Stereotactic body radiation therapy (SBRT) for lung cancer patients previously treated with conventional radiotherapy: a review

Effects of electron density force to 1.0 and fill to 1.0 on VMAT treatment plans for lung SBRT

PURPOSE

The aim of this study is to determine the effect of forcing and filling the electron density (ED) to 1.0 of the planning target volume (PTV) overdose distribution in lung SBRT treatment leading to shortening patient treatment time and increasing patient comfort by reducing MU/fraction due to ED manipulation effect.

METHODS

In this study, 36 lung SBRT plans of 12 suitable patients who prescribed a total dose of 50 Gy in five fractions were generated with Monaco v.5.10 TPS using the Monte Carlo (MC) algorithm and volumetric modulated arc therapy (VMAT) technique by PTV ED values forcing as well as filling to 1.0 and comparatively assessed. The first group of plans was created by using the patient's original ED, second and third groups of plans were reoptimized by forcing and filling the ED of PTV to 1.0, respectively, therefore acquiring a new dose distribution which lead to comparatively assessment the effects of changes in ED on PTV and OAR doses.

RESULTS

Assessment of treatment plans revealed that mean MU/fx numbers were decreased by 76% and 75.25% between Groups 1 and 2, Groups 1 and 3, respectively. The number of segments was also reduced in Group 1 by up to 15% compared with Groups 2 and 3. Maximum HI and CI differences for PTV between Groups 1 and 2 were less than 1% and Groups 1 and 3 were 1.5% which indicates all 3 group plans were comparable in terms of dose distribution within PTV.

CONCLUSIONS

Forcing and filling the ED of PTV to 1.0 strategy has provided reduced a number of segments and MU/fx without a significant change in PTV mean and maximum doses, thereby decreasing treatment time and patient discomfort during treatment. This process should be considered in line of a potential number of patients as well as prescribed dose and MU/fx numbers.

A novel predictor for dosimetry data of lung and the radiation pneumonitis incidence prior to SBRT in lung cancer patients

Normal tissue complication probability (NTCP) models for radiation pneumonitis (RP) in lung cancer patients with stereotactic body radiation therapy (SBRT), which based on dosimetric data from treatment planning, are limited to patients who have already received radiation therapy (RT). This study aims to identify a novel predictive factor for lung dose distribution and RP probability before devising actionable SBRT plans for lung cancer patients. A comprehensive correlation analysis was performed on the clinical and dose parameters of lung cancer patients who underwent SBRT. Linear regression models were utilized to analyze the dosimetric data of lungs. The performance of the regression models was evaluated using mean squared error (MSE) and the coefficient of determination (R2). Correlational analysis revealed that most clinical data exhibited weak correlations with dosimetric data. However, nearly all dosimetric variables showed "strong" or "very strong" correlations with each other, particularly concerning the mean dose of the ipsilateral lung (MI) and the other dosimetric parameters. Further study verified that the lung tumor ratio (LTR) was a significant predictor for MI, which could predict the incidence of RP. As a result, LTR can predict the probability of RP without the need to design an elaborate treatment plan. This study, as the first to offer a comprehensive correlation analysis of dose parameters, explored the specific relationships among them. Significantly, it identified LTR as a novel predictor for both dose parameters and the incidence of RP, without the need to design an elaborate treatment plan.

Invasive Nodal Staging via Endobronchial Ultrasound and Outcome in Patients Treated with Stereotactic Body Radiation Therapy for Early-Stage Non-Small Cell Lung Cancer - Results from a Single Institution Study

INTRODUCTION

Stereotactic body radiation therapy (SBRT) is an effective treatment for medically inoperable early-stage non-small cell lung cancer (NSCLC). The prognostic value of invasive nodal staging (INS) for patients undergoing SRBT has not been studied extensively. Herein, we report the impact of INS in addition to 18F-FDG-PET on treatment outcome for patients with NSCLC undergoing SBRT.

MATERIALS AND METHODS

Patients with stage I/ II NSCLC who underwent SBRT were included with IRB approval. Clinical, dosimetric, and radiological data were obtained. Overall survival (OS), regional recurrence free survival (RRFS), local recurrence free survival (LRFS), and distant recurrence free survival (DRFS) were analyzed using Kaplan Meyer method. Univariable analysis (UVA) and multivariable analysis (MVA) were performed to assess the relationship between the variables and the outcomes.

RESULTS

A total of 376 patients were included in the analysis. Median follow up was 43 months (IQ 32.6-45.8). Median OS, LRFS, RRFS, DRFS were 40, 32, 32, 33 months, respectively. The 5-year local, regional, and distant failure rates were 13.4%, 23.5% and 25.3%, respectively. The 1-year, 3-year and 5-year OS were 83.8%, 55.6%, and 36.3%, respectively. On MVA, INS was not a predictor of either improved overall or any recurrence free survival endpoints while larger tumor size, age, and adjusted Charleston co-morbidity index (aCCI) were significant for inferior LRFS, RRFS, and DRFS.

CONCLUSION

Invasive nodal staging did not improve overall or recurrence free survival among patients with early-stage NSCLC treated with SBRT whereas older age, aCCI, and larger tumor size were significant predictors of LRFS, RRFS, and DRFS.

Tetrahydrobiopterin metabolism attenuates ROS generation and radiosensitivity through LDHA S-nitrosylation: novel insight into radiogenic lung injury

Genotoxic therapy triggers reactive oxygen species (ROS) production and oxidative tissue injury. S-nitrosylation is a selective and reversible posttranslational modification of protein thiols by nitric oxide (NO), and 5,6,7,8-tetrahydrobiopterin (BH4) is an essential cofactor for NO synthesis. However, the mechanism by which BH4 affects protein S-nitrosylation and ROS generation has not been determined. Here, we showed that ionizing radiation disrupted the structural integrity of BH4 and downregulated GTP cyclohydrolase I (GCH1), which is the rate-limiting enzyme in BH4 biosynthesis, resulting in deficiency in overall protein S-nitrosylation. GCH1-mediated BH4 synthesis significantly reduced radiation-induced ROS production and fueled the global protein S-nitrosylation that was disrupted by radiation. Likewise, GCH1 overexpression or the administration of exogenous BH4 protected against radiation-induced oxidative injury in vitro and in vivo. Conditional pulmonary Gch1 knockout in mice (Gch1fl/fl; Sftpa1-Cre+/- mice) aggravated lung injury following irradiation, whereas Gch1 knock-in mice (Gch1lsl/lsl; Sftpa1-Cre+/- mice) exhibited attenuated radiation-induced pulmonary toxicity. Mechanistically, lactate dehydrogenase (LDHA) mediated ROS generation downstream of the BH4/NO axis, as determined by iodoacetyl tandem mass tag (iodoTMT)-based protein quantification. Notably, S-nitrosylation of LDHA at Cys163 and Cys293 was regulated by BH4 availability and could restrict ROS generation. The loss of S-nitrosylation in LDHA after irradiation increased radiosensitivity. Overall, the results of the present study showed that GCH1-mediated BH4 biosynthesis played a key role in the ROS cascade and radiosensitivity through LDHA S-nitrosylation, identifying novel therapeutic strategies for the treatment of radiation-induced lung injury.

Developing a clinical-radiomic prediction model for 3-year cancer-specific survival in lung cancer patients treated with stereotactic body radiation therapy

PURPOSE

The study aims to develop and validate a combined model for predicting 3-year cancer-specific survival (CSS) in lung cancer patients treated with stereotactic body radiation therapy (SBRT) by integrating clinical and radiomic parameters.

METHODS

Clinical data and pre-treatment CT images were collected from 102 patients treated with lung SBRT. Multivariate logistic regression and the least absolute shrinkage and selection operator were used to determine the clinical and radiomic factors associated with 3-year CSS. Three prediction models were developed using clinical factors, radiomic factors, and a combination of both. The performance of the models was assessed using receiver operating characteristic curve and calibration curve. A nomogram was also created to visualize the 3-year CSS prediction.

