63.8 months, and the median DMFS was 17.9 months, with one- and three-year rates of 63.4% and 36.6%, respectively. Multiple metastases were a negative predictive factor for DMFS (HR 2.39, p = 0.023), whereas lung metastases were associated with a more favorable outcome (HR 0.38, p = 0.011).

CONCLUSIONS

SABR offers a valuable treatment option for oligometastatic RCC, demonstrating significant potential for achieving long-term disease control and delaying the need for systemic therapy.

The role of radiation therapy for de novo metastatic bladder and renal cancers

Metastatic bladder and renal cancers account respectively for 2.1% and 1.8% of cancer deaths worldwide. The advent of immune checkpoint inhibitors has revolutionized the management of metastatic disease, by demonstrating considerable improvements in overall survival. However, despite initial sensitivity to immune checkpoint inhibitors for most patients, both bladder and renal cancer are associated with short progression-free survival and overall survival, raising the need for further strategies to improve their efficacy. Combining systemic therapies with local approaches is a longstanding concept in urological oncology, in clinical settings including both oligometastatic and polymetastatic disease. Radiation therapy has been increasingly studied with either cytoreductive, consolidative, ablative or immune boosting purposes, but the long-term impact of this strategy remains unclear. This review intends to address the impact of radiation therapy with either curative or palliative intent, for synchronous de novo metastatic bladder and renal cancers.

Local Control in Patients with Metastatic Renal Cell Carcinoma to the Spine: The Experience of an Institution with a Multidisciplinary Spine Oncology Program

BACKGROUND

The outcomes for patients with metastatic renal cell carcinoma (RCC) to the spine who underwent stereotactic body radiotherapy (SBRT) through a multidisciplinary spine oncology program are not well described. We sought to describe the clinical course and local control rates at 1 and 2 years for these patients.

METHODS

A retrospective analysis of a prospectively maintained database of adult oncologic patients receiving SBRT to the spine through a multidisciplinary spine oncology program at a single institution from 2010 to 2021 was performed. Patients with a pathologic diagnosis of RCC were included.

RESULTS

A total of 75 spinal sites were treated in 60 patients. Of the 60 patients, 75.0% were men, and the mean patient age was 59.2 ± 11.3 years. At 1 year after treatment, 6 of the 60 patients were lost to follow-up. Of the remaining 54 patients, 18 were censored by death and 7 treatment sites showed local recurrence, for 37 of 44 treatment sites with local control (87.8%). At 2 years, 1 additional local recurrence had developed, 15 patients were censored by death, and no additional patients had been lost to follow-up, resulting in 28 of 36 treatment sites with local control (83.2%). None of the patients who had undergone repeat SBRT had local recurrence at 1 or 2 years. For those with local recurrence, the average time from treatment to progression was 6.6 ± 6.5 months.

CONCLUSIONS

In this cohort, one of the largest reported studies of spine SBRT for metastatic RCC, local control was high at 1 and 2 years. Our findings support the role of coordinated, algorithmic treatment for these patients.

Beyond the Knife in Renal Cell Carcinoma: A Systematic Review-To Ablate or Not to Ablate?

Intensified systemic therapy in metastatic renal cell carcinoma (mRCC) has led to improved patient outcomes. Patients commonly require local control of one or a few metastases. The aim was to evaluate metastasis-directed ablative therapies in extracranial mRCC. Two databases and one registry were searched, using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach, for all prospective and matched-pair case-control mRCC studies of radiofrequency ablation (RFA), cryotherapy, microwave ablation (MWA), and stereotactic body radiotherapy (SBRT). Eighteen studies were identified. Fourteen investigated SBRT in 424 patients. Four thermal ablation studies were identified: two cryotherapy (56 patients) and two RFA studies (90 patients). The median participant number was 30 (range 12-69). The combined median follow-up was 17.3 months (range 8-52). Four SBRT studies reported local control (LC) at 12 months, median 84.4% (range 82.5-93). Seven studies (six SBRT and one cryotherapy) reported an LC rate of median 87% (79-100%). Median overall survival (OS) was reported in eight studies (five SBRT, two cryotherapy, and one RFA) with a median of 22.7 months (range 6.7-not reached). Median progression-free survival was reported in seven studies (five SBRT, one cryotherapy, and one RFA); the median was 9.3 months (range 3.0-22.7 months). Grade ≥ 3 toxicity ranged from 1.7% to 10%. SBRT has excellent local control outcomes and acceptable toxicity. Only four eligible thermal ablative studies were identified and could not be compared with SBRT. Translationally rich definitive studies are warranted.

Metastatic renal cell carcinoma to the pancreas and other sites-a multicenter retrospective study

Background

Metastatic renal cell carcinoma (mRCC) is a heterogenous disease with poor 5-year overall survival (OS) at 14%. Patients with mRCC to endocrine organs historically have prolonged OS. Pancreatic metastases are uncommon overall, with mRCC being the most common etiology of pancreatic metastases. In this study, we report the long-term outcomes of patients with mRCC to the pancreas in two separate cohorts.

