Definition of stereotactic body radiotherapy: principles and practice for the treatment of stage I non-small cell lung cancer

Cumulative rib fracture risk after stereotactic body radiotherapy in patients with localized non-small cell lung cancer

INTRODUCTION

Rib fracture is a known complication after stereotactic body radiotherapy (SBRT). Patient-related parameters are essential to provide patient-tailored risk estimation, however, their impact on rib fracture is less documented compared to dosimetric parameters. This study aimed to predict the risk of rib fractures in patients with localized non-small cell lung cancer (NSCLC) post-SBRT based on both patient-related and dosimetric parameters with death as a competing risk.

MATERIALS AND METHODS

In total, 602 patients with localized NSCLC treated with SBRT between 2010-2020 at Odense University Hospital, Denmark were included. All patients received SBRT with 45-66 Gray (Gy)/3 fractions. Rib fractures were identified in CT-scans using a word embedding model. The cumulative incidence function was based on cause-specific Cox hazard models with variable selection based on cross-validation model likelihood performed using 50 bootstraps.

RESULTS

In total, 19 % of patients experienced a rib fracture. The cumulative risk of rib fracture increased rapidly from 6-54 months post-SBRT. Female gender, bone density, near max dose to the rib, V30 and V40 to the rib, gross tumor volume, and mean lung dose were significantly associated with rib fracture risk in univariable analysis. The final multi-variable model consisted of V20 and V30 to the rib and mean lung dose.

CONCLUSION

Female gender and low bone density in male patients are significant predictors of rib fracture risk. The final model predicting cumulative rib fracture risk of 19 % in patients with localized NSCLC treated with SBRT contained no patient-related parameters, suggesting that dosimetric parameters are the primary drivers.

Targeted and cytotoxic inhibitors used in the treatment of lung cancers

Lung cancer is the leading cause of cancer deaths in the United States and the world. It is divided into two major types: small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). In the tumor-node-metastasis (TNM) cancer-staging classification system (Stages I/II/III/IV), the severity of neoplastic growth is characterized by the size of the tumor (T1 to T4), the extent of lymph node involvement (N0 to N3), and whether (M1) or not (M0) distant metastasis has occurred. Surgery is the treatment of choice for medically fit patients with Stage I/II NSCLC. Combination chemoradiotherapy and immune checkpoint inhibitor therapy are used across all NSCLC types. Oncogene-addicted tumors with sensitizing EGFR or BRAF mutations or activating ALK, ROS1 or NTRK translocations are treated with their cognate orally active small molecule protein kinase blockers. On the order of 20 % of NSCLCs bear activating mutations in EGFR and are treated with osimertinib and other kinase antagonists. SCLC, which accounts for approximately 15 % of lung cancer cases, is a deadly high-grade neuroendocrine carcinoma with a poor prognosis. Limited-stage SCLC is confined to one hemi-thorax and one radiation port and extensive-stage disease signifies those cancers that do not meet the criteria for limited-stage disease. Local treatment options to control thoracic disease include radiotherapy and surgery. In patients with extensive-stage disease, a platinum agent (cisplatin or carboplatin) combined with etoposide and an anti-PDL1 inhibitor (atezolizumab or durvalumab) for four cycles followed by anti-PDL1 maintenance therapy is the recommended first-line regimen.

The role of ALBI score in patients treated with stereotactic body radiotherapy for locally advanced primary liver tumors: a pooled analysis of two prospective studies

Introduction

To evaluate the outcomes after stereotactic body radiotherapy (SBRT) for locally advanced primary liver cancer.

Materials and methods

Patients with locally advanced liver cancer unsuitable for other loco-regional treatments were treated with SBRT with 50-60 Gy in 3-12 fractions in two consecutive prospective trials.

Results

A total of 83 patients were included, of whom 14 were excluded, leaving 69 evaluable patients with 74 treated lesions. A total of 50 patients had hepatocellular carcinoma (HCC), and 11 patients had cholangiocarcinoma (CCC). Approximately 76% had a Child-Pugh (CP) score of A, while 54% had an albumin-bilirubin (ALBI) score of 1. With a median follow-up of 29 months, the median overall survival (OS) was 11 months, and the progression-free survival (PFS) was 18 months. The ALBI score was an important predictor of overall survival (HR 2.094, p = 0.001), which remained significant also in the multivariate analysis. Patients with an ALBI grade of ≥1 had an OS of 4 months versus 23 months in patients with an ALBI grade of 1 (p ≤ 0.001). The local control at 1 and 2 years was 91%. Thirteen patients developed grade ≥ 3 toxicities, of whom nine patients experienced liver toxicities. Patients with a higher ALBI score had a high risk for developing hepatic failure (OR 6.136, p = 0.006).

Discussion

SBRT is a very effective treatment with low toxicity and should be considered as a local treatment option in patients with HCC and CCC. Patients with a higher ALBI grade are at risk for developing toxicities after SBRT and have a significantly lower survival rate.

LatticeOpt: An automatic tool for planning optimisation of spatially fractionated stereotactic body radiotherapy

PURPOSE

Lattice radiotherapy (LRT) is a three dimensional (3D) implementation of spatially fractionated radiation therapy, based on regular spatial distribution of high dose spheres (vertices) inside the target. Due to tumour shape heterogeneity, finding the best lattice arrangement is not trivial. The aim of this study was to develop the LatticeOpt tool to generate the best lattice structures on clinical cases for treatment planning.

METHODS

Developed in MATLAB, LatticeOpt finds the 3D-spatial configurations that maximize the number of vertices within the gross target volume (GTV). If organs at risk (OARs) are considered, it chooses the solution that minimizes the overlapping volume histograms (OVH). Otherwise, the lattice structure with the minimum Hausdorff distance between vertices and GTV boundary is chosen to avoid unpopulated regions. Different lattice structures were created for 20 patients, with (OVHopt) and without (OVHunopt) OVH minimization. Imported into TPS (Eclipse, Varian), corresponding plans were generated and evaluated in terms of OAR mean and maximum doses, GTV vertex coverage and dose gradients, as well as pre-clinical plan dosimetry.

RESULTS

Plans based on an optimized lattice structure (OVHopt, OVHunopt) had similar dose distributions in terms of vertex coverage and gradient index score. OAR sparing was observed in all patients, with a 4 % and 9 % difference for mean and max dose (both p-values <0.01), respectively. The best vertices dimensions and their relative distances were patient dependent.

CONCLUSIONS

LatticeOpt was able to reduce the time-consuming procedures of LRT, as well as to achieve standardized and reproducible results, useful for multicentre studies.

Stereotactic Body Radiotherapy for Renal Cell Carcinoma-A Review of Use in the Primary, Cytoreductive and Oligometastatic Settings

Renal cell carcinoma (RCC) has been increasing in incidence by around 1.5% per year for several years. However, the mortality rate has been decreasing by 1.6% per year, and this can be attributed to stage migration and improvements in treatment. One treatment modality that has emerged in recent years is stereotactic body radiotherapy (SBRT), which is an advanced radiotherapy technique that allows the delivery of high-dose radiation to the tumor while minimizing doses to the organs at risk. SBRT has developed a role in the treatment of early-stage, oligometastatic and oligoprogressive RCC. In localized disease, phase II trials and meta-analyses have shown that SBRT provides a very high probability of long-term local control with a low risk of severe late toxicity. In oligometastatic (OMD) RCC, the same level of evidence has similarly shown good local control and minimal toxicity. SBRT could also delay the necessity to start or switch systemic treatments. Medical societies have started to incorporate SBRT in their guidelines in the treatment of localized disease and OMD. A possible future role of SBRT involves cytoreduction. It is theorized that SBRT can lower tumor burden and enhance immune-related response, but it cannot be recommended until the results of the phase II trials are published.

Dose prescription for stereotactic body radiotherapy: general and organ-specific consensus statement from the DEGRO/DGMP Working Group Stereotactic Radiotherapy and Radiosurgery

PURPOSE AND OBJECTIVE

To develop expert consensus statements on multiparametric dose prescriptions for stereotactic body radiotherapy (SBRT) aligning with ICRU report 91. These statements serve as a foundational step towards harmonizing current SBRT practices and refining dose prescription and documentation requirements for clinical trial designs.

MATERIALS AND METHODS

Based on the results of a literature review by the working group, a two-tier Delphi consensus process was conducted among 24 physicians and physics experts from three European countries. The degree of consensus was predefined for overarching (OA) and organ-specific (OS) statements (≥ 80%, 60-79%, < 60% for high, intermediate, and poor consensus, respectively). Post-first round statements were refined in a live discussion for the second round of the Delphi process.

RESULTS

Experts consented on a total of 14 OA and 17 OS statements regarding SBRT of primary and secondary lung, liver, pancreatic, adrenal, and kidney tumors regarding dose prescription, target coverage, and organ at risk dose limitations. Degree of consent was ≥ 80% in 79% and 41% of OA and OS statements, respectively, with higher consensus for lung compared to the upper abdomen. In round 2, the degree of consent was ≥ 80 to 100% for OA and 88% in OS statements. No consensus was reached for dose escalation to liver metastases after chemotherapy (47%) or single-fraction SBRT for kidney primaries (13%). In round 2, no statement had 60-79% consensus.

