A systematic review of outcomes following stereotactic ablative radiotherapy in the treatment of early-stage primary lung cancer

Comparative analysis of delivered and planned doses in target volumes for lung stereotactic ablative radiotherapy

BACKGROUND

Adaptive therapy has been enormously improved based on the art of generating adaptive computed tomography (ACT) from planning CT (PCT) and the on-board image used for the patient setup. Exploiting the ACT, this study evaluated the dose delivered to patients with non-small-cell lung cancer (NSCLC) patients treated with stereotactic ablative radiotherapy (SABR) and derived relationship between the delivered dose and the parameters obtained through the evaluation procedure.

METHODS

SABR treatment records of 72 patients with NSCLC who were prescribed a dose of 60 Gy (Dprescribed) to the 95% volume of the planning target volume (PTV) in four fractions were analysed in this retrospective study; 288 ACTs were generated by rigid and deformable registration of a PCT to a cone-beam computed tomography (CBCT) per fraction. Each ACT was sent to the treatment planning system (TPS) and treated as an individual PCT to calculate the dose. Delivered dose to a patient was estimated by averaging four doses calculated from four ACTs per treatment. Through the process, each ACT provided the geometric parameters, such as mean displacement of the deformed PTV voxels (Warpmean) and Dice similarity coefficient (DSC) from deformation vector field, and dosimetric parameters, e.g. difference of homogeneity index (ΔHI, HI defined as (D2%-D98%)/Dprescribed*100) and mean delivered dose to the PTV (Dmean), obtained from the dose statistics in the TPS. Those parameters were analyzed using multiple linear regression and one-way-ANOVA of SPSS® (version 27).

RESULTS

The prescribed dose was confirmed to be fully delivered to internal target volume (ITV) within maximum difference of 1%, and the difference between the planned and delivered doses to the PTV was agreed within 6% for more than 95% of the ACT cases. Volume changes of the ITV during the treatment course were observed to be minor in comparison of their standard deviations. Multiple linear regression analysis between the obtained parameters and the dose delivered to 95% volume of the PTV (D95%) revealed four PTV parameters [Warpmean, DSC, ΔHI between the PCT and ACT, Dmean] and the PTV D95% to be significantly related with P-values < 0.05. The ACT cases of high ΔHI were caused by higher values of the Warpmean and DSC from the deformable image registration, resulting in lower PTV D95% delivered. The mean values of PTV D95% and Warpmean showed significant differences depending on the lung lobe where the tumour was located.

CONCLUSIONS

Evaluation of the dose delivered to patients with NSCLC treated with SABR using ACTs confirmed that the prescribed dose was accurately delivered to the ITV. However, for the PTV, certain ACT cases characterised by high HI deviations from the original plan demonstrated variations in the delivered dose. These variations may potentially arise from factors such as patient setup during treatment, as suggested by the statistical analyses of the parameters obtained from the dose evaluation process.

Clinical effects of re-evaluating a lung SBRT failure mode and effects analysis in a radiotherapy department

PURPOSE

The increasing complexity of radiation treatments can hinder its clinical success. This study aimed to better understand evolving risks by re-evaluating a Failure Mode and Effects Analysis (FMEA) in lung SBRT.

METHODS

An experienced multidisciplinary team conducted an FMEA and made a reassessment 3 years later. A process map was developed with potential failure modes (FMs) identified. High-risk FMs and their possible causes and corrective actions were determined. The initial FMEA analysis was compared to gain a deeper perspective.

RESULTS

We identified 232 FMs. The high-risk processes were plan approval, target contouring, and patient evaluation. The corrective measures were based on stricter standardization of plan approval, pre-planning peer review, and a supporting pretreatment checklist, which substantially reduced the risk priority number in the revised FMEA. In the FMEA reassessment, we observed that the increased complexity and number of patients receiving lung SBRT conditioned a more substantial presence of human factors and communication errors as causal conditions and a potential wrong dose as a final effect.

CONCLUSIONS

Conducting a lung SBRT FMEA analysis has identified high-risk conditions that have been effectively mitigated in an FMEA reanalysis. Plan approval has shown to be a weak link in the process. The increasing complexity of treatments and patient numbers have shifted causal factors toward human failure and communication errors. The potential of a wrong dose as a final effect augments in this scenario. We propose that digital and artificial intelligence options are needed to mitigate potential errors in high-complexity and high-risk RT scenarios.

The management of stage I Non-Small cell lung cancer (NSCLC) in Ontario: A Population-Based study of patterns of care and Stereotactic Ablative Body radiotherapy (SABR) utilization from 2010 to 2019

BACKGROUND

Stereotactic Ablative Body Radiotherapy (SABR) is the standard of care for medically inoperable patients with Stage I NSCLC. The adoption of SABR and its association with cancer outcomes requires characterization.

AIM

We described the management of biopsy-proven Stage I NSCLC with SABR, surgery, non-SABR curative radiotherapy (RT) and observation in Ontario, Canada, between 2010 and 2019. Temporal and geographic trends in practice and survival outcomes were analyzed.

METHODS

This was a retrospective population-based cohort study conducted by linking electronic radiotherapy (RT) records to a population-based cancer registry.

RESULTS

A total of 12,065 patients were identified, 61.7 % underwent surgery, 17.9 % received SABR, 8.6 % received non-SABR curative RT and 11.7 % were observed. Between 2010 and 2019, the utilization of surgery decreased (63.8 % to 49.9 %, p < 0.0001), while SABR use increased (7.5 % to 24.4 %, p < 0.0001), non-SABR curative RT use increased (6.7 % to 9.6 %, p < 0.0014) and patients observed decreased (14.4 % to 12.0 %, p < 0.0001). Substantial variation in practice exists across Ontario. Two- yr CSS improved for the entire cohort (81.9 % to 85.0 %, p < 0.0001). While there was improvement in 2 yr CSS for surgical patients (92.1 %% to 95.7 %, p < 0.001), survival for patients who received SABR, Non-SABR curative RT and observation remained stable.

CONCLUSION

There has been an increase in SABR utilization and a reduction in surgical utilization with a corresponding increased survival of stage I patients in Ontario between 2010 and 2019. Substantial differences in practice patterns exist across health regions, suggesting the need for strategies to improve access to SABR in many jurisdictions.

Multi-centre evaluation of variation in cumulative dose assessment in reirradiation scenarios

BACKGROUND AND PURPOSE

Safe reirradiation relies on assessment of cumulative doses to organs at risk (OARs) across multiple treatments. Different clinical pathways can result in inconsistent estimates. Here, we quantified the consistency of cumulative dose to OARs across multi-centre clinical pathways.

MATERIAL AND METHODS

We provided DICOM planning CT, structures and doses for two reirradiation cases: head & neck (HN) and lung. Participants followed their standard pathway to assess the cumulative physical and EQD2 doses (with provided α/β values), and submitted DVH metrics and a description of their pathways. Participants could also submit physical dose distributions from Course 1 mapped onto the CT of Course 2 using their best available tools. To assess isolated impact of image registrations, a single observer accumulated each submitted spatially mapped physical dose for every participating centre.

RESULTS

Cumulative dose assessment was performed by 24 participants. Pathways included rigid (n = 15), or deformable (n = 5) image registration-based 3D dose summation, visual inspection of isodose line contours (n = 1), or summation of dose metrics extracted from each course (n = 3). Largest variations were observed in near-maximum cumulative doses (25.4 - 41.8 Gy for HN, 2.4 - 33.8 Gy for lung OARs), with lower variations in volume/dose metrics to large organs. A standardised process involving spatial mapping of the first course dose to the second course CT followed by summation improved consistency for most near-maximum dose metrics in both cases.

CONCLUSION

Large variations highlight the uncertainty in reporting cumulative doses in reirradiation scenarios, with implications for outcome analysis and understanding of published doses. Using a standardised workflow potentially including spatially mapped doses improves consistency in determination of accumulated dose in reirradiation scenarios.

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

The Prehabilitation Radiotherapy Exercise, smoking Habit cessation and Balanced diet Study (PREHABS) protocol to explore the feasibility of embedding behavioural modifications into the clinical pathway for patients undergoing radical radiotherapy for lung cancer

Patients with curable non-surgical lung cancer are often current smokers, have co-existing medical comorbidities and are treated with curative radiotherapy. To maximise the benefits of modern radiotherapy, there is an urgent need to optimise the patient's health to improve survival and quality of life.