RESULTS

With a 36-month follow-up, 40 patients (39.2%) died of lung cancer and 62 patients (60.8%) survived. Three clinical factors, including gender, clinical stage, and lymphocyte ratio, along with three radiomic features, were found to be independent factors correlated with 3-year CSS. The area under the curve values for the clinical, radiomic, and combined model were 0.839 (95% CI 0.735-0.914), 0.886 (95% CI 0.790-0.948), and 0.914 (95% CI 0.825-0.966) in the training cohort, and 0.757 (95% CI 0.580-0.887), 0.818 (95% CI 0.648-0.929), and 0.843 (95% CI 0.677-0.944) in the validation cohort, respectively. Additionally, the calibration curve demonstrated good calibration performance and the nomogram created from the combined model showed potential for clinical utility.

CONCLUSION

A clinical-radiomic model was developed to predict the 3-year CSS for lung cancer patients treated with SBRT.

Developing a Prediction Model for Radiation Pneumonitis in Lung Cancer Patients Treated With Stereotactic Body Radiation Therapy Combined With Clinical, Dosimetric Factors, and Laboratory Biomarkers

BACKGROUND

The study aims to identify the risk factors and develop a model for predicting grade ≥2 radiation pneumonitis (RP) for lung cancer patients treated with stereotactic body radiation therapy (SBRT).

MATERIALS AND METHODS

Clinical data, dosimetric data, and laboratory biomarkers from 186 patients treated with lung SBRT were collected. Univariate and multivariate logistic regression were performed to determine the predictive factors for grade ≥2 RP. Three models were developed by using the clinical, dosimetric, and combined factors, respectively.

RESULTS

With a median follow-up of 36 months, grade ≥2 RP was recorded in 13.4% of patients. On univariate logistic regression analysis, clinical factors of age and lung volume, dosimetric factors of treatment durations, fractional dose and V10, and laboratory biomarkers of neutrophil, PLT, PLR, and Hb levels were significantly associated with grade ≥2 RP. However, on multivariate analysis, only age, lung volume, fractional dose, V10, and Hb levels were independent factors. AUC values for the clinical, dosimetric, and combined models were 0.730 (95% CI, 0.660-0.793), 0.711 (95% CI, 0.641-0.775) and 0.830 (95% CI, 0.768-0.881), respectively. The combined model provided superior discriminative ability than the clinical and dosimetric models (P < .05).

CONCLUSION

Age, lung volume, fractional dose, V10, and Hb levels were demonstrated to be significant factors associated with grade ≥2 RP for lung cancer patients after SBRT. A novel model combining clinical, dosimetric factors, and laboratory biomarkers improved predictive performance compared with the clinical and dosimetric model alone.

Non-small cell lung cancer (NSCLC): A review of risk factors, diagnosis, and treatment

Lung cancer remains the leading cause of cancer deaths. Non-small cell lung cancer (NSCLC) is the most frequent subtype of lung cancer. Surgery, radiation, chemotherapy, immunotherapy, or molecularly targeted therapy is used to treat NSCLC. Nevertheless, many patients who accept surgery likely develop distant metastases or local recurrence. In recent years, targeted treatments and immunotherapy have achieved improvement at a breakneck pace. Therapy must be customized for each patient based on the specific medical condition, as well as other variables. It is critical to have an accurate NSCLC sub-classification for tailored treatment, according to the latest World Health Organization standards.

Toward Improved Outcomes for Patients With Lung Cancer Globally: The Essential Role of Radiology and Nuclear Medicine

PURPOSE

Key to achieving better population-based outcomes for patients with lung cancer is the improvement of medical imaging and nuclear medicine infrastructure globally. This paper aims to outline why and spark relevant health systems strengthening.

METHODS

The paper synthesizes the global lung cancer landscape, imaging referral guidelines (including resource-stratified ones), the reliance of TNM staging upon imaging, relevant multinational health technology assessments, and precisely how treatment selection and in turn patient outcomes hinge upon imaging findings. The final discussion presents data on current global gaps in both diagnostics (including imaging) and therapies and how, informed by such data, improved population-based outcomes are tangible through strategic planning.

RESULTS

Imaging findings are central to appropriate lung cancer patient management and can variably lead to life-prolonging interventions and/or to life-enhancing palliative measures. Early-stage lung cancer can be treated with curative intent but, unfortunately, most patients with lung cancer still present at advanced stages and many patients lack access to both diagnostics and therapies. Furthermore, half of lung cancer cases occur in low- and middle-income countries. The role of medical imaging and nuclear medicine in lung cancer management, as outlined herein, may help inform strategic planning.

CONCLUSION

Lung cancer is the number one cancer killer worldwide. The essential role that medical imaging and nuclear medicine play in early diagnosis and disease staging cannot be overstated, pivotal in selecting the many patients for whom measurably improved outcomes are attainable. Prevention synergized with patient-centered, compassionate, high-quality lung cancer management provision mandate that strategic population-based planning, including universal health coverage strategies, should extend well beyond the scope of disease prevention to include both curative and noncurative treatment options for the millions afflicted with lung cancer.

Serum Metabolomic Analysis of Radiation-Induced Lung Injury in Rats

Radiation-induced lung injury is a common complication of radiotherapy for lung cancer, breast cancer, esophageal cancer, and thymoma. This study aims to illustrate biomarkers of radiation-induced lung injury and its potential mechanism through the study of metabolomic alterations in serum of Sprague-Dawley rats with different radiation doses. Serum from 0, 10, or 20 Gy irradiated rats were collected and subjected to gas chromatography-mass spectrometry. The result showed that there were 23 dysregulated metabolites between the 10 Gy irradiation group and the 0 Gy control group, whereas 36 preferential metabolites were found between the 20 Gy irradiated rat serum and the control groups. Among them, there were 19 common differential metabolites in the 2 irradiation groups, including 3 downregulated (benzyl thiocyanate, carbazole, and N-formyl-L-methionine) and 16 upregulated metabolites. We further analyzed the metabolic pathways of different metabolites; the results showed that there were 3 significant enrichment pathways in the 10 Gy vs 0 Gy group and 7 significant enrichment pathways in the 20 Gy vs 0 Gy group. Among them, taurine and hypotaurine metabolism, riboflavin metabolism, and glyoxylate and dicarboxylate metabolism were the common metabolic enrichment pathways of the 10 Gy vs 0 Gy group and the 20 Gy vs 0 Gy group.

A review on engineered magnetic nanoparticles in Non-Small-Cell lung carcinoma targeted therapy

There are growing appeals forthe design of efficacious treatment options for non-small-cell lung carcinoma (NSCLC) as it accrues to ~ 85% cases of lung cancer. Although platinum-based doublet chemotherapy has been the main therapeutic intervention in NSCLC management, this leads to myriad of problems including intolerability to the doublet regimens and detrimental side effects due to high doses. A new approach is therefore needed and warrants the design of targeted drug delivery systems that can halt tumor proliferation and metastasis by targeting key molecules, while exhibiting minimal side effects and toxicity. This review aims to explore the rational design of magnetic nanoparticles for the development of tumor-targeting systems for NSCLC. In the review, we explore the anticancer merits of conjugated linoleic acid (CLA) and provide a concise incursion into its application for the invention of functionalized magnetic nanoparticles in the targeted treatment of NSCLC. Recent nanoparticle-based targeted chemotherapies for targeting angiogenesis biomarkers in NSCLC will also be reviewed to further highlight versatility of magnetic nanoparticles. These developments through molecular tuning at the nanoscale and supported by comprehensive pre-clinical studies could lead to the establishment of precise nanosystems for tumor-homing cancer therapy.