CONCLUSION

In 29 of 31 statements a high consensus was achieved after a two-tier Delphi process and one statement (kidney) was clearly refused. The Delphi process was able to achieve a high degree of consensus for SBRT dose prescription. In summary, clear recommendations for both OA and OS could be defined. This contributes significantly to harmonization of SBRT practice and facilitates dose prescription and reporting in clinical trials investigating SBRT.

Application and dosimetric comparison of surface-guided deep inspiration breath-hold for lung stereotactic body radiotherapy

Respiratory motion management is the crucial challenge for safe and effective application of lung stereotactic body radiotherapy (SBRT). The present study implemented lung SBRT treatment in voluntary deep inspiration breath-hold (DIBH) with surface-guided radiotherapy (SGRT) system and evaluated the geometric and dosimetric benefits of DIBH to organs-at-risk (OARs), aiming to advising the choice between DIBH technology and conventional free breathing 4 dimensions (FB-4D) technology. Five patients of lung SBRT treated in DIBH with SGRT at our institution were retrospectively analyzed. CT scans were acquired in DIBH and FB-4D, treatment plans were generated for both respiratory phases. The geometric and dosimetry of tumor, ipsilateral lung, double lungs and heart were compared between the DIBH and FB-4D treatment plans. In terms of target coverage, utilizing DIBH significantly reduced the mean plan target volume (PTV) by 21.9% (p = 0.09) compared to FB-4D, the conformity index (CI) of DIBH and FB-4D were comparable, but the dose gradient index (DGI) of DIBH was higher. With DIBH expanding lung, the volumes of ipsilateral lung and double lungs were 2535.1 ± 403.0cm3 and 4864.3 ± 900.2cm3, separately, 62.2% (p = 0.009) and 73.1% (p = 0.009) more than volumes of ipsilateral lung (1460.03 ± 146.60cm3) and double lungs (2811.25 ± 603.64cm3) in FB-4D. The heart volume in DIBH was 700.0 ± 146.1cm3, 11.6% (p = 0.021) less than that in FB-4D. As for OARs protection, the mean dose, percent of volume receiving > 20Gy (V20) and percent of volume receiving > 5Gy (V5) of ipsilateral lung in DIBH were significantly lower by 33.2% (p = 0.020), 44.0% (p = 0.022) and 24.5% (p = 0.037) on average, separately. Double lungs also showed significant decrease by 31.1% (p = 0.019), 45.5% (p = 0.024) and 20.9% (p = 0.048) on average for mean dose, V20 and V5 in DIBH. Different from the lung, the mean dose and V5 of heart showed no consistency between DIBH and FB-4D, but lower maximum dose of heart was achieved in DIBH for all patients in this study. Appling lung SBRT in DIBH with SGRT was feasibly performed with high patient compliance. DIBH brought significant dosimetric benefits to lung, however, it caused more or less irradiated heart dose that depend on the patients' individual differences which were unpredictable.

Stereotactic Body Radiation Therapy for Gynecologic Malignancies: A Case-Based Radiosurgery Society Practice Review

PURPOSE

The use of stereotactic body radiation therapy (SBRT) for gynecologic malignancies is controversial. We discuss certain circumstances when highly precise SBRT may be a useful tool to consider in the management of selected patients.

METHODS AND MATERIALS

Case selection included the following scenarios, the first 2 with palliative intent, para-aortic nodal oligorecurrence of ovarian cancer, pelvic sidewall oligorecurrence of cervical cancer, and inoperable endometrial cancer boost after intensity modulated radiation to the pelvis treated with curative intent. Patient characteristics, fractionation, prescription dose, treatment technique, and dose constraints were discussed. Relevant literature to these cases was summarized to provide a framework for treatment of similar patients.

RESULTS

Treatment of gynecologic malignancies with SBRT requires many considerations, including treatment intent, optimal patient selection, fractionation selection, tumor localization, and plan optimization. Although other treatment paradigms including conventionally fractionated radiation therapy and brachytherapy remain the standard-of-care for definitive treatment of gynecologic malignancies, SBRT may have a role in palliative cases or those where high doses are not required due to the unacceptable toxicity that may occur with SBRT.

CONCLUSIONS

A case-based practice review was developed by the Radiosurgery Society to provide a practical guide to the common scenarios noted above affecting patients with gynecologic malignancies.

Stereotactic radiotherapy in the management of oligometastatic and recurrent head and neck cancer: a single-center experience

INTRODUCTION

Oligometastatic disease (OMD) is a metastatic stage that could benefit maximally from local therapies. Patients in this state have a better prognosis relative to those with disseminated metastases. Stereotactic radiotherapy provides a non-invasive ablative tool for primary malignant tumors and metastases.

MATERIALS AND METHODS

We searched our register for patients with oligometastatic or recurrent head and neck cancer (OMD/R-HNC) who received stereotactic radiotherapy to manage their OMD/R. We evaluated the survival outcomes and prognostic factors that affected the survival of those patients.

RESULTS

In all, 31 patients with 48 lesions met the inclusion criteria for the analysis. The lesions comprised various metastatic sites, with the majority being pulmonary (37 lesions). Squamous cell cancer was the most common histology (26 patients). The median overall survival (mOS) was 33 months, with a progression-free survival (PFS) of 9.6 months. Eight patients received subsequent stereotactic radiotherapy after disease progression. The local control (LC) rates were 91.3, 87.7, and 83% at 6, 12, and 36 months. Patients with the de novo OMD who received stereotactic radiotherapy as their initial treatment had a median systemic treatment-free survival of 23.9 months. In univariate analysis, a trend for better OS was observed in patients with p16-positive squamous cell tumors; patients who progressed within 150 days after diagnosis had a significantly lower OS. De novo OMD showed significantly better PFS compared to induced OMD. Multivariate analyses identified p16-positive squamous cell cancer, metachronous OMD and a longer time to progression as positive predictors of OS, while de novo OMD was the only positive predictor for PFS. Treatment-related toxicities were generally mild, with two cases of grade 3 dysphagia reported.

CONCLUSION

Stereotactic radiotherapy demonstrated favorable outcomes in patients with OMD/R-HNC with limited toxicities. Further studies are warranted to validate these findings and optimize treatment strategies for this patient population.

Safety and Efficacy of Moderate-Intensity Stereotactic Body Radiation Therapy for Ultra-Central Lung Tumor

Background and Objectives: Ultra-central (UC) lung tumors are defined as those abutting the proximal bronchial tree. Stereotactic body radiation therapy (SBRT) for UC tumors is difficult because of concerns about severe toxicities. Therefore, we report the safety and efficacy of moderate-intensity SBRT for UC tumors at our institution. Materials and Methods: From January 2017 to May 2021, we treated 20 patients with UC tumors with SBRT at a dose of 45-60 Gy in 10 fractions. The primary endpoints were local control (LC) and overall survival (OS). Results: The median follow-up time was 15.8 months (range: 2.7-53.8 months). Ten of the 20 patients (50.0%) showed a complete response, five (25.0%) had a partial response, two (10.0%) had stable disease, and three (15.0%) showed progressive disease (PD). The response and disease control rates were 75.0% and 85.0%, respectively. Patients with PD showed local progression at median 8.3 months (range: 6.8-19.1 months) after SBRT. One-year and 2-year OS rates were 79.4% and 62.4%, respectively. One-year and 2-year LC rates are 87.1% and 76.2%, respectively. Eight patients died due to a non-radiation therapy related cause. One patient experienced grade 5 massive hemoptysis 6 months after SBRT, resulting in death. One patient experienced grade 2 esophageal pain and two experienced grade 2 radiation pneumonitis. Otherwise, no grade 3 or higher toxicities were reported. Conclusions: Moderate-intensity SBRT offers effective control of UC tumors and is a well-tolerated treatment for such tumors.

Protocol of a phase II study to evaluate the efficacy and safety of deep-inspiration breath-hold daily online adaptive radiotherapy for centrally located lung tumours (PUDDING study)

BACKGROUND

Centrally located lung tumours present a challenge because of their tendency to exhibit symptoms such as airway obstruction, atelectasis, and bleeding. Surgical resection of these tumours often requires sacrificing the lungs, making definitive radiotherapy the preferred alternative to avoid pneumonectomy. However, the proximity of these tumours to mediastinal organs at risk increases the potential for severe adverse events. To mitigate this risk, we propose a dual-method approach: deep inspiration breath-hold (DIBH) radiotherapy combined with adaptive radiotherapy. The aim of this single-centre, single-arm phase II study is to investigate the efficacy and safety of DIBH daily online adaptive radiotherapy.