METHODS AND ANALYSIS

The Yorkshire Cancer Research-funded Prehabilitation Radiotherapy Exercise, smoking Habit cessation and Balanced diet Study (PREHABS) (L426) is a single-centre prospective feasibility study to assess embedding behavioural changes into the radical radiotherapy pathway of patients with lung cancer. Feasibility will be assessed by measuring acceptability, demand and implementation. The duration of the study is 24 months. PREHABS has two workstreams: the intervention study and the theory of change (ToC) study.Intervention study: PREHABS will commence at the R-IDEAL phase 2 trial (exploratory) based on existing evidence and includes support for smoking cessation, increasing activity and dietary well-being. Patients undergoing radical radiotherapy for lung cancer will be recruited from the oncology department at Leeds Teaching Hospitals NHS Trust (LTHT). ToC study: to maximise the acceptability and adherence to the PREHABS, we will use a ToC approach to qualitatively explore the key barriers and enablers of implementing a tailored programme of 'prehabilitation'. The PREHABS ToC study participants will be recruited from patients with lung cancer undergoing radical radiotherapy and staff from the LTHT oncology department.

ANALYSIS

The primary endpoint analysis will report the number of participants and adherence to the study interventions. Secondary endpoints include continued engagement with study interventions post-treatment. The analysis will focus on descriptive statistics. Thematic analysis of the qualitative data from the ToC study will identify consensus on intervention optimisation and delivery.

ETHICS AND DISSEMINATION

On 12 May 2021, the Cambridge East Ethics Committee granted ethical approval (21/EE/0048). The study is registered in the National Institute for Health and Care Research (NIHR) portfolio. The results will be disseminated through publication in peer-reviewed scientific journals and presented at conferences.

TRIAL REGISTRATION NUMBER

NIHR portfolio 48420.

Survival, Treatment Outcome, and Safety of Multiple and Repeated Courses of Stereotactic Body Radiotherapy for Pulmonary Oligometastases of Head and Neck Squamous Cell Carcinoma

Current literature regarding survival and treatment outcome of SBRT in patients with pulmonary oligometastatic head and neck squamous cell carcinoma (HNSCC) is limited. Additionally, most of the published studies include metastatic lesions deriving also from primaries with histologies other than SCC when investigating the outcome of SBRT. The aim of the present retrospective study is to explore local control (LC) of treated metastases, progression-free survival (PFS), and overall survival (OS) of exclusively pulmonary oligometastatic HNSCC-patients treated with SBRT. Between 2006 and 2021, a total of 46 patients were treated with SBRT for a maximum of four pulmonary oligometastases (PM) concurrently (mean PM per patient = 2.0; range 1 to 6 PM, total of 92). Of these, 17 patients (37.0%) developed new pulmonary metastases after their first SBRT. Repeated courses of SBRT were required once in 15 patients (88.2%) and twice in 2 patients (11.8%). Median follow-up was 17 months (range, 0-109 months). One year after completion of SBRT, LC rate, PFS, and OS were 98.7%, 37.9%, and 79.5%, respectively. After two years, LC rate, PFS, and OS were 98.7%, 28.7%, and 54.9%; as well as 98.7%, 16.7%, and 31.0% after five years. Radiochemotherapy (HR 2.72, p < 0.001) or radiotherapy as primary treatment (HR 8.60; p = 0.003), as well as reduced patient performance status (HR 48.30, p = 0.002), were associated with lower PFS. Inferior OS correlated with poor performance status (HR 198.51, p < 0.001) and surgery followed by radiochemotherapy (HR 4.18, p = 0.032) as primary treatment, as well as radiotherapy alone (HR 7.11, p = 0.020). Treatment of more than one PM is an independent predictor of impaired OS (HR 3.30, p = 0.016). SBRT of HNSCC-derived PMs results in excellent LC rates and encouraging OS rates of 54.9% at two years along with good tolerability (no more than grade 2 toxicities). Favourable outcome and low toxicity also apply to repeated courses of SBRT of newly emerging PMs.

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.

Real-World Results of Stereotactic Body Radiotherapy for 399 Medically Operable Patients with Stage I Histology-Proven Non-Small Cell Lung Cancer

Surgery is the standard treatment for stage I non-small cell lung cancer (NSCLC); however, no clear randomized trial demonstrates its superiority to stereotactic body radiotherapy (SBRT) regarding survival. We aimed to retrospectively evaluate the treatment outcomes of SBRT in operable patients with stage I NSCLC using a large Japanese multi-institutional database to show real-world outcome. Exactly 399 patients (median age 75 years; 262 males and 137 females) with stage I (IA 292, IB 107) histologically proven NSCLC (adenocarcinoma 267, squamous cell carcinoma 96, others 36) treated at 20 institutions were reviewed. SBRT was prescribed at a total dose of 48-70 Gy in 4-10 fractions. The median follow-up period was 38 months. Local progression-free survival rates were 84.2% in all patients and 86.1% in the T1, 78.6% in T2, 89.2% in adenocarcinoma, and 70.5% in squamous cell subgroups. Overall 3-year survival rates were 77.0% in all patients: 90.7% in females, 69.6% in males, and 41.2% in patients with pulmonary interstitial changes. Fatal radiation pneumonitis was observed in two patients, all of whom had pulmonary interstitial changes. This real-world evidence will be useful in shared decision-making for optimal treatment, including SBRT for operable stage I NSCLC, particularly in older patients.

The immunogenic radiation and new players in immunotherapy and targeted therapy for head and neck cancer

Although treatment modalities for head and neck cancer have evolved considerably over the past decades, survival rates have plateaued. The treatment options remained limited to definitive surgery, surgery followed by fractionated radiotherapy with optional chemotherapy, and a definitive combination of fractionated radiotherapy and chemotherapy. Lately, immunotherapy has been introduced as the fourth modality of treatment, mainly administered as a single checkpoint inhibitor for recurrent or metastatic disease. While other regimens and combinations of immunotherapy and targeted therapy are being tested in clinical trials, adapting the appropriate regimens to patients and predicting their outcomes have yet to reach the clinical setting. Radiotherapy is mainly regarded as a means to target cancer cells while minimizing the unwanted peripheral effect. Radiotherapy regimens and fractionation are designed to serve this purpose, while the systemic effect of radiation on the immune response is rarely considered a factor while designing treatment. To bridge this gap, this review will highlight the effect of radiotherapy on the tumor microenvironment locally, and the immune response systemically. We will review the methodology to identify potential targets for therapy in the tumor microenvironment and the scientific basis for combining targeted therapy and radiotherapy. We will describe a current experience in preclinical models to test these combinations and propose how challenges in this realm may be faced. We will review new players in targeted therapy and their utilization to drive immunogenic response against head and neck cancer. We will outline the factors contributing to head and neck cancer heterogeneity and their effect on the response to radiotherapy. We will review in-silico methods to decipher intertumoral and intratumoral heterogeneity and how these algorithms can predict treatment outcomes. We propose that (a) the sequence of surgery, radiotherapy, chemotherapy, and targeted therapy should be designed not only to annul cancer directly, but to prime the immune response. (b) Fractionation of radiotherapy and the extent of the irradiated field should facilitate systemic immunity to develop. (c) New players in targeted therapy should be evaluated in translational studies toward clinical trials. (d) Head and neck cancer treatment should be personalized according to patients and tumor-specific factors.

Stereotactic or Conventional Radiation for Early-Stage Non-small Cell Lung Cancer: A Systematic Review and Meta-Analysis

Stereotactic ablative radiotherapy (SABR) has been increasingly used for the treatment of inoperable early-stage non-small cell lung cancer (NSCLC). It has been shown to provide promising local control (LC) and toxicity in prospective trials. However, randomized trials have shown conflicting results in terms of whether SABR confers an overall survival (OS) advantage compared to conventionally fractionated radiotherapy (CFRT). A systematic review of Medline and Embase (inception to December 2020) was performed on early-stage NSCLC patients randomized to SABR versus CFRT. Two independent reviewers screened titles, abstracts, and manuscripts. A random-effects model was used to estimate treatment effects. Toxicity outcomes were compared by the Cochran-Mantel-Haenszel test. Individual patient data were digitally approximated and pooled as secondary analysis. The literature search identified 1494 studies, and 16 studies were included for full-text review. Two randomized trials were identified, including a total of 203 patients, of which 115 (57%) received SABR, and 88 (43%) received CFRT. The weighted mean age was 74 years and 48% of patients were male. Most patients had T1 cancers (67%). Stereotactic ablative radiotherapy was not associated with a significant improvement in OS (hazard ratio: 0.84; 95% confidence interval (CI) 0.34-2.08, p=0.71). There was no significant difference in LC between SABR and CFRT (relative risk: 0.59; CI 0.28-1.23, p=0.16). Of the commonly reported adverse events, one grade 4 toxicity of dyspnea was reported for SABR, while all others i.e., grade 3 or higher toxicities were similar. Stereotactic ablative radiotherapy demonstrated less esophagitis, dyspnea, and skin reaction of any grade. Despite widespread adoption and extensive single-arm prospective and retrospective studies suggesting its benefit, this systematic review and meta-analysis of randomized trials fail to confirm improvements in LC, OS, and toxicity profile of SABR over CFRT in early NSCLC. This small study is likely underpowered to detect clinically significant differences.