The interplay between DNA damage and autophagy in lung cancer: A mathematical study

The rising mortality in lung cancer, as well as the constraints of the existing drugs, have made it a major research topic. DNA damage marks the early onset of cancer as it often results from vulnerabilities due to UV rays, oxidative stress, ionizing radiation, and various types of genotoxic attacks. p53 plays an unequivocal role in the DNA repair process and has an abiding presence at the crossroads of the pathways linking DNA damage and cancer. p53 also regulates autophagy in a dual manner based on its cellular localization. The plexus of autophagy regulated by p53 includes AMPK and BCL2, which are positive and negative regulators of prime autophagy inducer beclin1, respectively. Although autophagy is a quintessential process, its levels need to be monitored as uncontrolled autophagy may lead to cell death. The association of p53 and autophagic cell death is very vital as the former acts whenever any threat comes to DNA while the latter may play a role in getting rid of the culprit cell. Therefore, in this paper, we have formulated a seven-dimensional mathematical model connecting p53, DNA damage, and autophagy in lung cancer. We performed both local and global sensitivity analysis along with parameter recalibration analysis to understand the system dynamics. We hypothesized that, by the modulation of beclin1 level, the regulation of AMPK and BCL2 could be a possible strategy to mitigate the progression of lung cancer.

Stereotactic lung reirradiation for local relapse: A case series

Introduction

Local recurrence after lung SBRT for early stage NSCLC is rare but its treatment remains a challenge due to limited surgical options. We report a case series of 5 patients treated by stereotactic lung salvage reirradiation for local relapse after a previous lung SBRT.

Material and methods

Included patients presented an isolated primary lung relapse within at least the 50% isodose of the previous SBRT treatment. Typical reirradiation schedule was 60 Gy in 8 fractions at isodose 80% and was delivered by Cyberknife® using Synchrony® fiducial tracking system. Dose summations were performed to evaluate the safety of the reirradiation.

Results

We identified 5 patients presenting peripheral lesions. All reirradiated lesions were locally controlled after a median follow-up of 11.1 months (6,7-12,2), while PFS at 6 months was 60% (n = 3). We did not notice any Grade 3 or more acute or late adverse event.

Conclusion

We observed encouraging short-term outcome of lung SBRT reirradiation in patients presenting isolated local relapse of an early-stage NSCLC. Further studies are necessary to confirm the safety and efficiency of this salvage treatment approach.

Evaluation of thoracic surface motion during the free breathing and deep inspiration breath hold methods

The aim of this study was to evaluate thoracic surface motion from chest wall expansion during free breathing (FB) and deep inspiration breath hold (DIBH) methods, measured with and without 4-dimensional computed tomography (4D-CT) simulation, using equipment developed in-house. The respiratory amplitude and chest wall expansion were evaluated at 5 levels of the thorax, (the sterno-clavicular joint (SCJ), the second level, the intermammary line (IML), the fourth level and the caudal end of the xiphoid process (XP)) using radiopaque wires and potentiometers, with a CT scan simultaneously. This study included 25 examinees (10 volunteers performed FB, 10 volunteers performed DIBH and 5 patients performed FB). For low and irregular respiration, coaching was used, and its impact was evaluated for both breathing methods, FB and DIBH. The breathing amplitude performed with FB between volunteers and patients was not detectable at the SCJ; increasing to the abdomen, 3 mm vs 2 mm (p = 0.326) at the second level; 6 mm vs 4 mm (p = 0.042) at the IML; 10 mm vs 8 mm (p < 0.01) at the fourth level; and 23 mm vs 19 mm (p < 0.001) at the XP. Contrary to the DIBH, where breathing amplitude was greater at 2 first levels 18 mm (SCJ) and 20 mm (second level), decreasing to the abdomen, 14 mm (IML); 11 mm (fourth level); and 10 mm (XP). Chest wall expansion was not detected at the SCJ, while at other levels measured from 1 to 7 mm. Coaching was improve breathing amplitude, for both methods, FB (3 mm) and DIBH (5 mm). The location of amplification is different depending on the breathing method and the in-house phantom was useful to check the amplification level.

Scarred Lung. An Update on Radiation-Induced Pulmonary Fibrosis

Radiation-induced pulmonary fibrosis is a common severe long-time complication of radiation therapy for tumors of the thorax. Current therapeutic options used in the clinic include only supportive managements strategies, such as anti-inflammatory treatment using steroids, their efficacy, however, is far from being satisfactory. Recent studies have demonstrated that the development of lung fibrosis is a dynamic and complex process, involving the release of reactive oxygen species, activation of Toll-like receptors, recruitment of inflammatory cells, excessive production of nitric oxide and production of collagen by activated myofibroblasts. In this review we summarized the current state of knowledge on the pathophysiological processes leading to the development of lung fibrosis and we also discussed the possible treatment options.

Primary and Acquired Resistance to Immunotherapy in Lung Cancer: Unveiling the Mechanisms Underlying of Immune Checkpoint Blockade Therapy

After several decades without maintained responses or long-term survival of patients with lung cancer, novel therapies have emerged as a hopeful milestone in this research field. The appearance of immunotherapy, especially immune checkpoint inhibitors, has improved both the overall survival and quality of life of patients, many of whom are diagnosed late when classical treatments are ineffective. Despite these unprecedented results, a high percentage of patients do not respond initially to treatment or relapse after a period of response. This is due to resistance mechanisms, which require understanding in order to prevent them and develop strategies to overcome them and increase the number of patients who can benefit from immunotherapy. This review highlights the current knowledge of the mechanisms and their involvement in resistance to immunotherapy in lung cancer, such as aberrations in tumor neoantigen burden, effector T-cell infiltration in the tumor microenvironment (TME), epigenetic modulation, the transcriptional signature, signaling pathways, T-cell exhaustion, and the microbiome. Further research dissecting intratumor and host heterogeneity is necessary to provide answers regarding the immunotherapy response and develop more effective treatments for lung cancer.

Risk factors for symptomatic radiation pneumonitis after stereotactic body radiation therapy (SBRT) in patients with non-small cell lung cancer

BACKGROUND AND PURPOSE

Radiation pneumonitis (RP) can be a potential fatal toxicity of stereotactic body radiation therapy (SBRT) for medically inoperable non-small cell lung cancer (NSCLC). This study aimed to examine the risk factors that predict RP and explore dosimetric tolerance for safe practice in a large institutional series of NSCLC patients.

MATERIALS AND METHODS

Patients with early-stage and locally recurrent NSCLC who received lung SBRT between 2002 and 2015 formed the study population. The primary endpoint was grade 2 or above radiation pneumonitis (RP2). Lungs were re-contoured consistently by one radiation oncologist according to the RTOG atlas for organs at risk. Dosimetric factors were computed consistently with exclusion of gross tumor volume of either ipsilateral, contralateral, or total lungs.

RESULTS

A total of 339 patients were eligible. With a median follow-up of 47 months, RP2 was recorded in 10% patients. History of respiratory comorbidity, previous thoracic radiation, right lung location, mean lung doses of total or ipsilateral lung, and total lung volume receiving 20 Gy were all significantly associated with the risk of RP2. The dosimetric parameters of contralateral lung, including mean dose and volume receiving more than 5, 10, and 20 Gy, were not significantly associated with RP2 (ps > 0.05). A model of combining significant clinical and dosimetric factors had a predictive accuracy AUC of 0.76. According to this model, RP2 can be limited to <10% should the patient have no previous lung radiation and the mean dose of total and ipsilateral lungs be kept less than 6 Gy and 20 Gy, respectively.

CONCLUSION

Dosimetric factors of total or ipsilateral lung together with important clinical factors were significant risk factors for symptomatic radiation pneumonitis after SBRT. Constraining mean lung dose can limit clinically significant lung toxicity.

Impact of Sarcopenia on Survival in Patients With Early-Stage Lung Cancer Treated With Stereotactic Body Radiation Therapy

Background

Sarcopenia has been associated with poor survival among cancer patients. Normalized total psoas area (NTPA) has been used as a surrogate for defining sarcopenia. Few data exist characterizing the impact of sarcopenia and other metrics of fitness on clinical outcomes in patients with early-stage non-small cell lung cancer (NSCLC) treated non-invasively with stereotactic body radiotherapy (SBRT).

