Is Stereotactic Body Radiotherapy (SBRT) in lymph node oligometastatic patients feasible and effective?

Ablative Radiation Therapy to Restrain Everything Safely Treatable (ARREST): A Phase 1 Study of Stereotactic Ablative Radiation Therapy for Polymetastatic Disease

PURPOSE

This phase 1 study aimed to assess the safety and feasibility of SABR therapy delivery to all sites of polymetastatic disease (>10 metastases).

METHODS AND MATERIALS

A 3 + 3 study design was used with 5 dose levels from 6 Gy (6 Gy × 1) to 30 Gy (6 Gy weekly × 5). Dose-limiting toxicity (DLT) was defined as any grade 4 or 5 toxicity or more than 3 grade 3 toxicities within 6 weeks of treatment. The primary endpoint was the maximal tolerated dose, defined as the dose level where ≥2/6 of patients experienced DLT. Secondary endpoints included quality of life (Functional Assessment of Cancer Therapy - General and European Quality of Life 5 Dimension 5 Level) at 6 weeks posttreatment, progression-free survival, and overall survival.

RESULTS

Thirteen patients were accrued: 12 Gy (n = 3), 18 Gy (n = 3), 24 Gy (n = 4), and 30 Gy (n = 3), and 207 lesions were treated. Nine patients (69%) had acute toxicity: grade 1 (n = 6, 46%), grade 2 (n = 2, 15%; n = 1 pneumonitis and n = 1 fatigue), and grade 3 (n = 1, 7.7% neutropenia). There were no grade 4 or 5 toxicities. Mean ± SD quality of life (Functional Assessment of Cancer Therapy - General and European Quality of Life 5 Dimension 5 Level health state) was 80.4 ± 21.9 and 77.4 ± 20.9 at baseline versus 76.4 ± 21.8 and 68.0 ± 24.2 at 6-week follow-up, respectively (p = .009 and p = .055, respectively). With a median follow-up of 8.7 months posttreatment (IQR, 2.4-24 months), 8 of 13 patients had disease progression (62%). The median and 12-month progression-free survival were 3.6 months and 11.3%, respectively. The median and 12-month overall survival were 13.8 months and 62%, respectively.

CONCLUSIONS

In this phase 1 trial, SABR therapy for polymetastatic disease was technically feasible with acceptable acute toxicity at dose levels up to 30 Gy (6 Gy weekly × 5). DLT was not observed.

Management of head and neck carcinomas with synchronous or metachronous oligometastatic disease: Role of locoregional radiotherapy and metastasis-directed radiotherapy

Head and neck carcinomas are initially metastatic in about 15% of cases. Radiotherapy is a cornerstone in the multimodal strategy at the locoregional phase. In patients with head and neck cancer, often heavily pretreated and with comorbidities, who relapse locoregionally or at distant sites, radiotherapy has also become increasingly important at the metastatic phase. Data on the optimal sequence of systemic treatments and metastasis-directed treatments including stereotactic irradiation are still lacking. Several randomized head and neck trials have been initiated that should provide important answers, including one recent GORTEC trial.

Quality assessment of automatically planned O-Ring linac SBRT plans for pelvic lymph node metastases, finding the optimal minimum target size by comparison with robotic SBRT

PURPOSE

The purpose of this study is to assess the quality of automatic planned O-Ring Halcyon linac SBRT plans for pelvic lymph node metastases and to establish an absolute PTV volume threshold as a plan quality prediction criterion. Compliance of the plans to institutional SBRT plan evaluation criteria and differences in plan quality and treatment delivery times between Halcyon Linac and CyberKnife robotic SBRT were evaluated.

METHODS

Twenty-one CyberKnife treatment plans were replanned for Halcyon. Prescription doses range was 26-40 Gy in mean three fractions. The mean/median planning target volume was 4.0/3.6 cm3 . Institutional criteria for the plan evaluation were: New Conformity Index (NCI), Conformity Index (CI), Modified Gradient Index (MGI), selectivity index reciprocal (PIV/TVPIV ), and the target coverage by prescription isodose (%PIV). Statistical analysis based on the receiver operating characteristic (ROC) curve was used to determine a plan quality predictor threshold of the PTV volume. Comparative analysis of normal tissue complication probabilities (NTCP) was used to assess the risk of toxicity in healthy tissues.

RESULTS

Seventy-one percent (n = 15)/95% (n = 20) of Halcyon and 81% (n = 17)/100% (n = 21) of CK plans fulfilled all ideal/tolerance criteria. For PTVs above a found optimal threshold of 2.6 cm3 (71%, n = 15), no statistically significant difference was observed between the CI, NCI, PIV/TVPIV , and MGI indexes of both groups, while the coverage (%PIV) was statistically but not clinically significantly different between cohorts. Significantly shorter delivery times are expected with Halcyon. No significant differences in NTCP were observed.

CONCLUSION

All but one automatically optimized Halcyon treatment plans demonstrated ideal or acceptable performance. PTV threshold of 2.6 cm3 can be used as decision criteria in clinical settings. The results of our study demonstrated the promising performance of the Halcyon for pelvic SBRT, although plan-specific QA is required to verify machine performance during plan delivery.

Stereotactic body radiotherapy for mediastinal lymph node with CyberKnife®: Efficacy and toxicity

PUPRPOSE

Stereotactic body radiotherapy is more and more used for treatment of oligometastatic mediastinal lymph nodes. The objective of this single-centre study was to evaluate its efficacy in patients with either a locoregional recurrence of a pulmonary or oesophageal cancer or with distant metastases of extrathoracic tumours.

PATIENTS AND METHODS

Patients with oligometastatic mediastinal lymph nodes treated with CyberKnife from June 2010 to September 2020 were screened. The primary endpoint was to assess local progression free survival and induced toxicity. Secondary endpoints were overall survival and progression free survival. The delay before introduction of systemic treatment in the subgroup of patients who did not receive systemic therapy for previous progression was also evaluated.

RESULTS

Fifty patients were included: 15 with a locoregional progression of a thoracic primary tumour (87% pulmonary) and 35 with mediastinal metastasis of especially renal tumour (29%). Median follow-up was 27 months (6-110 months). Local progression free survival at 6, 12 and 18 months was respectively 94, 88 and 72%. The rate of local progression was significantly lower in patients who received 36Gy in six fractions (66% of the cohort) versus other treatment schemes. Two grade 1 acute oesophagitis and one late grade 2 pulmonary fibrosis were described. Overall survival at 12, 18 and 24 months was respectively 94, 85 and 82%. Median progression free survival was 13 months. Twenty-one patients were treated by stereotactic body irradiation alone without previous history of systemic treatment. Among this subgroup, 11 patients (52%) received a systemic treatment following stereotactic body radiotherapy with a median introduction time of 17 months (5-52 months) and 24% did not progress.