Methods

We performed a multicenter, international retrospective cohort study of patients with mRCC to the pancreas at 15 academic centers. Cohort 1 included 91 patients with oligometastatic disease to the pancreas. Cohort 2 included 229 patients with multiples organ sites of metastases including the pancreas. The primary endpoint for Cohorts 1 and 2 was median OS from time of metastatic disease in the pancreas until death or last follow up.

Findings

In Cohort 1, the median OS (mOS) was 121 months with a median follow up time of 42 months. Patients who underwent surgical resection of oligometastatic disease had mOS of 100 months with a median follow-up time of 52.5 months. The mOS for patients treated with systemic therapy was not reached. In Cohort 2, the mOS was 90.77 months. Patients treated with first-line (1L) VEGFR therapy had mOS of 90.77 months; patients treated with IL immunotherapy (IO) had mOS of 92 months; patients on 1L combination VEGFR/IO had mOS of 74.9 months.

Interpretations

This is the largest retrospective cohort of mRCC involving the pancreas. We confirmed the previously reported long-term outcomes in patients with oligometastatic pancreas disease and demonstrated prolonged survival in patients with multiple RCC metastases that included the pancreas. In this retrospective study with heterogeneous population treated over 2 decades, mOS was similar when stratified by first-line therapy. Future research will be needed to determine whether mRCC patients with pancreatic metastases require a different initial treatment strategy.

Funding

Statistical analyses for this study were supported in part by the University of Colorado Cancer Center Support Grant from the NIH/NCI, P30CA046934-30.

Stereotactic body radiation therapy for kidney cancer. Where do we stand?

At present, surgery is still the gold standard for the local treatment of renal cancer. Nonetheless, in several clinical scenarios, stereotactic body radiation therapy (SBRT) also known as stereotactic ablative body radiotherapy (SABR) is emerging as a highly effective ablative technique in fragile patients and those with significant comorbidities, as well as in cases where percutaneous therapy (cryoablation or radiofrequency) is not viable. However, considering the intrinsic radioresistance of renal tumors, the optimal treatment schemes have not been established. In oligometastatic patients, it has been reported that the control of the oligometastases can be a potentially curable approach. Being a technique than can be administered exclusively or in combination with systemic therapy, treatment individualization based on patient characteristics is key. Another scenario under investigation is oligoprogression, where SBRT offers the possibility of delaying further lines of systemic therapy by eliminating subclones of resistant tumor with ablative doses, with the additional opportunity of stimulating the immune system (immunomodulatory role). In this review, we have conducted an analysis of recently published studies that test the role of this technique in different clinical scenarios of this disease. We have found promising results that make SBRT a potent therapeutic approach with low toxicity. We also comment on ongoing studies that will generate the necessary evidence needed for the implementation of this technique in our daily clinical practice.

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

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

The Emerging Role of Extracranial Stereotactic Ablative Radiotherapy for Metastatic Renal Cell Carcinoma: A Systematic Review

CONTEXT

Although the management of metastatic renal cell carcinoma (mRCC) has been revolutionized by the advent of new systemic agents, still few patients experience a long-term durable response. Stereotactic ablative radiotherapy (SABR) is nowadays commonly used as metastasis-directed therapy (MDT), but limited data exist on how best to implement this strategy as part of a multimodal approach.

OBJECTIVE

To evaluate the potential role of extracranial SABR in mRCC and to identify future therapeutic developments of SABR in different disease settings.

EVIDENCE ACQUISITION

A systematic review was conducted in May 2022 according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement on the PubMed database. Thirty-four studies were selected for inclusion in this systematic review.

EVIDENCE SYNTHESIS

SABR has been used with four main goals: (1) eradication of the whole metastatic burden in synchronous and metachronous oligometastatic patients, resulting in a long-term local control (LC) rate of >90% and median progression-free survival (PFS) ranging between 8 and 15 mo; (2) eradication of oligoprogressive lesions, enabling an extension of the duration of the systemic therapy by approximately 9 mo; (3) improvement of the response to systemic therapy in polymetastatic patients, resulting in an overall response rate ranging from 17% to 56%; and (4) cytoreduction in polymetastatic mRCC patients, with LC rates ranging between 71% and 100%, and preservation of the renal function, but unclear PFS and overall survival impact. Overall, the combination of SABR and systemic agents has been associated with overall good tolerance, with grade ≥3 toxicity ranging from 0% to 13%.

CONCLUSIONS

Current data highlight the role of SABR as an emerging MDT treatment option in both oligometastatic and oligoprogressive extracranial mRCC, able to ensure long-term disease control and delay the use of next-line systemic therapies. The use of SABR for cytoreduction in the de novo metastatic disease and as an immunological booster in the polymetastatic setting remains investigational and warrants further investigations.

PATIENT SUMMARY

Radiotherapy delivered with ablative doses (>6 Gy per fraction) is a promising treatment strategy for patients diagnosed with metastatic renal cell carcinoma. Excellent outcome results have been observed in patients with a limited number of metastases, improving metastasis-free survival by several months. For patients with a few metastases progressing under systemic therapy, radiotherapy allows an extension of the duration of the ongoing therapy by several months.