Regional lymph node recurrence after stereotactic body radiation therapy for lung cancer: Patterns of recurrence, treatment approaches, and clinical outcomes (KROG 21-09)

PURPOSE

To present the multi-institutional data on patterns of recurrence, treatment approaches, and clinical outcomes for regional lymph node (LN) recurrence after stereotactic body radiation therapy (SBRT) for primary lung cancer.

MATERIALS AND METHODS

The medical records of 114 patients who experienced regional LN recurrence as the first recurrence after lung SBRT were retrospectively reviewed. Patterns of recurrence were classified as local recurrence, regional recurrence, and distant metastasis. Clinical outcomes including progression-free survival (PFS) and overall survival (OS) were analyzed.

RESULTS

Half of the patients had regional LN recurrence only. The most common simultaneous recurrence was distant metastasis (38.6 %). Common sites of regional recurrence were ipsilateral hilar (47.2 %), ipsilateral upper mediastinal (40.6 %), and subcarinal (42.5 %) LN stations. 24 (21.1 %) patients underwent salvage radiation therapy (RT), and 44 (38.6 %) patients underwent palliative treatment. Better OS was observed in the salvage RT group (p = 0.025). The 1-year PFS and OS rates were 27.7 % and 55.2 %, respectively, with salvage RT, 14.0 % and 39.9 %, respectively, with palliative treatment, and 22.8 % and 26.8 %, respectively, with no additional treatment. Multivariate analysis showed that salvage RT (PFS, HR 0.463, p = 0.050; OS, HR 0.312, p = 0.002), palliative treatment (PFS, HR 0.436, p = 0.013; OS, HR 0.553, p = 0.050), and simultaneous distant metastasis (PFS, HR 2.335, p = 0.005; OS, HR 1.726, p = 0.054) affected clinical outcomes.

CONCLUSION

Many cases of regional LN recurrence are confined to the locoregional area of patients, and appropriate treatment can improve the prognosis of these patients.

Association of Pretreatment Physical and Geriatric Parameters with Treatment Tolerance and Survival in Elderly Patients with Stage I-II Non-Small Cell Lung Cancer: An Evaluation of Usual Care Data

In this study, the association of pretreatment physical and geriatric parameters with treatment tolerance and survival in elderly patients with stage I−II NSCLC was evaluated. Retrospective data for patients aged ≥70 years, diagnosed between 2016 and 2020 with stage I−II NSCLC, and who underwent surgery or stereotactic ablative radiotherapy (SABR) in a large Dutch teaching hospital were retrieved from medical records. Associations of pretreatment physical and geriatric parameters with treatment tolerance and survival were analyzed. Of 160 patients, 49 of 104 (47%) patients who underwent surgery and 21 of 56 (38%) patients who received SABR did not tolerate treatment. In univariable analysis, World Health Organization (WHO) performance status ≥ 2, short nutritional assessment questionnaire score > 1, short physical performance battery score ≤ 9, and geriatric-8 score ≤ 14 were significantly associated with postoperative complications. Forced expiratory volume of one second < 80% of predicted was significantly associated with intolerance of SABR. In multivariable analysis, WHO performance status ≥ 2 and diffusing capacity for carbon monoxide < 80% were significantly associated with decreased overall survival. This is the first study that investigated the association between pretreatment physical and geriatric parameters and treatment outcomes in patients with stage I−II NSCLC. Evaluation of physical and geriatric parameters before treatment initiation seems highly recommended to select patients who might benefit from preventive interventions before and/or during treatment.

Application of real-time MRI-guided linear accelerator in stereotactic ablative body radiotherapy for non-small cell lung cancer: one step forward to precise targeting

PURPOSE

Tumor motion is a major challenge in stereotactic ablative body radiotherapy (SABR) for non-small cell lung cancer (NSCLC), causing excessive irradiation to compensate for this motion. Real-time tumor tracking with a magnetic resonance imaging-guided linear accelerator (MR-Linac) could address this problem. This study aimed to assess the effects and advantages of MR-Linac in SABR for the treatment of lung tumors.

METHODS

Overall, 41 patients with NSCLC treated with SABR using MR-Linac between March 2019 and December 2021 were included. For comparison, 40 patients treated with SABR using computed tomography-based modalities were also enrolled. The SABR dose ranged from 48 to 60 Gy in 3-5 fractions. The primary endpoint was a lower radiation volume compared to CT-based SABR. The secondary endpoint was the local control rate of SABR using the MR-Linac.

RESULTS

The median follow-up time was 19 months (range: 3-105 months). There was no significant difference in the gross tumor volume between the MR and CT groups (7.1 ± 9.3 cm³ vs 8.0 ± 6.8 cm³, p = 0.643), but the planning target volume was significantly smaller in the MR group (20.8 ± 18.8 cm³ vs 34.1 ± 22.9 cm³, p = 0.005). The 1-year local control rates for the MR and CT groups were 92.1 and 75.4%, respectively (p = 0.07), and the 1-year overall survival rates were 87.4 and 87.0%, respectively (p = 0.30).

CONCLUSION

Lung SABR with MR-Linac can reduce the radiation field without compromising the local control rate. Further follow-up is needed to assess the long-term effects.

Role of Consolidative Stereotactic Body Radiation Therapy in Oligoresistant/Oligoprogressive Pulmonary Parenchymal Metastases

Aim

To extend the survival of patients by providing local control of metastases in oligoresistance/oligoprogressive disease.

Methods

We retrospectively evaluated the efficacy of stereotactic body radiotherapy (SBRT) applied to 30 lesions in the lungs of 19 patients who were considered inoperable by the tumor board upon the development of oligoresistance/oligoprogressive lung metastasis while undergoing chemotherapy between January 2016 and December 2017. Each patient had one to five metastases in their lungs. The median SBRT biologic effective dose at α/β of 10 (BED₁₀) was 180.0 (IQR: 115.5–180.0) Gy.

Results

We obtained effective, low-toxicity results. The rates of local control were 89.4%, 84.2%, and 78.9% for the 1st, 2nd, and 3rd years, respectively. The median local control time was 4 (IQR: 3–6) months. The median overall survival (OS) was 36.3 (IQR: 29.7–42.9) months. The rates of OS for the 1st, 2nd, and 3rd years were 89.5%, 73.7%, and 61.4%, respectively. Despite the nonoccurrence of grade 4–5 toxicity in the lungs, six (31.6%) patients had grade 1–3 pulmonary pneumonia, one patient had a grade 4 skin ulceration, and two patients had increased chronic obstructive pulmonary disease in the follow-up period.

Discussion

In patients with oligometastatic lung tumors, SBRT is very effective in terms of progression-free survival and OS.

Cellular bases of hypofractionated radiotherapy protocols for lung cancer

The extreme demand on health systems due to the COVID-19 pandemic has led to reconsider hypofractionation. Although the best clinical efficacy of these schemes is being demonstrated, the biological bases have not been established. Thus, after validating basic clinical parameters, through complementary in vitro models, we characterized the cellular and molecular mechanisms of hypofractionation protocols. Cell cultures of human lung cancer cell line A549 were irradiated with 0, 2, 4, 8, 12, 16 and 20 Gy. The clastogenic, cytotoxic, proliferative and clonogenic capacities and bystander effect were evaluated. In addition, we assessed survival and toxicity in a retrospective study of 49 patients with lung cancer. Our findings showed that the greater efficacy of ablative regimens should not only be attributed to events of direct cell death induced by genotoxic damage, but also to a lower cell repopulation and the indirect action of clastogenic factors secreted. These treatments were optimal in terms of 1- and 2-year overall survival (74 and 65%, respectively), and progression-free survival at 1 and 2 years (71 and 61%, respectively). The greater efficacy of high doses per fraction could be attributed to a multifactorial mechanism that goes beyond the 4Rs of conventional radiotherapy.

Applying PET-CT for predicting the efficacy of SBRT to inoperable early-stage lung adenocarcinoma: A Brazilian case-series

BACKGROUND

Stereotactic body radiotherapy (SBRT) is a treatment option for early-stage inoperable primary lung cancer. Here we report a thorough description of the prognostic value of pre-SBRT SUVmax for predicting the efficacy of SBRT in early-stage lung adenocarcinoma.