METHODS

Patients diagnosed with centrally located lung tumours according to the International Association for the Study of Lung Cancer recommendations, are enrolled and subjected to DIBH daily online adaptive radiotherapy. The primary endpoint is the one-year cumulative incidence of grade 3 or more severe adverse events, as classified by the Common Terminology Criteria for Adverse Events (CTCAE v5.0).

DISCUSSION

Delivering definitive radiotherapy for centrally located lung tumours presents a dilemma between ensuring optimal dose coverage for the planning target volume and the associated increased risk of adverse events. DIBH provides measurable dosimetric benefits by increasing the normal lung volume and distancing the tumour from critical mediastinal organs at risk, leading to reduced toxicity. DIBH adaptive radiotherapy has been proposed as an adjunct treatment option for abdominal and pelvic cancers. If the application of DIBH adaptive radiotherapy to centrally located lung tumours proves successful, this approach could shape future phase III trials and offer novel perspectives in lung tumour radiotherapy.

TRIAL REGISTRATION

Registered at the Japan Registry of Clinical Trials (jRCT; https://jrct.niph.go.jp/ ); registration number: jRCT1052230085 ( https://jrct.niph.go.jp/en-latest-detail/jRCT1052230085 ).

And Yet It Moves: Clinical Outcomes and Motion Management in Stereotactic Body Radiation Therapy (SBRT) of Centrally Located Non-Small Cell Lung Cancer (NSCLC): Shedding Light on the Internal Organ at Risk Volume (IRV) Concept

The internal organ at risk volume (IRV) concept might improve toxicity profiles in stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC). We studied (1) clinical aspects in central vs. peripheral tumors, (2) the IRV concept in central tumors, (3) organ motion, and (4) associated normal tissue complication probabilities (NTCPs). We analyzed patients who received SBRT for NSCLC (clinical aspects, n = 78; motion management, n = 35). We found lower biologically effective doses, larger planning target volume sizes, higher lung doses, and worse locoregional control for central vs. peripheral tumors. Organ motion was greater in males and tall patients (bronchial tree), whereas volume changes were lower in patients with a high body mass index (BMI) (esophagus). Applying the IRV concept (retrospectively, without new optimization), we found an absolute increase of >10% in NTCPs for the bronchial tree in three patients. This study emphasizes the need to optimize methods to balance dose escalation with toxicities in central tumors. There is evidence that organ motion/volume changes could be more pronounced in males and tall patients, and less pronounced in patients with higher BMI. Since recent studies have made efforts to further subclassify central tumors to refine treatment, the IRV concept should be considered for optimal risk assessment.

Stereotactic body radiotherapy for early-stage lung cancer: a systematic review on the choice of photon energy and linac flattened/unflattened beams

SBRT is an effective local treatment for patients with early-stage non-small cell lung cancer (NSCLC). This treatment is currently used in patients who have poor lung function or who decline surgery. As SBRT usually has small PTV margins, reducing the beam-on-time (BOT) is beneficial for accurate dose delivery by minimising intrafraction motion as well as improved patient comfort. Removal of the linear accelerator flattening filter can provide a higher dose rate which results in a faster treatment. In addition, the choice of photon energy can also affect the dose distribution to the target and the organs-at-risk (OAR). In this systematic review, studies analysing the choice of various photon beam energies, with a flattening filter or flattening filter free (FFF), were compared for their overall dosimetric benefit in the SBRT treatment for early-stage NSCLC. It was found that FFF treatment delivers a comparatively more conformal dose distribution, as well as a better homogeneity index and conformity index, and typically reduces BOT by between 30 and 50%. The trade-off may be a minor increase in monitor units for FFF treatment found in some studies but not others. Target conformity and OAR sparing, particularly lung doses appear better with 6MV FFF, but 10MV FFF was marginally more advantageous for skin sparing and BOT reduction. The favourable beam modality for clinical use would depend on the individual case, for which tumour size and depth, radiotherapy technique, as well as fractionation scheme need to be taken into account.

Role of Stereotactic Body Radiation Therapy in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC)is a common type of liver cancer with a poor prognosis, especially in patients with advanced stages or underlying liver disease. While surgical resection, liver transplantation, and ablation therapies have traditionally been the mainstay of treatment for HCC, radiation therapy has become increasingly recognized as an effective alternative, particularly for those who are not surgical candidates. Stereotactic Body Radiation Therapy (SBRT) is a highly precise form of radiation therapy that delivers very high doses of radiation to the tumor while sparing surrounding healthy tissue. Several studies have reported favorable outcomes with SBRT in HCC treatment. Moreover, SBRT can be used to treat recurrent HCC after prior treatment, offering a potentially curative approach in select cases. While SBRT has demonstrated its efficacy and safety in treating HCC, future studies are needed to further investigate the potential role of SBRT in combination with other treatments for HCC.

Large hepatocellular carcinoma treated with sequential SBRT and immunotherapy with anti-VEGF (Vascular Endothelial Growth Factor) therapy

Managing large solitary hepatocellular carcinoma (HCC) remains challenging as guidelines recommend a palliative approach given the general poor prognosis without accounting for variations in the underlying tumour biology. Surgical resection provides significantly better survival than other modalities for HCC, but only a small proportion of patients with large tumours qualify for surgical resection. Recently, with technological advances in radiation therapy, stereotactic body radiation therapy (SBRT) has emerged as an alternative treatment option for HCC . In this paper, we present a patient who was diagnosed with a 13 cm HCC with vascular invasion. SBRT was delivered as a locoregional therapy followed by immunotherapy with the outcome of complete pathological response observed on right hemi-hepatectomy.

A prospective study of immune responses in patients with lung metastases treated with stereotactic body radiotherapy with or without concurrent systemic treatment

We prospectively evaluated the effects of stereotactic body radiotherapy (SBRT) on circulating immune cells. Patients with oligo-metastatic and oligo-progressive pulmonary lesions were treated with SBRT with (cSBRT) or without (SBRT group) concurrent systemic treatment (chemotherapy or immune checkpoint blockade) using different fractionation regimes. Immunoprofiling of peripheral blood cells was performed at baseline, during, at the end of SBRT, and at the first and second follow-ups. The study accrued 100 patients (80 with evaluable samples). The proportion of proliferating CD8+ T-cells significantly increased after treatment. This increase remained significant at follow-up in the SBRT group, but not in the cSBRT group and was not detected with doses of >10Gy per fraction indicating that lower doses are necessary to increase proliferating T-cells' frequency. We detected no favorable impact of concurrent systemic treatment on systemic immune responses. The optimal timing of systemic treatment may be post-SBRT to leverage the immune-modulating effects of SBRT.

Novel combination of GammaTile cesium-131 brachytherapy with 5-aminolevulinic acid fluorescence-guided resection in the re-irradiation of pediatric recurrent high-grade glioma: illustrative case

BACKGROUND

Herein, the authors describe the successful utilization of 5-aminolevulinic acid (5-ALA) and the first case of GammaTile cesium-131 therapy in a pediatric patient with recurrent high-grade glioma. 5-ALA was utilized to optimize gross-total resection prior to GammaTile implantation. After conversion to an equivalent dose in 2-Gy fractions (EQD2), a composite was made of the GammaTile dose with the initial external beam radiotherapy. Two hypothetical plans consisting of a standard hypofractionated strategy for glioma reirradiation and a CyberKnife plan using GammaTile's planning target volume were developed and likewise underwent EQD2 conversion and composite plan generation with the initial radiotherapy.

OBSERVATIONS

5-ALA was useful in achieving gross-total resection with no acute toxicity from the surgery or GammaTile irradiation. When compared with the hypothetical composite doses, GammaTile's composite, axium point dose (D0.03cc) to the brainstem was 32.9 Gy less than the hypofractionated and the CyberKnife composite plans at 38.7 Gy and 40.2 Gy, respectively. The right hippocampus demonstrated a substantially reduced composite plan dose with GammaTile with a D0.03cc of 62.4 Gy versus 71.7 and 80.7 Gy for the hypofractionated and CyberKnife composite plans, respectively.

LESSONS

Utilization of 5-ALA and GammaTile therapy yielded clinically superior tumor debulking and effective radiotherapy dose localization with sparing of organs at risk, respectively.

Advancements of radiotherapy for recurrent head and neck cancer in modern era

Head and neck cancer is a kind of cancer which can be eradicated from radical radiation therapy. However, with best efforts, nearly 40% patients will experience locoregional recurrence. Locoregional recurrence is the main cause of cancer-related death in head and neck cancers, so local treatments play a key role in improving progression free survival. In the last decades, radiation techniques have been tremendously developed, highly conformal radiation techniques such as intensity-modulated radiotherapy, stereotactic body radiation therapy, brachytherapy and proton or heavy ion radiation therapy have their unique radiobiological advances. Although reirradiation is widely used in clinical practice, but little is known when comparing the different techniques. In this review, we will provide a comprehensive overview of the role of reirradiation in recurrent head and neck cancers including radiation techniques, patient selection, overall clinical benefits, and toxicities.