Evaluation of 5 Fraction Stereotactic Body Radiation Therapy (SBRT) for Osseous Renal Cell Carcinoma Metastases

OBJECTIVES

The best fractionation for stereotactic body radiotherapy (SBRT) in renal cell carcinoma (RCC) metastases has not been well defined. In addition, the literature on outcomes using 5-fraction SBRT in the setting of osseous metastases has not been well reported.

MATERIALS AND METHODS

Thirty-nine patients with 69 RCC osseous metastases were treated using 5-fraction SBRT at a single institution using 2 dose-fractionation schemes. Overall survival and local-control (LC) outcomes of the 2 fractionation schemes were studied using Kaplan-Meier curves.

RESULTS

Of the 69 lesions included in the study, 20 were treated with 30 grays (Gy) in 5 fractions and 49 were treated with 40 Gy in 5 fractions. The median age of patients at diagnosis was 58.4 years. The 1-year LC rate for all treated lesions was 85.5% (59/69) with an LC of 90% (18/20) for lesions receiving 30 Gy and 83.7% (41/49) in lesions receiving 40 Gy. There was no statistically significant difference in 1-year LC rate between the 2 fractionation schemes (P-value, 0.553).

CONCLUSIONS

Patients with osseous RCC metastases undergoing 5 fractions of SBRT had favorable LC outcomes. There was no difference in survival or LC between the 40 Gy and 30 Gy treatment arms.

Bone-only oligometastatic renal cell carcinoma patients treated with stereotactic body radiotherapy: a multi-institutional study

PURPOSE

This study aimed to analyze the prognostic factors associated with overall survival (OS) and progression-free survival (PFS) in patients with bone-only metastatic renal cell carcinoma (RCC) who have five or fewer lesions treated with stereotactic body radiotherapy (SBRT).

METHODS

The clinical data of 54 patients with 70 bone metastases undergoing SBRT treated between 2013 and 2020 with a dose of at least 5 Gy per fraction and a biologically effective dose (BED) of at least 90 Gy were retrospectively evaluated.

RESULTS

The majority of lesions were located in the spine (57.4%) and had only one metastasis (64.8%). After a median follow-up of 22.4 months, the 1‑ and 2‑year OS rates were 84.6% and 67.3%, respectively, and median OS was 43.1 months. The 1‑ and 2‑year PFS rates and median PFS were 63.0%, 38.9%, and 15.3 months, respectively. In SBRT-treated lesions, the 1‑year local control (LC) rate was 94.9%. Age, metastasis localization, and number of fractions of SBRT were significant prognostic factors for OS in univariate analysis. In multivariate analysis, patients with spinal metastasis had better OS compared to their counterparts, and patients who received single-fraction SBRT had better PFS than those who did not. No patient experienced acute or late toxicities of grade 3 or greater.

CONCLUSION

Despite excellent LC at the oligometastatic site treated with SBRT, disease progression was observed in nearly half of patients 13 months after metastasis-directed local therapy, particularly as distant disease progression other than the treated lesion, necessitating an effective systemic treatment to improve treatment outcomes.

The role of stereotactic body radiotherapy in switching systemic therapy for patients with extracranial oligometastatic renal cell carcinoma

BACKGROUND

Targeting oligometastatic lesions with metastasis-directed therapy (MDT) using stereotactic-body radiotherapy (SBRT) may improve treatment outcomes and postpone the need for second-line systemic therapy (NEST). We looked at the results of oligometastatic renal cell carcinoma (RCC) patients who had five or fewer lesions and were treated with SBRT.

METHODS

We examined the treatment outcomes of 70 extracranial metastatic RCC (mRCC) patients treated at two oncology centers between 2011 and 2020. The clinical parameters of patients with and without NEST changes were compared. The prognostic factors for overall survival (OS), progression-free survival (PFS), and NEST-free survival were evaluated.

RESULTS

Median age was 67 years (range 31-83 years). Lung and bone metastasis were found in 78.4% and 12.6% of patients, respectively. With a median follow-up of 21.1 months, median OS was 49.1 months and the median PFS was 18.3 months. Histology was a prognostic factor for OS, BED, and treatment switch for PFS in univariate analysis. In multivariate analysis, the significant predictor of poor OS was clear cell histology, and a lower BED for PFS. Following SBRT for oligometastatic lesions, 19 patients (27.2%) had a median NEST change of 15.2 months after MDT completion. There were no significant differences in median OS or PFS between patients who had NEST changes and those who did not. No patient experienced grade ≥ 3 acute and late toxicities.

CONCLUSIONS

The SBRT to oligometastatic sites is an effective and safe treatment option for ≤ 5 metastases in RCC patients by providing favorable survival and delaying NEST change.

Pan-Asian adapted ESMO Clinical Practice Guidelines for the diagnosis, treatment and follow-up of patients with renal cell carcinoma

The most recent version of the European Society for Medical Oncology (ESMO) Clinical Practice Guidelines for the diagnosis, treatment and follow-up of renal cell carcinoma was published in 2019 with an update planned for 2021. It was therefore decided by both the ESMO and the Singapore Society of Oncology (SSO) to convene a special, virtual guidelines meeting in May 2021 to adapt the ESMO 2019 guidelines to take into account the ethnic differences associated with the treatment of renal cell carcinomas in Asian patients. These guidelines represent the consensus opinions reached by experts in the treatment of patients with renal cell carcinoma representing the oncological societies of China (CSCO), India (ISMPO), Japan (JSMO), Korea (KSMO), Malaysia (MOS), Singapore (SSO) and Taiwan (TOS). The voting was based on scientific evidence and was independent of the current treatment practices and drug access restrictions in the different Asian countries. The latter were discussed when appropriate.

