Measuring the Integration of Stereotactic Ablative Radiotherapy Plus Surgery for Early-Stage Non-Small Cell Lung Cancer: A Phase 2 Clinical Trial

Measuring the Integration of Stereotactic Ablative Radiotherapy Plus Surgery for Early-Stage Non-Small Cell Lung Cancer: Long-Term Clinical Outcomes

PURPOSE

For early-stage non-small cell lung cancer, surgery is the preferred approach in operable patients, whereas SABR is preferred for patients who are medically inoperable. The combination of neoadjuvant SABR followed by surgery was tested in the Measuring the Integration of Stereotactic Ablative Radiotherapy Plus Surgery for Early-Stage Non-Small Cell Lung Cancer (MISSILE) phase 2 trial. We report long-term outcomes beyond 5 years of follow-up.

METHODS AND MATERIALS

Patients diagnosed with T1-2N0M0 non-small cell lung cancer with good performance status and adequate lung function were enrolled. Patients underwent neoadjuvant SABR followed by lobectomy/wedge resection. Forty enrolled patients received SABR, of which 36 patients proceeded to surgery.

RESULTS

The pathologic and major complete response rates were 60% and 63%, respectively. Median follow-up was 6.6 years following surgery. Five-year overall, disease-free, and cancer-specific survival were 66.7% (95% CI, 48.8%-79.5%), 58.3% (95% CI, 40.7%-72.4%), and 76.4% (95% CI, 58.2%-87.4%), respectively. Five-year local, regional, and distant control were 93.5% (95% CI, 76.3%-98.4%), 80.1% (95% CI, 62.7%-90.0%), and 82.4% (95% CI, 64.9%-91.7%), respectively. After SABR and surgery, 16.7% (n = 6) of patients experienced related grade ≥3 adverse events, and there were no grade 5 events.

CONCLUSIONS

The combined approach of SABR and surgery was safe and demonstrated reasonable long-term clinical outcomes, but similar to surgery alone.

Systematic Review of Stereotactic Ablative Radiotherapy (SABR)/Stereotactic Body Radiation Therapy (SBRT) for Treatment of High-Risk Patients with Stage I Non-Small Cell Lung Cancer: The American Association of Thoracic Surgery Expert Consensus Document

Stereotactic ablative radiotherapy (SABR) has emerged as an alternative, non-surgical treatment for high-risk patients with stage I non-small cell lung cancer (NSCLC) with increased use over time. The American Association for Thoracic Surgery (AATS) Clinical Practice Standards Committee (CPSC) assembled an expert panel and conducted a systematic review of the literature evaluating the results of SABR, which is also referred to as stereotactic body radiation therapy (SBRT) or stereotactic radiosurgery (SRS), prior to developing treatment recommendations for high-risk patients with stage I NSCLC based on expert consensus. Publications detailing the findings of 16 prospective studies of SABR and 14 retrospective studies of SABR for the management of early-stage lung cancer in 54,697 patients were identified by systematic review of the literature with further review by members of our expert panel. Medical inoperability (93-95%) was the primary reason for utilizing SABR. The median rate of histologically confirmed cancer in treated patients was 67% (range 57-86%). In retrospective studies and prospective studies, the most common dosing regimens were 48-54Gy in 3-5 fractions and 44-66Gy in 3-5 fractions respectively. The median follow-up after SABR was 30 months (range 15-50). The complications, oncological results and quality of life after SABR in high-risk patients with early-stage NSCLC are summarized in this Expert Review article. Further prospective randomized trials are needed and are currently underway to compare outcomes after SABR with outcomes after sublobar resection to fully evaluate treatment options applicable this high-risk group of patients.

Stereotactic body radiotherapy with sequential tislelizumab and chemotherapy as neoadjuvant therapy in patients with resectable non-small-cell lung cancer in China (SACTION01): a single-arm, single-centre, phase 2 trial

BACKGROUND

Neoadjuvant immunotherapy with chemotherapy improves outcomes in patients with resectable non-small-cell lung cancer (NSCLC). Given its immunomodulating effect, we investigated whether stereotactic body radiotherapy (SBRT) enhances the effect of immunochemotherapy.

METHODS

The SACTION01 study was a single-arm, open-label, phase 2 trial that recruited patients who were 18 years or older and had resectable stage IIA-IIIB NSCLC from the Sun Yat-sen University Cancer Center, Guangzhou, China. Eligible patients received SBRT (24 Gy in three fractions) to the primary tumour followed by two cycles of 200 mg intravenous PD-1 inhibitor, tislelizumab, plus platinum-based chemotherapy. Surgical resection was performed 4-6 weeks after neoadjuvant treatment. The primary endpoint was major pathological response (MPR), defined as no more than 10% residual viable tumour in the resected tumour. All analyses were conducted on an intention-to-treat basis, including all patients who were scheduled for neoadjuvant treatment. The trial was registered with ClinicalTrials.gov (NCT05319574) and is ongoing but closed to recruitment.

FINDINGS

Between May 18, 2022, and June 20, 2023, 46 patients (42 men and four women) were enrolled and scheduled for neoadjuvant treatment. MPR was observed in 35 (76%, 95% CI 61-87) of 46 patients. The second cycle of immunochemotherapy was withheld in four (9%) patients due to pneumonia (n=2), colitis (n=1), and increased creatinine (n=1). Grade 3 or worse adverse events related to neoadjuvant treatment occurred in 12 (26%, 95% CI 14-41) patients. The most frequent treatment-related adverse event (TRAE) was alopecia (16 [35%] patients), and the most frequent grade 3 or worse TRAE was neutropenia (six [13%]). There was one treatment-related death, caused by neutropenia. No deaths within 90 days of surgery were reported.

INTERPRETATION

Preoperative SBRT followed by immunochemotherapy is well tolerated, feasible, and leads to a clinically significant MPR rate. Future randomised trials are warranted to support these findings.

FUNDING

BeiGene.

Moving towards single fraction peripheral lung stereotactic body radiation therapy: patient care during and after the global COVID-19 pandemic

Aim/objectives: Single-fraction stereotactic body radiation therapy (SF-SBRT) for peripheral lung tumors was reviewed. Materials & methods: Medically inoperable peripheral lung tumors eligible for SF-SBRT 34 Gray were treated. Patient characteristics, treatment and toxicity parameters were retrospectively collected, and toxicities were evaluated. Results: A total of 26 patients were assessed with median age of 74 years. Ninety-six percent had early-stage cancer and 35% were treated as per the SABR-BRIDGE protocol. Twenty-six peripheral lesions were treated (median maximal dimension 1.7 cm). Sixty-five percent had grade ≤2 toxicities with radiation pneumonitis (42.3%) and chest wall pain (35%). Radiation pneumonitis and chest wall pain rates were higher in patients with tumor diameters more than 1.5 cm. Conclusion: SF-SBRT is practical and effective treatment technique.

Delta radiomics to track radiation response in lung tumors receiving stereotactic magnetic resonance-guided radiotherapy

Background and purpose

Lung cancer is a leading cause of cancer-related mortality, and stereotactic body radiotherapy (SBRT) has become a standard treatment for early-stage lung cancer. However, the heterogeneous response to radiation at the tumor level poses challenges. Currently, standardized dosage regimens lack adaptation based on individual patient or tumor characteristics. Thus, we explore the potential of delta radiomics from on-treatment magnetic resonance (MR) imaging to track radiation dose response, inform personalized radiotherapy dosing, and predict outcomes.

Materials and methods

A retrospective study of 47 MR-guided lung SBRT treatments for 39 patients was conducted. Radiomic features were extracted using Pyradiomics, and stability was evaluated temporally and spatially. Delta radiomics were correlated with radiation dose delivery and assessed for associations with tumor control and survival with Cox regressions.