CONCLUSION

Stereotactic body irradiation as treatment of oligometastatic mediastinal lymph nodes is a well-tolerated targeted irradiation that leads to a high control rate and delay the introduction of systemic therapy in selected patients.

Clinical Outcomes of Stereotactic Body Radiotherapy (SBRT) for Oligometastatic Patients with Lymph Node Metastases from Gynecological Cancers

BACKGROUND

To evaluate clinical outcomes of stereotactic body radiation therapy (SBRT) as a local treatment for lymph node metastases from gynecological cancers.

METHODS

Between November 2007 and October 2021, we retrospectively analyzed 29 lymph node metastases in 22 oligometastatic/oligoprogressive patients treated with SBRT. The Kaplan-Meier method was used to estimate the rates survival. Univariate analysis for prognostic factors were performed with the log-rank test, and Cox proportional hazards regression was used to estimate hazard ratios (HR).

RESULTS

Median age was 62 years (IQR, 50-80 years). Median follow-up was 17 months (IQR 10.5-31 months). The median survival was 22 months (CI 95%: 4.2-39.7, IQR: 12.5-34.5 months). Six months, one year and two year overall survival (OS) were 96.6%, 85.2%, and 48.7%, respectively. Median local control (LC) was not reached. Six months, 1one year and 2 year were 93.1%, 87.9%, and 79.9%, respectively. Distant metastasis free survival (DMFS) at one year, and two year was 53% and 37.1%, respectively Four patients (18%) experienced acute G1-G2 toxicities. No G3-4 acute toxicity was reported, and no late toxicity was observed.

CONCLUSIONS

SBRT for lymph node recurrence offers excellent in-field tumor control with safe profile and low toxicities. Size, number of oligometastases, and time primary tumor to RT seem to be significant prognostic factors.

Intra-fraction motion of pelvic oligometastases and feasibility of PTV margin reduction using MRI guided adaptive radiotherapy

Purpose

This study assesses the impact of intra-fraction motion and PTV margin size on target coverage for patients undergoing radiation treatment of pelvic oligometastases. Dosimetric sparing of the bowel as a function of the PTV margin is also evaluated.

Materials and methods

Seven patients with pelvic oligometastases previously treated on our MR-linac (35 Gy in 5 fractions) were included in this study. Retrospective adaptive plans were created for each fraction on the daily MRI datasets using PTV margins of 5 mm, 3 mm, and 2 mm. Dosimetric constraint violations and GTV coverage were measured as a function of PTV margin size. The impact of intra-fraction motion on GTV coverage was assessed by tracking the GTV position on the cine MR images acquired during treatment delivery and creating an intra-fraction dose distribution for each IMRT beam. The intra-fraction dose was accumulated for each fraction to determine the total dose delivered to the target for each PTV size.

Results

All OAR constraints were achieved in 85.7%, 94.3%, and 100.0% of fractions when using 5 mm, 3 mm, and 2 mm PTV margins while scaling to 95% PTV coverage. Compared to plans with a 5 mm PTV margin, there was a 27.4 ± 12.3% (4.0 ± 2.2 Gy) and an 18.5 ± 7.3% (2.7 ± 1.4 Gy) reduction in the bowel D_0.5cc dose for 2 mm and 3 mm PTV margins, respectively. The target dose (GTV V_{35 Gy}) was on average 100.0 ± 0.1% (99.6 - 100%), 99.6 ± 1.0% (97.2 - 100%), and 99.0 ± 1.4% (95.0 - 100%), among all fractions for the 5 mm, 3 mm, and 2 mm PTV margins on the adaptive plans when accounting for intra-fraction motion, respectively.

Conclusion

A 2 mm PTV margin achieved a minimum of 95% GTV coverage while reducing the dose to the bowel for all patients.

Multi-Institutional Outcomes of Stereotactic Magnetic Resonance Image-Guided Adaptive Radiation Therapy (SMART) with a Median Biologically Effective Dose of 100 Gy10 for Non-Bone Oligometastases

Purpose

Randomized data show a survival benefit of stereotactic ablative body radiation therapy in selected patients with oligometastases (OM). Stereotactic magnetic resonance guided adaptive radiation therapy (SMART) may facilitate the delivery of ablative dose for OM lesions, especially those adjacent to historically dose-limiting organs at risk, where conventional approaches preclude ablative dosing.

Methods and Materials

The RSSearch Registry was queried for OM patients (1-5 metastatic lesions) treated with SMART. Freedom from local progression (FFLP), freedom from distant progression (FFDP), progression-free survival (PFS), and overall survival (LS) were estimated using the Kaplan-Meier method. FFLP was evaluated using RECIST 1.1 criteria. Toxicity was evaluated using Common Terminology Criteria for Adverse Events version 4 criteria.

Results

Ninety-six patients with 108 OM lesions were treated on a 0.35 T MR Linac at 2 institutions between 2018 and 2020. SMART was delivered to mostly abdominal or pelvic lymph nodes (48.1%), lung (18.5%), liver and intrahepatic bile ducts (16.7%), and adrenal gland (11.1%). The median prescribed radiation therapy dose was 48.5 Gy (range, 30-60 Gy) in 5 fractions (range, 3-15). The median biologically effective dose corrected using an alpha/beta value of 10 was 100 Gy₁₀ (range, 48-180). No acute or late grade 3+ toxicities were observed with median 10 months (range, 3-25) follow-up. Estimated 1-year FFLP, FFDP, PFS, and OS were 92.3%, 41.1%, 39.3%, and 89.6%, respectively. Median FFDP and PFS were 8.9 months (95% confidence interval, 5.2-12.6 months) and 7.6 months (95% confidence interval, 4.5-10.6 months), respectively.

Conclusions

To our knowledge, this represents the largest analysis of SMART using ablative dosing for non-bone OM. A median prescribed biologically effective dose of 100 Gy₁₀ resulted in excellent early FFLP and no significant toxicity, likely facilitated by continuous intrafraction MR visualization, breath hold delivery, and online adaptive replanning. Additional prospective evaluation of dose-escalated SMART for OM is warranted.