Stereotactic Body Radiotherapy in Contralateral Kidney Oligometastasis From Renal Cell Carcinoma in a Nephrectomized Patient

Background: Renal cell carcinoma (RCC) frequently metastasizes to distal organs such as the lungs, abdomen, bones, and brain. Although rare cases of adrenal gland metastasis from RCC have been described, to our knowledge, no cases have reported the use of stereotactic body radiotherapy (SBRT) in contralateral kidney oligometastasis in a nephrectomized patient with RCC.

Case Report: We report a rare case of single contralateral renal metastasis from RCC in a 65-year-old female that occurred 1 year after right radical nephrectomy. At diagnosis of relapse, the patient received targeted therapy with sunitinib for 9 consecutive months, resulting in a partial regression of renal metastasis. To preserve the organ and consolidate response, SBRT was administered to the residual mass. Targeted therapy was temporarily discontinued 15 days before and after SBRT. Total SBRT dose was 40 Gy in 5 daily fractions given with volumetric modulated arc and image-guided technique. Three months later, magnetic resonance imaging documented a complete regression of disease, a result that persisted at the last follow-up 19 months after SBRT.

Conclusion: The combination of sequential targeted therapy and SBRT provided an excellent outcome in a patient with a solitary kidney who experienced contralateral kidney metastasis from RCC. This treatment approach was well tolerated and controlled the disease.

Oligo metastatic renal cell carcinoma: stereotactic body radiation therapy, if, when and how?

BACKGROUND AND PURPOSE

Renal cell carcinoma (RCC) has traditionally been considered radioresistant with a limited role for conventional fractionation as a local approach. Nevertheless, since the appearance of stereotactic body radiation therapy (SBRT), radiotherapy (RT) has been increasingly employed in the management of metastatic RCC (mRCC). The aim of this study was to evaluate the role of SBRT for synchronous and metachronous oligo metastatic RCC patients in terms of local control, delay of systemic treatment, overall survival and toxicity.

PATIENTS AND METHODS

A Monocentric single institution retrospective data collection was performed. Inclusion criteria were: (1) oligo-recurrent or oligo-progressive disease (less than 5 metastases) in mRCC patients after radical/partial nephrectomy or during systemic therapy, (2) metastasectomy or other metastasis-directed, rather than SBRT not feasible, (3) any contraindication to receive systemic therapy (such as comorbidities), (4) all the histologies were included, (5) available signed informed consent form for treatment. Tumor response and toxicity were evaluated using the response evaluation criteria in solid tumors and the Common Terminology Criteria for Adverse Events version 4.03, respectively. Progression-free survival in-field and out-field (in-field and out-field PFS) and overall survival (OS) were calculated via the Kaplan-Meier method. The drug treatment-free interval was calculated from the start of SBRT to the beginning of any systemic therapy.

RESULTS

From 2010 to December 2018, 61 patients with extracranial and intracranial metastatic RCC underwent SBRT on 83 lesions. Intracranial and extracranial lesions were included. Forty-five (74%) patients were treated for a solitary metastatic lesion. Median RT dose was 25 Gy (range 10-52) in 5-10 fractions. With a median follow-up of 2.3 years (range 0-7.15), 1-year in-field PFS was 70%, 2-year in-field PFS was 55%. One year out-field PFS was 39% and 1-year OS was 78%. Concomitant systemic therapy was employed for only 11 (18%) patients, for the others 50 (82%) the drug treatment-free rate was 70% and 50% at 1 and 2 years, respectively. No > G1 acute and late toxicities were reported.

CONCLUSION

The pattern of failure was pre-dominantly out-of-field, even if the population was negatively selected and the used RT dose could be considered palliative. Therefore, SBRT appears to be a well-tolerated, feasible and safe approach in oligo metastatic RCC patients with an excellent in-field PFS. SBRT might play a role in the management of selected RCC patients allowing for a delay systemic therapy begin (one out of two patients were free from new systemic therapy at 2 years after SBRT). Further research on SBRT dose escalation is warranted.

Stereotactic body radiotherapy for the treatment of oligometastatic gynecological malignancy in the abdomen and pelvis: A single-institution experience

PURPOSE/OBJECTIVES

Metastasis-directed therapy with stereotactic body radiotherapy (SBRT) in the setting of oligometastatic disease is a rapidly evolving paradigm given ongoing improvements in systemic therapies and diagnostic modalities. However, SBRT to targets in the abdomen and pelvis is historically associated with concerns about toxicity. The purpose of this study was to evaluate the safety and efficacy of SBRT to the abdomen and pelvis for women with oligometastases from primary gynecological tumors.