Results

Among 107 features, 49 demonstrated temporal stability, and 57 showed spatial stability. Fifteen stable and non-collinear features were analyzed. Median Skewness and surface to volume ratio decreased with radiation dose fraction delivery, while coarseness and 90th percentile values increased. Skewness had the largest relative median absolute changes (22 %-45 %) per fraction from baseline and was associated with locoregional failure (p = 0.012) by analysis of covariance. Skewness, Elongation, and Flatness were significantly associated with local recurrence-free survival, while tumor diameter and volume were not.

Conclusions

Our study establishes the feasibility and stability of delta radiomics analysis for MR-guided lung SBRT. Findings suggest that MR delta radiomics can capture short-term radiographic manifestations of the intra-tumoral radiation effect.

Chemoradiotherapy versus surgery after neoadjuvant chemoimmunotherapy in patients with stage III NSCLC: a real-world multicenter retrospective study

PURPOSE

The optimal treatment after neoadjuvant chemoimmunotherapy for patients with stage III non-small cell lung cancer (NSCLC) is unclear. This study aimed at comparing the efficacy and safety of chemoradiotherapy and surgery after neoadjuvant chemoimmunotherapy in stage III NSCLC.

MATERIALS AND METHODS

We conducted a real-world multicenter retrospective study on patients with stage III NSCLC who received surgery or chemoradiotherapy after neoadjuvant chemoimmunotherapy between October 2018 and December 2022. Progression-free survival (PFS) and overall survival (OS) were assessed from the initiation of neoadjuvant treatment and estimated by the Kaplan‒Meier method. Univariate and multivariate Cox regression models were used to examine potential prognostic factors. One-to-one propensity score matching (PSM) was used to further minimize confounding.

RESULTS

A total of 239 eligible patients were enrolled, with 104 (43.5%) receiving surgery and 135 (56.5%) receiving CRT. After 1:1 PSM, 1- and 2-year PFS rates in patients receiving radical surgery (rSurgery group) vs. patients receiving definitive cCRT (dCCRT group) were 80.0% vs. 79.2% and 67.2% vs. 53.1%, respectively (P = 0.774). One- and 2-year OS rates were 97.5% vs. 97.4% and 87.3% vs. 89.9%, respectively (P = 0.558). Patients in the dCCRT group had a numerically lower incidence of distant metastases compared to those in the rSurgery group (42.9% vs. 70.6%, P = 0.119). The incidence of treatment-related adverse events was similar in both groups, except that the incidence of grade 3/4 hematological toxicity was significantly higher in the dCCRT group (30.0% vs. 10.0%, P = 0.025).

CONCLUSION

Following neoadjuvant chemoimmunotherapy, definitive concurrent chemoradiotherapy may achieve noninferior outcomes to radical surgery in stage III NSCLC.

A systematic review and meta-analysis of pathologic complete response rates for patients with cholangiocarcinoma treated on liver transplant protocols

BACKGROUND AND OBJECTIVES: Many heterogenous orthotopic liver transplant (OLT) protocols exist for patients with unresectable cholangiocarcinoma. Little is known about the incidence, predictors for, and the significance of achieving a pathologic complete response (pCR).

METHODS

We performed a systematic review through September 2022 of the PubMed, Embase, and Web of Science databases. A random-effect meta-analysis was conducted to pool data across studies with reported pCR rates. Heterogeneity between treatment protocols was assessed via subgroup analysis. The pCR and 1-, 3-, and 5-year recurrence-free survival (RFS) and overall survival (OS) rates were extracted as outcomes of interest.

RESULTS

A total of 15 studies reported pCR rates and were grouped by use of the Mayo protocol (4/15), stereotactic body radiation therapy (2/15), and an Other category (9/15). The pooled pCR rate among all studies was 32%. Both radiation technique and duration of CHT showed no significant association with pCR (p = 0.05 and 0.13, respectively). Pooled 1-year RFS and OS after any neoadjuvant therapy and OLT was 80% (95% confidence interval [CI], 0.61-0.91), and 91% (95% CI, 0.87-0.94), respectively. There was no 1-year OS difference detected among the three groups. pCR was not associated with OS in the meta-regression. Pooled 3- and 5-year OS among all studies was 72% and 61%, respectively.

CONCLUSIONS

The pooled incidence of pCR was 32%. Differences in radiation technique did not appear to influence pCR rates and upon meta-regression, pCR was not a surrogate marker for survival.

Sub-lobar resections for peripheral non-small cell lung cancer measuring ≤ 2 cm: Insights from recent clinical trials

The findings of two well conducted trials that randomised 1803 patients with a peripheral non-small cell lung cancer measuring ≤ 2 cm to a lobar to sub-lobar resection have established the latter as a new standard of care. It is important for non-surgical oncologists to appreciate the details of study design and outcomes of both studies, given the possible impact they have for considerations of stereotactic ablative radiotherapy (SABR) for operable patients with early-stage NSCLC. Differences in overall survival between the study populations highlight the impact of confounding factors like smoking history and comorbidities on reported outcomes. For example, despite low post-operative mortality rates in both trials, the 5-year disease-free survival rate in the CALGB 140503 trial was only approximately 60 % with either surgical procedure. Both phase III trials required guideline recommended nodal staging, which does not reflect real world surgical practice, and which may limit the generalisability of the reported findings to local institutional outcomes. Furthermore, the emergence of other malignancies was recorded in 15-18 % of study patients during follow-up, and patients who underwent sub-lobar resections had a better long-term survival associated with a higher likelihood of undergoing additional curative treatments. These findings from the JCOG0802 and the CALGB 140503 will encourage more interest in enrolling patients into ongoing trials comparing surgical resection with SABR.

Stereotactic ablative radiotherapy before resection to avoid delay for early-stage lung cancer or oligometastases during the COVID-19 pandemic: Pathologic outcomes from the SABR-BRIDGE protocol

BACKGROUND

During coronavirus disease 2019 (COVID-19)-related operating room closures, some multidisciplinary thoracic oncology teams adopted a paradigm of stereotactic ablative radiotherapy (SABR) as a bridge to surgery, an approach called SABR-BRIDGE. This study presents the preliminary surgical and pathological results.

METHODS

Eligible participants from four institutions (three in Canada and one in the United States) had early-stage presumed or biopsy-proven lung malignancy that would normally be surgically resected. SABR was delivered using standard institutional guidelines, with surgery >3 months following SABR with standardized pathologic assessment. Pathological complete response (pCR) was defined as absence of viable cancer. Major pathologic response (MPR) was defined as ≤10% viable tissue.

RESULTS

Seventy-two patients underwent SABR. Most common SABR regimens were 34 Gy/1 (29%, n = 21), 48 Gy/3-4 (26%, n = 19), and 50/55 Gy/5 (22%, n = 16). SABR was well-tolerated, with one grade 5 toxicity (death 10 days after SABR with COVID-19) and five grade 2-3 toxicities. Following SABR, 26 patients underwent resection thus far (13 pending surgery). Median time-to-surgery was 4.5 months post-SABR (range, 2-17.5 months). Surgery was reported as being more difficult because of SABR in 38% (n = 10) of cases. Thirteen patients (50%) had pCR and 19 (73%) had MPR. Rates of pCR trended higher in patients operated on at earlier time points (75% if within 3 months, 50% if 3-6 months, and 33% if ≥6 months; p = .069). In the exploratory best-case scenario analysis, pCR rate does not exceed 82%.

CONCLUSIONS

The SABR-BRIDGE approach allowed for delivery of treatment during a period of operating room closure and was well-tolerated. Even in the best-case scenario, pCR rate does not exceed 82%.