Stereotactic body radiotherapy of lymph node metastases under MR-guidance: First clinical results and patient-reported outcomes

Objective

Stereotactic body radiotherapy (SBRT) is a noninvasive treatment option for lymph node metastases (LNM). Magnetic resonance (MR)-guidance offers superior tissue contrast and enables treatment of targets in close vicinity to radiosensitive organs at risk (OAR). However, literature on MR-guided SBRT of LNM is scarce with no report on outcome parameters.

Materials and methods

We report a subgroup analysis of a prospective observational study comprising patients with LNM. Patients received MR-guided SBRT at our MRIdian Linac (ViewRay Inc., Mountain View, CA, USA) between January 2019 and February 2020. Local control (LC), progression-free survival (PFS) and overall survival (OS) analysis were performed using the Kaplan–Meier method with log rank test to test for significance (p < 0.05). Our patient-reported outcome questionnaire was utilized to evaluate patients’ perspective. The CTCAE (Common Terminology Criteria for Adverse Events) v. 5.0 was used to describe toxicity.

Results

Twenty-nine patients (72.4% with prostate cancer; 51.7% with no distant metastases) received MR-guided SBRT for in total 39 LNM. Median dose was 27 Gy in three fractions, prescribed to the 80% isodose. At 1‑year, estimated LC, PFS and OS were 92.6, 67.4 and 100.0%. Compared to baseline, six patients (20.7%) developed new grade I toxicities (mainly fatigue). One grade II toxicity occurred (fatigue), with no adverse event grade ≥III. Overall treatment experience was rated particularly positive, while the technically required low room temperature still represents the greatest obstacle in the pursuit of the ideal patient acceptance.

Conclusion

MR-guided SBRT of LNM was demonstrated to be a well-accepted treatment modality with excellent preliminary results. Future studies should evaluate the clinical superiority to conventional SBRT.

Video online

The online version of this article contains one video. The article and the video are available online (10.1007/s00066-021-01834-w). The video can be found in the article back matter as “Supplementary Information”.

Online Magnetic Resonance-Guided Radiotherapy (oMRgRT) for Gynecological Cancers

Radiation therapy (RT) is increasingly being used in gynecological cancer management. RT delivered with curative or palliative intent can be administered alone or combined with chemotherapy or surgery. Advanced treatment planning and delivery techniques such as intensity-modulated radiation therapy, including volumetric modulated arc therapy, and image-guided adaptive brachytherapy allow for highly conformal radiation dose delivery leading to improved tumor control rates and less treatment toxicity. Quality on-board imaging that provides accurate visualization of target and surrounding organs at risk is a critical feature of these advanced techniques. As soft tissue contrast resolution is superior with magnetic resonance imaging (MRI) compared to other imaging modalities, MRI has been used increasingly to delineate tumor from adjacent soft tissues and organs at risk from initial diagnosis to tumor response evaluation. Gynecological cancers often have poor contrast resolution compared to the surrounding tissues on computed tomography scan, and consequently the benefit of MRI is high. One example is in management of locally advanced cervix cancer where adaptive MRI guidance has been broadly implemented for adaptive brachytherapy. The role of MRI for external beam RT is also steadily increasing. MRI information is being used for treatment planning, predicting, and monitoring position shifts and accounting for tissue deformation and target regression during treatment. The recent clinical introduction of online MRI-guided radiation therapy (oMRgRT) could be the next step in high-precision RT. This technology provides a tool to take full advantage of MRI not only at the time of initial treatment planning but as well as for daily position verification and online plan adaptation. Cervical, endometrial, vaginal, and oligometastatic ovarian cancers are being treated on MRI linear accelerator systems throughout the world. This review summarizes the current state, early experience, ongoing trials, and future directions of oMRgRT in the management of gynecological cancers.

SBRT treatment of abdominal and pelvic oligometastatic lymph nodes using ring-mounted Halcyon Linac

PURPOSE/OBJECTIVES

This work seeks to evaluate the plan quality, treatment delivery efficiency, and accuracy of single-isocenter volumetric modulated arc therapy (VMAT) of abdominal/pelvic oligometastatic lymph nodes (LNs) stereotactic body radiation therapy (SBRT) on Halcyon Linac.

MATERIALS AND METHODS

After completing the in-house multitarget end-to-end phantom testing and independent dose verification using MD Anderson's single-isocenter/multi-target (lung and spine target inserts) thorax phantom, eight patients with two to three abdominal/pelvic oligometastatic LNs underwent highly conformal single-isocenter VMAT-SBRT treatment using the Halcyon Linac 6MV flattening filter free (FFF) beam. Targets were identified using an Axumin PET/CT scan co-registered with planning CT images and a single-isocenter was placed between/among the targets. Doses between 25 and 36.25 Gy in 5 fractions were delivered. Patients were treated every other day. Plans were calculated in Eclipse with advanced AcurosXB algorithm for heterogeneity corrections. For comparison, Halcyon VMAT-SBRT plans were retrospectively generated for SBRT-dedicated TrueBeam with a 6MV-FFF beam using identical planning geometry and objectives. Target coverage, conformity index (CI), dose to 2 cm away from each target (D2cm) and dose to adjacent organs-at-risk (OAR) were evaluated. Additionally, various treatment delivery parameters including beam-on time were recorded.

RESULTS

Phantom measurements showed acceptable spatial accuracy of conebeam CT-guided Halcyon SBRT treatments including compliance with MD Anderson's single-isocenter/multi-targets phantom credentialing results. For patients, the mean isocenter to tumor center distance was 3.4 ± 1.2 cm (range, 1.5-4.8 cm). The mean combined PTV was 18.9 ± 10.9 cc (range, 5.6-39.5 cc). There was no clinically significant difference in dose to LNs, CI, D2cm and maximal doses to OAR between single-isocenter Halcyon and Truebeam VMAT-SBRT plans, although, Halcyon plans provided preferably lower maximal dose to adjacent OAR. Additionally, total monitor units, beam-on time and overall treatment time was lower with Halcyon plans. Halcyon's portal dosimetry demonstrated a high pass rate of 98.1 ± 1.6% for clinical gamma passing criteria of 2%/2 mm.

CONCLUSION

SBRT treatment of abdominal/pelvic oligometastatic LNs with single-isocenter VMAT on Halcyon was dosimetrically equivalent to TrueBeam. Faster treatment delivery to oligometastatic LNs via single-isocenter Halcyon VMAT can improve clinic workflow and patient compliance, potentially reducing intrafraction motion errors for well-suited patients. Clinical follow-up of these patients is ongoing.