METHODS

This is a retrospective study of consecutive cases of early-stage inoperable lung adenocarcinoma, staged with PET-CT, treated with SBRT between 2007 and 17. Kaplan-Meier (KM) curves were used to assess overall survival and compare time to event between those with PET-CT SUVmax values ≤ 5.0 and those > 5. Fisher's Exact tests and the Mann-Whitney U were used to compare the patient and clinical data of those with SUVmax≤5.0 and >5.0, and those with and without any failure.

FINDINGS

Amongst 50 lung carcinoma lesions, from 47 patients (34 (68%)-T1a or <T1b), estimated median overall survival from the KM was 44.9 months (95% confidence interval 35.5-54.3). Five experienced a local failure, which was inadequate for detecting differences between those with PET-CT SUVmax ≤5.0 and those >5 (p = 0.112). In addition, 5 experienced a regional failure and 4 a distant failure. Higher PET-CT SUVmax values before SBRT were associated with an increased risk of any failure (36% versus 0%, p = 0.0040 on Fisher's Exact test) and faster time to event (p = 0.010, log rank test). Both acute and late toxicities profile were acceptable.

INTERPRETATION

Patients with early-stage inoperable lung adenocarcinoma present good clinical outcomes when treated with SBRT. We raised the hypothesis that the value of PET-CT SUVmax before SBRT may be an important predictive factor in disease control.

FUNDING

None.

Combining Serial and Parallel Functionality in Functional Lung Avoidance Radiation Therapy

PURPOSE

Functional lung avoidance (FLA) radiation therapy (RT) aims to minimize post-RT pulmonary toxicity by preferentially avoiding dose to high-functioning lung (HFL) regions. A common limitation is that FLA approaches do not consider the conducting architecture for gas exchange. We previously proposed the functionally weighted airway sparing (FWAS) method to spare airways connected to HFL regions, showing that it is possible to substantially reduce risk of radiation-induced airway injury. Here, we compare the performance of FLA and FWAS and propose a novel method combining both approaches.

METHODS

We used breath-hold computed tomography (BHCT) and simulation 4-dimensional computed tomography (4DCT) from 12 lung stereotactic ablative radiation therapy patients. Four planning strategies were examined: (1) Conventional: no sparing other than clinical dose-volume constraints; (2) FLA: using a 4DCT-based ventilation map to delineate the HFL, plans were optimized to reduce mean dose and V_13.50 in HFL; (3) FWAS: we autosegemented 11 to 13 generations of individual airways from each patient's BHCT and assigned priorities based on the relative contribution of each airway to total ventilation. We used these priorities in the optimization along with airway dose constraints, estimated as a function of airway diameter and 5% probability of collapse; and (4) FLA + FWAS: we combined information from the 2 strategies. We prioritized clinical dose constraints for organs at risk and planning target volume in all plans. We performed the evaluation in terms of ventilation preservation accounting for radiation-induced damage to both lung parenchyma and airways.

RESULTS

We observed average ventilation preservation for FLA, FWAS, and FLA + FWAS as 3%, 8.5%, and 14.5% higher, respectively, than for Conventional plans for patients with ventilation preservation in Conventional plans <90%. Generalized estimated equations showed that all improvements were statistically significant (P ≤ .036). We observed no clinically relevant improvements in outcomes of the sparing techniques in patients with ventilation preservation in Conventional plans ≥90%.

CONCLUSIONS

These initial results suggest that it is crucial to consider the parallel and the serial nature of the lung to improve post-radiation therapy lung function and, consequently, quality of life for patients.

Normal tissue complication probabilities of lung SABR patients from a UK centre and its implication on personalised radiotherapy

Introduction:

This work reports on the normal tissue complication probabilities (NTCP) from a UK cohort of previously treated peripheral lung SABR patients (n = 198) supplementing our previous publication on tumour control probabilities (TCP). Each patient was recalculated for alternative schedules.

Materials and Methods:

NTCP for 3 (54 Gy), 5 (55 and 60 Gy) and 8 (50 Gy) fraction (#) schemes were calculated with the Lyman Kutcher Burman (LKB) model in the software platform ‘Biosuite’ (Version 12·01) for lung and chest wall. Patients treated with 5 # or 8 # were then recomputed for alternative fractionations and doses (3 # and 5 #, for both 55 Gy and 60 Gy).

Results:

The mean lung NTCP (NTCPLUNG, for the outcome of radiation pneumonitis) was 2·8% (range 0·6 – 10·6). The mean chest wall NTCP (NTCPCW, for the outcome of rib fracture) was 1·4% (range 0·0–55·9). There were no statistically significant differences observed between male and female, tumour status or fractionation groups except for the NTCPLUNG between 5 # and 3 #. When recalculating NTCP and TCP individually, for 8 # patients, no differences were observed between mean TCP, NTCPLUNG or NTCPCW compared with 3 # or 5 # indicating that fractionation reduction is possible. Parity was observed between the 60 Gy group when recalculated for 55 Gy. For the 60 Gy in 5 # group, the NTCPCW increased significantly when recalculated for 3 #.

Conclusion:

NTCPs achievable with current UK planning techniques have been presented indicating SABR Consortium compliant centres are likely to have low complication population risks (< 3 %). 5 # schedules could be justified for 8 # patients, thereby reducing the number of treatment visits. Where there is a large overlap of PTV and chest wall, this indicates an NTCP/TCP calculation is required to investigate if fractionation reduction is individually appropriate.

Comparison of stereotactic body radiotherapy and radiofrequency ablation for early-stage non-small cell lung cancer: a systematic review and meta-analysis

Background

Stereotactic body radiation therapy (SBRT) and radiofrequency ablation (RFA) are recommended for patients with inoperable early-stage non-small cell lung cancer (NSCLC), with both offering promising results. However, it is largely unknown which of these two treatment modalities provides superior benefits for patients. Therefore, this systematic review and meta-analysis compared clinical outcomes and safety between SBRT and RFA in patients with inoperable early-stage NSCLC.

Methods

Eligible studies published between 2001 and 2020 were obtained through a comprehensive search of the PubMed, Medline, Embase, and Cochrane Library databases. Original English-language studies on the treatment of early-stage NSCLC with SBRT or RFA were included. Local control (LC) rates, overall survival (OS) rates, and adverse events were obtained by pooled analyses.

Results

Eighty-seven SBRT studies (12,811 patients) and 18 RFA studies (1,535 patients) met the eligibility criteria. For SBRT, the LC rates (with 95% confidence intervals) at 1, 2, 3, and 5 years were 98% (97-98%), 95% (95-96%), 92% (91-93%), and 92% (91-93%), respectively, which were significantly higher than those for RFA [75% (69-82%), 31% (22-39%), 67% (58-76%), and 41% (30-52%), respectively] (P<0.01). There were no significant differences in short-term OS between SBRT and RFA [1-year OS rate: 87% (86-88%) versus 89% (88-91%), P=0.07; 2-year OS rate: 71% (69-72%) versus 69% (64-74%), P=0.42]. Regarding long-term OS, the 3- and 5-year OS rates for SBRT were 58% (56-59%) and 39% (37-40%), respectively, which were significantly (P<0.01) superior to those for RFA [48% (45-51%) and 21% (19-23%), respectively]. The most common complication of SBRT was radiation pneumonitis (grade ≥2), making up 9.1% of patients treated with SBRT, while pneumothorax was the most common complication of RFA, making up 27.2% of patients treated with RFA.

Discussion

Compared with RFA, SBRT has superior LC and long-term OS rates but similar short-term OS rates. Prospective randomized trials with large sample sizes comparing the efficacy of SBRT and RFA are warranted.

Evaluation of the impact of teaching on delineation variation during a virtual stereotactic ablative radiotherapy contouring workshop

Introduction:

Variation in delineation of target volumes/organs at risk (OARs) is well recognised in radiotherapy and may be reduced by several methods including teaching. We evaluated the impact of teaching on contouring variation for thoracic/pelvic stereotactic ablative radiotherapy (SABR) during a virtual contouring workshop.

Materials and methods:

Target volume/OAR contours produced by workshop participants for three cases were evaluated against reference contours using DICE similarity coefficient (DSC) and line domain error (LDE) metrics. Pre- and post-workshop DSC results were compared using Wilcoxon signed ranks test to determine the impact of teaching during the workshop.

Results:

Of 50 workshop participants, paired pre- and post-workshop contours were available for 21 (42%), 20 (40%) and 22 (44%) participants for primary lung cancer, pelvic bone metastasis and pelvic node metastasis cases, respectively. Statistically significant improvements post-workshop in median DSC and LDE results were observed for 6 (50%) and 7 (58%) of 12 structures, respectively, although the magnitude of DSC/LDE improvement was modest in most cases. An increase in median DSC post-workshop ≥0·05 was only observed for GTVbone, IGTVlung and SacralPlex, and reduction in median LDE > 1 mm was only observed for GTVbone, CTVbone and SacralPlex. Post-workshop, median DSC values were >0·7 for 75% of structures. For 92% of the structures, post-workshop contours were considered to be acceptable or within acceptable variation following review by the workshop faculty.