Trends and Outcomes of Salvage Lobectomy for Early-stage Non-Small Cell Lung Cancer

OBJECTIVES

There is little data describing the outcomes for patients who develop local recurrences after stereotactic body radiation therapy (SBRT), a standard-of-care treatment for patients with early-stage non-small cell lung cancer. One emerging option is salvage lobectomy. We investigated trends in the use of salvage lobectomy after SBRT and described patient outcomes using a nationally representative sample.

METHODS

This is a retrospective study using the National Cancer Database of patients with non-small cell lung cancer diagnosed from 2004 to 2017. We used descriptive statistics to describe patients who underwent salvage lobectomy. Kaplan-Meier analysis was used to estimate overall survival (OS). Cox proportional modeling was used to identify factors associated with OS.

RESULTS

We identified 276 patients who underwent salvage lobectomy. Ninety-day mortality was 0%. The median survival time for the cohort was 50 months (95% CI, 44 to 58). Median follow-up was 65 months (Interquartile Range: 39 to 96). The factors associated with decreased OS include squamous cell histology (hazard ratio (HR)=1.72, P =0.005) and high grade (1.50, P =0.038). Increased OS was associated with lobectomy performed between 3 and 6 months after SBRT (HR=0.53, P =0.021), lobectomy performed >6 months after SBRT (HR=0.59, P =0.015), and female sex (HR=0.56, P =0.004).

CONCLUSIONS

Salvage lobectomy after local failures of SBRT was associated with no perioperative mortality and favorable long-term outcomes. Our data suggest that lobectomy performed within 3 months of SBRT is associated with worse OS.

NeoAdjuvant pembrolizumab and STEreotactic radiotherapy prior to nephrectomy for renal cell carcinoma (NAPSTER): A phase II randomised clinical trial

Background

Surgery remains the standard of care for localised renal cell carcinoma (RCC). Nevertheless, nearly 50% of patients with high-risk disease experience relapse after surgery, with distant sites being common. Considering improved outcomes in terms of disease-free survival with adjuvant immunotherapy with pembrolizumab, we hypothesise that neoadjuvant SABR with or without the addition of pembrolizumab before nephrectomy will lead to improved disease outcomes by evoking better immune response in the presence of an extensive reserve of tumor-associated antigens.

Methods and analysis

This prospective, open-label, phase II, randomised, non-comparative, clinical trial will investigate the use of neoadjuvant stereotactic ablative body radiotherapy (SABR) with or without pembrolizumab prior to nephrectomy. The trial will be conducted at two centres in Australia that are well established for delivering SABR to primary RCC patients. Twenty-six patients with biopsy-proven clear cell RCC will be recruited over two years. Patients will be randomised to either SABR or SABR/pembrolizumab. Patients in both arms will undergo surgery at 9 weeks after completion of experimental treatment. The primary objectives are to describe major pathological response and changes in tumour-responsive T-cells from baseline pre-treatment biopsy in each arm. Patients will be followed for sixty days post-surgery.

Outcomes and significance

We hypothesize that SABR alone or SABR plus pembrolizumab will induce significant tumor-specific immune response and major pathological response. In that case, either one or both arms could justifiably be used as a neoadjuvant treatment approach in future randomized trials in the high-risk patient population.

CT-based radiomics prediction of complete response after stereotactic body radiation therapy for patients with lung metastases

PURPOSE

Stereotactic body radiotherapy (SBRT) is a key treatment modality for lung cancer patients. This study aims to develop a machine learning-based prediction model of complete response for lung oligometastatic cancer patients undergoing SBRT.

MATERIALS AND METHODS

CT images of 80 pulmonary oligometastases from 56 patients treated with SBRT were analyzed. The gross tumor volumes (GTV) were contoured on CT images. Patients that achieved complete response (CR) at 4 months were defined as responders. For each GTV, 107 radiomic features were extracted using the Pyradiomics software. The concordance correlation coefficients (CCC) between the region of interest (ROI)-based radiomics features obtained by the two segmentations were calculated. Pairwise feature interdependencies were evaluated using the Spearman rank correlation coefficient. The association of clinical variables and radiomics features with CR was evaluated with univariate logistic regression. Two supervised machine learning models, the logistic regression (LR) and the classification and regression tree analysis (CART), were trained to predict CR. The models were cross-validated using a five-fold cross-validation. The performance of models was assessed by receiver operating characteristic curve (ROC) and class-specific accuracy, precision, recall, and F1-measure evaluation metrics.

RESULTS

Complete response was associated with four radiomics features, namely the surface to volume ratio (SVR; p = 0.003), the skewness (Skew; p = 0.027), the correlation (Corr; p = 0.024), and the grey normalized level uniformity (GNLU; p = 0.015). No significant relationship between clinical parameters and CR was found. In the validation set, the developed LR and CART machine learning models had an accuracy, precision, and recall of 0.644 and 0.750, 0.644 and 0.651, and 0.635 and 0.754, respectively. The area under the curve for CR prediction was 0.707 and 0.753 for the LR and CART models, respectively.

CONCLUSION

This analysis demonstrates that radiomics features obtained from pretreatment CT could predict complete response of lung oligometastases following SBRT.

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.

Stereotactic Body Radiation Therapy Versus Ablation Versus Surgery for Early-Stage Lung Cancer in High-Risk Patients

Current treatment for early-stage lung cancer focuses on surgical intervention as the mainstay of treatment; however, this poses issues in patients that are high-risk or unable to tolerate any operation. In this case, sublobar resection or radiation therapy has been the primary treatment for these subsets of patients. Alternative approaches include stereotactic body radiation therapy (SBRT) and thermal ablation. In this article, we focus on treatment strategies using SBRT, thermal ablation, or surgery as it pertains to high-risk patients with early-stage lung cancer.

Research landscape and trends of lung cancer radiotherapy: A bibliometric analysis

BACKGROUND

radiotherapy is one of the major treatments for lung cancer and has been a hot research area for years. This bibliometric analysis aims to present the research trends on lung cancer radiotherapy.

METHOD

On August 31, 2022, the authors identified 9868 articles on lung cancer radiotherapy by the Web of Science (Science Citation Indexing Expanded database) and extracted their general information and the total number of citations. A bibliometric analysis was carried out to present the research landscape, demonstrate the research trends, and determine the most cited papers (top-papers) as well as top-journals on lung cancer radiotherapy. After that, the authors analyzed the recent research hotspots based on the latest publications in top-journals.

RESULTS

These 9868 papers were cited a total of 268,068 times. "Durvalumab after chemoradiotherapy in stage III non-small-cell lung cancer" published in 2017 by Antonia et al.was the most cited article (2110 citations). Among the journals, New England Journal of Medicine was most influential. Moreover, J. Clin. Oncol. and Int. J. Radiat. Oncol. Biol. Phys. was both influential and productive. Corresponding authors represented the USA (2610 articles) and China mainland (2060 articles) took part in most publications and articles with corresponding authors from Netherlands were most cited (46.12 citations per paper). Chemoradiotherapy was the hottest research area, and stereotactic body radiotherapy has become a research hotspot since 2006. Radiotherapy plus immunotherapy has been highly focused since 2019.

CONCLUSIONS

This bibliometric analysis comprehensively and quantitatively presents the research trends and hotspots based on 9868 relevant articles, and further suggests future research directions. The researchers can benefit in selecting journals and in finding potential collaborators. This study can help researchers gain a comprehensive picture of the research landscape, historical development, and recent hotspots in lung cancer radiotherapy and can provide inspiration for future research.

Stereotactic Ablative Radiotherapy in the Treatment of Early-Stage Lung Cancer - A Done Deal?