Methods

To assess the association between sarcopenia and clinical outcomes, we conducted a retrospective analysis of consecutive patients treated with SBRT from 2013 to 2019 . Overall survival (OS), local failure free survival (LFS), distant failure free survival (DFS), NTPA, body mass index (BMI), and Charlson comorbidity index (CCI) were included for analysis. NTPA was calculated by measuring the psoas volume at the L3 vertebra and normalizing for patient height and gender. Survival functions were evaluated using the Kaplan-Meier method. Log-rank test and Cox-proportional hazards were performed for categorical and continuous variables, respectively. Significance was set as p < 0.05.

Results

A total of 91 patients met the criteria. The median age was seven years and Karnofsky Performance Status score (KPS) was 80 (range: 60-100). Approximately 79% of patients had T1 tumors. Median radiation dose and number of fractions were 60 Gy (range: 45-60) and 5 fractions (range: 3-5). Median NTPA was 531.16 mm²/m² (range: 90.4-1356.2). After normalization (sarcopenia: <385 mm²/m², female; <585 mm²/m^2, male), 39 patients (42.8%) had sarcopenia. NTPA had no association with OS (p = 0.7), LFS (p = 0.9), or DFS (p = 0.5). Increasing BMI was associated with improved OS (HR 0.90, 95% CI 0.83-0.98). With a median follow-up of 23.4 months, median OS was 60, 60, and 45.9 months (p = 0.37) in all patients, non-sarcopenic patients, and sarcopenic patients, respectively.

Conclusion

Sarcopenia was not associated with OS, LFS, or DFS. Increasing BMI is associated with improved OS. Future, prospective work is needed to define the impact of sarcopenia and other fitness metrics on clinical outcomes among NSCLC patients treated non-invasively with SBRT.

A long-term survival case following salvage stereotactic radiotherapy for local recurrence after definitive chemoradiotherapy for stage III non-small cell lung cancer

A 56-year-old male with stage IIIA (UICC 7th) non-small cell lung cancer (adenocarcinoma) received radiotherapy with 66 Gy/33 fractions concomitant with CBDCA and PTX. A partial response was achieved after chemoradiotherapy and the tumor continued to shrink over a period of 1 year; however, regrowth of the tumor attached to the aortic arch was observed without any other residual tumor or metastases. We diagnosed recurrence with slightly increased ¹⁸F-FDG uptake (maximum standardized uptake value: 12.2). Stereotactic radiotherapy was performed for the relapsed lesion with 60 Gy/10 fractions. The patient has survived for more than 5 years after stereotactic radiotherapy without recurrence or metastases, although he has been suffering from chest pain that has required treatment with a low dose of oxycodone.

Effectiveness and Safety of Reirradiation With Stereotactic Ablative Radiotherapy of Lung Cancer After a First Course of Thoracic Radiation: A Meta-analysis

OBJECTIVE

The effectiveness and safety of reirradiation with stereotactic ablative radiotherapy (re-SABR) in patients with recurrence after a previous course of radiation are limited to small series. We carried out a meta-analysis to summarize existing data and identify trends in overall survival (OS), local control (LC), and toxicity after re-SABR in patients with recurrence of lung cancer.

MATERIALS AND METHODS

Eligible studies were identified on Medline, Embase, the Cochrane Library, and the proceedings of annual meetings through June 2019. We followed the PRISMA and MOOSE guidelines. A meta-regression analysis was carried out to assess whether there is a relationship between moderator variables and outcomes. A P-value<0.05 was considered significant.

RESULTS

Twenty observational studies with a total of 595 patients treated were included. The 2-year OS and LC were 0.54 (95% confidence interval [CI]: 0.48-0.61) and 0.73 (95% CI: 0.66-0.80), respectively. The rate of any toxicity grade ≥3 was 0.098 (95% CI: 0.06-13.6), with 9 grade 5 toxicity (1.5%). In the meta-regression, the re-SABR dose (P=0.028), tumor size (P=0.031), and time to recurrence (P=0.018) showed an association with survival. For LC, the re-SABR dose (P=0.034) and tumor size (P=0.040) were statistically significant. Any toxicity grade ≥3 showed a relationship with the cumulative dose (P=0.024). Cumulative dose ≤145 versus >145 Gy2 had 3% versus 15% (P=0.013) of any grade ≥3 toxicity.

CONCLUSIONS

Re-SABR produces satisfactory LC and OS rates with an acceptable rate of toxicity. The balancing between the re-SABR dose and the tumor location has the potential to reduce severe and fatal toxicity.

Stereotactic Body Radiation Therapy for Salvage Treatment of Recurrent Non-Small Cell Lung Cancer

PURPOSE

This study analyzes the outcomes and toxicity of stereotactic body radiation therapy (SBRT) as salvage treatment for recurrent non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

This retrospective analysis considered patients treated with thoracic SBRT and a history of prior external beam radiation therapy (EBRT), SBRT, or surgical resection for NSCLC. Follow-up included positron emission tomography and computed tomography imaging at 2- to 3-month intervals. Key outcomes were presented with the Kaplan-Meier method.

RESULTS

Forty patients with 52 treatments were included at a mean of 11.82 months after treatment with EBRT (n = 21), SBRT (n = 15), surgical resection (n = 9), and SBRT after EBRT (n = 7). Median imaging and clinical follow-up were 13.39 and 19.01 months, respectively. SBRT delivered a median dose of 40 Gy in 4 fractions. Median biologically effective dose (BED) was 79.60 Gy. Median gross tumor volume and planning target volume were 10.80 and 26.25 cm³, respectively. Local control was 65%, with a median time to local failure of 13.52 months. Local control was 87% after previous SBRT but only 33% after surgery. Median overall survival was 24.46 months, and median progression-free survival (PFS) was 14.11 months. Patients presenting after previous SBRT had improved local control (P = .021), and the same result was obtained including patients with SBRT after EBRT (P = .0037). Treatments after surgical resection trended toward worse local control (P = .061). Patients with BED ≥80 Gy had improved local PFS (P = .032), PFS (P = .021), time without any treatment failure (P = .033), and time to local failure (P = .041). Using the Kaplan-Meier method, BED ≥80 Gy was predictive of improved local PFS (P = .01) and PFS (P < .005). Toxicity consisted of 10 instances of grade <3 toxicity (16%) and no grade ≥3 toxicity.

CONCLUSIONS

Salvage treatment for recurrent NSCLC with SBRT was effective and well tolerated, particularly after initial treatment with SBRT. When possible, salvage SBRT should aim to achieve a BED of ≥80 Gy.

Bench to Bedside: Animal Models of Radiation Induced Musculoskeletal Toxicity

Ionizing radiation is a critical aspect of current cancer therapy. While classically mature bone was thought to be relatively radio-resistant, more recent data have shown this to not be the case. Radiation therapy (RT)-induced bone loss leading to fracture is a source of substantial morbidity. The mechanisms of RT likely involve multiple pathways, including changes in angiogenesis and bone vasculature, osteoblast damage/suppression, and increased osteoclast activity. The majority of bone loss appears to occur rapidly after exposure to ionizing RT, with significant changes in cortical thickness being detectable on computed tomography (CT) within three to four months. Additionally, there is a dose–response relationship. Cortical thinning is especially notable in areas of bone that receive >40 gray (Gy). Methods to mitigate toxicity due to RT-induced bone loss is an area of active investigation. There is an accruing clinical trial investigating the use of risderonate, a bisphosphonate, to prevent rib bone loss in patients undergoing lung stereotactic body radiation therapy (SBRT). Additionally, several other promising therapeutic/preventative approaches are being explored in preclinical studies, including parathyroid hormone (PTH), amifostine, and mechanical loading of irradiated bones.