Conclusions:

This study has demonstrated that virtual SABR contouring training is feasible and was associated with some improvements in contouring variation for multiple target volumes/OARs.

[Radiation Oncology - Recent Status]

Radiation Oncology - Recent Status Abstract. We summarize the most important developments and innovations in the field over the past years and illustrate resulting external radiation treatment schedules and related treatment tolerance, focusing on hypofractionation.

Phase I Trial of Stereotactic Body Radiation Therapy Dose Escalation in Pancreatic Cancer

PURPOSE

Stereotactic body radiation therapy (SBRT) has demonstrated encouraging local tumor control rates in the treatment of pancreatic cancer, yet we lack prospective clinical trials evaluating dose-escalation strategies among patients treated with 5-fraction SBRT. This phase 1 dose-escalation trial was conducted to determine the maximum tolerated dose of SBRT in patients with pancreatic cancer.

METHODS AND MATERIALS

Thirty patients with pancreatic cancer were enrolled and treated with 40, 45, or 50 Gy SBRT in 5 fractions with doses determined using a time-to-event continual reassessment method trial design. Systemic therapy was permitted before and after SBRT, but not mandated by the study protocol. Toxicity was the primary study endpoint, and any grade ≥3 acute or late toxicity potentially attributable to SBRT was considered a dose-limiting toxicity. Secondary endpoints included local progression, distant progression, and overall survival.

RESULTS

The median follow up from SBRT was 8.9 months (range, 1.7-62.6 months). Nineteen patients (63%) had locally advanced disease, 3 patients (10%) had metastatic disease, and 8 patients (27%) had medically unresectable disease. Three patients (10%) received 40 Gy, 16 patients (53%) received 45 Gy, and 11 patients (37%) received 50 Gy. Seven patients (23%) experienced grade ≤2 acute toxicity, and 2 patients (6.7%) experienced grade 4 to 5 late toxicity, both of which occurred in the 45 Gy group. Median survival time was 17.1 months from the time of diagnosis and 9.8 months from SBRT. The 1-year cumulative incidence of local progression was 14.2% (95% confidence interval, 4.2%-30%).

CONCLUSIONS

This dose-escalation trial evaluated high-dose SBRT delivered in 5 fractions, and overall demonstrated favorable local control and survival, but was associated with nontrivial rates of severe late gastrointestinal toxicity potentially attributable to radiation. Further prospective studies are needed to define the safety and efficacy of high-dose SBRT in patients with pancreatic cancer.

Cost-Effectiveness Analysis of Stereotactic Ablative Body Radiotherapy for the Treatment of Oligometastatic Tumors versus Standard of Care

BACKGROUND

Recent clinical trial results reported that stereotactic radiotherapy (SABR) may improve survival for patients with oligometastatic (OM) cancer. Given that these results come from a phase II trial, there remains considerable uncertainty about this finding, and about the cost-effectiveness of SABR for patients with OM cancer. In this analysis, we estimate the cost-effectiveness of SABR for oligometastatic cancer patients.

METHODS

A probabilistic time-dependent Markov model was constructed to simulate treatment of oligometastatic cancer patients over five- and ten-year time horizons. The primary data source was the phase II, Stereotactic Ablative Radiotherapy for the Comprehensive Treatment of Oligometastases (SABR-COMET )trial and supplemented with data from the literature. We estimated the effect of SABR and the standard of care (SoC) using quality-adjusted life-years (QALYs). Costs were measured from a provincial payer perspective (2018 Canadian dollars).

RESULTS

In the reference case analysis (five-year time horizon), SABR was associated with additional incremental costs of CAD 38,487 and an incremental QALY gain of 0.84. This resulted in an incremental cost-effectiveness ratio (ICER) of CAD 45,726 per QALY gained. Over a ten-year time horizon, the increased uncertainty in the long-term effectiveness of SABR resulted in an ICER of CAD 291,544 per QALY gained. Estimates from the probabilistic analysis indicated that at a willingness-to-pay (WTP) threshold of CAD 50,000 and CAD 100,000 per QALY gained, there is 54% and 78% probability (respectively) that SABR would be cost-effective using the five-year time horizon.

CONCLUSIONS

The adoption of SABR therapy requires a considerable upfront capital investment. Our results suggest that the cost-effectiveness of SABR is contingent on the uncertainty in the evidence base. Further clinical trials to confirm the effectiveness of SABR and research into the real-world costs associated with this treatment could reduce the uncertainty around implementation of the technology.

High-dose hypofractionated pencil beam scanning carbon ion radiotherapy for lung tumors: Dosimetric impact of different spot sizes and robustness to interfractional uncertainties

PURPOSE

The robustness against setup and motion uncertainties of gated four-dimensional restricted robust optimization (4DRRO) was investigated for hypofractionated carbon ion radiotherapy (CIRT) of lung tumors.

METHODS

CIRT plans of 9 patients were optimized using 4DRRO strategy with 3 mm setup errors, 3% density errors and 3 breathing phases related to the gate window. The prescription was 60 Gy(RBE) in 4 fractions. Standard spots (SS) were compared to big spots (BS). Plans were recalculated on multiple 4DCTs acquired within 3 weeks from treatment simulation and rigidly registered with planning images using bone matching. Warped dose distributions were generated using deformable image registration and accumulated on the planning 4DCTs. Target coverage (D98%, D95% and V95%) and dose to lung were evaluated in the recalculated and accumulated dose distributions.

RESULTS

Comparable target coverage was obtained with both spot sizes (p = 0.53 for D95%). The mean lung dose increased of 0.6 Gy(RBE) with BS (p = 0.0078), still respecting the dose constraint of a 4-fraction stereotactic treatment for the risk of radiation pneumonitis. Statistically significant differences were found in the recalculated and accumulated D95% (p = 0.048 and p = 0.024), with BS showing to be more robust. Using BS, the average degradations of the D98%, D95% and V95% in the accumulated doses were -2.7%, -1.6% and -1.5%.

CONCLUSIONS

Gated 4DRRO was highly robust against setup and motion uncertainties. BS increased the dose to healthy tissues but were more robust than SS. The selected optimization settings guaranteed adequate target coverage during the simulated treatment course with acceptable risk of toxicity.

Long-term Overall Survival Outcomes in Patients with Early Stage, Peripherally Located, Non-small Cell Lung Cancer Treated with Stereotactic Ablative Radiotherapy in a Non-academic Cancer Centre

AIMS

To report long-term outcomes of patients treated with stereotactic ablative radiotherapy (SABR) for early stage, peripherally located non-small cell lung cancer.

MATERIALS AND METHODS

Data were collected retrospectively between September 2009 and May 2019. Electronic medical records were reviewed for baseline characteristics, treatment details and outcomes. All patients were treated according to local protocol based on the national UK SABR Consortium guidelines. Risk-adapted treatment schedules were used depending on the size and the location of the tumour (54 Gy in three fractions, 55 Gy in five fractions, 60 Gy in eight fractions or 50 Gy in 10 fractions). Overall survival outcomes were evaluated using the Kaplan-Meier method.

RESULTS

In total, 412 patients were included in the analysis. The median age was 76 years (range 48-93 years). Histological confirmation was obtained in 233 cases (56.6%). The median overall survival for all patients was 42.3 months (95% confidence interval 37.3-47.3 months), with 3- and 5-year overall survival of 52.8% and 37.3%, respectively. For biopsy-proven patients (56.6%), 3- and 5-year overall survival was 57.3% and 40.1%, respectively. With respect to overall survival, univariate and multivariate analysis revealed no significant difference in survival by technique (volume-modulated arc therapy versus conformal; three-dimensional computed tomography versus four-dimensional computed tomography), tumour location, smoking status at first contact, pre-treatment tumour stage or pre-treatment standardised uptake value. Survival was poorer for patients who received the 50 Gy in 10 fractions schedule. Treatment was very well tolerated with very low rates of grade 3-4 toxicity (1%).

CONCLUSIONS

SABR for peripherally located, medically inoperable non-small cell lung cancer can be safely and effectively implemented in a non-academic institution with appropriate equipment and training. Overall survival outcomes and toxicity rates are comparable with internationally published studies. Patients treated with 50 Gy in 10 fractions had a poorer survival outcome.