Stereotactic ablative radiotherapy (SABR) is an important curative-intent treatment option for early-stage non-small cell lung cancer. It offers good cancer control without invasive surgery and has become the standard of care for medically inoperable patients. The literature on SABR for early-stage non-small cell lung cancer is substantial and continues to grow. However, there remain areas of controversy where data are limited - notably the use of SABR in medically operable patients. Other areas of some debate include the treatment of central/ultra-central and large (>5 cm) lesions, as well as treatment with co-existing interstitial lung disease. This review article provides an overview of the current literature together with a discussion of future directions.

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.

Rationale for Combing Stereotactic Body Radiation Therapy with Immune Checkpoint Inhibitors in Medically Inoperable Early-Stage Non-Small Cell Lung Cancer

Simple Summary

The rate of recurrence remains high for lymph node negative early-stage non-small cell lung cancer that are over 2–3 cm in size following stereotactic body radiation therapy (SBRT). This is due to the increased incidence of out-of-field failures, which warrants the addition of systemic therapy. Immune checkpoint inhibitors (ICIs), a class of immunotherapy, may induce a strong distant therapeutic effect known as the “abscopal” effect. This makes them a very suitable class of drugs to be combined with SBRT when treating early lung cancer with high-risk features, such as larger tumor size. In this review, we discuss the rationale and evidence for doing so.

Abstract

Stereotactic body radiation therapy (SBRT) has been widely adopted as an alternative to lobar resection in medically inoperable patients with lymph-node negative (N0) early-stage (ES) non-small cell lung cancer (NSCLC). Excellent in-field local control has been consistently achieved with SBRT in ES NSCLC ≤ 3 cm in size. However, the out-of-field control following SBRT remains suboptimal. The rate of recurrence, especially distant recurrence remains high for larger tumors. Additional systemic therapy is warranted in N0 ES NSCLC that is larger in size. Radiation has been shown to have immunomodulatory effects on cancer, which is most prominent with higher fractional doses. Strong synergistic effects are observed when immune checkpoint inhibitors (ICIs) are combined with radiation doses in SBRT’s dose range. Unlike chemotherapy, ICIs can potentiate a strong systemic response outside of the irradiated field when combined with SBRT. Together with their less toxic nature, ICIs represent a very suitable class of systemic agents to be combined with SBRT when treating ES NSCLC with high-risk features, such as larger tumor size. In this review, we describe the rationale and emerging evidence, as well as ongoing investigations in this area.

A guide for managing patients with stage I NSCLC: deciding between lobectomy, segmentectomy, wedge, SBRT and ablation-part 4: systematic review of evidence involving SBRT and ablation

Background

Clinical decision-making for patients with stage I lung cancer is complex. It involves multiple options [lobectomy, segmentectomy, wedge, stereotactic body radiotherapy (SBRT), thermal ablation], weighing multiple outcomes (e.g., short-, intermediate-, long-term) and multiple aspects of each (e.g., magnitude of a difference, the degree of confidence in the evidence, and the applicability to the patient and setting at hand). A structure is needed to summarize the relevant evidence for an individual patient and to identify which outcomes have the greatest impact on the decision-making.

Methods

A PubMed systematic review from 2000-2021 of outcomes after SBRT or thermal ablation vs. resection is the focus of this paper. Evidence was abstracted from randomized trials and non-randomized comparisons with at least some adjustment for confounders. The analysis involved careful assessment, including characteristics of patients, settings, residual confounding etc. to expose degrees of uncertainty and applicability to individual patients. Evidence is summarized that provides an at-a-glance overall impression as well as the ability to delve into layers of details of the patients, settings and treatments involved.

Results

Short-term outcomes are meaningfully better after SBRT than resection. SBRT doesn't affect quality-of-life (QOL), on average pulmonary function is not altered, but a minority of patients may experience gradual late toxicity. Adjusted non-randomized comparisons demonstrate a clinically relevant detriment in long-term outcomes after SBRT vs. surgery. The short-term benefits of SBRT over surgery are accentuated with increasing age and compromised patients, but the long-term detriment remains. Ablation is associated with a higher rate of complications than SBRT, but there is little intermediate-term impact on quality-of-life or pulmonary function tests. Adjusted comparisons show a meaningful detriment in long-term outcomes after ablation vs. surgery; there is less difference between ablation and SBRT.

Conclusions

A systematic, comprehensive summary of evidence regarding Stereotactic Body Radiotherapy or thermal ablation vs. resection with attention to aspects of applicability, uncertainty and effect modifiers provides a foundation for a framework for individualized decision-making.

The Controversial Role of IL-33 in Lung Cancer

Interleukin-33 (IL-33) belongs to the interleukin-1 (IL-1) family, and its structure is similar to IL-18. When cells are damaged or undergo necrosis, mature form of IL-33 is secreted as a cytokine, which can activate the immune system and provide danger signals. The IL-33/ST2 signaling pathway is composed of IL-33, suppression of tumorigenicity 2 (ST2), and IL-1 receptor accessory protein (IL-1RAcP). IL-33 has been reported to be strongly associated with lung cancer progression, and can exhibit opposite effects on lung cancer under different conditions. In this review, we have summarized the structure and basic functions of IL-33, its possible function in immune regulation, and its role in pulmonary fibrosis as well as in lung cancer. We have highlighted the dual regulation of IL-33 in lung cancer and proposed potential lung cancer treatment regimens, especially new immunotherapies, based on its mechanism of action.

Evaluation of the impact of pre-operative stereotactic radiotherapy on the acute changes in histopathologic and immune marker profiles of brain metastases

The unique acute effects of the large fractional doses that characterize stereotactic radiosurgery (SRS) or radiotherapy (SRT), specifically in terms of antitumor immune cellular processes, vascular damage, tumor necrosis, and apoptosis on brain metastasis have yet to be empirically demonstrated. The objective of this study is to provide the first in-human evaluation of the acute biological effects of SRS/SRT in resected brain metastasis. Tumor samples from patients who underwent dose-escalated preoperative SRT followed by resection with available non-irradiated primary tumor tissues were retrieved from our institutional biorepository. All primary tumors and irradiated metastases were evaluated for the following parameters: tumor necrosis, T-cells, natural killer cells, vessel density, vascular endothelial growth factor, and apoptotic factors. Twenty-two patients with irradiated and resected brain metastases and paired non-irradiated primary tumor samples met inclusion criteria. Patients underwent a median preoperative SRT dose of 18 Gy (Range: 15–20 Gy) in 1 fraction, with 3 patients receiving 27–30 Gy in 3–5 fractions, followed by resection within median interval of 67.8 h (R: 18.25–160.61 h). The rate of necrosis was significantly higher in irradiated brain metastases than non-irradiated primary tumors (p < 0.001). Decreases in all immunomodulatory cell populations were found in irradiated metastases compared to primary tumors: CD3 + (p = 0.003), CD4 + (p = 0.01), and CD8 + (p = 0.01). Pre-operative SRT is associated with acute effects such as increased tumor necrosis and differences in expression of immunomodulatory factors, an effect that does not appear to be time dependent, within the limited intervals explored within the context of this analysis.

Neoadjuvant Programmed Cell Death Protein 1 Blockade Combined With Stereotactic Body Radiation Therapy for Stage III(N2) Non-Small Cell Lung Cancer: A Case Series

The addition of radiotherapy in neoadjuvant chemotherapy did not improve event-free or overall survival in resectable non-small cell lung carcinoma (NSCLC). Neoadjuvant immunotherapy produced major pathologic response(MPR) rate of up to 45%. The potential synergy between radiotherapy and immunotherapy has been described in several studies. We reported outcomes of three cases of stage III/N2 NSCLC treated with neoadjuvant immunotherapy and stereotactic body radiation therapy (SBRT) in a single center. This explanatory trial included treatment-naive patients with stage III resectable NSCLC who received two doses of the programmed cell death protein 1 (PD-1) inhibitor toripalimab after 1 week of receiving SBRT for lung lesions. Thereafter, surgery was planned 4–6 weeks after the second dose. The primary endpoints were safety and feasibility, while the secondary endpoint was the pathologic response rate. Toripalimab combined with SBRT as a neoadjuvant treatment had well-tolerable side effects and did not lead to a delay in surgery. Among the included patients, one achieved pathologic complete response (PCR), one achieved MPR, and one with 20% residual tumor did not achieve MPR. There were few side effects of toripalimab combined with SBRT as a neoadjuvant treatment, and the treatment did not cause a delay in surgery. This study preliminarily explored the outcomes of a new neoadjuvant treatment.