Comparing local control and distant metastasis in NSCLC patients between CyberKnife and conventional SBRT

BACKGROUND AND PURPOSE

Previous literature suggests that the dose proximally outside the PTV could have an impact on the incidence of distant metastasis (DM) after SBRT in stage I NSCLC patients. We investigated this observation (along with local failure) in deliveries made by different treatment modalities: robotic mounted linac SBRT (CyberKnife) vs conventional SBRT (VMAT/CRT).

MATERIALS AND METHODS

This study included 422 stage I NSCLC patients from 2 institutions who received SBRT: 217 treated conventionally and 205 with CyberKnife. The dose behavior outside the PTV of both sub-cohorts were compared by analyzing the mean dose in continuous shells extending 1, 2, 3, …, 100 mm from the PTV. Kaplan-Meier analysis was performed between the two sub-cohorts with respect to DM-free survival and local progression-free survival. A multivariable Cox proportional hazards model was fitted to the combined cohort (n = 422) with respect to DM incidence and local failure.

RESULTS

The shell-averaged dose fall-off beyond the PTV was found to be significantly more modest in CyberKnife plans than in conventional SBRT plans. In a 30 mm shell around the PTV, the mean dose delivered with CyberKnife (38.1 Gy) is significantly larger than with VMAT/CRT (22.8 Gy, p<10^-8). For 95% of CyberKnife plans, this region receives a mean dose larger than the 21 Gy threshold dose discovered in our previous study. In contrast, this occurs for only 75% of VMAT/CRT plans. The DM-free survival of the entire CyberKnife cohort is superior to that of the 25% of VMAT/CRT patients receiving less than the threshold dose (VMAT/CRT_<21Gy), with a hazard ratio of 5.3 (95% CI: 3.0-9.3, p<10^-8). The 2 year DM-free survival rates were 87% (95% CI: 81%-91%) and 44% (95% CI: 28%-58%) for CyberKnife and the below-threshold dose conventional cohorts, respectively. A multivariable analysis of the combined cohort resulted in the confirmation that threshold dose was a significant predictor of DM(HR = 0.28, 95% CI: 0.15-0.55, p<10^-3) when adjusted for other clinical factors. CyberKnife was also found to be superior to the entire VMAT/CRT with respect to local control (HR = 3.44, CI: 1.6-7.3). The 2-year local progression-free survival rates for the CyberKnife cohort and the VMAT/CRT cohort were 96% (95% CI: 92%-98%) and 88% (95% CI: 82%-92%) respectively.

CONCLUSIONS

In standard-of-care CyberKnife treatments, dose distributions that aid distant control are achieved 95% of the time. Although similar doses could be physically achieved by conventional SBRT, this is not always the case with current prescription practices, resulting in worse DM outcomes for 25% of conventional SBRT patients. Furthermore, CyberKnife was found to provide superior local control compared to VMAT/CRT.

Exhaustive Review on Lung Cancers: Novel Technologies

BACKGROUND

Lung cancers or (Bronchogenic-Carcinomas) are the disease in certain parts of the lungs in which irresistible multiplication of abnormal cells leads to the inception of a tumor. Lung cancers consisting of two substantial forms based on the microscopic appearance of tumor cells are: Non-Small-Cell-Lung-Cancer (NSCLC) (80 to 85%) and Small-Cell-Lung-Cancer (SCLC) (15 to 20%).

DISCUSSION

Lung cancers are existing luxuriantly across the globe and the most prominent cause of death in advanced countries (USA & UK). There are many causes of lung cancers in which the utmost imperative aspect is the cigarette smoking. During the early stage, there is no perspicuous sign/symptoms but later many symptoms emerge in the infected individual such as insomnia, headache, pain, loss of appetite, fatigue, coughing etc. Lung cancers can be diagnosed in many ways, such as history, physical examination, chest X-rays and biopsy. However, after the diagnosis and confirmation of lung carcinoma, various treatment approaches are existing for curing of cancer in different stages such as surgery, radiation therapy, chemotherapy, and immune therapy. Currently, novel techniques merged that revealed advancements in detection and curing of lung cancer in which mainly includes: microarray analysis, gene expression profiling.

CONCLUSION

Consequently, the purpose of the current analysis is to specify and epitomize the novel literature pertaining to the development of cancerous cells in different parts of the lung, various preeminent approaches of prevention, efficient diagnostic procedure, and treatments along with novel technologies for inhibition of cancerous cell growth in advance stages.

mRNA and lncRNA Expression Profiling of Radiation-Induced Gastric Injury Reveals Potential Radiation-Responsive Transcription Factors

Radiation-induced gastric injury is a serious concern that may limit the duration and the delivered dose of radiation. However, the genome-wide molecular changes in stomach upon ionizing radiation have not been reported. In this study, mouse stomach was irradiated with 6 or 12 Gy X-ray irradiation and we found that radiation resulted in the atrophy of gastric mucosa and abnormal morphology of chief and parietal cells. Radiation-induced gastric injury was accompanied by an increase in the serum levels of pepsinogen A and pepsinogen C but not gastrin-17. The expression profiles of messenger RNA (mRNA) and long noncoding RNA (lncRNA) in normal and irradiated gastric tissues were measured by microarray analysis. Results revealed 17 upregulated and 10 downregulated mRNAs were consistent in 6 and 12 Gy irradiated gastric tissues, including D site-binding protein (Dbp) and fibrinogen-like protein 1 (Fgl1). Thirteen upregulated and 96 downregulated lncRNAs were commonly changed in 6 and 12 Gy irradiated gastric tissues. The dysregulated mRNAs were implicated in multiple pathways and showed coexpression with lncRNAs. To identify motifs for transcription factors and coactivators in the proximal promoter regions of the dysregulated RNAs, the bioinformatic tool Biopython was used. A variety of common motifs that are associated with transcription factors were identified, including ZNF263, LMX1B, and Dlx1. Our findings illustrate the molecular changes during radiation-induced gastric injury and the potential transcription factors driving this alteration.

Pembrolizumab and Nivolumab in the treatment of Non-small cell lung cancer (NSCLC)

Lung cancer is a disease difficult to treat and with low survival rates, especially non-smaller cell lung cancer (NSCLC). To treat cancer in advanced stages, new methods had arisen like immunotherapy. Pembrolizumab and nivolumab are IgG4 antibodies targeting programmed death cell receptor (PD-1) used for cancer immunotherapy, that blocks the protection that has cancer cells against the immune system. This antibody works binding and blocking the PD-1 membrane protein of T cells, which is responsible for cell recognition. If T cells cannot recognize the cells, then it would attack, so in this way, the immune system can be enhanced. Pembrolizumab and nivolumab have a variable region that is capable of recognizing the PD-1 receptor, and this plays an important role to kill cancer cells. The structure of the complex PD -1 and its ligand PD-L1 or PD-L2 reveals the structural basis of the PD-1. The interaction with a human antibody has been studied with antibody fragments revealing the molecular basis for the blockade of PD1 / PDL1-PDL2 interaction by pembrolizumab and nivolumab. Different studies involving immunotherapy have shown the remarkable results of pembrolizumab and nivolumab over current chemotherapy for cancer treatment making available a possible way for a new treatment for lung cancer. In a comparative analysis made between those immune checkpoint inhibitors had found the efficacy of pembrolizumab for treatment of NSCLC.

Comparing rib cortical thickness measurements from computed tomography (CT) and Micro-CT

BACKGROUND

The objective of this study was to compare cortical thickness of rib specimens scanned with clinical computed tomography (clinical-CT) at 0.5 and 1.0 mm slice thickness versus micro-CT at 0.05 mm slice thickness. Cortical thickness variation and accuracy was explored by anatomical region (anterior vs. lateral) and cross-sectional quadrants (superior, interior, inferior, and exterior).