[Prevention, Diagnosis, Therapy, and Follow-up of Lung Cancer - Interdisciplinary Guideline of the German Respiratory Society and the German Cancer Society - Abridged Version]

The current S3 Lung Cancer Guidelines are edited with fundamental changes to the previous edition based on the dynamic influx of information to this field:The recommendations include de novo a mandatory case presentation for all patients with lung cancer in a multidisciplinary tumor board before initiation of treatment, furthermore CT-Screening for asymptomatic patients at risk (after federal approval), recommendations for incidental lung nodule management , molecular testing of all NSCLC independent of subtypes, EGFR-mutations in resectable early stage lung cancer in relapsed or recurrent disease, adjuvant TKI-therapy in the presence of common EGFR-mutations, adjuvant consolidation treatment with checkpoint inhibitors in resected lung cancer with PD-L1 ≥ 50%, obligatory evaluation of PD-L1-status, consolidation treatment with checkpoint inhibition after radiochemotherapy in patients with PD-L1-pos. tumor, adjuvant consolidation treatment with checkpoint inhibition in patients withPD-L1 ≥ 50% stage IIIA and treatment options in PD-L1 ≥ 50% tumors independent of PD-L1status and targeted therapy and treatment option immune chemotherapy in first line SCLC patients.Based on the current dynamic status of information in this field and the turnaround time required to implement new options, a transformation to a "living guideline" was proposed.

Optimal timing for local ablative treatment of bone oligometastases in non-small cell lung cancer

Oligometastases is a term commonly used to describe a disease state characterized by a limited number of distant metastases, and represents a transient phase between localized and widespread systemic diseases. This subgroup of stage IV cancer has increased in clinical importance due to the possibility of curative rather than palliative treatment. Among advanced lung cancer patients, 30-40% show bone metastases, and can show complications such as pathological fractures. Many prospective studies have shown efficacy of localized treatment in oligometastatic non-small cell lung cancer (NSCLC) in improving progression-free survival and overall survival. Compared to metastases in other organs, bone metastases are unique in terms of tumor microenvironment and clinical outcomes. Radiotherapy is the most frequently used treatment modality for local ablative treatment for both primary and metastatic lesions. Stereotactic body radiation therapy demonstrated more rapid and effective pain control compared to conventional 3D conformal radiotherapy. Radiotherapy improved outcomes in terms of time-to-skeletal related events skeletal-related events (SRE), hospitalization for SRE, pain relief, and overall survival in patients with bone metastases. Decision on timing of local ablative treatment depends on patient's overall clinical status, treatment goals, potential side effects of each approach, and expected initial responses to systemic anti-cancer treatment.

Comparing Predicted Toxicities between Hypofractionated Proton and Photon Radiotherapy of Liver Cancer Patients with Different Adaptive Schemes

With the availability of MRI linacs, online adaptive intensity modulated radiotherapy (IMRT) has become a treatment option for liver cancer patients, often combined with hypofractionation. Intensity modulated proton therapy (IMPT) has the potential to reduce the dose to healthy tissue, but it is particularly sensitive to changes in the beam path and might therefore benefit from online adaptation. This study compares the normal tissue complication probabilities (NTCPs) for liver and duodenal toxicity for adaptive and non-adaptive IMRT and IMPT treatments of liver cancer patients. Adaptive and non-adaptive IMRT and IMPT plans were optimized to 50 Gy (RBE = 1.1 for IMPT) in five fractions for 10 liver cancer patients, using the original MRI linac images and physician-drawn structures. Three liver NTCP models were used to predict radiation-induced liver disease, an increase in albumin-bilirubin level, and a Child-Pugh score increase of more than 2. Additionally, three duodenal NTCP models were used to predict gastric bleeding, gastrointestinal (GI) toxicity with grades >3, and duodenal toxicity grades 2-4. NTCPs were calculated for adaptive and non-adaptive IMRT and IMPT treatments. In general, IMRT showed higher NTCP values than IMPT and the differences were often significant. However, the differences between adaptive and non-adaptive treatment schemes were not significant, indicating that the NTCP benefit of adaptive treatment regimens is expected to be smaller than the expected difference between IMRT and IMPT.

Evaluation of tumour motion and internal/external correlation in lung SABR

OBJECTIVE

This study aims to analyse lung tumour motion and to investigate the correlation between the internal tumour motion acquired from four-dimensional computed tomography (4DCT) and the motion of an external surrogate.

METHODS

A data set of 363 4DCT images was analysed. Tumours were classified based on their anatomical lobes. The recorded gross tumour volume (GTV) information included the centroid GTV motion in the superior-inferior, anteroposterior and left-right directions, and in three-dimensions (3D). For the internal/external correlation, the RPM surrogate breathing signals of 260 patients were analysed via an in-house script. The external motion was correlated with the 3D centroid motion, and the maximum tumour motion via Spearman's correlation. The effect of tumour volume on the amount of motion was evaluated.

RESULTS

The greatest 3D tumour amplitude was found for tumours located in the lower part of the lung, with a maximum of 26.7 mm. The Spearman's correlation of the internal 3D motion was weak in the upper (r = 0.21) and moderate in the middle (r = 0.51) and the lower (r = 0.52) lobes. There was no obvious difference in the correlation coefficients between the maximum tumour displacement and the centroid motion. No correlation was found between the tumour volume and the magnitude of motion.

CONCLUSION

Our results suggest that tumour location can be a good predictor of its motion. However, tumour size is a poor predictor of the motion.

ADVANCES IN KNOWLEDGE

This knowledge of the distribution of tumour motion throughout the thoracic regions will be valuable to research groups investigating the refinement of motion management strategies.

Local control and survival after stereotactic body radiation therapy of early-stage lung cancer patients in Slovenia

BACKGROUND

Stereotactic body radiation therapy (SBRT) precisely and non-invasively delivers ablative radiation dose to tumors in early-stage lung cancer patients who are not candidates for surgery or refuse it. The aim of research was to evaluate local control, overall survival (OS), local progression free survival (LPFS), distant metastases free survival (DMFS), disease free survival (DFS) and toxicity in early-stage lung cancer patients treated with SBRT in a single tertiary cancer centre.

PATIENTS AND METHODS

We retrospectively evaluated medical records and radiation treatment plan parameters of 228 tumors irradiated in 206 early-stage lung cancer patients between 2016 and 2021 at the Institute of Oncology Ljubljana.

RESULTS

After 25 months of median follow up, 68 of 206 (33%) patients died. Median OS was 46 months (CI 36-56), 1-year, 2-year and 3-year OS were 87%, 74% and 62% and 5-year OS was 31%. A total of 45 disease progressions have been identified in 41 patients. Local progress only was noticed in 5 (2%) patients, systemic progress in 32 (16%) and combined systemic and local in 4 (2%) patients. Local control rate (LCR) at 1 year was 98%, at 2 and 3 years 96% and 95% at 5 years. The 1-, 2- and 3-year LPFS were 98%, 96% and 94%, respectively and 5-year LPFS was 82%. One, 2-, 3- and 5-year DFS were 89%, 81%, 72% and 49%, respectively. Among 28 toxicities recorded only one was Grade 4 (pneumonitis), all others were Grade 1 or 2. No differences in LCR, LPFS, DFS were found in univariate analysis comparing patient, tumor, and treatment characteristics. For OS the only statistically significant difference was found in patients with more than 3 comorbidities compared to those with less comorbidities.

CONCLUSIONS

Early lung cancer treated with SBRT at single tertiary cancer centre showed that LCR, LPFS, DFS, DMFS and OS were comparable to published studies. Patients with many comorbidities had significantly worse overall survival compared to those with less comorbidities. No other significant differences by patient, tumor, or treatment characteristics were found for DMFS, LPFS, and DFS. Toxicity data confirmed that treatment was well tolerated.

The Role of Stereotactic Body Radiation Therapy in the Management of Liver Metastases

The liver is a common site for metastatic spread for various primary tumor histologies. Stereotactic body radiation therapy (SBRT) is a non-invasive treatment technique with broad patient candidacy for the ablation of tumors in the liver and other organs. SBRT involves focused, high-dose radiation therapy delivered in one to several treatments, resulting in high rates of local control. Use of SBRT for ablation of oligometastatic disease has increased in recent years and emerging prospective data have demonstrated improvements in progression free and overall survival in some settings. When delivering SBRT to liver metastases, clinicians must balance the priorities of delivering ablative tumor dosing while respecting dose constraints to surrounding organs at risk (OARs). Motion management techniques are crucial for meeting dose constraints, ensuring low rates of toxicity, maintaining quality of life, and can allow for dose escalation. Advanced radiotherapy delivery approaches including proton therapy, robotic radiotherapy, and real-time MR-guided radiotherapy may further improve the accuracy of liver SBRT. In this article, we review the rationale for oligometastases ablation, the clinical outcomes with liver SBRT, tumor dose and OAR considerations, and evolving strategies to improve liver SBRT delivery.