Indications and Parameters Around Postoperative Radiation Therapy for Lung Cancer

Patients with locally advanced resected non-small-cell lung cancer present a high risk of relapse. Although adjuvant platinum-based chemotherapy has become the standard of care, the role of postoperative radiation therapy (PORT) has been controversial for years. In patients with incomplete resection, PORT should be proposed, on the basis of a strong consensus, despite the absence of randomized evidence. In patients with completely resected (R0) non-small-cell lung cancer, a meta-analysis showed poorer outcomes after PORT in the absence of mediastinal involvement (pN0 and pN1). In patients with pN2, the role of PORT was less clear and required further research. The meta-analysis included trials using older radiation techniques and poorer quality of surgery according to today's standards, and selection of patients was not positron emission tomography-based. Newer retrospective and nonrandomized studies and subgroup analyses of randomized trials evaluating adjuvant chemotherapy suggested a survival benefit of PORT in patients with pN2 R0. Two recent randomized trials (Lung ART and PORT-C) evaluating conformal PORT versus no PORT retrieved no disease-free survival advantage for stage IIIA-N2 patients, even if mediastinal relapse was significantly decreased with PORT. PORT had no effect on survival, possibly given the high rate of distant relapse and risk of additional cardiopulmonary toxicity. Ongoing and future analyses are planned in Lung ART to identify patients for whom PORT could be recommended. Incorporation of newer systemic treatments (immune checkpoint inhibitors or targeted therapy in oncogene-addicted patients) is underway in the neoadjuvant and/or adjuvant setting. Better identification of patients at a high risk of disease recurrence, with analysis of circulating tumor DNA, on the basis of the detection of postsurgical minimal (or molecular) residual disease is warranted in future studies.

Inoperable Early-Stage Non-Small-Cell Lung Cancer: Stereotactic Ablative Radiotherapy and Rationale for Systemic Therapy

Stereotactic ablative radiotherapy (SABR) is the standard treatment for medically inoperable, early-stage non-small-cell lung cancer. SABR results in high rates of in-field tumor control, but among larger and more biologically aggressive tumors, regional and distant failures are problematic. Cytotoxic chemotherapy is rarely used in this patient population and the benefit is unclear. Alternative systemic therapy options with a milder side-effect profile are of considerable interest, and several randomized phase III trials are currently testing immune checkpoint inhibitors in this setting. We review the rationale, data, and ongoing studies evaluating systemic therapy in medically inoperable, early-stage non-small-cell lung cancer treated with SABR.

Computed tomography-based radiomic model predicts radiological response following stereotactic body radiation therapy in early-stage non-small-cell lung cancer and pulmonary oligo-metastases

Purpose

Radiomic models elaborate geometric and texture features of tumors extracted from imaging to develop predictors for clinical outcomes. Stereotactic body radiation therapy (SBRT) has been increasingly applied in the ablative treatment of thoracic tumors. This study aims to identify predictors of treatment responses in patients affected by early stage non-small cell lung cancer (NSCLC) or pulmonary oligo-metastases treated with SBRT and to develop an accurate machine learning model to predict radiological response to SBRT.

Materials and Methods

Computed tomography (CT) images of 85 tumors (stage I–II NSCLC and pulmonary oligo-metastases) from 69 patients treated with SBRT were analyzed. Gross tumor volumes (GTV) were contoured on CT images. Patients that achieved complete response (CR) or partial response (PR) were defined as responders. One hundred ten radiomic features were extracted using PyRadiomics module based on the GTV. The association of features with response to SBRT was evaluated. A model using support vector machine (SVM) was then trained to predict response based solely on the extracted radiomics features. Receiver operating characteristic curves were constructed to evaluate model performance of the identified radiomic predictors.

Results

Sixty-nine patients receiving thoracic SBRT from 2008 to 2018 were retrospectively enrolled. Skewness and root mean squared were identified as radiomic predictors of response to SBRT. The SVM machine learning model developed had an accuracy of 74.8%. The area under curves for CR, PR, and non-responder prediction were 0.86 (95% confidence interval [CI], 0.794–0.921), 0.946 (95% CI, 0.873–0.978), and 0.857 (95% CI, 0.789–0.915), respectively.

Conclusion

Radiomic analysis of pre-treatment CT scan is a promising tool that can predict tumor response to SBRT.

Definitive radiotherapy in lieu of systemic therapy for oligometastatic renal cell carcinoma: a single-arm, single-centre, feasibility, phase 2 trial

BACKGROUND

The role of radiotherapy in metastatic renal cell carcinoma is controversial. We prospectively tested the feasibility and efficacy of radiotherapy to defer systemic therapy for patients with oligometastatic renal cell carcinoma.

METHODS

This single-arm, phase 2, feasibility trial was done at one centre in the USA (The MD Anderson Cancer Center, Houston, TX, USA). Patients (aged ≥18 years) with five or fewer metastatic lesions, an Eastern Cooperative Oncology Group status of 0-2, and no more than one previous systemic therapy (if this therapy was stopped at least 1 month before enrolment) without limitations on renal cell carcinoma histology were eligible for inclusion. Patients were treated with stereotactic body radiotherapy (defined as ≤5 fractions with ≥7 Gy per fraction) to all lesions and maintained off systemic therapy. When lesion location precluded safe stereotactic body radiotherapy, patients were treated with hypofractionated intensity-modulated radiotherapy regimes consisting of 60-70 Gy in ten fractions or 52·5-67·5 Gy in 15 fractions. Additional rounds of radiotherapy were allowed to treat subsequent sites of progression. Co-primary endpoints were feasibility (defined as all planned radiotherapy completed with <7 days unplanned breaks) and progression-free survival. All efficacy analyses were intention-to-treat. Safety was analysed in the as-treated population. A second cohort, with the aim of assessing the feasibility of sequential stereotactic body radiotherapy alone in patients with low-volume metastatic disease, was initiated and will be reported separately. This study is registered with ClinicalTrials.gov, NCT03575611.

FINDINGS

30 patients (six [20%] women) were enrolled from July 13, 2018, to Sept 18, 2020. All patients had clear cell histology and had a nephrectomy before enrolment. All patients completed at least one round of radiotherapy with less than 7 days of unplanned breaks. At a median follow-up of 17·5 months (IQR 13·2-24·6), median progression-free survival was 22·7 months (95% CI 10·4-not reached; 1-year progression-free survival 64% [95% CI 48-85]). Three (10%) patients had severe adverse events: two grade 3 (back pain and muscle weakness) and one grade 4 (hyperglycaemia) adverse events were observed. There were no treatment-related deaths.

INTERPRETATION

Sequential radiotherapy might facilitate deferral of systemic therapy initiation and could allow sustained systemic therapy breaks for select patients with oligometastatic renal cell carcinoma.

FUNDING

Anna Fuller Foundation, the Cancer Prevention and Research Institute of Texas (CPRIT), and the National Cancer Institute.

