Radiographic patterns of symptomatic radiation pneumonitis in lung cancer patients: Imaging predictors for clinical severity and outcome

A chromosome 2 locus influences the onset of radiation-induced lung disease in mice

PURPOSE

The onset of distress from radiation-induced lung disease differs among patients and among inbred strains of mice exposed to thoracic cavity radiotherapy. For the latter specifically, C3H/HeJ mice present distress due to pneumonitis at approximately 10-14 weeks following thoracic irradiation, while C57BL/6J mice show distress due to pneumonitis with pulmonary fibrosis at 22-30 weeks. Mapping studies completed in offspring derived from these inbred strains revealed a chromosome 2 locus to be linked to onset of distress in irradiated mice. Herein, we bred and phenotyped a panel of chromosome 2 subcongenic mice with 64 Mb of C3H/HeJ alleles on a C57BL/6J background, to investigate the contribution of the chromosome 2 locus to radiation-induced lung disease.

MATERIALS AND METHODS

Mice received 18 Gy to the thoracic cavity and were monitored for the onset of distress. Lung disease was assessed histologically and with bronchoalveolar lavage.

RESULTS

Following whole thorax irradiation, subcongenic mice with C3H/HeJ alleles from 95 to 123 Mb showed significantly earlier onset of respiratory distress (16-22 weeks; p < .02) from pneumonitis and fibrosis compared to C57BL/6J mice. These subcongenic mice did not differ from C57BL/6J mice in pneumonitis (p = .23), mast cell counts (p = .96), or lavage neutrophils (p = .69), evident at distress. In silico analyses reveal 246 protein coding genes mapped within the reduced region, 52 of which differ in pulmonary expression of C3H/HeJ, compared to C57BL/6J, mice after whole thorax irradiation.

CONCLUSIONS

We have identified a 28 Mb region of chromosome 2 to influence the onset of radiation-induced lung disease in mice.

The Role of Chest Radiography in Lung Cancer

Chest radiography is one of the most commonly performed imaging tests, and benefits include accessibility, speed, cost, and relatively low radiation exposure. Lung cancer is the third most common cancer in the United States and is responsible for the most cancer deaths. Knowledge of the role of chest radiography in assessing patients with lung cancer is important. This article discusses radiographic manifestations of lung cancer, the utility of chest radiography in lung cancer management, as well as the limitations of chest radiography and when computed tomography (CT) is indicated.

Radiation Pneumonitis With 99m Tc-MDP Uptake in a Patient With Breast Cancer

ABSTRACT

We present MDP bone scan findings of radiation pneumonitis in a 45-year-old woman with invasive ductal carcinoma of the right breast, classified as stage IIIa, T3N2M0. The patient underwent a modified radical mastectomy, neoadjuvant chemotherapy, and subsequent radiotherapy, receiving the last session 7 months before the bone scan. Whole-body images acquired 3 hours postinjection of 20 mCi (730 MBq) 99m Tc-MDP showed incidentally increased uptake in the right hemithorax, confined to the lung parenchyma of the right lung on SPECT/CT images.

Computed tomography patterns and clinical outcomes of radiation pneumonitis in non-small-cell lung cancer patients

Background

Radiation pneumonitis (RP) is not an uncommon complication in lung cancer patients undergoing radiation therapy (RT) and symptomatic RP can affect their quality of life.

Purpose

To investigate the CT findings of RP in non-small cell lung cancer (NSCLC) patients and their relationship with clinical outcomes.

Materials and methods

We reviewed data from 240 NSCLC patients who underwent RT between 2014 and 2022. CT findings of RP were evaluated for parenchymal abnormalities and distribution, which were then classified into three patterns: localized pneumonia (LP), cryptogenic organizing pneumonia (COP), and acute interstitial pneumonia (AIP). Clinical outcomes of RP were evaluated based on Common Terminology Criteria for Adverse Events (CTCAE) grade.

Results

Of the 153 patients, 135 developed RP. The most common pattern was LP (n = 78), followed by COP (n = 30) and AIP (n = 25). Among the three CT patterns, CTCAE grade and days between the start of RT and the onset of RP (RT-RP days) were statistically significantly different (p < 0.05). The patients with AIP patterns exhibited higher CTCAE grade, and fewer RT-RP days compared to those with non-AIP patterns (p < 0.05). In these patients, lung-to-lung metastasis and underlying interstitial lung abnormality were observed more frequently (p < 0.05). Underlying pulmonary fibrosis, the AIP pattern, and higher CT extent scores were more frequently observed in higher CTCAE grade group (p < 0.001). In multiple regression analysis, age, bilateral distribution, RT-RP days, and CT extent score ≥3 were independent predicting factors for higher CTCAE grade.

Conclusions

RP in NSCLC patients can be classified into LP, COP, and AIP patterns and they exhibit different severities in clinical outcomes.

Quantifying Regional Radiation-Induced Lung Injury in Patients Using Hyperpolarized 129Xe Gas Exchange Magnetic Resonance Imaging

PURPOSE

Radiation-induced lung injury has been shown to alter regional ventilation and perfusion in the lung. However, changes in regional pulmonary gas exchange have not previously been measured.