Oligometastatic non-small cell lung cancer: Current management

BACKGROUND

In the past decade, major developments have improved the survival of patients with oligometastatic non-small cell lung cancer (NSCLC). About 20% - 50% of patients with NSCLC present with oligometastases at diagnosis. For this group of patients, it seems that an increase in survival would justify aggressive local therapies. The development of minimally invasive surgery and advanced radiotherapy techniques like stereotactic body radiation therapy (SBRT) makes local control possible for selected patients with metastatic NSCLC. The advantage of SBRT over surgery is that it is a non-invasive technique, with minimum side effects, and is more suitable for fragile and elderly patients, non-candidates for surgery, or patients who refuse surgery.

AIM

The purpose of this review is to summarize the latest scientific evidence on the management of oligometastatic NSCLC, focusing on the role of radiotherapy.

RELEVANCE FOR PATIENTS

The initial treatment recommended for patients with oligometastatic NSCLC is systemic therapy. Patients should be considered for radical treatment to both the primary tumor and oligometastases. Aggressive local therapy comprises surgery and/or definitive radiotherapy such as SRS or SBRT, and may be preceded or followed by systemic treatment. Recent clinical evidence from Phase II trials reports benefits in terms of PFS in patients with good performance status and long disease-free periods, with good response to systemic therapy, especially in EGFR wild-type tumors. Phase I and II trials have shown that radiotherapy combined with immunotherapy can improve tumor response rate and possibly overall survival. The recommendation is also to include OM patients in ongoing clinical trials.

Stereotactic Body Radiotherapy for Lymph Node Oligometastases: Real-World Evidence From 90 Consecutive Patients

AIMS

To evaluate the efficacy and toxicity of extracranial stereotactic body radiotherapy (SBRT) in the treatment of oligometastatic lymph node involvement in the mediastinum, retroperitoneum, or pelvis, in a consecutive group of patients from real clinical practice outside clinical trials.

METHODS

A retrospective analysis of 90 patients with a maximum of four oligometastases and various primary tumors (the most common being colorectal cancers). The endpoints were local control of treated metastases (LC), freedom from widespread dissemination (FFWD), progression-free survival (PFS), overall survival (OS), and freedom from systemic treatment (FFST). Acute and delayed toxicities were also evaluated.

RESULTS

The median follow-up after SBRT was 34.9 months. The LC rate at three and five years was 68.4 and 56.3%, respectively. The observed median FFWD was 14.6 months, with a five-year FFWD rate of 33.7%. The median PFS was 9.4 months; the three-year PFS rate was 19.8%. The median FFST was 14.0 months; the five-year FFST rate was 23.5%. The OS rate at three and five years was 61.8 and 39.3%, respectively. Median OS was 53.1 months. The initial dissemination significantly shortened the time to relapse, death, or activation of systemic treatment-LC (HR 4.8, p < 0.001), FFWD (HR 2.8, p = 0.001), PFS (HR 2.1, p = 0.011), FFST (HR 2.4, p = 0.005), OS (HR 2.2, p = 0.034). Patients classified as having radioresistant tumors noticed significantly higher risk in terms of LC (HR 13.8, p = 0.010), FFWD (HR 3.1, p = 0.006), PFS (HR 3.5, p < 0.001), FFST (HR 3.2, p = 0.003). The multivariable analysis detected statistically significantly worse survival outcomes for initially disseminated patients as well as separately in groups divided according to radiosensitivity. No grade III or IV toxicity was reported.

CONCLUSION

Our study shows that targeted SBRT is a very effective and low toxic treatment for oligometastatic lymph node involvement. It can delay the indication of cytotoxic chemotherapy and thus improve and maintain patient quality of life. The aim of further studies should focus on identifying patients who benefit most from SBRT, as well as the correct timing and dosage of SBRT in treatment strategy.

Systematic review of stereotactic body radiotherapy for nodal metastases

The aim of this analysis was to assess the efficacy of stereotactic body radiotherapy (SBRT) in terms of local control (LC) and progression-free survival (PFS) in patients with lymph node metastases (NMs) from solid tumors. A systematic literature search from the earliest date to July 25th, 2019 was performed following PRISMA guidelines. Papers reporting LC and/or PFS of NMs using SBRT (< 10 fractions) were selected. The clinical outcomes rates were pooled by means of a random or fixed-effect model. Twenty-nine studies were eligible (969 patients: 938 (LC) and 698 (PFS)). LC and PFS results were reported in 28 and 18 papers, respectively. Heterogeneity was observed in terms of patient and treatment characteristics. Pooled 2-year LC reported in 11 studies was 79.3% (95%CI, 72.8%-85.7%) with substantial heterogeneity between studies (Q2 test: p = 0.0083; I2 = 57.9%), while pooled 2-year PFS reported in 8 studies was 35.9% (95%CI, 22.1%-49.7%) with very high heterogeneity between studies (Q2 test: p < 0.0001; I2 = 86.1%). Grade ≥ 3 and Grade 5 toxicity rates were 2.0% and 0.2%, respectively. SBRT of NMs seems to be safe and effective in terms of LC. However, due to the marked heterogeneity of the included series, prospective studies are required.

Stereotactic Body Radiation Therapy (SBRT) in Pelvic Lymph Node Oligometastases

The role of stereotactic body radiation therapy (SBRT) in achieving durable local control and palliation of pain in pelvic lymph node oligometastatic disease is not well-studied. We performed a retrospective analysis of 30 patients with 43 pelvic lymph node oligometastases from various primary cancers all but one with non-prostate primaries treated at our institution with SBRT. The median follow-up time was 21 months. The median SBRT dose was 24 Gy in four fractions. The one-, two-, and five-year local control was 74%, 71%, and 70% and one-, two-, and five-year overall survival was 70%, 47%, and 31%. Toxicities were mild with no grade 3 or higher.

Role of high-dose salvage radiotherapy for oligometastases of the localised abdominal/pelvic lymph nodes: a retrospective study

Background

Abdominal/pelvic lymph node (LN) oligometastasis, a pattern of treatment failure, is observed occasionally, and radiotherapy may work as salvage therapy. The optimal prescription dose, however, is yet to be determined. This study assessed the efficacy of high-dose radiotherapy.

Methods

The medical records of 113 patients at 4 institutes were retrospectively analysed who had 1 to 5 abdominal/pelvic LN oligometastases and were treated with definitive radiotherapy between 2008 and 2018. The exclusion criteria included non-epithelial tumours, uncontrolled primary lesions, palliative intent, and re-irradiation. The prescription dose was evaluated by using the equivalent dose in 2 Gy fractions (EQD2). Patients receiving EQD2 ≥ 60 Gy were placed into the high-dose group, and the remaining others the low-dose group. Kaplan-Meier analyses were performed to evaluate overall survival (OS), local control (LC), and progression-free survival (PFS). Univariate log-rank and multivariate Cox proportional hazards model analyses were performed to explore predictive factors. Adverse events were compared between the high-dose and low-dose groups.