To fly or not to fly: Stereotactic MR-guided adaptive radiotherapy effectively treats ultracentral lung tumors with favorable long-term outcomes

BACKGROUND

Stereotactic radiotherapy of ultracentral lung tumors (ULT) is challenging as it may cause overdoses to sensitive mediastinal organs with severe complications. We aimed to describe long-term outcomes after stereotactic magnetic resonance (MR)-guided online adaptive radiotherapy (SMART) as an innovative treatment of ULT.

PATIENTS & METHODS

We analyzed 36 patients that received SMART to 40 tumors between 02/2020 - 08/2021 inside prospective databases. ULT were defined by planning target volume (PTV) overlap with the proximal bronchial tree or esophagus. We calculated Kaplan Meier estimates for overall survival (OS) and progression-free survival (PFS), and competing risk estimates for the incidence of tumor progression and treatment-related toxicities. ULT patients (N = 16) were compared to non-ULT patients (N = 20).

RESULTS

Baseline characteristics were similar between ULT and non-ULT, but ULT were larger (median PTV: ULT 54.7 cm³, non-ULT 19.2 cm³). Median follow-up was 23.6 months. ULT and non-ULT showed a similar OS (2-years: ULT 67%, non-ULT 60%, p = 0.7) and PFS (2-years: ULT 37%, non-ULT 34%, p = 0.73). Progressions occurred mainly at distant sites (2-year incidence of distant progression: ULT 63%, non-ULT 61%, p = 0.77), while local tumor control was favorable (2-year incidence of local progression: ULT 7%, non-ULT 0%, p = 0.22). Treatment of ULT led to significantly more toxicities ≥ grade (G) 2 (ULT: 9 (56%), non-ULT: 1 (5%), p = 0.002). Most toxicities were moderate (G2). Two ULT patients developed high-grade toxicities: 1) esophagitis G3 and bronchial bleeding G4 after VEGF treatment, 2) bronchial bleeding G3. Estimated incidence of high-grade toxicities was 19% (3-48%) in ULT, and no treatment-related death occurred.

CONCLUSION

Our small series supports SMART as potentially effective treatment of ULT. SMART with careful fractionation could reduce severe complications, but treatment of ULT remains a high-risk procedure and needs careful benefit-risk-assessment.

Mortality after radiotherapy or surgery in the treatment of early-stage non-small-cell lung cancer: a population-based data analysis in the clinical cancer registry of Brandenburg-Berlin

PURPOSE

Stereotactic body radiotherapy (SBRT) is an established treatment method with favorable toxicity for inoperable early-stage non-small-cell lung cancer (NSCLC) patients. This paper aims to evaluate the importance of SBRT in the treatment of early-stage lung cancer patients compared to surgery as standard of care.

METHODS

The German clinical cancer register of Berlin-Brandenburg was assessed. Cases of lung cancer were considered if they had a TNM stage (clinical or pathological) of T1-T2a and N0/x and M0/x, corresponding to UICC stages I and II. In our analyses, cases diagnosed between 2000 and 2015 were included. We adjusted our models with propensity score matching. We compared patients treated with SBRT or surgery regarding age, Karnofsky performance status (KPS), sex, histological grade, and TNM classification. Further, we assessed the association of cancer-related parameters with mortality; hazard ratios (HR) from Cox proportional hazards models were computed.

RESULTS

A total of 558 patients with UICC stages I and II NSCLC were analyzed. In univariate survival models, we found similar survival rates in patients who underwent radiotherapy compared with surgery (HR 1.2, 95% confidence interval [CI] 0.92-1.56; p = 0.2). Our univariate subgroup analyses of patients > 75 years showed a statistically nonsignificant survival benefit for patients treated with SBRT (HR 0.86, 95% CI 0.54-1.35; p = 0.5). Likewise, in our T1 subanalysis, survival rates were similar between the two treatment groups regarding overall survival (HR 1.12, 95% CI 0.57-2.19; p = 0.7). The availability of histological data might be slightly beneficial in terms of survival (HR 0.89, 95% CI 0.68-1.15; p = 0.4). This effect was also not significant. Regarding the availability of histological status in our subgroup analyses of elderly patients, we could show similar survival rates as well (HR 0.70, 95% CI 0.44-1.23; p = 0.14). T1-staged patients also had a statistically nonsignificant survival benefit if histological grading was available (HR 0.75, 95% CI 0.39-1.44; p = 0.4). Concerning adjusted covariates, better KPS scores were associated with better survival in our matched univariate Cox regression models. Further, higher histological grades and TNM stages were related to a higher mortality risk.

CONCLUSION

Using population-based data, we observed an almost equal survival of patients treated with SBRT compared to surgery in stage I and II lung cancer. The availability of histological status might not be decisive in treatment planning. SBRT is comparable to surgery in terms of survival.

How Stereotactic Radiotherapy Changed the Landscape in Cancer Care

The term “stereotactic body radiotherapy” (SBRT) refers to high-precision radiotherapy techniques using numerous beams converging in a small target volume, allowing the delivery of high doses per fraction (>6–7 Gy) in a very few number of fractions [...]

Systemic immune modulation by stereotactic radiotherapy in early-stage lung cancer

We performed a prospective study of circulating immune cell changes after stereotactic body radiotherapy (SBRT) in 50 early-stage NSCLC patients. We found no significant increase in CD8⁺ cytotoxic T lymphocytes at first follow-up (the primary endpoint) but detected a significant increase in expanding Ki-67⁺CD8⁺ and Ki-67⁺CD4⁺ T-cell fractions in patients treated with 10 Gy or less per fraction. SBRT can induce significant expansion in circulating effector T-cells immediately post-treatment.

Stereotactic Body Radiation Therapy (SBRT) Plus Immune Checkpoint Inhibitors (ICI) in Hepatocellular Carcinoma and Cholangiocarcinoma

The combination of stereotactic body radiation therapy (SBRT) plus immune checkpoint inhibitors (ICI) must be explored to treat advanced primary liver tumors such as hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Limited retrospective reviews and case reports/series suggest this combination can be effective and safe in both cancer types. With ICIs moving into the first line (IMbrave 150, HIMALAYA, and TOPAZ-1) to manage these cancers, identifying a suitable population for this approach is challenging. Patients with macrovascular invasion (MVI)-positive HCC (especially if larger veins are involved) or recurrent HCCs post-locoregional therapies (such as transarterial radioembolization (TARE), transarterial chemoembolization (TACE), or ablation), as well as those ineligible for bevacizumab or tyrosine kinase inhibitors (TKIs), should be the focus of exploring this combination in HCC. Unresectable or oligometastatic CCA patients who cannot tolerate gemcitabine/cisplatin (GC) or those who progressed on GC without durvalumab and do not have targetable mutations could also be considered for this approach. In both HCC and CCA disease groups, SBRT plus ICI can be examined post-ICI as these two modalities act synergistically to enhance anti-tumor activity (based on pre-clinical studies). Large-scale randomized trials are needed to identify the subsets of primary liver cancers suitable for this approach and to clearly define its clinical benefit.

Difference in failure patterns after stereotactic body radiotherapy for lung cancer according to clinical T stage based on 4D computed tomography

PURPOSE

Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage lung cancer. We aimed to examine the differences in failure patterns after SBRT according to the clinical T stage.

METHODS

A total of 120 patients with early-stage lung cancer (T1-3N0M0) who underwent SBRT were analysed. The clinical stage in patients whose tumours were in contact with the chest wall was confirmed using four-dimensional computed tomography (4D-CT). Local failure, regional node metastasis, and distant metastasis were confirmed from clinical charts.

RESULTS

Median follow-up time was 27.5 months (range 7-122) after SBRT. Thirteen patients were restaged from clinical T2 with visceral pleural invasion to T3 with chest wall invasion using 4D-CT analysis. Thirty-seven patients developed recurrences. The median progression-free survival (PFS) and overall survival (OS) were 38.1 and 53.8 months, respectively. The 3‑year PFS and OS rates were 50.7% and 60.3%, respectively. A significant difference was observed in PFS according to the clinical T stage (p = 0.001). No significant differences were observed in OS according to the clinical T stage (p = 0.213). The proportion of locoregional failures relative to distant metastasis decreased with progression from T1 to T3. The pleural dissemination rate was significantly higher in T3 tumours than in T1 and T2 tumours (p = 0.010).

CONCLUSION

Clinical T stage is associated with PFS after SBRT for lung cancer. There were differences in the failure patterns according to T stage. 4D-CT might provide significant information for assessing chest wall invasion associated with unfavourable PFS.

Clinical validation of a semi‐automated segmentation algorithm for target volume definition on planning CT and CBCT in stereotactic body radiotherapy ( SBRT ) for peripheral lung lesions

INTRODUCTION

Stereotactic body radiotherapy (SBRT) is an ablative method for lung malignancies. Here, the definition of the gross target volume (GTV) is subject to interobserver variation. In this study, we aimed to evaluate the interobserver variability during SBRT and its dosimetric impact, as well as to introduce a semi-automated delineation tool for both planning computer tomography (P-CT) and cone beam CT (CBCT) to help to standardise GTV delineation and adaptive volume-change registration.