METHODS AND MATERIALS

Ten patients receiving conventional radiation therapy (RT) for lung cancer underwent pre-RT and 3-month post-RT magnetic resonance imaging (MRI) using an established hyperpolarized 129Xe gas exchange technique to map lung function. Four patients underwent an additional 8-month post-RT MRI. The MR signal from inhaled xenon was measured in the following 3 pulmonary compartments: the lung airspaces, the alveolar membrane tissue, and the pulmonary capillaries (interacting with red blood cells [RBCs]). Thoracic 1H MRI scans were acquired, and deformable registration was used to transfer 129Xe functional maps to the RT planning computed tomography scan. The RT-associated changes in ventilation, membrane uptake, and RBC transfer were computed as a function of regional lung dose (equivalent dose in 2-Gy fractions). Pearson correlations and t tests were used to determine statistical significance, and weighted sum of squares linear regression subsequently characterized the dose dependence of each functional component. The pulmonary function testing metrics of forced vital capacity and diffusing capacity for carbon monoxide were also acquired at each time point.

RESULTS

Compared with pre-RT baseline, 3-month post-RT ventilation decreased by an average of -0.24 ± 0.05%/Gy (ρ = -0.88; P < .001), membrane uptake increased by 0.69 ± 0.14%/Gy (ρ = 0.94; P < .001), and RBC transfer decreased by -0.41 ± 0.06%/Gy (ρ = -0.92; P < .001). Membrane uptake maintained a strong positive correlation with regional dose at 8 months post-RT, demonstrating an increase of 0.73 ± 0.11%/Gy (ρ = 0.92; P = .006). Changes in membrane uptake and RBC transfer appeared greater in magnitude (%/Gy) for individuals with low heterogeneity in their baseline lung function. An increase in whole-lung membrane uptake showed moderate correlation with decreases in forced vital capacity (ρ = -0.50; P = .17) and diffusing capacity for carbon monoxide (ρ = -0.44; P = .23), with neither correlation reaching statistical significance.

CONCLUSIONS

Hyperpolarized 129Xe MRI measured and quantified regional, RT-associated, dose-dependent changes in pulmonary gas exchange. This tool could enable future work to improve our understanding and management of radiation-induced lung injury.

Expression of Tenascin-C Is Upregulated in the Early Stages of Radiation Pneumonitis/Fibrosis in a Novel Mouse Model

The lung is a major dose-limiting organ for radiation therapy (RT) for cancer in the thoracic region, and the clarification of radiation-induced lung damage (RILD) is important. However, there have been few reports containing a detailed comparison of radiographic images with the pathological findings of radiation pneumonitis (RP)/radiation fibrosis (RF). We recently reported the upregulated expression of tenascin-C (TNC), an inflammation-associated extracellular matrix molecule, in surgically resected lung tissue, and elevated serum levels were elevated in a RILD patient. Therefore, we have developed a novel mouse model of partial lung irradiation and studied it with special attention paid to the computed tomography (CT) images and immunohistological findings. The right lungs of mice (BALB/c) were irradiated locally at 30 Gy/1fr, and the following two groups were created. In Group 1, sequential CT was performed to confirm the time-dependent changes in RILD. In Group 2, the CT images and histopathological findings of the lung were compared. RP findings were detected histologically at 16 weeks after irradiation; they were also observed on the CT images from 20 weeks. The immunostaining of TNC was observed before the appearance of RP on the CT images. The findings suggest that TNC could be an inflammatory marker preceding lung fibrosis.

Oxytocin: A Shield against Radiation-Induced Lung Injury in Rats

BACKGROUND

Radiation-induced lung injury (RILI), a serious side effect of thoracic radiotherapy, can lead to acute radiation pneumonitis (RP) and chronic pulmonary fibrosis (PF). Despite various interventions, no effective protocol exists to prevent pneumonitis. Oxytocin (OT), known for its anti-inflammatory, antiapoptotic, and antioxidant properties, has not been explored for its potential in mitigating RILI.

MATERIALS AND METHODS

This study involved 24 female Wistar albino rats, divided into three groups: control group, radiation (RAD) + saline, and RAD + OT. The RAD groups received 18 Gy of whole-thorax irradiation. The RAD + OT group was treated with OT (0.1 mg/kg/day) intraperitoneally for 16 weeks. Computerizing tomography (CT) imaging and histopathological, biochemical, and blood gas analyses were performed to assess lung tissue damage and inflammation.

RESULTS

Histopathological examination showed significant reduction in alveolar wall thickening, inflammation, and vascular changes in the RAD + OT group compared to the RAD + saline group. Biochemical analysis revealed decreased levels of TGF-beta, VEGF, and PDGF, and increased BMP-7 and prostacyclin in the RAD + oxytocin group (p < 0.05). Morphometric analysis indicated significant reductions in fibrosis, edema, and immune cell infiltration. CT imaging demonstrated near-normal lung parenchyma density in the RAD + oxytocin group (p < 0.001).

CONCLUSION

Oxytocin administration significantly mitigates radiation-induced pneumonitis in rats, implying that is has potential as a therapeutic agent for preventing and treating RILI.