Results

The primary tumour sites included the colorectum (n = 28), uterine cervix (n = 27), endometrium (n = 15), and ovaries (n = 10). The rate of 2-year OS was 63.1%, that of LC 59.7%, and that of PFS 19.4%. On multivariate analyses, OS were significantly associated with solitary oligometastasis (hazard ratio [HR]: 0.48, p = 0.02), LC with high-dose radiotherapy (HR: 0.93, p < 0.001), and PFS with long disease-free interval (HR: 0.59, p = 0.01). Whereas high-dose radiotherapy did not significantly improve 2-year OS in the entire cohort (74.8% in the high-dose vs. 52.7% in the low-dose; p = 0.08), it did in the subgroup of solitary oligometastasis (88.8% in the high-dose vs. 56.3% in the low-dose; p = 0.009). As for Late grade ≥ 3 adverse event, ileus was observed in 7 patients (6%) and gastrointestinal bleeding in 4 (4%). No significant association between the irradiation dose and adverse event incidence was found.

Conclusions

As salvage therapy, high-dose radiotherapy was recommendable for oligometastasis in the abdominal/pelvic LNs. For solitary oligometastasis, LC and OS were significantly better in the high-dose group.

Stereobody radiotherapy for nodal recurrences in oligometastatic patients: a pooled analysis from two phase I clinical trials

Stereotactic body radiotherapy (SBRT) has been shown to achieve high local control rates in limited metastatic burden of disease. Few papers reported on the efficacy of SBRT in nodal oligometastases. The primary aim of the present paper was to analyze the treatment outcome in this setting. Data from DESTROY-1 and SRS-DESTROY-2 phase I clinical trials were reviewed and analyzed. These trials were based on a 5 fractions and a single fraction regimens, respectively. End-points of this analysis were toxicity rates, overall response rate (ORR), and local control (LC). Patients treated between December 2003 and January 2018, with any metastatic site, and primary tumor type and histology were included. One hundred-eighty-one patients (M/F: 93/88; median age: 67, range 37-88) treated with SBRT on 253 nodal lesions were analyzed. Initially, the used technique was 3D-CRT (20.9%), while subsequently treatments were delivered by VMAT (79.1%). The total dose to the PTV ranged between 12 Gy/single fraction to 50 Gy/5 fractions. With a median follow-up of 21 months (2-124), no grade 3 acute or late toxicity was recorded. ORR based on functional imaging was 92.5% with a complete response rate of 76%. Two- and three-year actuarial LC were 81.6% and 76.0%, respectively. Our large pooled analysis confirms the efficacy and safety of SBRT/SRS in patients with nodal metastases and identifies clinical and treatment variables able to predict complete response and local control rate.

Efficacy and safety of percutaneous computed tomography-guided high-dose-rate interstitial brachytherapy in treatment of oligometastatic lymph node metastases of retroperitoneal space

Purpose

To assess efficacy, safety, and outcome of computed tomography (CT)-guided high-dose-rate (HDR) interstitial brachytherapy in patients with oligometastatic lymph node metastases of the retroperitoneal space.

Material and methods

24 patients with a total of 47 retroperitoneal lymph node metastases from different primary tumors were treated with CT-guided interstitial brachytherapy using an ¹⁹²Ir source (single fraction irradiation). Every three months after treatment, clinical and imaging follow-up were conducted to evaluate local control and safety.

Results

Median follow-up was 9.6 months (range, 2.9-39.0 months). Local tumor control rate was 95.7%. The median diameter of the gross tumor volume was 2.2 cm (range, 1-8.6 cm), treated with a median D₁₀₀ (minimal enclosing tumor dose) of 14.9 Gy (range, 4.5-20.6 Gy). One severe adverse event (grade three) was recorded.

Cumulative median progression-free survival was 4.2 months (range, 1.4-23.7 months), and cumulative median overall survival after interstitial brachytherapy was 15.9 months (range, 3.8-39.0 months).

Conclusions

CT-guided HDR interstitial brachytherapy is a safe and feasible method for local ablation of oligometastatic lymph node metastases of the retroperitoneal space, and might provide a well-tolerated additional therapeutic option in the multidisciplinary management of selected patients.

Management of oligometastatic non-small cell lung cancer patients: Current controversies and future directions

Oligometastatic non-small cell lung cancer (NSCLC) describes an intermediate stage of NSCLC between localized and widely-disseminated disease. This stage of NSCLC is characterized by a limited number of metastases and a more indolent tumor biology. Currently, the management of oligometastatic NSCLC involves radical treatment (radiotherapy or surgery) that targets the metastatic lesions and the primary tumor to achieve disease control. This approach offers the potential to achieve prolonged survival in patients who, in the past, would have only received palliative measures. The optimal therapeutic strategies for the different scenarios of oligometastatic disease (intracranial vs extracranial disease, synchronous vs metachronous) remain undefined. Given the lack of head-to-head studies comparing radiotherapy to surgery in these patients, the decision to apply surgery or radiotherapy (with or without systemic treatment) must be based on prognostic factors that allow us to classify patients. This classification will allow us to select the most appropriate therapeutic strategy on an individualized basis. In the future, the molecular or microRNA profiles will likely improve the treatment selection process. The objective of the present article is to review the most relevant scientific evidence on the management of patients with oligometastatic NSCLC, focusing on the role of radiotherapy and surgery. We also discuss areas of controversy and future directions.

Hypofractionated Image-Guided Radiation Therapy With Simultaneous-Integrated Boost Technique for Limited Metastases: A Multi-Institutional Analysis

Purpose: To perform a multi-institutional analysis following treatment of limited osseous and/or nodal metastases in patients using a novel hypofractionated image-guided radiotherapy with simultaneous-integrated boost (HIGRT-SIB) technique.

Methods: Consecutive patients treated with HIGRT-SIB for ≤5 active metastases at Duke University Medical Center or Durham Veterans' Affairs Medical Center between 2013 and 2018 were analyzed to determine toxicities and recurrence patterns following treatment. Most patients received 50 Gy to the PTV_boost and 30 Gy to the PTV_elect simultaneously in 10 fractions. High-dose treatment volume recurrence (HDTVR) and low-dose treatment volume recurrence (LDTVR) were defined as recurrences within PTV_boost and PTV_elect, respectively. Marginal recurrence (MR) was defined as recurrence outside PTV_elect, but within the adjacent bone or nodal chain. Distant recurrence (DR) was defined as recurrences not meeting HDTVR, LDTVR, or MR criteria. Freedom from pain recurrence (FFPR) was calculated in patients with painful osseous metastases prior to HIGRT-SIB. Outcome rates were estimated at 12 months using the Kaplan-Meier method.