MATERIALS/METHODS

From our IRB-approved registry, all patients who were treated with SBRT between 2014 and 2020 were identified. Oligometastatic disease was defined as 1 to 5 discrete foci of clinical metastasis radiographically diagnosed by positron emission tomography (PET) and/or computerized tomography (CT) imaging. The primary endpoint was local control at 12 months. Local and distant control rates were estimated using the Kaplan-Meier method. Time intervals for development of local progression and distant progression were calculated based on follow up visits with re-staging imaging. Acute and late toxicity outcomes were determined based on Common Terminology Criteria for Adverse Events (CTCAE) version 5.0.

RESULTS

We identified 34 women with 43 treated lesions. Median age was 68 years (range 32-82), and median follow up time was 12 months (range 0.2-54.0). Most common primary tumor sites were ovarian (n=12), uterine (n=11), and cervical (n=7). Median number of previous lines of systemic therapy agents at time of SBRT was 2 (range 0-10). Overall, SBRT was delivered to 1 focus of oligometastasis in 29 cases, 2 foci in 2 cases, 3 foci in 2 cases, and 4 foci in 1 case. All patients were treated comprehensively with SBRT to all sites of oligometastasis. Median prescription dose was 24 Gy (range 18-54 Gy) in 3 fractions (range 3-6) to a median prescription isodose line of 83.5% (range 52-95). Local control by lesion at 12 and 24 months was 92.5% for both time points. Local failure was observed in three treated sites among two patients, two of which were at 11 months in one patient, and the other at 30 months. Systemic control rate was 60.2% at 12 months. Overall survival at 12 and 24 months was 85% and 70.2%, respectively. Acute grade 2 toxicities included nausea (n=3), and there were no grade > 3 acute toxicities. Late grade 1 toxicities included diarrhea (n=1) and fatigue (n=1), and there were no grade > 2 toxicities.

CONCLUSION

SBRT to oligometastatic gynecologic malignancies in the abdomen and pelvis is feasible with encouraging preliminary safety and local control outcomes. This approach is associated with excellent local control and low rates of toxicity during our follow-up interval. Further investigations into technique, dose-escalation and utilization are warranted.

Survival Outcomes After Adding Stereotactic Body Radiotherapy to Metastatic Renal Cell Carcinoma Patients Treated With Tyrosine Kinase Inhibitors

OBJECTIVE

Long-lasting control is rarely achieved with tyrosine kinase inhibitors (TKI) alone in metastatic renal cell carcinoma (mRCC). Our study aimed to investigate the survival outcomes of adding stereotactic body radiotherapy (SBRT) to TKI in mRCC.

MATERIALS AND METHODS

From September 2015 to September 2018, 56 patients treated with TKI received SBRT for 103 unresectable lesions. A total of 24 and 32 patients were irradiated before and after TKI failure, respectively. Overall survival (OS) was calculated from metastases. Progression-free survival (PFS) was calculated from SBRT.

RESULTS

Overall, 10, 32, and 12 patients had International Metastatic Renal Cell Carcinoma Database Consortium favorable, intermediate, and poor risk. Median follow-up was 21.7 months (range, 5.1 to 110.6 mo). Median OS was 61.2 months. The median PFS was 11.5 months, while the 2-year LC rate was 94%. Sixteen (34%) lesions achieved complete response (CR) in patients irradiated before TKI failure, whereas only 4 (7%) lesions yielded CR in those irradiated after TKI failure (P=0.001). The median PFS in CR group was significantly longer than that of non-CR group (18.9 vs. 7.1 mo; P=0.003). The 5-year OS in CR group was 86%, compared with 48% in non-CR group (P=0.010). Four (7%) patients experienced Grade 3 toxicity.

CONCLUSIONS

Adding SBRT to TKI is safe and seems to improve survival in mRCC. Patients irradiated before TKI failure have higher CR rate, and the favorable local response might turn into survival benefit.

Stereotactic body radiation therapy (SBRT) for metastatic renal cell carcinoma: A multi-institutional experience

Objectives: Examine local control(LC), overall survival(OS), and toxicity following stereotactic body radiation therapy(SBRT) for patients with metastatic renal cell carcinoma(mRCC). Methods: A multi-institutional registry was queried. Potential predictive factors of LC and OS were evaluated with a Cox-proportional hazards model for multivariate analysis(MVA). Results: We identified 115 mRCC patients with 181 lesions. Median biologically effective dose (BED₇) was 72.9 Gy₇ (range: 42.9-231.4 Gy₇) with a median dose/fraction of 10 Gy (range: 5-24 Gy). Utilizing both Karnofsky Performance Score (KPS) and presence of osseous metastatic disease as prognostic indicators, estimated 2-year OS rates were 67.7% (95% CI: 49.9-89.5%), 31.8% (95% CI: 19.0-45.3%), and 20% (95% CI: 1.4-54.7%; p=0.0012). One- and 2-year LC rates were 88.2% and 82.7%, respectively, with no prognostic factors identified. Roughly 13% of patients reported toxicities with one Grade 3-5 toxicity. Conclusion: SBRT was well-tolerated with promising LC. Both KPS and osseous metastatic disease should be considered in determining which patients with mRCC may preferentially benefit from SBRT.