From pixels to prognosis: unveiling radiomics models with SHAP and LIME for enhanced interpretability

Radiomics-based prediction models have shown promise in predicting Radiation Pneumonitis (RP), a common adverse outcome of chest irradiation. Τhis study looks into more than just RP: it also investigates a bigger shift in the way radiomics-based models work. By integrating multi-modal radiomic data, which includes a wide range of variables collected from medical images including cutting-edge PET/CT imaging, we have developed predictive models that capture the intricate nature of illness progression. Radiomic features were extracted using PyRadiomics, encompassing intensity, texture, and shape measures. The high-dimensional dataset formed the basis for our predictive models, primarily Gradient Boosting Machines (GBM)-XGBoost, LightGBM, and CatBoost. Performance evaluation metrics, including Multi-Modal AUC-ROC, Sensitivity, Specificity, and F1-Score, underscore the superiority of the Deep Neural Network (DNN) model. The DNN achieved a remarkable Multi-Modal AUC-ROC of 0.90, indicating superior discriminatory power. Sensitivity and specificity values of 0.85 and 0.91, respectively, highlight its effectiveness in detecting positive occurrences while accurately identifying negatives. External validation datasets, comprising retrospective patient data and a heterogeneous patient population, validate the robustness and generalizability of our models. The focus of our study is the application of sophisticated model interpretability methods, namely SHAP (SHapley Additive exPlanations) and LIME (Local Interpretable Model-Agnostic Explanations), to improve the clarity and understanding of predictions. These methods allow clinicians to visualize the effects of features and provide localized explanations for every prediction, enhancing the comprehensibility of the model. This strengthens trust and collaboration between computational technologies and medical competence. The integration of data-driven analytics and medical domain expertise represents a significant shift in the profession, advancing us from analyzing pixel-level information to gaining valuable prognostic insights.

Trastuzumab Deruxtecan‒Related Interstitial Lung Disease/Pneumonitis: Computed Tomography Imaging Patterns to Guide Diagnosis and Management

PURPOSE

Trastuzumab deruxtecan (T-DXd) is an antibody-drug conjugate approved for the treatment of several advanced cancers; however, severe or fatal interstitial lung disease/pneumonitis can occur. We characterized the computed tomography (CT) patterns of T-DXd‒related pneumonitis as a marker for its clinical severity.

MATERIALS AND METHODS

Ninety patients with advanced cancers who developed T-DXd‒related pneumonitis in two completed single-arm clinical trials were included. Three radiologists independently characterized the CT patterns of pneumonitis at diagnosis, for analyses of those patterns' relationships with clinical severity and pneumonitis outcome.

RESULTS

T-DXd‒related pneumonitis most commonly presented with cryptogenic organizing pneumonia (COP) pattern, observed in 65 patients (72%), followed by a newly identified COP/hypersensitivity pneumonitis (HP) pattern (13%), acute interstitial pneumonia (AIP)/acute respiratory distress syndrome (ARDS) pattern (11%), and HP pattern (3%). A subset of cases with COP pattern demonstrated an atypical distribution with upper and peripheral lung involvement (6/65; 9%). CT patterns were associated with Common Terminology Criteria for Adverse Events severity grades of pneumonitis, with the AIP/ARDS pattern having higher grades compared with others (P < .0001). Fatal pneumonitis was more common in the AIP/ARDS pattern than in others (P = .005). The onset of pneumonitis was earlier in the AIP/ARDS pattern compared with others (median time to onset: at 17.9 v 32.7 weeks of therapy; P = .019). Pneumonitis was treated by withholding T-DXd with or without corticosteroids in most patients (78/90; 87%).

CONCLUSION

T-DXd‒related pneumonitis most commonly demonstrated a COP pattern, with a subset having an atypical distribution. The AIP/ARDS pattern was indicative of severe, potentially fatal pneumonitis, and requires immediate clinical attention to mitigate serious adverse events.

Radiomics and Dosiomics Signature From Whole Lung Predicts Radiation Pneumonitis: A Model Development Study With Prospective External Validation and Decision-curve Analysis

PURPOSE

Radiation pneumonitis (RP) is one of the common side effects of radiation therapy in the thoracic region. Radiomics and dosiomics quantify information implicit within medical images and radiation therapy dose distributions. In this study we demonstrate the prognostic potential of radiomics, dosiomics, and clinical features for RP prediction.

METHODS AND MATERIALS

Radiomics, dosiomics, dose-volume histogram (DVH) metrics, and clinical parameters were obtained on 314 retrospectively collected and 35 prospectively enrolled patients diagnosed with lung cancer between 2013 to 2019. A radiomics risk score (R score) and dosiomics risk score (D score), as well as a DVH-score, were calculated based on logistic regression after feature selection. Six models were built using different combinations of R score, D score, DVH score, and clinical parameters to evaluate their added prognostic power. Overoptimism was evaluated by bootstrap resampling from the training set, and the prospectively collected cohort was used as the external test set. Model calibration and decision-curve characteristics of the best-performing models were evaluated. For ease of further evaluation, nomograms were constructed for selected models.

RESULTS

A model built by integrating all of the R score, D score, and clinical parameters had the best discriminative ability with areas under the curve of 0.793 (95% confidence interval [CI], 0.735-0.851), 0.774 (95% CI, 0.762-0.786), and 0.855 (95% CI, 0.719-0.990) in the training, bootstrapping, and external test sets, respectively. The calibration curve image showed good agreement between the predicted and actual values, with a slope of 1.21 and intercept of -0.04. The decision curve image showed a positive net benefit for the final model based on the nomogram.