METHODS

A validated cortical thickness algorithm was applied to clinical-CT and micro-CT scans of 17 rib specimens from six male post mortem human subjects aged 42-81 years. Each rib specimen was segmented and the thickness measurements were partitioned into cross-sectional quadrants in the anterior and lateral regions of the rib. Within each rib quadrant, the following were calculated: average thickness ± standard deviation, mean thickness difference between clinical-CT and micro-CT, and a thickness ratio between clinical-CT and micro-CT. Correlations from linear regression and paired-t tests were determined for paired clinical-CT and micro-CT results.

RESULTS

On average, the 0.5 mm clinical-CT underestimated the micro-CT thickness by 0.005 mm, while the 1.0 mm clinical-CT overestimated the micro-CT thickness by 0.149 mm. Thickness derived from 0.5 mm clinical-CT showed greater significant linear correlations (p < 0.05) with micro-CT thickness compared to 1.0 mm clinical-CT.

CONCLUSIONS

The small mean differences and thickness ratios near 1 show validation for the cortical thickness algorithm when applied to rib clinical-CT scans. Using clinical-CT scans as way to accurately measure rib cortical thickness offers a non-invasive way to analyze millions of CT scans collected each year from males and females of all ages.

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

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

Long term efficacy and toxicity after stereotactic ablative reirradiation in locally relapsed stage III non-small cell lung cancer

BACKGROUND

In stage III non-small cell lung cancer (NSCLC) treated with concomitant chemoradiotherapy, there is a high rate of relapse. Some of these relapses are only local and can be treated by stereotactic ablative radiation therapy (SABR). Previous studies reporting outcome after SABR reirradiation of the thorax consisted of a heterogeneous population of various lung cancer stages or even different types of cancer. The purpose of study is to evaluate toxicity and outcome of this strategy in locally relapsed stage III NSCLC only.

METHODS

From February 2007 to November 2015, 46 Stage III NSCLC patients treated with SABR, for lung recurrence following conventionally fractionated radiation therapy (CFRT), were retrospectively analyzed.

RESULTS

Median follow-up was 47.3 months (1-76.9). The 2 and 4-year progression-free survival (PFS), and overall survival (OS) were of 25.5%/8.6 and 48.9%/30.8%, respectively. Highest presenting toxicity in patients (grade 1 through 5) was: 13 (28.3%), 7 (15.2%), 1 (2.2%), 0 and 2 (4.4%), with deaths due to hemoptysis (n = 1) and alveolitis (n = 1). Although the Biological Effective Dose (at Planning Tumor Volume isocenter) was lower for central tumors treated for an in-field relapse (n = 21, 116 Gy versus 168 Gy, p = 0.005), they had no significant difference in OS than the remaining cohort, but with a higher rate of grade 2-5 toxicities (OR = 0.22, [0.06-0.8], p = 0.02).

CONCLUSION

Reirradiation with SABR for local relapse in patients previously treated for stage III NSCLC, is feasible and associated with good outcome. This is also true for central tumors treated for an in-field relapse, but should be radiated with caution to mitigate toxicity.

Organs at Risk Considerations for Thoracic Stereotactic Body Radiation Therapy: What Is Safe for Lung Parenchyma?

PURPOSE

Stereotactic body radiation therapy (SBRT) has become the standard of care for inoperable early-stage non-small cell lung cancer and is often used for recurrent lung cancer and pulmonary metastases. Radiation-induced lung toxicity (RILT), including radiation pneumonitis and pulmonary fibrosis, is a major concern for which it is important to understand dosimetric and clinical predictors.

METHODS AND MATERIALS

This study was undertaken through the American Association of Physicists in Medicine's Working Group on Biological Effects of Stereotactic Body Radiotherapy. Data from studies of lung SBRT published through the summer of 2016 that provided detailed information about RILT were analyzed.

RESULTS

Ninety-seven studies were ultimately considered. Definitions of the risk organ and complication endpoints as well as dose-volume information presented varied among studies. The risk of RILT, including radiation pneumonitis and pulmonary fibrosis, was reported to be associated with the size and location of the tumor. Patients with interstitial lung disease appear to be especially susceptible to severe RILT. A variety of dosimetric parameters were reported to be associated with RILT. There was no apparent threshold "tolerance dose-volume" level. However, most studies noted safe treatment with a rate of symptomatic RILT of <10% to 15% after lung SBRT with a mean lung dose (MLD) of the combined lungs ≤8 Gy in 3 to 5 fractions and the percent of total lung volume receiving more than 20 Gy (V₂₀) <10% to 15%.

CONCLUSIONS

To allow more rigorous analysis of this complication, future studies should standardize reporting by including standardized endpoint and volume definitions and providing dose-volume information for all patients, with and without RILT.

The dosimetric effect of electron density overrides in 3DCRT Lung SBRT for a range of lung tumor dimensions

The combined effects of lung tumor motion and limitations of treatment planning system dose calculations in lung regions increases uncertainty in dose delivered to the tumor and surrounding normal tissues in lung stereotactic body radiotherapy (SBRT). This study investigated the effect on plan quality and accuracy when overriding treatment volume electron density values. The QUASAR phantom with modified cork cylindrical inserts, each containing a simulated spherical tumor of 15‐mm, 22‐mm, or 30‐mm diameter, was used to simulate lung tumor motion. Using Monaco 5.1 treatment planning software, two standard plans (50% central phase (50%) and average intensity projection (AIP)) were compared to eight electron density overridden plans that focused on different target volumes (internal target volume (ITV), planning target volume (PTV), and a hybrid plan (HPTV)). The target volumes were set to a variety of electron densities between lung and water equivalence. Minimal differences were seen in the 30‐mm tumor in terms of target coverage, plan conformity, and improved dosimetric accuracy. For the smaller tumors, a PTV override showed improved target coverage as well as better plan conformity compared to the baseline plans. The ITV plans showed the highest gamma pass rate agreement between treatment planning system (TPS) and measured dose (P < 0.040). However, the low electron density PTV and HPTV plans also showed improved gamma pass rates (P < 0.035, P < 0.011). Low‐density PTV overrides improved the plan quality and accuracy for tumor diameters less than 22 mm only. Although an ITV override generated the most significant increase in accuracy, the low‐density PTV plans had the additional benefit of plan quality improvement. Although this study and others agreed that density overrides improve the treatment of SBRT, the optimal density override and the conditions under which it should be applied were found to be department specific, due to variations in commissioning and calculation methods.

Cortical Thinning and Structural Bone Changes in Non-Human Primates after Single-Fraction Whole-Chest Irradiation

Stereotactic body radiation therapy (SBRT) is associated with an increased risk of vertebral compression fracture. While bone is typically considered radiation resistant, fractures frequently occur within the first year of SBRT. The goal of this work was to determine if rapid deterioration of bone occurs in vertebrae after irradiation. Sixteen male rhesus macaque non-human primates (NHPs) were analyzed after whole-chest irradiation to a midplane dose of 10 Gy. Ages at the time of exposure varied from 45-134 months. Computed tomography (CT) scans were taken 2 months prior to irradiation and 2, 4, 6 and 8 months postirradiation for all animals. Bone mineral density (BMD) and cortical thickness were calculated longitudinally for thoracic (T) 9, lumbar (L) 2 and L4 vertebral bodies; gross morphology and histopathology were assessed per vertebra. Greater mortality (related to pulmonary toxicity) was noted in NHPs <50 months at time of exposure versus NHPs >50 months ( P = 0.03). Animals older than 50 months at time of exposure lost cortical thickness in T9 by 2 months postirradiation ( P = 0.0009), which persisted to 8 months. In contrast, no loss of cortical thickness was observed in vertebrae out-of-field (L2 and L4). Loss of BMD was observed by 4 months postirradiation for T9, and 6 months postirradiation for L2 and L4 ( P < 0.01). For NHPs younger than 50 months at time of exposure, both cortical thickness and BMD decreased in T9, L2 and L4 by 2 months postirradiation ( P < 0.05). Regions that exhibited the greatest degree of cortical thinning as determined from CT scans also exhibited increased porosity histologically. Rapid loss of cortical thickness was observed after high-dose chest irradiation in NHPs. Younger age at time of exposure was associated with increased pneumonitis-related mortality, as well as greater loss of both BMD and cortical thickness at both in- and out-of-field vertebrae. Older NHPs exhibited rapid loss of BMD and cortical thickness from in-field vertebrae, but only loss of BMD in out-of-field vertebrae. Bone is sensitive to high-dose radiation, and rapid loss of bone structure and density increases the risk of fractures.