Revisiting neoadjuvant therapy in non-small-cell lung cancer

Despite the rapidly evolving treatment landscape in advanced non-small-cell lung cancer (NSCLC), developments in neoadjuvant and adjuvant treatments have been nascent by comparison. Establishing overall survival benefit in the early-stage setting has been challenging because of the need for large trials and long-term survival data. Encouraged by improved treatment outcomes with a biomarker-driven approach in advanced NSCLC, and recognising the need to improve survival outcomes in early-stage NSCLC, there has been renewed interest in revisiting neoadjuvant strategies. Multiple neoadjuvant trials with targeted therapy and immunotherapy, either alone or in combination with chemotherapy, have yielded unique insights into traditional response parameters, such as the discordance between RECIST response and pathological response, and expanded opportunities for biomarker discovery. With further standardisation of trial endpoints across studies, coupled with the implementation of novel technologies including radiomics and digital pathology, individual risk-stratified neoadjuvant treatment approaches are poised to make a striking impact on the outcomes of early-stage NSCLC.

Stereotactic ablative radiotherapy for operable stage I non-small-cell lung cancer (revised STARS): long-term results of a single-arm, prospective trial with prespecified comparison to surgery

BACKGROUND

A previous pooled analysis of the STARS and ROSEL trials showed higher survival after stereotactic ablative radiotherapy (SABR) than with surgery for operable early-stage non-small-cell lung cancer (NSCLC), but that analysis had notable limitations. This study reports long-term results of the revised STARS trial, in which the SABR group was re-accrued with a larger sample size, along with a protocol-specified propensity-matched comparison with a prospectively registered, contemporary institutional cohort of patients who underwent video-assisted thoracoscopic surgical lobectomy with mediastinal lymph node dissection (VATS L-MLND).

METHODS

This single-arm prospective trial was done at the University of Texas MD Anderson Cancer Center (Houston, TX, USA) and enrolled patients aged 18 years or older with a Zubrod performance status of 0-2, newly diagnosed and histologically confirmed NSCLC with N0M0 disease (squamous cell, adenocarcinoma, large cell, or NSCLC not otherwise specified), and a tumour diameter of 3 cm or less. This trial did not include patients from the previous pooled analysis. SABR dosing was 54 Gy in three fractions (for peripheral lesions) or 50 Gy in four fractions (for central tumours; simultaneous integrated boost to gross tumour totalling 60 Gy). The primary endpoint was the 3-year overall survival. For the propensity-matching analysis, we used a surgical cohort from the MD Anderson Department of Thoracic and Cardiovascular Surgery's prospectively registered, institutional review board-approved database of all patients with clinical stage I NSCLC who underwent VATS L-MLND during the period of enrolment in this trial. Non-inferiority could be claimed if the 3-year overall survival rate after SABR was lower than that after VATS L-MLND by 12% or less and the upper bound of the 95% CI of the hazard ratio (HR) was less than 1·965. Propensity matching consisted of determining a propensity score using a multivariable logistic regression model including several covariates (age, tumour size, histology, performance status, and the interaction of age and sex); based on the propensity scores, one patient in the SABR group was randomly matched with one patient in the VATS L-MLND group using a 5:1 digit greedy match algorithm. This study is registered with ClinicalTrials.gov, NCT02357992.

FINDINGS

Between Sept 1, 2015, and Jan 31, 2017, 80 patients were enrolled and included in efficacy and safety analyses. Median follow-up time was 5·1 years (IQR 3·9-5·8). Overall survival was 91% (95% CI 85-98) at 3 years and 87% (79-95) at 5 years. SABR was tolerated well, with no grade 4-5 toxicity and one (1%) case each of grade 3 dyspnoea, grade 2 pneumonitis, and grade 2 lung fibrosis. No serious adverse events were recorded. Overall survival in the propensity-matched VATS L-MLND cohort was 91% (95% CI 85-98) at 3 years and 84% (76-93) at 5 years. Non-inferiority was claimed since the 3-year overall survival after SABR was not lower than that observed in the VATS L-MLND group. There was no significant difference in overall survival between the two patient cohorts (hazard ratio 0·86 [95% CI 0·45-1·65], p=0·65) from a multivariable analysis.

INTERPRETATION

Long-term survival after SABR is non-inferior to VATS L-MLND for operable stage IA NSCLC. SABR remains promising for such cases but multidisciplinary management is strongly recommended.

FUNDING

Varian Medical Systems and US National Cancer Institute (National Institutes of Health).

Neoadjuvant durvalumab with or without stereotactic body radiotherapy in patients with early-stage non-small-cell lung cancer: a single-centre, randomised phase 2 trial

BACKGROUND

Previous phase 2 trials of neoadjuvant anti-PD-1 or anti-PD-L1 monotherapy in patients with early-stage non-small-cell lung cancer have reported major pathological response rates in the range of 15-45%. Evidence suggests that stereotactic body radiotherapy might be a potent immunomodulator in advanced non-small-cell lung cancer (NSCLC). In this trial, we aimed to evaluate the use of stereotactic body radiotherapy in patients with early-stage NSCLC as an immunomodulator to enhance the anti-tumour immune response associated with the anti-PD-L1 antibody durvalumab.

METHODS

We did a single-centre, open-label, randomised, controlled, phase 2 trial, comparing neoadjuvant durvalumab alone with neoadjuvant durvalumab plus stereotactic radiotherapy in patients with early-stage NSCLC, at NewYork-Presbyterian and Weill Cornell Medical Center (New York, NY, USA). We enrolled patients with potentially resectable early-stage NSCLC (clinical stages I-IIIA as per the 7th edition of the American Joint Committee on Cancer) who were aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0 or 1. Eligible patients were randomly assigned (1:1) to either neoadjuvant durvalumab monotherapy or neoadjuvant durvalumab plus stereotactic body radiotherapy (8 Gy × 3 fractions), using permuted blocks with varied sizes and no stratification for clinical or molecular variables. Patients, treating physicians, and all study personnel were unmasked to treatment assignment after all patients were randomly assigned. All patients received two cycles of durvalumab 3 weeks apart at a dose of 1·12 g by intravenous infusion over 60 min. Those in the durvalumab plus radiotherapy group also received three consecutive daily fractions of 8 Gy stereotactic body radiotherapy delivered to the primary tumour immediately before the first cycle of durvalumab. Patients without systemic disease progression proceeded to surgical resection. The primary endpoint was major pathological response in the primary tumour. All analyses were done on an intention-to-treat basis. This trial is registered with ClinicalTrial.gov, NCT02904954, and is ongoing but closed to accrual.

FINDINGS

Between Jan 25, 2017, and Sept 15, 2020, 96 patients were screened and 60 were enrolled and randomly assigned to either the durvalumab monotherapy group (n=30) or the durvalumab plus radiotherapy group (n=30). 26 (87%) of 30 patients in each group had their tumours surgically resected. Major pathological response was observed in two (6·7% [95% CI 0·8-22·1]) of 30 patients in the durvalumab monotherapy group and 16 (53·3% [34·3-71·7]) of 30 patients in the durvalumab plus radiotherapy group. The difference in the major pathological response rates between both groups was significant (crude odds ratio 16·0 [95% CI 3·2-79·6]; p<0·0001). In the 16 patients in the dual therapy group with a major pathological response, eight (50%) had a complete pathological response. The second cycle of durvalumab was withheld in three (10%) of 30 patients in the dual therapy group due to immune-related adverse events (grade 3 hepatitis, grade 2 pancreatitis, and grade 3 fatigue and thrombocytopaenia). Grade 3-4 adverse events occurred in five (17%) of 30 patients in the durvalumab monotherapy group and six (20%) of 30 patients in the durvalumab plus radiotherapy group. The most frequent grade 3-4 events were hyponatraemia (three [10%] patients in the durvalumab monotherapy group) and hyperlipasaemia (three [10%] patients in the durvalumab plus radiotherapy group). Two patients in each group had serious adverse events (pulmonary embolism [n=1] and stroke [n=1] in the durvalumab monotherapy group, and pancreatitis [n=1] and fatigue [n=1] in the durvalumab plus radiotherapy group). No treatment-related deaths or deaths within 30 days of surgery were reported.