CONCLUSIONS

Radiomic and dosiomic features have the potential to assist with the prediction of RP, and the combination of radiomics, dosiomics, and clinical parameters led to the best prognostic model in the present study.

Association of Clinical and Radiological Features with Disease Severity of Symptomatic Immune Checkpoint Inhibitor-Related Pneumonitis

OBJECTIVES

To investigate the predictive ability of clinical and chest computed tomography (CT) features to predict the severity of symptomatic immune checkpoint inhibitor-related pneumonitis (CIP).

METHODS

This study included 34 patients diagnosed with symptomatic CIP (grades 2-5) and divided into mild (grade 2) and severe CIP (grades 3-5) groups. The groups' clinical and chest CT features were analyzed. Three manual scores (extent, image finding, and clinical symptom scores) were conducted to evaluate the diagnostic performance alone and in combination.

RESULTS

There were 20 cases of mild CIP and 14 cases of severe CIP. More severe CIP occurred within 3 months than after 3 months (11 vs. 3 cases, p = 0.038). Severe CIP was significantly associated with fever (p < 0.001) and the acute interstitial pneumonia/acute respiratory distress syndrome pattern (p = 0.001). The diagnostic performance of chest CT scores (extent score and image finding score) was better than that of clinical symptom score. The combination of the three scores demonstrated the best diagnostic value, with an area under the receiver operating characteristic curve of 0.948.

CONCLUSIONS

The clinical and chest CT features have important application value in assessing the disease severity of symptomatic CIP. We recommend the routine use of chest CT in a comprehensive clinical evaluation.

Imaging of Drug-Related Pneumonitis in Oncology

Clinical applications of novel anticancer agents in the past few decades brought marked advances in cancer treatment, enabling remarkable efficacy and effectiveness; however, these novel agents are also associated with toxicities. Among various toxicities, drug-related pneumonitis is one of the major clinical challenges in the management of cancer patients. Imaging plays a key role in detection, diagnosis, and monitoring of drug-related pneumonitis during cancer treatment. In the current era of precision oncology, pneumonitis from molecular targeted therapy and immune-checkpoint inhibitors (ICI) has been recognized as an event of clinical significance. Additionally, further advances of therapeutic approaches in cancer have brought several emerging issues in diagnosis and monitoring of pneumonitis. This article will describe the computed tomography (CT) pattern-based approach for drug-related pneumonitis that has been utilized to describe the imaging manifestations of pneumonitis from novel cancer therapies. Then, we will discuss pneumonitis from representative agents of precision cancer therapy, including mammalian target of rapamycin inhibitors, epidermal growth factor receptor inhibitors, and ICI, focusing on the incidence, risk factors, and the spectrum of CT patterns. Finally, the article will address emerging challenges in the diagnosis and monitoring of pneumonitis, including pneumonitis from combination ICI and radiation therapy and from antibody conjugate therapy, as well as the overlapping imaging features of drug-related pneumonitis and coronavirus disease 2019 pneumonia. The review is designed to provide a practical overview of drug-related pneumonitis from cutting-edge cancer therapy with emphasis on the role of imaging.

Interstitial Lung Abnormalities at CT: Subtypes, Clinical Significance, and Associations with Lung Cancer

Interstitial lung abnormality (ILA) is defined as an interstitial change detected incidentally on CT images. It is seen in 4%-9% of smokers and 2%-7% of nonsmokers. ILA has a tendency to progress with time and is associated with respiratory symptoms, decreased exercise capability, reduced pulmonary function, and increased mortality. ILAs can be classified into three subcategories: nonsubpleural, subpleural nonfibrotic, and subpleural fibrotic. In cases of ILA, clinically significant interstitial lung disease should be identified and requires clinically driven management by a pulmonologist. Risk factors for the progression of ILA include clinical elements (ie, inhalation exposures, medication use, radiation therapy, thoracic surgery, physiologic findings, and gas exchange findings) and radiologic elements (ie, basal and peripheral predominance and fibrotic findings). It is recommended that individuals with one or more clinical or radiologic risk factors for progression of ILA be actively monitored with pulmonary function testing and CT. To avoid overcalling ILA at CT, radiologists must recognize the imaging pitfalls, including centrilobular nodularity, dependent abnormality, suboptimal inspiration, osteophyte-related lesions, apical cap and pleuroparenchymal fibroelastosis-like lesions, aspiration, and infection. There is a close association between ILA and lung cancer, and many studies have reported an increased incidence of lung cancer, worse prognoses, and/or increased pulmonary complications in relation to cancer treatment in patients with ILA. ILA is considered to be an important comorbidity in patients with lung cancer. Accordingly, all radiologists involved with body CT must have sound knowledge of ILAs owing to the high prevalence and potential clinical significance of these anomalies. An overview of ILAs, including a literature review of the associations between ILAs and lung cancer, is presented. ©RSNA, 2022.