Renal cell carcinoma lung metastases treated by radiofrequency ablation integrated with systemic treatments: over 10 years of experience

Background

To determine safety and efficacy of radiofrequency ablation (RFA) for local treatment of lung metastases of renal cell carcinoma (RCC), sequenced or combined with systemic treatments.

Methods

Retrospectively, we studied 53 patients treated by RFA for a maximum of six lung metastases of RCC. The endpoints were local efficacy, overall (OS), disease-free (DFS), pulmonary progression-free (PPFS) and systemic treatment-free (STFS) survivals, complications graded by the CTCAE classification and factors associated with survivals. Potential factors analysed were: clinical and pathological data, tumoral staging of TNM classification, primary tumor histology, Fuhrman’s grade, age, number and size of lung metastases and extra-pulmonary metastases pre-RFA.

Results

One hundred metastases were treated by RFA. Median follow-up time was 61 months (interquartile range 90–34). Five-year OS was 62% (95% confidence interval (CI): 44–75). Median DFS was 9.9 months (95% CI: 6–16). PPFS at 1 and 3 years was 58.9% (95%CI: 44.1–70.9) and 35.2% (95%CI: 21.6–49.1), respectively. We observed 3% major complications (grade 3 and 4 of CTCAE classification). Local efficacy was 91%. Median STFS was 28.3 months. Thirteen patients (25%) with lung recurrence could be treated by another RFA. T3/T4 tumors had significantly worse OS, PPFS and STFS. Having two or more lung metastases increased the risk of pulmonary progression more than threefold.

Conclusion

Integrated to systemic treatment strategy, RFA is safe and effective for the treatment strategy of lung metastasis from RCC with good OS and long systemic treatment-free survival. RFA offers the possibility of repeat procedures, with low morbidity.

Combination with Stereotactic Body Radiotherapy Offers a Promising Strategy to Overcome Resistance to Immunotherapy in Advanced Renal Cell Cancer

Immunotherapy for renal cell cancer (RCC) has witnessed several developments for more than two decades. Checkpoint inhibitors, including anti-CTLA-4 and anti-PD-1/PD-L1 blockers, have changed the treatment landscape for patients with advanced RCC in the past 3 years. Despite these advances, more than 55% RCC patients become resistant to different immunotherapies without other treatment combination. Among various attempts at overcoming resistance to immunotherapy, stereotactic body radiotherapy (SBRT) has been found to potentiate the activity of immunotherapy agents through several potential mechanisms, including normalization of microvessels to alleviate tumor hypoxia, improvement in efficient delivery of drugs, abundant neoantigen exposure, and recruitment of antitumor immune cells to alter the immunosuppressive tumor microenvironment. Preclinical studies and clinical case reports have predicted that the combination of SBRT, an immunotherapy, may lead to remarkable results. This review aims to provide the biological basis for the feasibility of combining SBRT to overcome immunotherapy resistance and to review the currently available clinical evidence of this combination therapy in patients with advanced RCC.

Treatment Outcome of metastatic lesions from renal cell carcinoma underGoing Extra-cranial stereotactic body radioTHERapy: The together retrospective study

OBJECTIVES

stereotactic body radiation therapy (SBRT) use has increased overtime for the management of metastatic renal cell carcinoma (mRCC) patients, with a likely good control of irradiated lesions. We planned a retrospective multicenter Italian study, with the aim of investigating the outcome of treatment with SBRT for non-brain secondary lesions in mRCC patients.

METHODS

all consecutive metastatic non-brain lesions from mRCC that underwent SBRT at nine Italian institutions from January 2015 to June 2017 were considered. The primary endpoint of the study was the lesion-PFS, calculated from SBRT initiation to the local progression of the irradiated lesion.

RESULTS

57 extracranial metastatic lesions from 48 patients with primary mRCC were treated with SBRT. At the median follow-up of 26.4 months, the median lesion-PFS was not reached (43 censored); 72.4% of lesions were progression-free at 40 months, with significantly better lesion-PFS for small metastatic lesions (<14 mm). SBRT was safe and the 1-year local disease control was 87.7%. After SBRT, 18 patients (37.5%) permanently interrupted systemic therapy.

CONCLUSIONS

consistently with the previous literature, our findings support the use of SBRT in selected mRCC patients.

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

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

Treating the Chameleon: Radiotherapy in the management of Renal Cell Cancer

PURPOSE

To review the role of radiotherapy (RT) in the treatment of renal cell cancer (RCC) in the curative and palliative setting.

CONTENT

Details related to the clinical outcomes of primary, preoperative, postoperative and palliative RT are discussed, along with a presentation of the established role of surgery and systemic therapy. An overview of data derived from mono- and multi-institutional trials is provided.

CONCLUSION

Radiotherapy has been shown to provide good symptom palliation and local control in RCC depending on the dose that can be delivered. There is emerging data suggesting that with the use of high-precision RT methods the indication spectrum of RT can be exploited covering different clinical situations particularly for unresectable local recurrences and oligometastatic disease.

Radiation therapy in renal cell carcinoma

Renal cell carcinoma (RCC) is classically regarded as extremely resistant to classical fractionated radiation therapy (RT). Nowadays, there is convincing data supporting RCC radiosensitivity to high fraction doses, which may represent an ideal issue for new treatment strategies in primary and oligometastatic RCC disease. This review discusses the role of RT in RCC and its potential therapeutic scenario focusing on the most interesting clinical trials.