Results: Forty-two patients met inclusion criteria with 59 sites treated with HIGRT-SIB (53% nodal and 47% osseous). Median time from diagnosis to first metastasis was 31 months and the median age at HIGRT-SIB was 69 years. The most common primary tumors were prostate (36%), gastrointestinal (24%), and lung (24%). Median follow-up was 11 months. One acute grade ≥3 toxicity (febrile neutropenia) occurred after docetaxel administration immediately following HIGRT-SIB. Four patients developed late grade ≥3 toxicities: two ipsilateral vocal cord paralyzes and two vertebral compression fractures. The overall pain response rate was 94% and the estimated FFPR at 12 months was 72%. The estimated 12 month rate of HDTVR, LDTVR, MR, and DR was 3.6, 6.2, 7.6, and 55.8%, respectively. DR preceded MR, HDTVR, or LDTVR in each instance. The estimated 12 month probability of in-field and marginal control was 90.0%.

Conclusion: Targeting areas at high-risk for occult disease with a lower radiation dose, while simultaneously boosting gross disease with HIGRT in patients with limited osseous and/or nodal metastases, has a high rate of treated metastasis control, a low rate of MR, acceptable toxicity, and high rate of pain palliation. Further investigation with prospective trials is warranted.

MR-guidance in clinical reality: current treatment challenges and future perspectives

Magnetic Resonance-guided radiotherapy (MRgRT) marks the beginning of a new era. MR is a versatile and suitable imaging modality for radiotherapy, as it enables direct visualization of the tumor and the surrounding organs at risk. Moreover, MRgRT provides real-time imaging to characterize and eventually track anatomical motion. Nevertheless, the successful translation of new technologies into clinical practice remains challenging. To date, the initial availability of next-generation hybrid MR-linac (MRL) systems is still limited and therefore, the focus of the present preview was on the initial applicability in current clinical practice and on future perspectives of this new technology for different treatment sites.MRgRT can be considered a groundbreaking new technology that is capable of creating new perspectives towards an individualized, patient-oriented planning and treatment approach, especially due to the ability to use daily online adaptation strategies. Furthermore, MRL systems overcome the limitations of conventional image-guided radiotherapy, especially in soft tissue, where target and organs at risk need accurate definition. Nevertheless, some concerns remain regarding the additional time needed to re-optimize dose distributions online, the reliability of the gating and tracking procedures and the interpretation of functional MR imaging markers and their potential changes during the course of treatment. Due to its continuous technological improvement and rapid clinical large-scale application in several anatomical settings, further studies may confirm the potential disruptive role of MRgRT in the evolving oncological environment.

Stereotactic body radiation therapy in patients with hepatocellular carcinoma: A mini-review

Stereotactic body radiation therapy (SBRT) is an emerging treatment for hepatocellular carcinoma. This technique results in excellent local control rates with favorable toxicity profile despite being predominantly used in heavily pretreated patients or those unsuitable for other local therapies. SBRT may be used as a sole treatment or in combination with other local therapies as well as a bridging strategy for patient awaiting liver transplants. This brief review describes current practice of SBRT with respect to radiation technique, patient selection and treatment concepts. It summarizes available evidence from retro- and prospective studies evaluating SBRT alone, SBRT in combination with other treatments and SBRT compared to other local treatment approaches.

Radiotherapy for oligometastatic cancer: a survey among radiation oncologists of Lombardy (AIRO-Lombardy), Italy

AIMS

To evaluate the use of radiotherapy (RT) for oligometastatic cancer (OMC) among radiation oncologists in Lombardy, Italy.

METHODS AND STUDY DESIGN

A survey with 12 items regarding data of 2016 was sent to all 34 Lombardy RT centers. The survey included six general items and six specific items regarding patient/disease/treatment characteristics.

RESULTS

Thirteen centers answered the survey (38%). All centers responded to general items and 12 centers submitted patient/disease/treatment data. General items The majority of centers (8/13) consider OMC if metastases number is less than 5. The most commonly prescribed dose/fraction is 5-10 Gy (8/13) using schedules of 3-5 fractions (11/13). Patient data items A total of 15.681 patients were treated in 2016 with external beam RT in 12 responding centers, and 1.087 patients were treated for OMC (7%). Primary tumor included lung, prostate, breast, colorectal and other malignancies in 33%, 21%, 12%, 9% and 25% of all OMC patients, respectively. Brain, lymph node, lung, bone, liver and others were the most common treated sites (24%, 24%, 22%, 17%, 8% and 5%, respectively). One and more than one metastasis were treated in 75 and 25% of patients, respectively. The vast majority of patients (95%) were treated with image-guided intensity-modulated RT or stereotactic RT.

CONCLUSIONS

Seven percent of all RT patients in Lombardy are treated for OMC. Extreme hypofractionation and high-precision RT are commonly employed. The initiative of multicenter and multidisciplinary collaboration has been undertaken in order to prepare the platform for prospective and/or observational studies in OMC.

Stereotactic Body Radiation Therapy for Oligometastatic Ovarian Cancer: A Step Toward a Drug Holiday

PURPOSE

To evaluate stereotactic body radiation therapy (SBRT) for metachronous oligometastatic ovarian cancer patients in terms of local control, delay of systemic treatment, survival outcomes, and toxicity.

METHODS AND MATERIALS

Retrospective data collection from a single institution was performed. The inclusion criteria were as follows: (1) oligorecurrent or oligoprogressive disease in ovarian cancer patients during or after systemic therapy; (2) surgery or other local therapies not feasible; and (3) relative contraindication to systemic therapy for reasons such as unavailability of additional chemotherapy lines or refusal of the patient. 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. A new systemic therapy regimen was started after an SBRT treatment course in 57 of 109 cases (52.3%). Local progression-free survival, progression-free survival, and overall survival were calculated via the Kaplan-Meier method. The systemic treatment-free interval was calculated in cases without concomitant systemic therapy.