Radiation-Induced Lung Injury: Prevention, Diagnostics and Therapy in the Era of the COVID-19 Pandemic

Thoracic radiotherapy (TRT) plays an integral role in the multimodal treatment of lung cancer, breast cancer, esophageal cancer, thymoma and mesothelioma, having been used as either a definitive, neoadjuvant or adjuvant treatment or for palliative intention to achieve symptom control [...]

Radiation and immune checkpoint inhibitor-mediated pneumonitis risk stratification in patients with locally advanced non-small cell lung cancer: role of functional lung radiomics?

BACKGROUND

Patients undergoing chemoradiation and immune checkpoint inhibitor (ICI) therapy for locally advanced non-small cell lung cancer (NSCLC) experience pulmonary toxicity at higher rates than historical reports. Identifying biomarkers beyond conventional clinical factors and radiation dosimetry is especially relevant in the modern cancer immunotherapy era. We investigated the role of novel functional lung radiomics, relative to functional lung dosimetry and clinical characteristics, for pneumonitis risk stratification in locally advanced NSCLC.

METHODS

Patients with locally advanced NSCLC were prospectively enrolled on the FLARE-RT trial (NCT02773238). All received concurrent chemoradiation using functional lung avoidance planning, while approximately half received consolidation durvalumab ICI. Within tumour-subtracted lung regions, 110 radiomics features (size, shape, intensity, texture) were extracted on pre-treatment [99mTc]MAA SPECT/CT perfusion images using fixed-bin-width discretization. The performance of functional lung radiomics for pneumonitis (CTCAE v4 grade 2 or higher) risk stratification was benchmarked against previously reported lung dosimetric parameters and clinical risk factors. Multivariate least absolute shrinkage and selection operator Cox models of time-varying pneumonitis risk were constructed, and prediction performance was evaluated using optimism-adjusted concordance index (c-index) with 95% confidence interval reporting throughout.

RESULTS

Thirty-nine patients were included in the study and pneumonitis occurred in 16/39 (41%) patients. Among clinical characteristics and anatomic/functional lung dosimetry variables, only the presence of baseline chronic obstructive pulmonary disease (COPD) was significantly associated with the development of pneumonitis (HR 4.59 [1.69-12.49]) and served as the primary prediction benchmark model (c-index 0.69 [0.59-0.80]). Discrimination of time-varying pneumonitis risk was numerically higher when combining COPD with perfused lung radiomics size (c-index 0.77 [0.65-0.88]) or shape feature classes (c-index 0.79 [0.66-0.91]) but did not reach statistical significance compared to benchmark models (p > 0.26). COPD was associated with perfused lung radiomics size features, including patients with larger lung volumes (AUC 0.75 [0.59-0.91]). Perfused lung radiomic texture features were correlated with lung volume (adj R2 = 0.84-1.00), representing surrogates rather than independent predictors of pneumonitis risk.

CONCLUSIONS

In patients undergoing chemoradiation with functional lung avoidance therapy and optional consolidative immune checkpoint inhibitor therapy for locally advanced NSCLC, the strongest predictor of pneumonitis was the presence of baseline chronic obstructive pulmonary disease. Results from this novel functional lung radiomics exploratory study can inform future validation studies to refine pneumonitis risk models following combinations of radiation and immunotherapy. Our results support functional lung radiomics as surrogates of COPD for non-invasive monitoring during and after treatment. Further study of clinical, dosimetric, and radiomic feature combinations for radiation and immune-mediated pneumonitis risk stratification in a larger patient population is warranted.

Pneumonitis after Stereotactic Thoracic Radioimmunotherapy with Checkpoint Inhibitors: Exploration of the Dose-Volume-Effect Correlation

Simple Summary

Stereotactic body radiation therapy (SBRT) is widely applied for treatment of early stage lung cancer and pulmonary metastases. Modern immune checkpoint blockade (ICB) is progressively used in cancer treatment. Pneumonitis is a relevant side effect of both thoracic SBRT and ICB. Currently, it remains unclear whether we can presume the same radiation dose–volume–effect correlations and dose constraints for safe application of SBRT + ICB. We present a dose–volume–effect correlation analysis method using pneumonitis contours and dose–volume histograms (DVH). We showed dosimetric differences for pneumonitis volumes between SBRT + ICB and SBRT alone. We found a large extent of pneumonitis, even bilateral and apart from the radiation field for combined SBRT + ICB. We noticed a shift in pneumonitis DVHs towards lower doses and a trend towards decreased areas under the curve (AUC) for SBRT + ICB. This provides a direction for re-evaluation and potential adaptation of lung dose constraints for combined SBRT and ICB.

Abstract

Thoracic stereotactic body radiation therapy (SBRT) is extensively used in combination with immune checkpoint blockade (ICB). While current evidence suggests that the occurrence of pneumonitis as a side effect of both treatments is not enhanced for the combination, the dose–volume correlation remains unclear. We investigate dose–volume–effect correlations for pneumonitis after combined SBRT + ICB. We analyzed patient clinical characteristics and dosimetric data for 42 data sets for thoracic SBRT with ICB treatment (13) and without (29). Dose volumes were converted into 2 Gy equivalent doses (EQD2), allowing for dosimetric comparison of different fractionation regimes. Pneumonitis volumes were delineated and corresponding DVHs were analyzed. We noticed a shift towards lower doses for combined SBRT + ICB treatment, supported by a trend of smaller areas under the curve (AUC) for SBRT+ ICB (median AUC 1337.37 vs. 5799.10, p = 0.317). We present a DVH-based dose–volume–effect correlation method and observed large pneumonitis volumes, even with bilateral extent in the SBRT + ICB group. We conclude that further studies using this method with enhanced statistical power are needed to clarify whether adjustments of the radiation dose constraints are required to better estimate risks of pneumonitis after the combination of SBRT and ICB.