Role of metastasis-directed treatment in kidney cancer

Despite the rapid elaboration of multiple, novel systemic agents introduced for metastatic renal cell carcinoma (mRCC) in recent years, a durable complete response remains elusive with systemic therapy alone. Definitive treatment of the metastatic deposit remains the sole potentially curative option and is a cornerstone of mRCC therapy, offering potential for both local control and palliation of tumor-related symptoms. In this review, the evidence supporting the definitive treatment of mRCC is examined and summarized, including the use of surgical metastasectomy, thermal ablation, radiotherapy, and other minimally invasive options. Multimodal approaches, including the combination of metastasectomy with novel systemic agents, are discussed. Finally, the authors review considerations for patient selection for this type of therapy and summarize available risk-stratification tools that may help guide shared decision making.

Imaging and Management of Intrathoracic Renal Cell Carcinoma Metastases

OBJECTIVE

Renal cell carcinoma (RCC) has a propensity to metastasize to the chest, with the lungs being the most common distant metastatic site. The histologic subtype of RCC has implications for prognosis.

CONCLUSION

Significant advances have been made in the management of metastatic RCC, both in systemic and locoregional therapies. The aim of this article is to review appearances of intrathoracic metastases from RCC and to discuss treatment considerations.

The Efficacy of Conventionally Fractionated Radiation in the Management of Osseous Metastases from Metastatic Renal Cell Carcinoma

Background

There is little data regarding the effectiveness of palliative radiation with conventional fractionation for metastatic renal cell carcinoma (RCC), which has been described as radioresistant. We conducted a retrospective analysis of patients with metastatic bony disease from RCC treated with radiation therapy at our institution.

Methods

Forty patients with histologically confirmed RCC with a total of 53 treatment courses were included. Pain response after radiotherapy was recorded and freedom from progression was generated using posttreatment radiographs. Patient data was analyzed to assess influence on local control.

Results

Patients had a median age of 63. Median follow-up was 9.3 months. The most common radiation dose was 30 Gy in 10 fractions. Pain control after radiotherapy was achieved in 73.6% of patients. Increasing age was associated with nonresponse at the initial pain assessment post-RT (p = 0.02). In lesions with initial pain response, nonclear cell histology was associated with increased pain recurrence (p = 0.01) and a shorter duration to pain recurrence (p = 0.01). Radiographic control at 1 year was 62%.

Conclusions

Pain response and control rates for osseous metastatic disease in RCC are comparable to other histologies when treated with conventional fractionation. These appear to be inferior to reported control rates from stereotactic treatments.

Stereotactic body radiotherapy (SBRT) for pulmonary metastases from renal cell carcinoma-a multicenter analysis of the German working group "Stereotactic Radiotherapy"

Background

Renal cell carcinoma (RCC) is traditionally considered to be radioresistant. Radiotherapy response rates are believed to improve with hypofractionated, high dose stereotactic body radiotherapy (SBRT). However, limited data exist regarding the role of SBRT in the treatment of pulmonary metastases.

Methods

The working group "Stereotactic Radiotherapy" of the German Society of Radiation Oncology analyzed its multi-institutional database of more than 700 patients who received SBRT for pulmonary metastases. Treatment was performed at 10 centers between 2001 and 2016. Patients with metastatic RCC were included in the study. Tumor characteristics, treatment details, and follow-up data including survival, local control (LC), distant metastases, and toxicity were evaluated.

Results

A total of 46 RCC patients treated with SBRT for 67 lung metastases were identified, who received a median total biologically effective dose (BED_iso) at planning target volume (PTV) isocenter of 117.0 Gy (range, 48.0-189.0 Gy). A median fractional dose of 20.8 Gy at isocenter (range, 6.0-37.9 Gy) was administered in a median number of 3 fractions (1-8 fractions). After a median follow-up time of 28.3 months for all patients, 1- and 3-year LC rates were 98.1% and 91.9%, with corresponding 1- and 3-year overall survival (OS) of 84.3% and 43.8%, respectively. Pulmonary metastases treated with BEDiso ≥130 Gy showed a trend for superior LC (P=0.054). OS was significantly improved in both uni- and multivariate analysis for patients with higher Karnofsky performance scale, lower maximum pulmonary metastasis diameter and lack of post-SBRT systemic therapy due to progression (P=0.014; P=0.049; P=0.006). Only mild acute and late toxicity was reported.

Conclusions

SBRT for pulmonary metastases from RCC was associated with low treatment-associated toxicity, promising survival, and excellent LC, especially in those patients receiving a BED_iso ≥130 Gy.

Combined high dose radiation and pazopanib in metastatic renal cell carcinoma: a phase I dose escalation trial

Background

The primary objective was to determine maximum tolerated radiation dose in patients with metastatic renal cell carcinoma on pazopanib treatment.