METHODS

The interobserver variation of GTV manual contours from five physicians was analysed in 15 patients after lung SBRT on free breathing (FB) P-CT (n = 15) and CBCT (n = 90) before and after each fraction. The dosimetric impact from interobserver variations of GTV based on the original treatment plan was analysed. Next, the accuracy of an in-house easy-to-use semi-automated-segmentation algorithm for pulmonary lesions was compared with gold standard contours in FB P-CT and CBCT, as well as 4D P-CT of additional 10 patients.

RESULTS

The interobserver variability in manual contours resulted in violations of dose coverage of the planning target volume (PTV), which, in turn, resulted in compromised tumour control probability in contours from four physicians. The validation of the semi-automated delineation algorithm using thorax phantom led to a highly reliable accuracy in defining GTVs. Comparing the unsupervised auto-contours with the gold standard delineation revealed high equal high concordance for FB P-CT, 4D P-CT and CBCT, with a DSC of 0.83, 0.76 and 0.8, respectively. The supervised use of the semi-automated delineation tool improved its accuracy, with DSCs of 0.86, 0.86 and 0.8 for FB P-CT, 4D P-CT and CBCT, respectively. The use of the algorithm was associated with a significantly shorter working time. The semi-automated delineation tool can accurately register volume changes in CBCTs.

CONCLUSION

The segmentation algorithm provides a reliable, standardised and time-saving alternative for manual delineation in lung SBRT in P-CT and CBCT.

Dosimetric and biological comparisons of single planning and double plannings for bilateral lung cancer SBRT planning based on the Cyber-Knife system

Objective

The aim is to investigate the influence of single planning (Plan S) and double plannings (Plan D) on bilateral lung cancer stereotactic body radiation therapy planning from the perspective of dosimetry and biology respectively. Methods Cases with bilateral lung cancer patients who had undergone SBRT with the Cyber-Knife were enrolled, and a single planning and double plannings were designed in the Multiplan@4.2 treatment planning system equipped with the Cyber-Knife system. The single plan was to optimize the two target volumes in a separate plan, while the dual plan is to optimize two target volumes respectively in two separate plans, then perform dose superposition. Then based on the dosimetric results, the biological parameters were calculated. Thus the quality of SBRT plans for those bilateral lung cancer designed by the two methods were compared and evaluated according to the dosimetric and biological results.

Results

The dose distribution of both planning target volumes and surrounding organs at risk in Plan S and Plan D could meet the clinical prescription requirements. The target conformity index and the new conformity index of PTV were closer to 1 in the Double plannings, and the dose gradient GI in the Plan D was smaller than Plan S. For organs at risks, the doses received by the Plan D were relatively small. In terms of biological models, for the equivalent uniform dose of normal lung tissue, heart and esophagus, the Plan D was 6.51% (P=0.045), 19.8% (P=0.022), 27.08% (P&gt;0.05) lower than Plan S respectively. The results showed that the equivalent uniform dose of normal tissue in the Plan D was lower relative to Plan S.

Conclusions

Dosimetric and biological results show that both the use of Plan D have an advantage of protecting normal tissues, and it was suggested that to design double plannings for bilateral lung cancer stereotactic body radiation therapy planning based on Cyber-Knife in the clinical practice.

Biological and Clinical Aspects of Metastatic Spinal Tumors

Simple Summary

Spine metastases are a common life-threatening complication of advanced-stage malignancies and often result in poor prognosis. Symptomatic spine metastases develop in the course of about 10% of malignant neoplasms. Therefore, it is essential for contemporary medicine to understand metastatic processes in order to find appropriate, targeted therapeutic options. Our literature review aimed to describe the up-to-date knowledge about the molecular pathways and biomarkers engaged in the spine’s metastatic processes. Moreover, we described current data regarding bone-targeted treatment, the emerging targeted therapies, radiotherapy, and immunotherapy used for the treatment of spine metastases. We hope that knowledge comprehensively presented in our review will contribute to the development of novel drugs targeting specific biomarkers and pathways. The more we learn about the molecular aspects of cancer metastasis, the easier it will be to look for treatment methods that will allow us to precisely kill tumor cells.

Abstract

Spine metastases are a common life-threatening complication of advanced-stage malignancies and often result in poor prognosis. Symptomatic spine metastases develop in the course of about 10% of malignant neoplasms. Therefore, it is essential for contemporary medicine to understand metastatic processes in order to find appropriate, targeted therapeutic options. Thanks to continuous research, there appears more and more detailed knowledge about cancer and metastasis, but these transformations are extremely complicated, e.g., due to the complexity of reactions, the variety of places where they occur, or the participation of both tumor cells and host cells in these transitions. The right target points in tumor metastasis mechanisms are still being researched; that will help us in the proper diagnosis as well as in finding the right treatment. In this literature review, we described the current knowledge about the molecular pathways and biomarkers engaged in metastatic processes involving the spine. We also presented a current bone-targeted treatment for spine metastases and the emerging therapies targeting the discussed molecular mechanisms.

Statistical breathing curve sampling to quantify interplay effects of moving lung tumors in a 4D Monte Carlo dose calculation framework

PURPOSE

The interplay between respiratory tumor motion and dose application by intensity modulated radiotherapy (IMRT) techniques can potentially lead to undesirable and non-intuitive deviations from the planned dose distribution. We developed a 4D Monte Carlo (MC) dose recalculation framework featuring statistical breathing curve sampling, to precisely simulate the dose distribution for moving target volumes aiming at a comprehensive assessment of interplay effects.

METHODS

We implemented a dose accumulation tool that enables dose recalculations of arbitrary breathing curves including the actual breathing curve of the patient. This MC dose recalculation framework is based on linac log-files, facilitating a high temporal resolution up to 0.1 s. By statistical analysis of 128 different breathing curves, interplay susceptibility of different treatment parameters was evaluated for an exemplary patient case. To facilitate prospective clinical application in the treatment planning stage, in which patient breathing curves or linac log-files are not available, we derived a log-file free version with breathing curves generated by a random walk approach. Interplay was quantified by standard deviations σ in D_5%, D_50% and D_95%.

RESULTS

Interplay induced dose deviations for single fractions were observed and evaluated for IMRT and volumetric arc therapy (σ_D95% up to 1.3 %) showing a decrease with higher fraction doses and an increase with higher MU rates. Interplay effects for conformal treatment techniques were negligible (σ<0.1%). The log-file free version and the random walk generated breathing curves yielded similar results (deviations in σ< 0.1 %) and can be used as substitutes for interplay assessment.

CONCLUSION

It is feasible to combine statistically sampled breathing curves with MC dose calculations. The universality of the presented framework allows comprehensive assessment of interplay effects in retrospective and prospective clinically relevant scenarios.

Dosimetric effects of respiratory motion during stereotactic body radiation therapy of lung tumors

BACKGROUND

Respiratory-induced lung tumor motion may affect the delivered dose in stereotactic body radiation therapy (SBRT). Previous studies are often based on phantom studies for one specific treatment technique. In this study, the dosimetric effect of tumor motion was quantified in real patient geometries for different modulated treatments and tumor motion amplitudes for lung-SBRT.

MATERIAL AND METHODS

A simulation method using deformable image registrations and 4-dimensional computed tomographies (4DCT) was developed to assess the dosimetric effects of tumor motion. The method was evaluated with ionization chamber and Gafchromic film measurements in a thorax phantom and used to simulate the effect for 15 patients with lung tumors moving 7.3-27.4 mm. Four treatment plans with different complexities were created for each patient and the motion-induced dosimetric effect to the gross tumor volume (GTV) was simulated. The difference between the planned dose to the static tumor and the simulated delivered dose to the moving tumor was quantified for the near minimum (D_98%), near maximum (D_2%) and mean dose (D_mean) to the GTV as well as the largest observed local difference within the GTV (Max_diff).

RESULTS

No correlation was found between the dose differences and the tumor motion amplitude or plan complexity. However, the largest deviations were observed for tumors moving >15.0 mm. The simulated delivered dose was within 2.5% from the planned dose for D_98% (tumors moving <15 mm) and within 3.3% (tumors moving >15 mm). The corresponding values were 1.7% vs. 6.4% (D_2%); 1.7% vs. 2.4% (D_mean) and 8.9% vs. 35.2% (Max_diff). Using less complex treatment techniques minimized Max_diff for tumors moving >15.0 mm.

CONCLUSION

The dosimetric effects of respiratory-induced motion during lung SBRT are patient and plan specific. The magnitude of the dosimetric effect cannot be assessed solely based upon tumor motion amplitude or plan complexity.