Inhaled curcumin mesoporous polydopamine nanoparticles against radiation pneumonitis

Radiation therapy is an effective method to kill cancer cells and shrink tumors using high-energy X-ray or γ-ray. Radiation pneumonitis (RP) is one of the most serious complications of radiation therapy for thoracic cancers, commonly leading to serious respiratory distress and poor prognosis. Here, we prepared curcumin-loaded mesoporous polydopamine nanoparticles (CMPN) for prevention and treatment of RP by pulmonary delivery. Mesoporous polydopamine nanoparticles (MPDA) were successfully synthesized with an emulsion-induced interface polymerization method and curcumin was loaded in MPDA via π‒π stacking and hydrogen bonding interaction. MPDA owned the uniform spherical morphology with numerous mesopores that disappeared after loading curcumin. More than 80% curcumin released from CMPN in 6 h and mesopores recovered. CMPN remarkably protected BEAS-2B cells from γ-ray radiation injury by inhibiting apoptosis. RP rat models were established after a single dose of 15 Gy ⁶⁰Co γ-ray radiation was performed on the chest area. Effective therapy of RP was achieved by intratracheal administration of CMPN due to free radical scavenging and anti-oxidation ability, and reduced proinflammatory cytokines, high superoxide dismutase, decreased malondialdehyde, and alleviated lung tissue damages were observed. Inhaled CMPN paves a new avenue for the treatment of RP.

Outcomes of proton therapy for non-small cell lung cancer in patients with interstitial pneumonia

Background

Interstitial pneumonia (IP) is a disease with a poor prognosis. In addition, IP patients are more likely to develop lung cancer. Since IP patients frequently develop toxicities during cancer treatment, minimally invasive cancer treatment is warranted for such patients to maintain their quality of life. This study retrospectively investigated the efficacy and safety of proton therapy (PT) for non-small cell lung cancer (NSCLC) in patients with IP.

Methods

Twenty-nine NSCLC patients with IP were treated with PT between September 2013 and December 2019. The patients had stage IA to IIIB primary NSCLC. Ten of the 29 patients exhibited the usual interstitial pneumonia pattern. The prescribed dose was 66–74 Grays (relative biological effectiveness) in 10–37 fractions.

Results

The median follow-up period was 21.1 months [interquartile range (IQR), 15.6–37.3] for all patients and 37.2 months (IQR, 24.0–49.9) for living patients. The median patient age was 77 years (IQR, 71–81). The median planning target volume was 112.0 ml (IQR, 56.1–246.3). The 2-year local control, progression-free survival, and overall survival rates were 85% (95% confidence interval: 57–95), 30% (15–47), and 45% (26–62), respectively. According to the Common Terminology Criteria for Adverse Events (version 4.0), grade 3 acute radiation pneumonitis (RP) was observed in 1 patient. Two patients developed grade 3 late RP, but no other patients experienced serious toxicities. The patients’ quality of life (European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-LC13 and SF-36) scores had not changed after 3 months.

Conclusions

PT may be a relatively safe treatment for NSCLC patients with IP, without deteriorating quality of life scores within 3 months.

Normal Lung Tissue CT Density Changes after Volumetric-Arc Radiotherapy (VMAT) for Lung Cancer

Radiation-induced lung injury remains a significant toxicity in thoracic radiotherapy. Because a precise diagnosis is difficult and commonly used assessment scales are unclear and subjective, there is a need to establish quantitative and sensitive grading methods. The lung tissue density change expressed in Hounsfield units (HUs) derived from CT scans seems a useful numeric surrogate. The study aimed to confirm a dose-response effect on HU value changes (ΔHU), their evolution in time, and the impact of selected clinical and demographic factors. We used dedicated, self-developed software to register and analyze 120 pairs of initial and follow-up CT scans of 47 lung cancer patients treated with dynamic arc radiotherapy. The differences in HU values between CT scans were calculated within discretized dose-bins limited by isodose lines. We have proved the dose-effect relationship, which is well described with a sigmoid model. We found the time evolution of HU changes to suit a typical clinical presentation of radiation-induced toxicity. Some clinical factors were found to correlate with ΔHU degree: planning target volume (PTV), V35 in the lung, patient’s age and a history of arterial hypertension, and initial lung ventilation intensity. Lung density change assessment turned out to be a sensitive and valuable method of grading post-RT lung toxicity.

Dosimetric Risk Factors for Acute Radiation Pneumonitis in Patients With Prior Receipt of Immune Checkpoint Inhibitors

Purpose

Dosimetric parameters (e.g., mean lung dose (MLD), V20, and V5) can predict radiation pneumonitis (RP). Constraints thereof were formulated before the era of combined immune checkpoint inhibitors (ICIs) and radiotherapy, which could amplify the RP risk. Dosimetric predictors of acute RP (aRP) in the context of ICIs are urgently needed because no data exist thus far.