INTERPRETATION

Neoadjuvant durvalumab combined with stereotactic body radiotherapy is well tolerated, safe, and associated with a high major pathological response rate. This neoadjuvant strategy should be validated in a larger trial.

FUNDING

AstraZeneca.

Managing screening-detected subsolid nodules-the Asian perspective

The broad application of low-dose computed tomography (CT) screening has resulted in the detection of many small pulmonary nodules. In Asia, a large number of these detected nodules with a radiological ground glass pattern are reported as lung adenocarcinomas or premalignant lesions, especially among female non-smokers. In this review article, we discuss controversial issues and conditions involving these subsolid pulmonary nodules that we often face in Asia, including a lack or insufficiency of current guidelines; the roles of preoperative biopsy and imaging; the location of lesions; appropriate selection of localization techniques; the roles of dissection and sampling of frozen sections and lymph nodes; multifocal lesions; and the roles of non-surgical treatment modalities. For these complex issues, we have tried to present up-to-date evidence and our own opinions regarding the management of subsolid nodules. It is our hope that this article helps surgeons and physicians to manage the complex issues involving ground glass nodules (GGNs) in a balanced manner in their daily practice and provokes further discussion towards better guidelines and/or algorithms.

Surgeon's Perspective to Local Therapy in Oligometastatic Cancer

Oligometastatic cancer has been recognized as a distinct clinical entity for over 100 years. For decades surgeons have been devising strategies to identify patients with oligmetastatic cancer that have the potential to be cured by surgically removing the oligometastases ("curative intent metastasectomy"). More recently, several studies have suggested there may be benefits to local therapy in oligometastatic cancer patients that are less likely to be cured. This has transformed the practice of local therapy in this setting away from "curative intent" to a broader purpose of "lesion-specific cytoreduction." As a result, the pool of oligometastatic patients eligible for local therapy has been expanded. However, the boundaries that had previously framed the practice of local therapy in oligometastatic cancer have been obscured. The following is a single surgeon's attempt to align the promise of this expanded role of local therapy, with the principles of risk-benefit deliberation that are intrinsic to the surgical discipline.

Integration of Risk Survival Measures Estimated From Pre- and Posttreatment Computed Tomography Scans Improves Stratification of Patients With Early-Stage Non-small Cell Lung Cancer Treated With Stereotactic Body Radiation Therapy

PURPOSE

To predict overall survival of patients receiving stereotactic body radiation therapy (SBRT) for early-stage non-small cell lung cancer (ES-NSCLC), we developed a radiomic model that integrates risk of death estimates and changes based on pre- and posttreatment computed tomography (CT) scans. We hypothesize this innovation will improve our ability to stratify patients into various oncologic outcomes with greater accuracy.

METHODS AND MATERIALS

Two cohorts of patients with ES-NSCLC uniformly treated with SBRT (a median dose of 50 Gy in 4-5 fractions) were studied. Prediction models were built on a discovery cohort of 100 patients with treatment planning CT scans, and then were applied to a separate validation cohort of 60 patients with pre- and posttreatment CT scans for evaluating their performance.

RESULTS

Prediction models achieved a c-index up to 0.734 in predicting survival outcomes of the validation cohort. The integration of the pretreatment risk of survival measures (risk-high vs risk-low) and changes (risk-increase vs risk-decrease) in risk of survival measures between the pretreatment and posttreatment scans further stratified the patients into 4 subgroups (risk: high, increase; risk: high, decrease; risk: low, increase; risk: low, decrease) with significant difference (χ² = 18.549, P = .0003, log-rank test). There was also a significant difference between the risk-increase and risk-decrease groups (χ² = 6.80, P = .0091, log-rank test). In addition, a significant difference (χ² = 7.493, P = .0062, log-rank test) was observed between the risk-high and risk-low groups obtained based on the pretreatment risk of survival measures.

CONCLUSION

The integration of risk of survival measures estimated from pre- and posttreatment CT scans can help differentiate patients with good expected survival from those who will do more poorly following SBRT. The analysis of these radiomics-based longitudinal risk measures may help identify patients with early-stage NSCLC who will benefit from adjuvant treatment after lung SBRT, such as immunotherapy.

Mitigation of radiation-induced pulmonary fibrosis by small-molecule dye IR-780

Radiation-induced pulmonary fibrosis (RIPF) is a common complication during thoracic radiotherapy, but there are few effective treatments. Here, we identify IR-780, a mitochondria-targeted near-infrared (NIR) dye, can selectively accumulate in the irradiated lung tissues. Besides, IR-780 significantly alleviates radiation-induced acute lung injury and fibrosis. Furthermore, our results show that IR-780 prevents the differentiation of fibroblasts and the release of pro-fibrotic factors from alveolar macrophages induced by radiation. Besides, IR-780 downregulates the expression of glycolysis-associated genes, and 2-Deoxy-d-glucose (2-DG) also prevents the development of fibrosis in vitro, suggesting radioprotective effects of IR-780 on RIPF might be related to glycolysis regulation. Finally, IR-780 induces tumour cell apoptosis and enhances radiosensitivity in representative H460 and A549 cell lines. These findings indicate that IR-780 is a potential therapeutic small-molecule dye during thoracic radiotherapy.

Predicting pathological complete response (pCR) after stereotactic ablative radiation therapy (SABR) of lung cancer using quantitative dynamic [18F]FDG PET and CT perfusion: a prospective exploratory clinical study

BACKGROUND

Stereotactic ablative radiation therapy (SABR) is effective in treating inoperable stage I non-small cell lung cancer (NSCLC), but imaging assessment of response after SABR is difficult. This prospective study aimed to develop a predictive model for true pathologic complete response (pCR) to SABR using imaging-based biomarkers from dynamic [¹⁸F]FDG-PET and CT Perfusion (CTP).

METHODS

Twenty-six patients with early-stage NSCLC treated with SABR followed by surgical resection were included, as a pre-specified secondary analysis of a larger study. Dynamic [¹⁸F]FDG-PET and CTP were performed pre-SABR and 8-week post. Dynamic [¹⁸F]FDG-PET provided maximum and mean standardized uptake value (SUV) and kinetic parameters estimated using a previously developed flow-modified two-tissue compartment model while CTP measured blood flow, blood volume and vessel permeability surface product. Recursive partitioning analysis (RPA) was used to establish a predictive model with the measured PET and CTP imaging biomarkers for predicting pCR. The model was compared to current RECIST (Response Evaluation Criteria in Solid Tumours version 1.1) and PERCIST (PET Response Criteria in Solid Tumours version 1.0) criteria.

RESULTS

RPA identified three response groups based on tumour blood volume before SABR (BV_pre-SABR) and change in SUV_max (ΔSUV_max), the thresholds being BV_pre-SABR = 9.3 mL/100 g and ΔSUV_max = - 48.9%. The highest true pCR rate of 92% was observed in the group with BV_pre-SABR < 9.3 mL/100 g and ΔSUV_max < - 48.9% after SABR while the worst was observed in the group with BV_pre-SABR ≥ 9.3 mL/100 g (0%). RPA model achieved excellent pCR prediction (Concordance: 0.92; P = 0.03). RECIST and PERCIST showed poor pCR prediction (Concordance: 0.54 and 0.58, respectively).

CONCLUSIONS

In this study, we developed a predictive model based on dynamic [¹⁸F]FDG-PET and CT Perfusion imaging that was significantly better than RECIST and PERCIST criteria to predict pCR of NSCLC to SABR. The model used BV_pre-SABR and ΔSUV_max which correlates to tumour microvessel density and cell proliferation, respectively and warrants validation with larger sample size studies.