Longitudinal in-vivo quantification of tumour microvascular heterogeneity by optical coherence angiography in pre-clinical radiation therapy

Stereotactic body radiotherapy (SBRT) is an emerging cancer treatment due to its logistical and potential therapeutic benefits as compared to conventional radiotherapy. However, its mechanism of action is yet to be fully understood, likely involving the ablation of tumour microvasculature by higher doses per fraction used in SBRT. In this study, we hypothesized that longitudinal imaging and quantification of the vascular architecture may elucidate the relationship between the microvasculature and tumour response kinetics. Pancreatic human tumour xenografts were thus irradiated with single doses of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$10$$\end{document}10, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$20$$\end{document}20 and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$30$$\end{document}30 Gy to simulate the first fraction of a SBRT protocol. Tumour microvascular changes were monitored with optical coherence angiography for up to \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$8$$\end{document}8 weeks following irradiation. The temporal kinetics of two microvascular architectural metrics were studied as a function of time and dose: the diffusion-limited fraction, representing poorly vascularized tissue \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$>150$$\end{document}>150 μm from the nearest detected vessel, and the vascular distribution convexity index, a measure of vessel aggregation at short distances. These biological metrics allowed for dose dependent temporal evaluation of tissue (re)vascularization and vessel aggregation after radiotherapy, showing promise for determining the SBRT dose–response relationship.

The Palliative Care in the Metastatic Spinal Tumors. A Systematic Review on the Radiotherapy and Surgical Perspective

Spine represents the most common site for metastatic disease involvement. Due to the close relationship between the spinal cord and critical structures, therapeutical management of metastatic spinal cord disease remains challenging. Spinal localization can lead to neurological sequelae, which can significantly affect the quality of life in patients with a limited life expectancy. The authors conducted a systematic literature review according to PRISMA guidelines in order to determine the impact of the most updated palliative care on spinal metastases. The initial literature search retrieved 2526 articles, manually screened based on detailed exclusion criteria. Finally, 65 studies met the inclusion criteria and were finally included in the systematic review. In the wide scenario of palliative care, nowadays, recent medical or surgical treatments represent valuable options for ameliorating pain and improving patients QoL in such this condition.

3D Kinect Camera Scheme with Time-Series Deep-Learning Algorithms for Classification and Prediction of Lung Tumor Motility

This paper proposes a time-series deep-learning 3D Kinect camera scheme to classify the respiratory phases with a lung tumor and predict the lung tumor displacement. Specifically, the proposed scheme is driven by two time-series deep-learning algorithmic models: the respiratory-phase classification model and the regression-based prediction model. To assess the performance of the proposed scheme, the classification and prediction models were tested with four categories of datasets: patient-based datasets with regular and irregular breathing patterns; and pseudopatient-based datasets with regular and irregular breathing patterns. In this study, 'pseudopatients' refer to a dynamic thorax phantom with a lung tumor programmed with varying breathing patterns and breaths per minute. The total accuracy of the respiratory-phase classification model was 100%, 100%, 100%, and 92.44% for the four dataset categories, with a corresponding mean squared error (MSE), mean absolute error (MAE), and coefficient of determination (R²) of 1.2-1.6%, 0.65-0.8%, and 0.97-0.98, respectively. The results demonstrate that the time-series deep-learning classification and regression-based prediction models can classify the respiratory phases and predict the lung tumor displacement with high accuracy. Essentially, the novelty of this research lies in the use of a low-cost 3D Kinect camera with time-series deep-learning algorithms in the medical field to efficiently classify the respiratory phase and predict the lung tumor displacement.

Is hepatocellular carcinoma complicated with portal vein tumor thrombosis potentially curable by radiotherapy in the form of stereotactic body radiation therapy?

PURPOSE

The prognosis of hepatocellular carcinoma (HCC) with portal vein tumor thrombosis (PVTT) is dismal. Despite best treatment and care, the patients with this malignancy only showed 2.7-4 months of overall survival. It is debatable whether liver transplantation helps PVTT sufferers. The effectiveness of radiation therapy in treating HCC patients with PVTT should not be undervalued. By limiting the high dosage region to a small planning target volume, stereotactic radiation delivery has shifted toward hypofractionation, limiting the radiation exposure to healthy organs and tissues. Stereotactic body radiotherapy (SBRT) has a local control rate of 75-100%, depending on the treatment. The major limitation in SBRT for hepatocellular carcinoma with PVTT is the paucity of prospective evidence for longer periods beyond the first two years after treatment. More prospective studies/randomized clinical trials with a longer follow-up, larger sample size, and adequate statistical power are the dire need of the present situation to ascertain the curative effect of SBRT as primary therapy for advanced HCC with PVTT.

CONCLUSION

SBRT can improve survival, particularly for patients receiving multidisciplinary treatment. This review sums up our most current understanding of how radiation therapy, notably SBRT, can be used to treat hepatocellular carcinoma when combined with PVTT. Recent research has led us to believe that irradiation in the form of SBRT may cure hepatocellular carcinoma complicated by PVTT.

Does stereotactic body radiation improve outcomes compared to conventional radiation for liver cancer patients?

•

There has been a paradigm shift to SBRT without evidence that these high-dose ultra-low fractions result in improved outcomes.

•

This prospective cohort compares the survival of patients treated with conventional versus SBRT treatments for liver tumours.

•

The SBRT group received an average of 5 fractions, and the conventional group received an average of 17 fractions.

•

397 patients were included. Overall survival was higher for SBRT patients at the 2-year time point (42% vs 27% p = 0.01).

Introduction

Methods

Results

Conclusion

MR-guided adaptive versus ITV-based stereotactic body radiotherapy for hepatic metastases (MAESTRO): a randomized controlled phase II trial

Background

Stereotactic body radiotherapy (SBRT) is an established local treatment method for patients with hepatic oligometastasis or oligoprogression. Liver metastases often occur in close proximity to radiosensitive organs at risk (OARs). This limits the possibility to apply sufficiently high doses needed for optimal local control. Online MR-guided radiotherapy (oMRgRT) is expected to hold potential to improve hepatic SBRT by offering superior soft-tissue contrast for enhanced target identification as well as the benefit of gating and daily real-time adaptive treatment. The MAESTRO trial therefore aims to assess the potential advantages of adaptive, gated MR-guided SBRT compared to conventional SBRT at a standard linac using an ITV (internal target volume) approach.

Methods

This trial is conducted as a prospective, randomized, three-armed phase II study in 82 patients with hepatic metastases (solid malignant tumor, 1–3 hepatic metastases confirmed by magnetic resonance imaging (MRI), maximum diameter of each metastasis ≤ 5 cm (in case of 3 metastases: sum of diameters ≤ 12 cm), age ≥ 18 years, Karnofsky Performance Score ≥ 60%). If a biologically effective dose (BED) ≥ 100 Gy (α/β = 10 Gy) is feasible based on ITV-based planning, patients will be randomized to either MRgRT or ITV-based SBRT. If a lesion cannot be treated with a BED ≥ 100 Gy, the patient will be treated with MRgRT at the highest possible dose. Primary endpoint is the non-inferiority of MRgRT at the MRIdian Linac® system compared to ITV-based SBRT regarding hepatobiliary and gastrointestinal toxicity CTCAE III or higher. Secondary outcomes investigated are local, locoregional (intrahepatic) and distant tumor control, progression-free survival, overall survival, possible increase of BED using MRgRT if the BED is limited with ITV-based SBRT, treatment-related toxicity, quality of life, dosimetric parameters of radiotherapy plans as well as morphological and functional changes in MRI. Potential prognostic biomarkers will also be evaluated.

Discussion

MRgRT is known to be both highly cost- and labor-intensive. The MAESTRO trial aims to provide randomized, higher-level evidence for the dosimetric and possible consecutive clinical benefit of MR-guided, on-table adaptive and gated SBRT for dose escalation in critically located hepatic metastases adjacent to radiosensitive OARs.

Trial registration

The study has been prospectively registered on August 30th, 2021: Clinicaltrials.gov, “Magnetic Resonance-guided Adaptive Stereotactic Body Radiotherapy for Hepatic Metastases (MAESTRO)”, NCT05027711.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-022-02033-2.

Hepatocellular carcinoma effective stereotactic body radiotherapy using Gold Anchor and the Synchrony system: Two case reports and review of literature

BACKGROUND

Radiotherapy for hepatocellular carcinoma (HCC) is considered to have limited efficacy because of treatment intensity considering that the irradiated area includes the liver, which is highly radiosensitive. In this report, we present two cases in which tumor control by surgical resection, radiofrequency ablation, transcatheter arterial chemoembolization (TACE), and lenvatinib administration was difficult, but stereotactic body radiotherapy (SBRT) using the Synchrony system by Radixact™ and Gold Anchor^® (GA) was effective.