Methods

Treatment-naïve patients received pazopanib according to standard of care. Stereotactic body radiotherapy (SBRT) was delivered concurrently to the largest metastatic lesion at day 8, 10 and 12. SBRT doses were escalated in 3 dose levels (24 Gy/3, 30 Gy/3 and 36 Gy/3). Dose level was assigned using Time-to-Event Continual Reassessment Method with the target dose-limiting toxicity rate set to 0.25.

Results

Thirteen patients were included. One patient experienced dose limiting toxicity (DLT) at dose level 3 (grade 4 hypoglycemia). Maximum tolerated dose was not reached with a recommended dose of 36 Gy/3 having a probability of DLT of 11%. One-year local control was 83% (95% confidence interval 61–100) and 1-year progression-free survival was 28% (95% confidence interval 1–55).

Conclusions

SBRT in combination with pazopanib is well tolerated with good local control and response rates outside the radiation field.

Trial registration

This trial was retrospectively registered on clinicaltrials.gov(NCT02334709) on January 6th, 2015.

Electronic supplementary material

The online version of this article (10.1186/s13014-017-0893-x) contains supplementary material, which is available to authorized users.

Radiotherapy for renal cell carcinoma: renaissance of an overlooked approach

Conventional radiotherapy previously had a limited role in the definitive treatment of renal cell carcinoma (RCC), owing to the disappointing outcomes of several trials and the perceived radioresistance of this type of cancer. In this context, radiotherapy has been relegated largely to the palliation of symptoms in patients with metastatic disease, with variable rates of response. Following the availability of newer technologies that enable safe delivery of high-dose radiotherapy, stereotactic ablative radiotherapy (SABR) has become increasingly used in patients with RCC. Preclinical evidence demonstrates that RCC cells are sensitive to ablative doses of radiotherapy (≥8-10 Gy). Trials in the setting of intracranial and extracranial oligometastases, as well as primary RCC, have demonstrated excellent tumour control using this approach. Additionally, an awareness of the capacity of high-dose radiation to stimulate antitumour immunity has resulted in novel combinations of SABR with immunotherapies. Here we describe the historical application of conventional radiotherapy, the current biological understanding of the effects of radiation, and the clinical evidence supporting the use of ablative radiotherapy in RCC. We also explore emerging opportunities to combine systemic targeted agents or immunotherapies with radiation. Radiotherapy, although once an overlooked approach, is moving towards the forefront of RCC treatment.

Role of Radiotherapy in the Treatment of Renal Cell Cancer: Updated and Critical Review

Purpose

The growing incidence of renal cell carcinoma (RCC) raises many questions about the management of these patients. The late clinical presentation, the presence of locally advanced or metastatic disease at diagnosis, the difficulty of radical surgical excision, and radioresistance make it one of the more challenging tumors to treat. The primary objective of this article is to propose an updated and critical review of the role of radiotherapy (RT) in the treatment of RCC.

Methods

This literature review is based on data from meta-analyses and randomized, prospective, and retrospective studies. We collected reports from 1970 to the present about preoperative RT, postoperative RT, stereotactic body RT, radiosurgery, and intraoperative RT in locally advanced renal cancer and in metastatic diseases.

Results

We emphasize the progress made in RT technology that allowed the creation of a more personalized and focused treatment with a minimum rate of complications.

Conclusions

In the coming years, new studies will be published to confirm and increase the indications for use of RT.

Retrospective analysis of stereotactic ablative radiotherapy (SABR) for metastatic lung lesions (MLLs) in comparison with a contemporaneous cohort of primary lung lesions (PLLs)

BACKGROUND

The net benefit from local ablative therapy for pulmonary oligometastases remains unknown. The outcomes of stereotactic ablative radiotherapy (SABR) for metastatic lung lesions (MLLs) were analyzed retrospectively and compared with those of SABR for primary lung lesions (PLLs).

METHODS

Medical records of patients treated with lung SABR between 2011 and 2014 were retrospectively reviewed. Basic patient, lesion and treatment characteristics were compared using the Pearson chi-square test for categorical and Mann-Whitney U test for continuous variables. To estimate the rates of local control (LC), progression-free survival (PFS), survival after the first progression post-SABR (SAPF) and overall survival (OS), the Kaplan-Meier method was used, and the differences between groups were assessed by means of the log rank test. The uni- and multivariate Cox proportional hazards regression model was used to identify predictive factors for these endpoints.

RESULTS

Twenty-nine MLLs in 18 consecutive patients and 51 PLLs in 42 patients were treated stereotactically and included in the study. Median follow-up was 14 months (range, 4-40 months). Although patients with MLLs had a significantly better cardiopulmonary function (P=0.0001), more conservative dose-fractionation schedules were prescribed (P=0.0001), but this did not result in a significant difference in LC (P=0.98), PFS (P=0.06) and OS (P=0.14). Multivariate analysis revealed that the dose per fraction (≥ or <12 Gy) was an independent predictor for LC (P=0.02) and PFS (P=0.01) for the whole population, and for PFS (P=0.02) in the PLLs group. Late toxicities ≥ G2 occurred in six patients with PLLs, compared with none in the metastatic group.

CONCLUSIONS

SABR for MLLs was as successful as for PLLs with respect to LC and OS with lower long-term toxicity in patients with MLLs. Dose per fraction ≥12 Gy turned out to be an independent, favorable prognostic factor.