Gallic acid-coated sliver nanoparticle alters the expression of radiation-induced epithelial-mesenchymal transition in non-small lung cancer cells

BACKGROUND

Radiotherapy is the most widely used treatment method for treating cancer with or without surgery and chemotherapy. In lung cancer, it is one of the important treatment steps in excising the tumor from the lung tissue; unfortunately, radiation can induce epithelial- mesenchymal transition (EMT), a typical physiological process in which cuboidal shaped epithelial cell loses its phenotype and acquires mesenchymal-like phenotype thus, increases the metastasis progression in the body. To prevent EMT mediated metastasis, we aimed to 1) synthesize silver nanoparticles by using Gallic acid, a potential antioxidant which acts as stabilizing and reducing agent in the form of silver nanoparticle (GA-AgNPs) 2) to analyze its effect on EMT markers during radiation-induced EMT in A549 cells.

METHODS

A549 cells were irradiated with 8Gy (X-ray) and treated with GA-AgNPs at a fixed concentration under in vitro condition. GA-AgNPs were prepared and characterized for absorption, potential stability, size and morphology by UV-Visible spectrophotometer, Zeta potential and Transmission electron microscopy respectively. After irradiation, the morphology changes were observed using an inverted microscope, the gene and protein expression of EMT markers were analyzed by RT-PCR and western blotting.

RESULTS/CONCLUSION

GA-AgNPs are in nano size with fair stability. The synthesized nanoparticles suppressed the EMT markers including Vimentin, N-cadherin, Snail-1 and increased E-cadherin expression which might inhibit cancer cells to acquire radio resistant metastasis potential.

Can dose outside the PTV influence the risk of distant metastases in stage I lung cancer patients treated with stereotactic body radiotherapy (SBRT)?

BACKGROUND AND PURPOSE

In an era where little is known about the "abscopal" (out-of-the-field) effects of lung SBRT, we investigated correlations between the radiation dose proximally outside the PTV and the risk of cancer recurrence after SBRT in patients with primary stage I non-small cell lung cancer (NSCLC).

MATERIALS AND METHODS

This study included 217 stage I NSCLC patients across 2 institutions who received SBRT. Correlations between clinical and dosimetric factors were investigated. The clinical factors considered were distant metastasis (DM), loco-regional control (LRC) and radiation pneumonitis (RP). The dose (converted to EQD2) delivered to regions of varying size directly outside of the PTV was computed. For each feature, area under the curve (AUC) and odds ratios with respect to the outcome parameters DM, LRC and RP were estimated; Kaplan-Meier (KM) analysis was also performed.

RESULTS

Thirty-seven (17%) patients developed DM after a median follow-up of 24 months. It was found that the mean dose delivered to a shell-shaped region of thickness 30 mm outside the PTV had an AUC of 0.82. Two years after treatment completion, the rate of DM in patients where the mean dose delivered to this region was higher than 20.8 Gy₂ was 5% compared to 60% in those who received a dose lower than 20.8 Gy₂. KM analysis resulted in a hazard ratio of 24.2 (95% CI: 10.7, 54.4); p < 10^-5. No correlations were found between any factor and either LRC or RP.

CONCLUSIONS

The results of this study suggest that the dose received by the region close to the PTV has a significant impact on the risk of distant metastases in stage I NSCLC patients treated with SBRT. If these results are independently confirmed, caution should be taken, particularly when a treatment plan results in a steep dose gradient extending outwards from the PTV.

Stereotactic body radiotherapy for central lung tumors, yes we can!

BACKGROUND

SBRT is standard therapy for early stage lung cancer. Toxicity in central tumors has been a concern. RTOG 0813 showed that central SBRT is safe and effective. We report our experience with central SBRT.

METHODS

We reviewed the records of patients treated with SBRT for central lung tumors (< 2 cm of the carina). Patients included primary lung cancer and recurrence following surgery and\ or conventional radiotherapy. All patients underwent 4DCT simulation and treatment planning was done with IMRT or VMAT techniques. Dose to the PTV was prescribed to the 95% isodose line.

RESULTS

Seventy patients, between 5/09 and 4/13, were treated. Patients had early non-small cell lung cancer (n = 13) or locally recurrent lung cancer (n = 29) and pulmonary oligometastases (n = 28). Fifty-seven percent of the patients received BED of 132 with a schedule of 60Gy in 12 Gy fractions. Median follow up time was 18.3 months, 4/70 patients experienced local failure (6%). Median OS for the whole cohort was 4.6 years (CI 3-7 years). Ten patients had grade 1-2 radiation pneumonitis. One patient developed fatal bronchial bleeding.

CONCLUSIONS

SBRT for central tumors is safe and effective in patients with central disease, reiradiation, recurrence following surgery and in oligometastes.

Feasibility of Adaptive MR-guided Stereotactic Body Radiotherapy (SBRT) of Lung Tumors

Online adaptive radiotherapy (ART) with frequent imaging has the potential to improve dosimetric accuracy by accounting for anatomical and functional changes during the course of radiotherapy. Presented are three interesting cases that provide an assessment of online adaptive magnetic resonance-guided radiotherapy (MRgRT) for lung stereotactic body radiotherapy (SBRT).

The study includes three lung SBRT cases, treated on an MRgRT system where MR images were acquired for planning and prior to each treatment fraction. Prescription dose ranged from 48 to 50 Gy in four to five fractions, normalized to where 95% of the planning target volume (PTV) was covered by 100% of the prescription dose. The process begins with the gross tumor volume (GTV), PTV, spinal cord, lungs, heart, and esophagus being delineated on the planning MRI. The treatment plan was then generated using a step-and-shoot intensity modulated radiotherapy (IMRT) technique, which utilized a Monte Carlo dose calculation. Next, the target and organs at risk (OAR) contours from the planning MRI were deformably propagated to the daily setup MRIs. These deformed contours were reviewed and modified by the physician. To determine the efficacy of ART, two different strategies were explored: 1) Calculating the plan created for the planning MR on each fraction setup MR dataset (Non-Adapt) and 2) creating a new optimized IMRT plan on the fraction setup MR dataset (FxAdapt). The treatment plans from both strategies were compared using the clinical dose-volume constraints.

PTV coverage constraints were not met for 33% Non-Adapt fractions; all FxAdapt fractions met this constraint. Eighty-eight percent of all OAR constraints studied were better on FxAdapt plans, while 12% of OAR constraints were superior on Non-Adapt fractions. The OAR that garnered the largest benefit would be the uninvolved lung, with superior sparing in 92% of the FxAdapt studied. Similar, but less pronounced, benefits from adaptive planning were experienced for the spinal cord, chest wall, and esophagus.

Online adaptive MR-guided lung SBRT can provide better target conformality and homogeneity and OAR sparing compared with non-adaptive SBRT in selected cases. Conversely, if the PTV isn’t adjacent to multiple OARs, then the benefit from ART may be limited. Further studies, which incorporate a larger cohort of patients with uniform prescriptions, are needed to thoroughly evaluate the benefits of daily online ART during MRgRT.

Dosimetric comparison of helical tomotherapy and conventional Linac-based X-knife stereotactic body radiation therapy for primary lung cancer or pulmonary metastases

Background

To compare helical tomotherapy (HT) with X-knife stereotactic body radiation therapy (HT-SBRT/X-SBRT) for primary or metastatic lung cancer regarding planning target volume (PTV) coverage, such as homogeneity index (HI), conformity index (CI) and dose-volume histogram (DVH) of organs at risk (OARs).