CASE SUMMARY

A 60-year-old man had a single 10-cm HCC in the right lobe. Viable lesions remained after TACE, and levels of alpha-fetoprotein and protein induced by vitamin K antagonists II (PIVKA-II) decreased and quickly re-elevated. We performed SBRT with GA. Three weeks after implantation, localized radiotherapy (SBRT; 40 Gy/5 fractions) was performed using the Synchrony system by Radixact™. Four weeks later, the viable lesion had disappeared, and the PIVKA-II levels decreased. A 77-year-old man had a single 12-cm HCC in the right lobe. The patient experienced recurrence after hepatectomy. Further recurrence occurred after TACE, and we performed SBRT with GA. Because of the proximity of the HCC to the gastrointestinal tract, localized radiotherapy (SBRT; 39 Gy/13 fractions) to the HCC was performed 3 wk after implantation using the Synchrony system by Radixact™. Four weeks later, the viable lesion had disappeared on computed tomography, and the PIVKA-Ⅱ levels decreased.

CONCLUSION

SBRT using the Synchrony system and GA can deliver a large dose accurately and safely, and could have a high therapeutic effect.

Optimal and actual rates of Stereotactic Ablative Body Radiotherapy (SABR) utilisation for primary lung cancer in Australia

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Stereotactic Ablative Body Radiotherapy (SABR) plays a major role in the management of early-stage non-small cell lung cancer (NSCLC).

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An evidence-based model is developed to estimate optimal rates of lung SABR utilisation within the Australian population.

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Optimal utilisation rates are compared against actual utilisation rates to evaluate service provision.

Background and purpose

Radiotherapy utilisation rates considerably vary across different countries and service providers, highlighting the need to establish reliable benchmarks against which utilisation rates can be assessed. Here, optimal utilisation rates of Stereotactic Ablative Body Radiotherapy (SABR) for lung cancer are estimated and compared against actual utilisation rates to identify potential shortfalls in service provision.

Materials and Methods

An evidence-based optimal utilisation model was constructed after reviewing practice guidelines and identifying indications for lung SABR based on the best available evidence. The proportions of patients likely to develop each indication were obtained, whenever possible, from Australian population-based studies. Sensitivity analysis was performed to account for variations in epidemiological data. Practice pattern studies were reviewed to obtain actual utilisation rates.

Results

A total of 6% of all lung cancer patients were estimated to optimally require SABR at least once during the course of their illness (95% CI: 4–6%). Optimal utilisation rates were estimated to be 32% for stage I and 10% for stage II NSCLC. Actual utilisation rates for stage I NSCLC varied between 6 and 20%. For patients with inoperable stage I, 27–74% received SABR compared to the estimated optimal rate of 82%.

Conclusion

The estimated optimal SABR utilisation rates for lung cancer can serve as useful benchmarks to highlight gaps in service delivery and help plan for more adequate and efficient provision of care. The model can be easily modified to determine optimal utilisation rates in other populations or updated to reflect any changes in practice guidelines or epidemiological data.

Stereotactic radiotherapy for soft tissue and bone sarcomas: real-world evidence

Introduction:

Selected patients with locally advanced or metastatic soft tissue and bone sarcomas (STBS) may benefit from intensive local treatment, such as stereotactic radiotherapy (SRT). This study aimed to summarize the utilization and outcomes of SRT in STBS and to identify predictive factors for progression and survival.

Materials and methods:

Consecutive patients with advanced STBS who underwent STBS in a sarcoma tertiary center were identified. We collected tumor- and treatment-related factors. Endpoints comprised time to local progression (TTLP), local progression-free survival (LPFS), time to progression, progression-free survival, and overall survival (OS). The Cox proportional-hazards model was used to identify prognostic factors.

Results:

We identified 141 patients who underwent 233 SRTs. Median follow-up was 21 months. Local and distant progression occurred after 19 and 163 SRTs, respectively. SRT for lung metastases was predictive for better TTLP and LPFS (hazard ratio, HR = 0.12, p = 0.007 and HR = 0.42, p = 0.002, respectively). Bone sarcoma (HR for TTLP = 3.18, p = 0.043; HR for LPFS = 1.99, p = 0.028) and lower administered dose (HR for TTLP = 0.98, p = 0.007; HR for LPFS = 0.99, p = 0.012) were predictive for worse TTLP and LPFS. SRT for oligometastases (HR = 0.46, p = 0.021) and lung metastases (HR = 0.55, p = 0.046) was predictive for better OS, whereas diagnosis of bone sarcoma (HR = 2.05, p = 0.029) was predictive for worse OS.

Conclusion:

SRT provides excellent local control in STBS patients without significant toxicity. Patients with oligometastatic disease, lung metastases, and soft tissue sarcomas benefit the most from SRT. The dose escalation moderately enhances local control; however, it does not translate into better survival.

Adaptive MR-Guided Stereotactic Radiotherapy is Beneficial for Ablative Treatment of Lung Tumors in High-Risk Locations

PURPOSE

To explore the benefit of adaptive magnetic resonance-guided stereotactic body radiotherapy (MRgSBRT) for treatment of lung tumors in different locations with a focus on ultracentral lung tumors (ULT).

PATIENTS & METHODS

A prospective cohort of 21 patients with 23 primary and secondary lung tumors was analyzed. Tumors were located peripherally (N = 10), centrally (N = 2) and ultracentrally (N = 11, planning target volume (PTV) overlap with proximal bronchi, esophagus and/or pulmonary artery). All patients received MRgSBRT with gated dose delivery and risk-adapted fractionation. Before each fraction, the baseline plan was recalculated on the anatomy of the day (predicted plan). Plan adaptation was performed in 154/165 fractions (93.3%). Comparison of dose characteristics between predicted and adapted plans employed descriptive statistics and Bayesian linear multilevel models. The posterior distributions resulting from the Bayesian models are presented by the mean together with the corresponding 95% compatibility interval (CI).

RESULTS

Plan adaptation decreased the proportion of fractions with violated planning objectives from 94% (predicted plans) to 17% (adapted plans). In most cases, inadequate PTV coverage was remedied (predicted: 86%, adapted: 13%), corresponding to a moderate increase of PTV coverage (mean +6.3%, 95% CI: [5.3-7.4%]) and biologically effective PTV doses (BED₁₀) (BED_min: +9.0 Gy [6.7-11.3 Gy], BED_mean: +1.4 Gy [0.8-2.1 Gy]). This benefit was smaller in larger tumors (-0.1%/10 cm³ PTV [-0.2 to -0.02%/10 cm³ PTV]) and ULT (-2.0% [-3.1 to -0.9%]). Occurrence of exceeded maximum doses inside the PTV (predicted: 21%, adapted: 4%) and violations of OAR constraints (predicted: 12%, adapted: 1%, OR: 0.14 [0.04-0.44]) was effectively reduced. OAR constraint violations almost exclusively occurred if the PTV had touched the corresponding OAR in the baseline plan (18/19, 95%).

CONCLUSION

Adaptive MRgSBRT is highly recommendable for ablative treatment of lung tumors whose PTV initially contacts a sensitive OAR, such as ULT. Here, plan adaptation protects the OAR while maintaining best-possible PTV coverage.

Planning benchmark study for SBRT of liver metastases: Results of the DEGRO/DGMP working group stereotactic radiotherapy and radiosurgery

PURPOSE

To investigate, if liver SBRT treatment planning can be harmonized across different treatment planning systems, delivery techniques and institutions by using a specific prescription method and to minimize the knowledge gap concerning inter-system and inter-user differences. To provide best practice guidelines for all used techniques.

METHODS

A multiparametric specification of target dose (GTV_D50%, GTV_D0.1cc, GTV_V90%, PTV_V70%) with a prescription dose of GTV_D50% = 3 × 20 Gy and OAR limits were distributed with CTs and structure sets from three liver metastases patients. Thirty-five institutions provided 132 treatment plans using different irradiation techniques. These plans were first analyzed for target and OAR doses. Four different renormalization methods were performed (PTV_Dmin, PTV_D98%, PTV_D2%, PTV_Dmax). The resulting 660 treatments plans were evaluated regarding target doses in order to study the effect of dose renormalization to different prescription methods. A relative scoring system was used for comparisons.

RESULTS

GTV_D50% prescription can be performed in all systems. Treatment plan harmonization was overall successful with standard deviations for D_max, PTV_D98%, GTV_D98% and PTV_Dmean of 1.6 Gy, 3.3 Gy, 1.9 Gy and 1.5 Gy, respectively. Primary analysis showed 55 major deviations from clinical goals in 132 plans, while in only <20% of deviations GTV/PTV dose was traded for meeting OAR limits. GTV_D50% prescription produced the smallest deviation from target planning objectives and between techniques, followed by the PTV_Dmax, PTV_D98%, PTV_D2% and PTV_Dmin prescription. Deviations were significant for all combinations but for the PTV_Dmax prescription compared with GTV_D50% and PTV_D98%. Based on the various dose prescription methods, all systems significantly differed from each other, while GTV_D50% and PTV_D98% prescription showed the least differences between the systems.

CONCLUSIONS

This study showed the feasibility of harmonizing liver SBRT treatment plans across different treatment planning systems and delivery techniques when a sufficient set of clinical goals is given.