PET/CT features of lung SABR chest wall toxicity

Stereotactic ablative radiotherapy offers a radical treatment approach for early stage lung cancers and an aggressive local therapy for pulmonary oligometastases from other tumour sites. Chest wall toxicity is one of the key dose-limiting toxicities for intrathoracic stereotactic treatments. The description of stereotactic radiotherapy chest wall toxicity using functional imaging has not been reported previously. A 56-year-old male received 60 Gy in 8 fractions delivered by volumetric modulated arc therapy for a T1bN0M0 clinical left upper lobe lung cancer. The past medical history included poorly controlled type 1 diabetes mellitus, severe peripheral vascular disease and obesity. The patient attended 9 months later with left-sided, slowly progressive chest pain. An ¹⁸ FDG PET/CT performed in order to investigate contralateral pulmonary lesions revealed FDG-avid focal thickening at the left superio-lateral thoracic wall with overlying inflammatory stranding in keeping with an indolent inflammatory process. Chest wall toxicity may present as pain, swelling, fracture and skin changes, and has the ¹⁸ FDG PET/CT chjmirocteristics of an inflammatory process. Patients with risk factors for chest wall toxicity, such as obesity, diabetes and smoking should be informed of their higher propensity for this clinically significant treatment side effect. For patients developing chest wall toxicity as demonstrated in this case with associated functional imaging findings, anti-inflammatory treatment should be promptly commenced.

Tumour control probability of a UK cohort of lung SABR patients

Aims:

The aim of this work is to report on the tumour control probability (TCP) of a UK cohort of lung stereotactic ablative radiotherapy patients (n = 198) for a range of dose and fractionations common in the UK.

Materials and methods:

TCP values for 3 (54 Gy), 5 (55 and 60 Gy) and 8 (50 Gy) fraction (#) schemes were calculated with the linear-quadratic Marsden TCP model using the Biosuite software.

Results:

TCP values of 100% were computed for the 3 # and for 5 # (α/β = 10 Gy) cohorts; reduced to 99% (range 97–100) for the 5 # cohort only when an α/β of 20 Gy was used. The average TCP value for the 50 Gy in 8 # regime was 97% (range 92–99, α/β = 10 Gy) and 64% (range 48–79, α/β = 20 Gy). Statistical significant differences were observed between the α/β of 10 Gy versus 20 Gy groups and between all data grouped by fraction.

Conclusion:

TCPs achievable with current planning techniques in the UK have been presented. The ultra-conservative 50 Gy in 8 # scheme returns a significantly lower TCP than the other regimes.

SABR-BRIDGE: Stereotactic ABlative Radiotherapy Before Resection to AvoId Delay for Early-Stage LunG Cancer or OligomEts During the COVID-19 Pandemic

Surgical resection is the standard-of-care approach for early-stage non-small cell lung cancer (NSCLC). Surgery is also considered an acceptable standard infit patients with oligometastatic lesions in the lungs. The COVID-19 pandemic has led to worldwide issues with access to operating room time, with patients and physicians facing uncertainty as to when surgical resection will be available, with likely delays of months. Further compounding this are concerns about increased risks of respiratory complications with lung cancer surgery during active phases of the pandemic. In this setting, many thoracic oncology teams are embracing a paradigm where stereotactic ablative radiotherapy (SABR) is used as a bridge, to provide radical-intent treatment based on a combination of immediate SABR followed by planned surgery in 3–6 months. This pragmatic approach to treatment has been named SABR-BRIDGE (Stereotactic ABlative Radiotherapy Before Resection to avoId Delay for early-stage lunG cancer or oligomEts). This term has also been applied to the pragmatic study of the outcomes of this approach. In this paper, we discuss the standards of care in treatment of early-stage (NSCLC) and pulmonary oligometastases, the impetus for the SABR-BRIDGE approach, and the controversies surrounding assessment of pathological response to neo-adjuvant radiation therapy.

Commonwealth Neuroendocrine Tumour Research Collaboration and the North American Neuroendocrine Tumor Society Guidelines for the Diagnosis and Management of Patients With Lung Neuroendocrine Tumors: An International Collaborative Endorsement and Update of the 2015 European Neuroendocrine Tumor Society Expert Consensus Guidelines

Lung neuroendocrine tumors (LNETs) are uncommon cancers, and there is a paucity of randomized evidence to guide practice. As a result, current guidelines from different neuroendocrine tumor societies vary considerably. There is a need to update and harmonize global consensus guidelines. This article reports the best practice guidelines produced by a collaboration between the Commonwealth Neuroendocrine Tumour Research Collaboration and the North American Neuroendocrine Tumor Society. We performed a formal endorsement and updating process of the 2015 European Neuroendocrine Tumor Society expert consensus article on LNET. A systematic review from January 2013 to October 2017 was conducted to procure the most recent evidence. The stepwise endorsement process involved experts from all major subspecialties, patients, and advocates. Guided by discussion of the most recent evidence, each statement from the European Neuroendocrine Tumor Society was either endorsed, modified, or removed. New consensus statements were added if appropriate. The search yielded 1109 new publications, of which 230 met the inclusion criteria. A total of 12 statements were endorsed, 22 statements were modified or updated, one was removed, and two were added. Critical answered questions for each topic in LNET were identified. Through the consensus process, guidelines for the management of patients with local and metastatic neuroendocrine tumors have been updated to include both recent evidence and practice changes relating to technological and definitional advances. The guidelines provide clear, evidence-based statements aimed at harmonizing the global approach to patients with LNETs, on the basis of the principles of person-centered and LNET-specific care. The importance of LNET-directed research and person-centered care throughout the diagnosis, treatment, and follow-up journey is emphasized along with directions for future collaborative research.

Outcomes and toxicities following stereotactic ablative radiotherapy for pulmonary metastases in patients with primary head and neck cancer

BACKGROUND

Metastatic head and neck cancers (HNCs) predominantly affect the lungs and have a two-year overall survival (OS) of 15% to 50%, if amenable for pulmonary metastasectomy.

METHODS

Retrospective review of the two-year local control (LC), local-regional control (LRC) within the same lobe, OS, and toxicity rates in consecutive patients with metastatic pulmonary HNC who underwent stereotactic ablative radiotherapy (SABR) January 2007 to May 2018.

RESULTS

Evaluated 82 patients with 107 lung lesions, most commonly squamous cell carcinoma (SCC; 64%). Median follow-up was 20 months (range: 9.0-97.6). Systemic therapy administered in 34%. LC, LRC, and OS rates were 94%, 90%, and 62%. Patients with oligometastatic disease had a higher OS than polymetastatic disease, 72% vs 44% (HR = 0.30, 95% CI: 0.14-0.64; P = .008). OS in oligometastatic non-SCC and SCC were 100% and 66% (P = .03). There were no grade ≥3 toxicities.

CONCLUSIONS

Metastatic pulmonary HNCs after SABR have a two-year OS rate comparable to pulmonary metastasectomy.

Stereotactic body radiotherapy for moderately central and ultra-central oligometastatic disease: Initial outcomes

BACKGROUND

Delivery of SBRT to central thoracic tumours within 2 cm of the proximal bronchial tree (PBT), and especially ultra-central tumours which directly abut the PBT, has been controversial due to concerns about high risk of toxicity and treatment-related death when delivering high doses close to critical mediastinal structures. We present dosimetric and clinical outcomes from a group of oligometastatic patients treated with a risk-adapted SBRT approach.

METHODS

Between September 2015 and October 2018, 27 patients with 28 central thoracic oligometastases (6 moderately central, 22 ultra-central) were treated with 60 Gy in 8 fractions under online CBCT guidance. PTV dose was compromised where necessary to meet mandatory OAR constraints. Patients were followed up for toxicity and disease status.

RESULTS

Mandatory OAR constraints were met in all cases; this required PTV coverage compromise in 23 cases, with V100% reduced to <70% in 11 cases. No acute or late toxicities of Grade ≥ 3 were reported. One and 2 year in-field control rates were 95.2% and 85.7% respectively, progression-free survival rates were 42.8% and 23.4% respectively, and overall survival rates were 82.7% and 69.5% respectively. No significant differences were seen in control or survival rates by extent of PTV underdosage or between moderately and ultra-central cases.

CONCLUSION

It appears that compromising PTV coverage to meet OAR constraints allows safe and effective delivery of SBRT to moderately and ultra-central tumours, with low toxicity rates and high in-field control rates. This treatment can be delivered on standard linear accelerators with widely available imaging technology.

Choice of Treatment for Stage IA Non-small Cell Lung Cancer Patients Ineligible for Surgery: Ablation or Stereotactic Body Radiotherapy?

Purpose: To compare the survival outcomes of ablation and stereotactic body radiotherapy (SBRT) in inoperable patients with stage IA non-small cell lung cancer (NSCLC).