TRIAL REGISTRATION

MISSILE-NSCLC, NCT02136355 (ClinicalTrials.gov). Registered May 8, 2014, https://clinicaltrials.gov/ct2/show/NCT02136355.

Neoadjuvant Immunotherapy for High-Risk, Resectable Malignancies: Scientific Rationale and Clinical Challenges

Neoadjuvant immunotherapy involves administering immune checkpoint inhibitors before surgical resection in high-risk resectable disease. This strategy was shown to have a high pathological response rate and prolonged relapse-free survival in randomized trials in melanoma, glioblastoma, and colon cancer with small numbers of patients. In resectable cancers, immune checkpoint inhibitors such as anti-programmed cell death-1 (PD1) and anti-cytotoxic T-lymphocyte-associated protein-4 (CTLA-4) can enhance antitumor immunity by activating antigen-specific T cells found in the primary tumor. These tumor-reactive T cells continue to exert antitumor effects on remaining neoplastic cells after the resection of the primary tumor, potentially preventing relapses from occurring. Based on the scientific rationale and early clinical observations with surrogate survival endpoints, neoadjuvant immunotherapy may provide an effective alternative to other therapeutic strategies such as adjuvant treatment. However, this can be determined only by conducting randomized controlled trials comparing neoadjuvant immunotherapy with the current standard of care for each tumor site. This review discusses the cellular mechanisms that occur during successful neoadjuvant immunotherapy and highlights the clinical data from the available human studies that support the preclinical mechanistic data. Here we also discuss strategies required for successful neoadjuvant immunotherapy, including combination treatment strategies and resistance mechanisms to neoadjuvant treatment.

Radiotherapy and Immunotherapy Combinations for Lung Cancer

PURPOSE OF REVIEW

Positive results from recent immunotherapy trials of non-small cell lung cancer (NSCLC) have coincided with a greater appreciation for the impact of radiation therapy (RT) on tumor immunity. Here, we summarize key clinical findings and ongoing efforts to combine immunotherapy and RT for the treatment of NSCLC.

RECENT FINDINGS

The role of immunotherapy for NSCLC has expanded significantly following the pivotal approvals of nivolumab and pembrolizumab for metastatic NSCLC, maintenance durvalumab in unresectable stage III NSCLC, and atezolizumab for metastatic NSCLC. Several small early-phase trials have demonstrated the ability of RT to elicit clinically significant tumor immunity. These positive findings support current trial efforts combining RT with immunotherapy for NSCLC. Recently initiated trials of RT and immunotherapy hold significant promise in expanding the therapeutic options for NSCLC. Optimization of therapy will require careful patient selection to yield meaningful improvements in clinical outcomes.

Final results of a dose escalation protocol of stereotactic body radiotherapy for poor surgical candidates with localized renal cell carcinoma

BACKGROUND AND PURPOSE

We previously demonstrated the safety of doses up to 48 Gy in 4 fractions with stereotactic body radiotherapy (SBRT) in poor surgical candidates with localized renal cell carcinoma (RCC). In an additional expansion cohort, we aimed to assess the safety of further dose escalation to 48-60 Gy in 3 fractions.

MATERIAL AND METHODS

Patients were required to have localized RCC and be poor surgical candidates due to medical comorbidities. Dose-limiting toxicity (DLT) was defined as acute (<180 days) grade ≥3 gastrointestinal/genitourinary toxicity by CTCAEv4. Tumor response was assessed using RECIST 1.1 criteria measurements every 6 months for 3 years and optional percutaneous biopsy.

RESULTS

Groups of 4, 4, and 3 patients received 48, 54, and 60 Gy in 3 fractions, respectively from 2012 to 2016. Median follow-up was 34.3 months. Zero DLTs were observed. Acute toxicities were limited to grade 1 fatigue and nausea in 45.5% and 18.1%. Late grade 2+ and grade 3+ possibly treatment-related events occurred in 18.1% and 9.1%, respectively. Three-year local control was 90% by RECIST 1.1 criteria. Five of 5 post-treatment biopsies in the expansion cohort were positive by Hematoxylin and Eosin staining. Three of the 5 patients with positive biopsies have been observed for 1.2-3.9 years without evidence of progression.

CONCLUSION

Dose escalation to 60 Gy in 3 fractions was achieved without DLTs. Favorable local control rates were observed, and the interpretation of post-SBRT biopsies remains uncertain. Further studies comparing SBRT to percutaneous ablation for poor surgical candidates with RCC are warranted.

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.

Tumour response 3 months after neoadjuvant single-fraction radiotherapy for low-risk breast cancer

Introduction

Standard treatment for early-stage invasive breast cancer (bca) consists of breast-conserving surgery and several weeks of adjuvant radiotherapy (rt). Neoadjuvant single-fraction rt is a novel approach for early-stage bca. We sought to investigate the effect of delaying surgery after neoadjuvant rt with respect to the rate of pathologic response (pr).

Methods

Women 65 years of age or older with a new diagnosis of stage i luminal A bca were eligible for inclusion. A single 20 Gy dose to the primary breast tumour was given, followed by breast-conserving surgery 3 months later. The primary endpoint was the pr rate assessed by microscopic evaluation using the Miller-Payne system.

Results

To date, 10 patients have been successfully treated. Median age of the patients was 72 years (range: 65-84 years). In 8 patients, neoadjuvant rt resulted in a tumour pr with median residual cellularity of 3%. No immediate rt complications other than mild dermatitis were noted.

Conclusions

This study demonstrates a method for delivering single-fraction rt that can lead to a high level of pr in most patients. Continued accrual to this study and subsequent trials are needed to determine the feasibility, safety, and role of this novel technique in the management of early-stage bca.

Circulating Tumor Cells Are Associated with Recurrent Disease in Patients with Early-Stage Non-Small Cell Lung Cancer Treated with Stereotactic Body Radiotherapy

PURPOSE

Although stereotactic body radiotherapy (SBRT) is effective in early-stage non-small cell lung cancer (NSCLC), approximately 10%-15% of patients will fail regionally and 20%-25% distantly. We evaluate a novel circulating tumor cell (CTC) assay as a prognostic marker for increased risk of recurrence following SBRT.

EXPERIMENTAL DESIGN

Ninety-two subjects (median age, 71 years) with T1a (64%), T1b (23%), or T2a (13%) stage I NSCLC treated with SBRT were prospectively enrolled. CTCs were enumerated by utilizing a GFP-expressing adenoviral probe that detects elevated telomerase activity in cancer cells. Samples were obtained before, during, and serially up to 24 months after treatment. SBRT was delivered to a median dose of 50 Gy (range, 40-60 Gy), mostly commonly in four to five fractions (92%).

RESULTS

Thirty-eight of 92 subjects (41%) had a positive CTC test prior to SBRT. A cutoff of ≥5 CTCs/mL before treatment defined favorable (n = 78) and unfavorable (n = 14) prognostic groups. Increased risk of nodal (P = 0.04) and distant (P = 0.03) failure was observed in the unfavorable group. Within 3 months following SBRT, CTCs continued to be detected in 10 of 35 (29%) subjects. Persistent detection of CTCs was associated with increased risk of distant failure (P = 0.04) and trended toward increased regional (P = 0.08) and local failure (P = 0.16).

CONCLUSIONS

Higher pretreatment CTCs and persistence of CTCs posttreatment is significantly associated with increased risk of recurrence outside the targeted treatment site. This suggests that CTC analysis may potentially identify patients at higher risk for regional or distant recurrences and who may benefit from either systemic therapy and/or timely locoregional salvage treatment.