Methods and Materials

All included patients underwent thoracic intensity-modulated radiotherapy, previously received ICIs, and followed-up at least once. Logistic regression models examined predictors of aRP (including a priori evaluation of MLD, V20, and V5), and their discriminative capacity was assessed by receiver operating characteristic analysis.

Results

Median follow-up of the 40 patients was 5.3 months. Cancers were lung (80%) or esophageal (20%). ICIs were PD-1 (85%) or PD-L1 (15%) inhibitors (median 4 cycles). Patients underwent definitive (n=19), consolidative (n=14), or palliative (n=7) radiotherapy; the median equivalent dose in 2 Gy fractions (EQD2) was 60 Gy (IQR, 51.8-64 Gy). Grades 1-5 aRP occurred in 25%, 17.5%, 15%, 2.5%, and 5%, respectively. The only variables associated with any-grade aRP were V20 (p=0.014) and MLD (p=0.026), and only V20 with grade ≥2 aRP (p=0.035). Neither the number of prior ICI cycles nor the delivery of concurrent systemic therapy significantly associated with aRP risk. Graphs were constructed showing the incrementally increasing risk of aRP based on V20 and MLD (continuous variables).

Conclusions

This is the first study illustrating that V20 and MLD may impact aRP in the setting of prior ICIs. However, these data should not be extrapolated to patients without pre-radiotherapy receipt of prior ICIs, or to evaluate the risk of chronic pulmonary effects. If these results are validated by larger studies with more homogeneous populations, the commonly accepted V20/MLD dose constraints could require revision if utilized in the setting of ICIs.

Differentiation between immune checkpoint inhibitor-related and radiation pneumonitis in lung cancer by CT radiomics and machine learning

Purpose

Consolidation immunotherapy after completion of chemoradiotherapy has become the standard of care for unresectable locally advanced non‐small cell lung cancer and can induce potentially severe and life‐threatening adverse events, including both immune checkpoint inhibitor‐related pneumonitis (CIP) and radiation pneumonitis (RP), which are very challenging for radiologists to diagnose. Differentiating between CIP and RP has significant implications for clinical management such as the treatments for pneumonitis and the decision to continue or restart immunotherapy. The purpose of this study is to differentiate between CIP and RP by a CT radiomics approach.

Methods

We retrospectively collected the CT images and clinical information of patients with pneumonitis who received immune checkpoint inhibitor (ICI) only (n = 28), radiotherapy (RT) only (n = 31), and ICI+RT (n = 14). Three kinds of radiomic features (intensity histogram, gray‐level co‐occurrence matrix [GLCM] based, and bag‐of‐words [BoW] features) were extracted from CT images, which characterize tissue texture at different scales. Classification models, including logistic regression, random forest, and linear SVM, were first developed and tested in patients who received ICI or RT only with 10‐fold cross‐validation and further tested in patients who received ICI+RT using clinicians’ diagnosis as a reference.

Results

Using 10‐fold cross‐validation, the classification models built on the intensity histogram features, GLCM‐based features, and BoW features achieved an area under curve (AUC) of 0.765, 0.848, and 0.937, respectively. The best model was then applied to the patients receiving combination treatment, achieving an AUC of 0.896.

Conclusions

This study demonstrates the promising potential of radiomic analysis of CT images for differentiating between CIP and RP in lung cancer, which could be a useful tool to attribute the cause of pneumonitis in patients who receive both ICI and RT.

Radiation Versus Immune Checkpoint Inhibitor Associated Pneumonitis: Distinct Radiologic Morphologies

BACKGROUND

Patients with non-small cell lung cancer may develop pneumonitis after thoracic radiotherapy (RT) and immune checkpoint inhibitors (ICIs). We hypothesized that distinct morphologic features are associated with different pneumonitis etiologies.

MATERIALS AND METHODS

We systematically compared computed tomography (CT) features of RT- versus ICI-pneumonitis. Clinical and imaging features were tested for association with pneumonitis severity. Lastly, we constructed an exploratory radiomics-based machine learning (ML) model to discern pneumonitis etiology.

RESULTS

Between 2009 and 2019, 82 patients developed pneumonitis: 29 after thoracic RT, 23 after ICI, and 30 after RT + ICI. Fifty patients had grade 2 pneumonitis, 22 grade 3, and 7 grade 4. ICI-pneumonitis was more likely bilateral (65% vs. 28%; p = .01) and involved more lobes (66% vs. 45% involving at least three lobes) and was less likely to have sharp border (17% vs. 59%; p = .004) compared with RT-pneumonitis. Pneumonitis morphology after RT + ICI was heterogeneous, with 47% bilateral, 37% involving at least three lobes, and 40% sharp borders. Among all patients, risk factors for severe pneumonitis included poor performance status, smoking history, worse lung function, and bilateral and multifocal involvement on CT. An ML model based on seven radiomic features alone could distinguish ICI- from RT-pneumonitis with an area under the receiver-operating curve of 0.76 and identified the predominant etiology after RT + ICI concordant with multidisciplinary consensus.