Patients and Methods: Using the Surveillance, Epidemiology, and End Results (SEER) database, we identified 6,395 patients with stage IA NSCLC who had complete clinical information from 2004 to 2015. Kaplan-Meier analysis was performed to determine the propensity score based on the clinical characteristics of patients with stage IA NSCLC. Overall survival (OS) was compared between patients with stage IA NSCLC who were treated with ablation and SBRT after adjusting, stratifying, or matching.

Results: Kaplan-Meier analysis demonstrated no significant difference in survival curves (log-rank, p>0.05) between the ablation and SBRT groups. Compared with the SBRT group, the hazard ratio (HR) (95% confidence interval [CI]) of OS was 0.930 (0.817-1.058, p=0.269) in the ablation group on univariate analysis. On multivariate analysis, similar effects on OS (HR: 0.974, 95% CI: 0.858-1.105, p=0.680) were seen in patients with stage IA NSCLC in both the groups.

Conclusions: This study suggests that survival does not differ significantly between patients with stage IA NSCLC treated with ablation and SBRT. These results will be helpful for patients with stage IA NSCLC who are ineligible for surgery.

Radiofrequency Ablation for Stage I Non-Small Cell Lung Cancer: An Updated Review of Literature from the Last Decade

This review summarizes the current findings on radiofrequency ablation (RFA) for stage I non-small cell lung cancer (NSCLC) from relevant literature published in the last decade. While most earlier studies included small populations and had short follow-up periods, more robust data have become available owing to prospective or large cohort studies. The reported overall survival rates after RFA for stage I NSCLC were 83-96%, 40-74%, and 23-61% at 1, 3, and 5 years, respectively, in recent studies. Furthermore, many comparative studies on the outcomes of RFA and stereotactic body radiotherapy have been performed. Most of these studies report no significant difference in survival outcomes between the therapies. Currently, major guidelines define RFA as a reasonable alternative treatment for stage I NSCLC in non-surgical candidates.

Stereotactic Ablative Body Radiotherapy Versus Radical Radiotherapy: Comparing Real-World Outcomes in Stage I Lung Cancer

AIMS

Stereotactic ablative body radiotherapy (SABR) is now considered the standard of care for medically inoperable stage I non-small cell lung cancer (NSCLC). The English National Cancer Registration and Analysis Service (NCRAS) collects data on all patients diagnosed with lung cancer, including information on treatment. We wanted to compare outcomes for patients with stage I NSCLC treated with radical radiotherapy with either SABR or fractionated radiotherapy.

MATERIALS AND METHODS

All patients diagnosed with stage I NSCLC in 2015 and 2016 were identified from the NCRAS dataset, validated by the National Lung Cancer Audit, and their treatment data were collated. For patients who received radiotherapy, those receiving radical dose fractionations, including SABR, were identified through linkage to the national Radiotherapy Dataset. Clinical outcomes for those receiving SABR or more fractionated radical radiotherapy were compared using univariate and fully adjusted Cox proportional hazards models.

RESULTS

In total, 12 384 patients with stage I NSCLC were identified during the study period; 53.5% underwent surgical resection, 24.3% received no documented treatment, 18.6% received radical radiotherapy and 3.5% received other non-curative-intent treatments. For those receiving radical radiotherapy, 69% received SABR and 31% received fractionated treatment. The hazard ratio of death for the 1587 patients who received SABR was 0.69 (95% confidence interval 0.61-0.79) compared with 717 patients who received radical fractionated radiotherapy; this benefit was seen for both stage Ia and stage Ib disease. The median overall survival was also longer for SABR versus radical radiotherapy (715 days versus 648 days). Exploratory travel time analysis shows that compared with stage I NSCLC patients receiving SABR, those receiving fractionated radiotherapy and those receiving no active treatment would have to travel longer and further to reach their nearest radiotherapy SABR centre.

CONCLUSION

This study adds to the data that SABR has a survival benefit when compared with fractionated radical radiotherapy. Although the use of SABR increased in England over this study period, it has still not reached levels of use seen in other countries. This study also highlights that one quarter of stage I NSCLC patients overall received no active treatment.

Is microwave ablation an alternative to stereotactic ablative body radiotherapy in patients with inoperable early-stage primary lung cancer?

A best evidence topic was written according to a structured protocol. The question addressed was: in patients with inoperable early-stage primary lung cancer does microwave ablation (MWA) or stereotactic ablative body radiotherapy (SBRT) achieve improved outcomes in terms of local control, recurrence, survival and complications? Altogether, more than 550 papers were found using the reported search, of which 12 represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. No single study directly compared the effects of MWA with SBRT. However, the best available evidence for MWA (7 studies) was compared to that for SBRT (5 studies). The range of 3-year survival reported for MWA was 29.2–84.7%, compared with 42.7–63.5% for SBRT. The range of median survival was 35–60 months for MWA and 32.6–48 months for SBRT. This suggests similar outcomes between these two 2 techniques. Different side-effect profiles were observed between techniques with MWA associated with pneumothorax and fever and SBRT most commonly causing radiation pneumonitis and rib fractures. The evidence base for MWA is less than that for SBRT and is heterogenous in terms of participants and technical design. However, within these limitations, we conclude that MWA appears comparable with SBRT in terms of local control and survival rates.

FLT-PET-CT for the Detection of Disease Recurrence After Stereotactic Ablative Radiotherapy or Hyperfractionation for Thoracic Malignancy: A Prospective Pilot Study

Differentiating local recurrence from post-treatment changes on PET scans following stereotactic ablative radiotherapy (SABR) or hyperfractionation for lung tumors is challenging. We performed a prospective pilot study of 3-deoxy-3-[¹⁸F]-fluorothymidine (FLT)-PET-CT in patients with equivocal post-radiation FDG-PET-CT to assess disease recurrence.

Methods: We prospectively enrolled 10 patients, 9 treated with SABR and 1 with hyperfractionated external beam radiotherapy for thoracic malignancy with subsequent equivocal follow-up FDG-PET-CT, to undergo FLT-PET-CT prior to biopsy or serial imaging. FLT-PET scans were interpreted by a radiologist with experience in reading FLT-PET-CT and blinded to the results of any subsequent biopsy or imaging.

Results: Of the 10 patients enrolled, 8 were evaluable after FLT-PET-CT. Based on the FLT-PET-CT, a blinded radiologist accurately predicted disease recurrence vs. inflammatory changes in 7 patients (87.5%). The combination of higher lesion SUV_max and higher ratio of lesion SUV_max to SUV_max of mediastinal blood pool was indicative of recurrence. Qualitative assessment of increased degree of focality of the lesion also appears to be indicative of disease recurrence.

Conclusion: Adjunctive FLT-PET-CT imaging can complement FDG-PET-CT scan in distinguishing post-treatment radiation changes from disease recurrence in thoracic malignancies. These findings support the investigation of FLT-PET-CT in a larger prospective study.

Stereotactic ablative radiation therapy in lung cancer: an emerging standard

PURPOSE OF REVIEW

Significant advances have been made in the field of stereotactic ablative radiotherapy (SABR) for the treatment of pulmonary neoplasms in recent years. This review aims to summarize recent salient evidence on SABR for early-stage nonsmall cell lung cancer (ES-NSCLC).

RECENT FINDINGS

In medically inoperable patients, SABR remains the standard of care. The optimal SABR dosing regimen is being studied. Comparisons with non-SABR radiotherapy regimens with lower doses per fraction revealed benefit of SABR. In operable patients, no prospective clinical trial comparing SABR and surgery has been completed, although multiple trials are currently underway to address this question. SABR is generally cost-effective and safe in most patients, with preserved patient-reported quality of life. However, increased toxicity with SABR is noted in patients with disease close to, or invading the proximal tracheobronchial tree. Significant SABR-related toxicity and mortality is also reported in patients with coexisting interstitial lung disease. Considerations on pathologic confirmation, surveillance and multiple primaries are also addressed.

SUMMARY

SABR is an effective and safe treatment for inoperable ES-NSCLC. Ongoing trials and comparative effectiveness research will help to clarify SABR's role in various lung cancer indications going forward.

Treatment of T3N0 non-small cell lung cancer with chest wall invasion using stereotactic body radiotherapy

•

The role of SBRT for T3N0 lung cancer invading the chest wall is unknown.

•

We treated 12 patients with T3N0 chest wall-invading lung cancer with SBRT.

•

Local control was excellent and no grade 3+ toxicity was observed.

•

Pre-treatment chest wall pain was relieved after SBRT in most patients.

Objectives

Chest wall invasion (CWI) is observed in 5% of localized non-small cell lung cancer (NSCLC). The role of stereotactic body radiotherapy (SBRT) in these patients is unknown. We investigate the safety and efficacy of SBRT in patients with T3N0 NSCLC due to CWI.