RESULTS

Between May 2012 and December 2016, 82 patients (156 lesions) underwent SBRT with a median dose of 24 Gy in 3 fractions. The median follow-up period was 17.4 months. Patients received a median of 3 systemic therapy regimens prior to SBRT. Concomitant systemic therapy was performed for 29 lesions (18.6%). Among 152 evaluable lesions, a complete radiologic response, partial response, stabilization, and progressive disease were observed in 91 (60%), 26 (17%), 24 (16%), and 11 (7%), respectively. No grade 3 or 4 acute or late toxicities were observed. The median systemic treatment-free interval after SBRT was 7.4 months, and 1 of 3 patients was disease free at 1 year after SBRT. The actuarial 2-year local progression-free survival, progression-free survival, and overall survival rates were 68%, 18%, and 71%, respectively. The pattern of failure was predominantly out of field.

CONCLUSIONS

SBRT for oligometastatic ovarian cancer showed good local control and a good toxicity profile. It might be an appealing alternative to other invasive local therapies to delay systemic therapy in the case of chemorefractory disease or intolerance to systemic agents.

Acute toxicity of the bowel after stereotactic robotic radiotherapy for abdominopelvic oligometastases

AIM

To correlate dose-volume histogram (DVH) parameters with appearance of grade ≥2 acute and late gastrointestinal toxicity of stereotactic body radiotherapy (SBRT) in patients with abdominopelvic solitary or oligometastatic disease outside the liver.

MATERIAL AND METHODS

Acute and late bowel toxicity of 84 abdominopelvic oligometastatic patients was registered. A logistic regression was performed between different DVH parameters and presence of grade ≥2 acute and late toxicity. A Normal Tissue Complication Probability (NTCP) model was built with significant parameters to determine complication probabilities (CP).

RESULTS

Thirteen (15%) of 84 patients experienced of grade ≥2 acute toxicity, while 8 (10%) reported late toxicity complications. A significant relationship was found for EQD2 (V_30Gy, V_40Gy, V_50Gy and V_65Gy) and grade ≥2 acute toxicity. D_max and D2 were not significant. Late grade ≥2 toxicity was not significantly correlated with any DVH parameter. According to our NTCP model for V_40Gy, an irradiated bowel volume of 10 cm³ of V_40Gy resulted in CP of grade ≥2 acute toxicity of less than 10%. Local control was 87% at 2 years and 82% at 5 years. Overall survival was 61% at 2 years and 32% at 5 years.

CONCLUSIONS

After SBRT for abdominopelvic oligometastases, in general, the presence of acute and late toxicity was low. A significant relationship was found for V_30Gy, V_40Gy, V_50Gy and V_65Gy and grade ≥2 acute toxicity. We estimated acute complication probabilities per volume of irradiated bowel by V_40Gy and V_50Gy.

Stereotactic Radiotherapy for Oligometastases in Lymph Nodes-A Review

In recent years, the concept of oligometastases has become accepted and reports on stereotactic body radiotherapy as a treatment method have been published. Lesions in the brain, lung, and liver have been reported as target lesions. However, lymph node oligometastases could be a good candidate for stereotactic body radiotherapy as well. In this study, the usability of stereotactic body radiotherapy for oligometastases to lymph nodes is assessed by researching for each primary site. As a result, we could consider that stereotactic body radiotherapy could be almost well applied for lymph node oligometastases from the breast, gynecological organs, and prostate. However, doubts remain concerning the usefulness of stereotactic body radiotherapy for cervical node metastases from head and neck cancer or for mediastinal node metastases from lung or esophageal cancer since late toxicities have occurred with a large radiation dose at hypofractionation to major vessels or the central respiratory tract, especially in patients with irradiation histories. In addition, high-dose irradiation is required to control lymph node metastases from colorectal cancer due to its radioresistance, and severe late adverse events would therefore occur in adjacent organs such as the gastrointestinal tract. In cases of lymph node oligometastases with a primary tumor in the stomach or esophagus, stereotactic body radiotherapy should be used limitedly at present because this patient population is not so large and these metastases are often located close to organs at risk. Because of the varied status of recurrence and varied conditions of patients, it is difficult to determine the optimal dose for tumor control. It might be reasonable to determine the treatment dose individually based on dose constraints of adjacent organs. The oligometastatic state is becoming more frequently identified with more sensitive methods of detecting such oligometastases. In addition, there seems to be another type of oligometastases, so-called induced oligometastases, following successful systemic treatment. To determine the optimal indication of stereotactic body radiotherapy for lymph node oligometastases, further investigation about the mechanisms of oligometastases and further clinical studies including a phase III study are needed.

Institutional analysis of stereotactic body radiotherapy (SBRT) for oligometastatic lymph node metastases

BACKGROUND

In limited metastatic burden of disease, stereotactic body radiotherapy (SBRT) has been shown to achieve high local control rates. It has been hypothesized that SBRT may translate to a better quality of life by delaying the need for systemic chemotherapy and possibly increasing survival. There is limited published literature on the efficacy of SBRT in limited nodal metastases. The primary aim is to review institutional outcomes of patients with solitary or oligometastatic lymph nodes treated with SBRT.

METHODS

A retrospective study of patients treated with SBRT to metastatic lymph nodes (March 2010-June 2015) was conducted. Endpoints of this study were local control (LC), chemotherapy-free survival (CFS) following SBRT, toxicities, progression free survival (PFS), and overall survival (OS).

RESULTS

Eighteen patients with a mean age of 65 years underwent SBRT to metastatic lymph nodes. Median follow-up was 33.6 months. There were four hepatocellular carcinoma, seven colorectal, four pancreatic, one esophageal, one gallbladder and one lung primary. Eleven (61%) patients had lymph node metastases at initial presentation of metastatic disease. Seven patients (39%) had systemic therapy prior to SBRT, with five patients receiving two lines of chemotherapy. Eight patients had solitary metastatic disease at the time of radiotherapy. All patients had <5 metastases. Median size of lymph node metastases was 1.95 cm (range: 0.8-6.2 cm). RT doses were 31 to 60 Gy in four to ten fractions, with 44% of patients receiving 35 Gy in 5 fractions. At 1 year, LC was 94% and CFS from SBRT was 60%. One-year PFS and OS were 39% and 89% respectively. There were no grade 3 or higher toxicities.

CONCLUSIONS

In this single institution study, SBRT to oligometastatic lymph nodes provided excellent LC and a moderate chemotherapy-free interval with minimal toxicities. Disease progression remains prominent in these patients and larger studies are warranted to identify those who benefit most from SBRT.

Clinical Outcomes of 130 Patients with Primary and Secondary Lung Tumors treated with Cyberknife Robotic Stereotactic Body Radiotherapy

Background

Authors report clinical outcomes of patients treated with robotic stereotactic body radiotherapy (SBRT) for primary, recurrent and metastatic lung lesions.