CONCLUSION

RT- and ICI-pneumonitis exhibit distinct spatial features on CT. Bilateral and multifocal lung involvement is associated with severe pneumonitis. Integrating these morphologic features in the clinical management of patients who develop pneumonitis after RT and ICIs may improve treatment decision-making.

IMPLICATIONS FOR PRACTICE

Patients with non-small cell lung cancer often receive thoracic radiation and immune checkpoint inhibitors (ICIs), both of which can cause pneumonitis. This study identified similarities and differences in pneumonitis morphology on computed tomography (CT) scans among pneumonitis due to radiotherapy (RT) alone, ICI alone, and the combination of both. Patients who have bilateral CT changes involving at least three lobes are more likely to have ICI-pneumonitis, whereas those with unilateral CT changes with sharp borders are more likely to have radiation pneumonitis. After RT and/or ICI, severe pneumonitis is associated with bilateral and multifocal CT changes. These results can help guide clinicians in triaging patients who develop pneumonitis after radiation and during ICI treatment.

Imaging of Oncologic Treatment-Related Pneumonitis: A Focused Review on Emerging Issues of Immune Checkpoint Inhibitor Pneumonitis, From the AJR Special Series on Inflammation

Treatment-related pneumonitis represents a major challenge in oncology patients undergoing therapy, and imaging plays an essential role in detection, diagnosis, and monitoring of pneumonitis in these patients. Among various types of pneumonitis from different kinds of cancer treatments, immune checkpoint inhibitor (ICI)-related pneumonitis has been recognized as an important topic in the radiology and oncology communities since 2015, given the increasing clinical indications for ICI therapy in patients with cancer. Moreover, clinical applications of ICIs continue to advance rapidly with novel combination approaches, leading to further emerging challenges. This focused review describes the current knowledge about ICI pneumonitis and discusses several newly emerging issues involving recurrence and flare of ICI pneumonitis, as well as involving pneumonitis from new combination approaches including ICI with epidermal growth factor receptor (EGFR) inhibitors and ICI with radiotherapy. The article concludes with a summary of unmet needs in the care of patients with ICI pneumonitis as well as of future directions in the advancement of knowledge about ICI pneumonitis and patient care for ICI pneumonitis. Given the proven multifaceted value of imaging in ICI pneumonitis, radiologists will remain central in the ongoing multidisciplinary journey to further understand and overcome this challenging toxicity for patients with cancer.

Safety of thoracic radiotherapy in patients with prior immune-related adverse events from immune checkpoint inhibitors

BACKGROUND

Immune checkpoint inhibitors (ICIs) and thoracic radiotherapy are increasingly used to treat advanced cancers. Despite data indicating exaggerated radiation toxicities in patients with autoimmune disease, the safety of thoracic radiotherapy in patients with prior ICI-associated immune-related adverse events (irAEs) is undefined.

PATIENTS AND METHODS

Patients treated from 2014 to 2020 with ICIs were queried for receipt of corticosteroids and radiotherapy. Patients who received thoracic radiation after symptomatic irAEs were assessed for ≥grade 2 radiation pneumonitis (RP). Characteristics predictive of RP were assessed using logistic regression and response relationships were modeled.

RESULTS

Among 496 assessed patients, 41 with irAE history subsequently treated with thoracic radiotherapy were analyzed. Most irAEs were grade 2 (n = 21) and 3 (n = 19). Median time from irAE onset to radiotherapy was 8.1 months. Most patients received stereotactic body radiation therapy (n = 20) or hypofractionated radiotherapy (n = 18). In total, 25 patients (61%) developed ≥grade 2 RP at a median of 4 months from radiotherapy and 11 months from onset of irAEs. Three months from RP onset, 16 of 24 (67%) assessable patients had persistent symptoms. Among patients with prior ICI pneumonitis (n = 6), five patients (83%) developed ≥grade 2 RP (grade 2, n = 3; grade ≥3, n = 2). The mean lung radiation dose (MLD) predicted for RP (odds ratio: 1.60, P = 0.00002). The relationship between MLD and RP was strong (area under the receiver-operating characteristic curve: 0.85) and showed an exaggerated dose-response. Among patients with an MLD >5 Gy (n = 26), 21 patients (81%) developed ≥grade 2 RP.

CONCLUSION

This is the first study assessing the toxicity of radiotherapy among patients with prior irAEs from ICIs. Patients with prior irAEs were found to be at very high risk for clinically significant and persistent RP from thoracic radiotherapy. Careful consideration should be given to the possibility of an increased risk of RP, and close monitoring is recommended in these patients.

Radiation-induced lung toxicity - cellular and molecular mechanisms of pathogenesis, management, and literature review

Lung, breast, and esophageal cancer represent three common malignancies with high incidence and mortality worldwide. The management of these tumors critically relies on radiotherapy as a major part of multi-modality care, and treatment-related toxicities, such as radiation-induced pneumonitis and/or lung fibrosis, are important dose limiting factors with direct impact on patient outcomes and quality of life. In this review, we summarize the current understanding of radiation-induced pneumonitis and pulmonary fibrosis, present predictive factors as well as recent diagnostic and therapeutic advances. Novel candidates for molecularly targeted approaches to prevent and/or treat radiation-induced pneumonitis and pulmonary fibrosis are discussed.