Methods

Patients with T3N0 NSCLC due to CWI were identified using a prospective registry. CWI was defined as radiographic evidence of soft tissue invasion or bony destruction. We excluded patients with recurrent or metastatic disease. All patients were treated with definitive SBRT. Prescribed dose was 50 Gy in 5 fractions for most patients. Kaplan-Meier analysis was used to estimate survival outcomes.

Results

We identified 12 patients treated between 2006 and 2017. Median age was 70 (range, 58–85). Median tumor diameter was 3.0 cm (range, 0.9–7.2). Median survival was 12.0 months (range, 2.4–63). At a median follow-up of 8.9 months (range, 2.1–63), 1-year primary tumor control was 89%, involved lobar control was 89%, local–regional control was 82%, distant control was 91%, and survival was 63%. Of the 4 patients with pre-treatment chest wall pain, 3 reported improvement after SBRT. Two patients reported new grade 1–2 chest wall pain. No grade 3+ toxicity was reported, with 1 patient experiencing grade 1 skin toxicity and 3 patients experiencing grade 1–2 radiation pneumonitis.

Conclusions

SBRT for CWI NSCLC is safe, with high early tumor control and low treatment-related toxicity. Most patients with pre-treatment chest wall pain experienced relief after SBRT, with no grade 3+ toxicity observed.

Prediction of early mortality following stereotactic body radiotherapy for peripheral early-stage lung cancer

BACKGROUND/PURPOSE

To investigate prognostic factors for death within 6 months of stereotactic body radiotherapy (SBRT) for patients with peripheral early-stage non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

This analysis included 586 NSCLC patients with peripheral tumors treated with SBRT. Potential patient and tumor prognostic factors, including the Charlson Comorbidity Index (CCI) and Cumulative Illness Rating Scale (CIRS), were analyzed by logistic regression analysis for association with early mortality (death <6 months after SBRT). Additionally, CCI and CIRS were compared with respect to their predictive ability for early mortality by comparing multivariate models with each comorbidity index, and assessing their respective discriminatory abilities (C-index).

RESULTS

A total of 36 patients (6.1%) died within 6 months of the start of SBRT. With a median follow-up of 25 months, 3-year overall survival was 54%. CIRS and tumor diameter were significant predictors of early mortality on multivariate analysis (p = .001). Patients with a CIRS score of 8 or higher and a tumor diameter over 3 cm had a 6-month survival of 70% versus 97% for those lacking these two features (p < .001). CCI was not predictive for early mortality on univariate nor multivariate analysis; the model containing CCI had a C-index of 0.65 versus 0.70 for the model containing CIRS.

CONCLUSION

CIRS and tumor diameter predict for early-mortality in peripheral early-stage NSCLC treated with SBRT. CIRS may be a more useful comorbidity index than CCI in this population when assessing short-term life expectancy.

Assessing the Role of Artificial Intelligence (AI) in Clinical Oncology: Utility of Machine Learning in Radiotherapy Target Volume Delineation

The fields of radiotherapy and clinical oncology have been rapidly changed by the advances of technology. Improvement in computer processing power and imaging quality heralded precision radiotherapy allowing radiotherapy to be delivered efficiently, safely and effectively for patient benefit. Artificial intelligence (AI) is an emerging field of computer science which uses computer models and algorithms to replicate human-like intelligence and perform specific tasks which offers a huge potential to healthcare. We reviewed and presented the history, evolution and advancement in the fields of radiotherapy, clinical oncology and machine learning. Radiotherapy target delineation is a complex task of outlining tumour and organ at risks volumes to allow accurate delivery of radiotherapy. We discussed the radiotherapy planning, treatment delivery and reviewed how technology can help with this challenging process. We explored the evidence and clinical application of machine learning to radiotherapy. We concluded on the challenges, possible future directions and potential collaborations to achieve better outcome for cancer patients.

Developments in Stereotactic Body Radiotherapy

Stereotactic body radiotherapy is the technique of accurately delivering high doses of radiotherapy to small volume targets in a single or small number of sessions. The high biological effective dose of this treatment is reflected in the high rates of local control achieved across multiple tumour sites. Toxicity of the treatment can be significant and ongoing prospective trials will help define the utility of this treatment as an alternative to surgery in treating primary tumours and oligometastatic disease. Longer follow-up and survival data from prospective trials will be essential in determining the value of this resource-intensive treatment. The opportunity to combine this treatment with systemic therapies and its potential synergy with immunotherapy opens up interesting avenues for research in the future.

A National Cancer Database Analysis of Radiofrequency Ablation versus Stereotactic Body Radiotherapy in Early-Stage Non-Small Cell Lung Cancer

PURPOSE

To compare overall survival (OS) after radiofrequency (RF) ablation and stereotactic body radiotherapy (SBRT) at high-volume centers in patients with early-stage non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

Cases in the National Cancer Database of stage 1a and 1b NSCLC treated with primary RF ablation or SBRT from 2004 to 2014 were included. Patients treated at low-volume centers, defined as facilities below the 95th percentile in volume of cases performed, were excluded. Outcomes measured include OS and rate of 30-day readmission. The Kaplan-Meier method was used to estimate OS. The log-rank test was used to compare survival curves. Propensity score matched cohort analysis was performed. P < .05 was considered statistically significant.

RESULTS

The final cohort comprised 4,454 cases of SBRT and 335 cases of RF ablation. Estimated median survival and follow-up were 38.8 months and 42.0 months, respectively. Patients treated with RF ablation had significantly more comorbidities (P < .001) and higher risk for an unplanned readmission within 30 days (hazard ratio = 11.536; P < .001). No difference in OS for the unmatched groups was found on multivariate Cox regression analysis (P = .285). No difference was found in the matched groups with 1-, 3-, and 5-year OS of 85.5%, 54.3%, and 31.9% in the SBRT group vs 89.3%, 52.7%, and 27.1% in the RF ablation group (P = .835).

CONCLUSIONS

No significant difference in OS was seen between patients with early-stage NSCLC treated with RF ablation and SBRT.

Ultracentral Tumors Treated With Stereotactic Body Radiotherapy: Single-Institution Experience

INTRODUCTION

Patients with ultracentral lung tumors, whose planning target volume directly contacts or overlaps the proximal bronchial tree, trachea, esophagus, pulmonary vein, or pulmonary artery, may be at higher risk of toxicity when treated with stereotactic body radiotherapy (SBRT). We reviewed the outcomes and toxicities of ultracentral lung tumors and compared the results with central lung tumors.

PATIENTS AND METHODS

A review of our institutional prospective database of patients treated with lung SBRT from January 2006 to December 2015 was conducted. Patients with central tumors (RTOG 0813 definition) and ultracentral tumors were included.

RESULTS

In total, 180 central and 26 ultracentral tumors were analyzed. The majority of patients received 60 Gy in 8 fractions (53.9%) or 48 Gy in 4 fractions (29.1%). The rates of any grade 2 or higher toxicity were 8.4% (n = 16) in the central group and 7.9% (n = 2) in the ultracentral group (P = .88). There were no observed grade 4 or 5 toxicities. In the nonmetastatic primary lung cancer cohort (n = 182), the median overall survival was 39.4 months versus 23.8 months (P = .40) and cause-specific survival was 55.5 months versus 28.2 months (P = .34) for central and ultracentral tumors, respectively. The 2-year cumulative local, regional, and distant failure rates were 3.3% versus 0 (P = .36), 9.1% versus 5.0% (P = .5), and 17.7% versus 18.7% (P = .63) in the central and ultracentral groups, respectively.

CONCLUSION

In our experience, with strict adherence to planning parameters, SBRT to ultracentral tumors resulted in effective local control and no excessive risk of toxicity compared to central tumors.

An overview on personalisation of radiotherapy prescriptions in locally advanced non-small cell lung cancer: Are we there yet?

Standard of care radiotherapy in LA-NSCLC is 60-66 Gy in 30-33 fractions. However outcomes for these patients are poor with 5-year survival in the range of 10-20%. Randomised controlled trials have shown that dose escalation in a linear fashion does not improve outcomes for all patients, thus there is a need to tailor the prescription to the individual patient. This review assesses the strategies published to personalise the radiation therapy dose prescription in LA-NSCLC. A systematic and scoping search of the literature was performed to identify studies that met the inclusion criteria. 19 relevant studies were identified ranging from prospective clinical trials to mathematically modelled concept studies. Heterogeneity existed between all clinical studies. Nine heterogeneous publications proposed methodology to adapt the dose prescription to the individual patient. A number of encouraging strategies have been identified but fall short of the evidence level required to influence clinical practice.