Methods

We retrospectively analyzed 21 patients receiving definitive radiation treatment for non-small cell lung cancer (NSCLC) or pulmonary metastases at our institution between March 2015 and October 2016. Tumors were irradiated with 4-10 Gy per fraction in 5-15 fractions. Plans were compared according to PTV coverage and OARs sparing.

Results

Significant differences between HT and X-knife were observed for both HI (P=0.003) and CI (P<0.001). The V5 (P=0.001), V10 (P=0.009), V20 (P=0.001), the mean lung dose (P=0.005) of total lung and maximum dose of the spinal cord (P=0.010) were significantly lower in the X-SBRT group than the HT-SBRT group. There were no significant differences for the V30 (P=0.075) and the mean heart dose (P=0.584) between the two groups.

Conclusions

X-SBRT was dosimetrically superior to HT-SBRT, when applied in these tumors' maximum diameters <5 cm. As HT resulted in increased low-dose volume, it is essential to optimize the patient selection in order to avoid severe radiation pneumonitis in HT-SBRT.

Pattern of Imaging after Lung Cancer Resection. 1992-2005

RATIONALE

Imaging intensity after lung cancer resection performed with curative intent is unknown.

OBJECTIVES

To describe the pattern and trends in the use of computed tomography (CT) and positron emission tomography (PET) scans in patients after resection of early-stage lung cancer.

METHODS

Retrospective analysis of the linked Surveillance, Epidemiology and End Results (SEER)-Medicare database. Subjects included 8,621 Medicare beneficiaries (age, ≥66 yr) who underwent lung cancer resection with curative intent between 1992 and 2005. A surveillance CT or PET examination was defined as CT or PET imaging performed in an outpatient setting on patients who did not undergo chest radiography in the preceding 30 days.

MEASUREMENTS AND MAIN RESULTS

Overall, imaging use was higher within the first 2 years versus Years 3-5 after surgical resection. Use of surveillance CT scans increased sharply from 13.7 to 57.3% of those diagnosed in 1996-1997 and 2004-2005, respectively. PET scan use increased threefold, from 6.2% in 2000-2001 to 19.6% in 2004-2005. In multivariable analyses, we observed a 32% increase in the odds of undergoing surveillance CT or PET imaging for every year of diagnosis between 1998 and 2005. There was no substantial decline in the odds of having a surveillance CT or PET scan during each successive follow-up period, suggesting no change in the intensity of surveillance over the first 5 years after surgical resection. The proportion of surveillance CT imaging performed at freestanding imaging centers increased from 18.0% in 1998-1999 to 30.6% in 2004-2005.

CONCLUSIONS

The use of CT and PET imaging for surveillance after curative-intent surgical resection of early-stage lung cancer increased sharply in the United States between 1997-1998 and 2005. In the absence of evidence demonstrating favorable outcomes, this practice was likely driven by prevailing expert opinion embedded in clinical practice guidelines made available during that time. Research is clearly needed to determine the role and optimal approach to surveillance thoracic imaging after surgical resection of lung cancer.

Variation of the prescription dose using the analytical anisotropic algorithm in lung stereotactic body radiation therapy

PURPOSE

The aim of the present investigation was to evaluate the dosimetric variation regarding the analytical anisotropic algorithm (AAA) relative to other algorithms in lung stereotactic body radiation therapy (SBRT). We conducted a multi-institutional study involving six institutions using a secondary check program and compared the AAA to the Acuros XB (AXB) in two institutions.

METHODS

All lung SBRT plans (128 patients) were generated using the AAA, pencil beam convolution with the Batho (PBC-B) and adaptive convolve (AC). All institutions used the same secondary check program (simple MU analysis [SMU]) implemented by a Clarkson-based dose calculation algorithm. Measurement was performed in a heterogeneous phantom to compare doses using the three different algorithms and the SMU for the measurements. A retrospective analysis was performed to compute the confidence limit (CL; mean±2SD) for the dose deviation between the AAA, PBC, AC and SMU. The variations between the AAA and AXB were evaluated in two institutions, then the CL was acquired.

RESULTS

In comparing the measurements, the AAA showed the largest systematic dose error (3%). In calculation comparisons, the CLs of the dose deviation were 8.7±9.9% (AAA), 4.2±3.9% (PBC-B) and 5.7±4.9% (AC). The CLs of the dose deviation between the AXB and the AAA were 1.8±1.5% and -0.1±4.4%, respectively, in the two institutions.

CONCLUSIONS

The CL of the AAA showed much larger variation than the other algorithms. Relative to the AXB, larger systematic and random deviations still appeared. Thus, care should be taken in the use of AAA for lung SBRT.

Radioresistant human lung adenocarcinoma cells that survived multiple fractions of ionizing radiation are sensitive to HSP90 inhibition

Despite the common usage of radiotherapy for the treatment of NSCLC, outcomes for these cancers when treated with ionizing radiation (IR) are still unsatisfactory. A better understanding of the mechanisms underlying resistance to IR is needed to design approaches to eliminate the radioresistant cells and prevent tumor recurrence and metastases. Using multiple fractions of IR we generated radioresistant cells from T2821 and T2851 human lung adenocarcinoma cells. The radioresistant phenotypes present in T2821/R and T2851/R cells include multiple changes in DNA repair genes and proteins expression, upregulation of EMT markers, alterations of cell cycle distribution, upregulation of PI3K/AKT signaling and elevated production of growth factors, cytokines, important for lung cancer progression, such as IL-6, PDGFB and SDF-1 (CXCL12). In addition to being radioresistant these cells were also found to be resistant to cisplatin.

HSP90 is a molecular chaperone involved in stabilization and function of multiple client proteins implicated in NSCLC cell survival and radioresistance. We examined the effect of ganetespib, a novel HSP90 inhibitor, on T2821/R and T2851/R cell survival, migration and radioresistance. Our data indicates that ganetespib has cytotoxic activity against parental T2821 and T2851 cells and radioresistant T2821/R and T2851/R lung tumor cells. Ganetespib does not affect proliferation of normal human lung fibroblasts. Combining IR with ganetespib completely abrogates clonogenic survival of radioresistant cells.

Our data show that HSP90 inhibition can potentiate the effect of radiotherapy and eliminate radioresistant and cisplatin -resistant residual cells, thus it may aid in reducing NSCLC tumor recurrence after fractionated radiotherapy.

Checkpoint inhibitors in lung cancer: latest developments and clinical potential

Lung cancer is the leading cause of cancer death in the United States. The vast majority of patients are diagnosed with metastatic disease with a 5-year survival rate of less than 5%. After first-line chemotherapy or biomarker-matched targeted therapy, only suitable for a small group of patients, further systemic therapy options rendered very limited, if any, benefit until recently. Checkpoint inhibitors have significantly improved outcomes in patients with metastatic non-small cell lung cancer (NSCLC) and are currently an established second-line therapeutic option. In this manuscript, we review the mechanism of action of checkpoint inhibitors, present the available data with approved and experimental agents, discuss the progress that has already been made in the field, as well as toxicity awareness, and future perspectives.

Non-small cell lung cancer: current treatment and future advances

Lung cancer has a poor prognosis; over half of people diagnosed with lung cancer die within one year of diagnosis and the 5-year survival is less than 18%. Non-small cell lung cancer (NSCLC) accounts for the majority of all lung cancer cases. Risk factors for developing NSCLC have been identified, with cigarette smoking being a major factor along with other environmental and genetic risk factors. Depending on the staging of lung cancer, patients are eligible for certain treatments ranging from surgery to radiation to chemotherapy as well as targeted therapy. With the advancement of genetics and biomarkers testing, specific mutations have been identified to better target treatment for individual patients. This review discusses current treatments including surgery, chemotherapy, radiotherapy, and immunotherapy as well as how biomarker testing has helped improve survival in patients with NSCLC.