Patients and methods

130 patients with 160 lesions were treated with Cyberknife SBRT, including T1-3 primary lung cancers (54%), recurrent tumors (22%) and pulmonary metastases (24%). The mean biologically equivalent dose (BED_10Gy) was 151 Gy (72–180 Gy). Median prescribed dose for peripheral and central lesions was 3×20 Gy and 3×15 Gy, respectively. Local control (LC), overall survival (OS), and cause-specific survival (CSS) rates, early and late toxicities are reported. Statistical analysis was performed to identify factors influencing local tumor control.

Results

Median follow-up time was 21 months. In univariate analysis, higher dose was associated with better LC and a cut-off value was detected at BED_10Gy ≤ 112.5 Gy, resulting in 1-, 2-, and 3-year actuarial LC rates of 93%, vs 73%, 80% vs 61%, and 63% vs 54%, for the high and low dose groups, respectively (p = 0.0061, HR = 0.384). In multivariate analysis, metastatic origin, histological confirmation and larger Planning Target Volume (PTV) were associated with higher risk of local failure. Actuarial OS and CSS rates at 1, 2, and 3 years were 85%, 74% and 62%, and 93%, 89% and 80%, respectively. Acute and late toxicities ≥ Gr 3 were observed in 3 (2%) and 6 patients (5%), respectively.

Conclusions

Our favorable LC and survival rates after robotic SBRT, with low rates of severe toxicities, are coherent with the literature data in this mixed, non-selected study population.

Clinical Outcomes for Stereotactic Ablative Radiotherapy in Oligometastatic and Oligoprogressive Gynecological Malignancies

Objectives

We report single-institution clinical outcomes of women treated with stereotactic ablative radiotherapy (SABR) for oligometastatic or progressive gynecological malignancies.

Materials and Methods

From 2009 to 2015, 47 lesions from 28 patients were treated with SABR and retrospectively analyzed. All patients had oligometastatic (93%) or oligoprogressive (7%) disease. Primary cancer diagnoses were 15 ovarian, 8 endometrial, 2 cervical, 2 vaginal, and 1 uterine carcinosarcoma. Treatment was delivered using a median of 5 fractions to a median total dose of 40 Gy. Targets were grouped by treatment site and assessed for response using Response Evaluation Criteria in Solid Tumors v1.1. Mean biologically effective dose and pre-SABR tumor size were compared with response. Progression-free survival (PFS) was determined using Kaplan-Meier analysis, and toxicity outcomes were graded using Common Terminology Criteria for Adverse Events version 4.03.

Results

Median follow-up was 12.8 months. Target locations were 17% liver, 21% lung, 17% paraaortic node, 26% other node, and 19% pelvic soft tissue. After treatment, 34% of targets were stable (SD), 32% had a partial response (PR), 17% had a complete response (CR), and 17% had progressive disease (PD). No failures occurred in lung or nodal targets. Mean ± standard deviation pre-SABR tumor diameter was 24 ± 22 mm. There was a significant difference in mean size between lesions that had a favorable (SD, PR, and CR) versus unfavorable response (PD) (17.2 vs 57.6 mm,P= 0.0044). Lesions that responded favorably were also more likely to have received a higher biologically effective dose (79.0 vs 59.6 Gy,P= 0.027). Median PFS was 10.8 months, and 1 patient experienced grade 3 toxicity.

Conclusions

The SABR is a safe and effective local treatment modality in patients with oligometastatic gynecological disease. Distant progression remains the primary mode of failure in this patient population. In carefully selected patients, a combination of systemic treatment and SABR may offer long-term PFS.

Salvage Stereotactic Body Radiotherapy for Isolated Lymph Node Recurrent Prostate Cancer: Single Institution Series of 94 Consecutive Patients and 124 Lymph Nodes

BACKGROUND

The purpose of the study was to evaluate the prostate serum antigen (PSA) response, local control, progression-free survival (PFS), and toxicity of stereotactic body radiotherapy (SBRT) for lymph node (LN) oligorecurrent prostate cancer.

PATIENTS AND METHODS

Between May 2012 and October 2015, 124 lesions were treated in 94 patients with a median dose of 24 Gy in 3 fractions. Seventy patients were treated for a single lesion and 25 for > 1 lesion. In 34 patients androgen deprivation (AD) was combined with SBRT. We evaluated biochemical response according to PSA level every 3 months after SBRT: a 3-month PSA decrease from pre-SBRT PSA of more than 10% identified responder patients. In case of PSA level increase, imaging was performed to evaluate clinical progression. Toxicity was assessed every 6 to 9 months after SBRT.

RESULTS

Median follow-up was 18.5 months. In 13 patients (14%) Grade 1 to 2 toxicity was reported without any Grade 3 to 4 toxicity. Biochemical response, stabilization, and progression were observed in 64 (68%), 10 (11%), and 20 (21%) of 94 evaluable patients. Clinical progression was observed in 31 patients (33%) after a median time of 8.1 months. In-field progression occurred in 12 lesions (9.7%). Two-year local control and PFS rates were 84% and 30%, respectively. Age older than 75 years correlated with better biochemical response rate. Age older than 75 years, concomitant AD administered up to 12 months, and pelvic LN involvement correlated with longer PFS.

CONCLUSION

SBRT is safe and offers good in-field control. At 2 years after SBRT, 1 of 3 patients is progression-free. Further investigation is warranted to identify patients who benefit most from SBRT and to define the optimal combination with AD.

Spanish Society of Radiation Oncology clinical guidelines for stereotactic body radiation therapy in lymph node oligometastases

Data in the literature support the existence of a state of limited metastases or oligometastases. Favorable outcomes have been observed in selected patients with such oligometastases that are treated with local ablative therapies, which include surgical extirpation, stereotactic body radiation therapy (SBRT), and radiofrequency ablation. The role of SBRT in the setting of lymph node oligometastases is still emerging but the early results for local control are promising. However, the biggest challenge is to identify patients who will benefit from treatment of their oligometastatic disease with local aggressive therapy. Patients are initially categorized based upon examination of the initial biopsy, location, stage, and previous treatments received. Appropriate patient management with SBRT requires an understanding of several clinicopathological features that help to identify several subsets of patients with more responsive tumors and a good tolerance to SBRT. In an effort to incorporate the most recent evidence, here the Spanish Society of Radiation Oncology presents guidelines for using SBRT in lymph node oligometastases.