Radiation effects on the lung: clinical features, pathology, and imaging findings

Radiation Therapy for Lung Cancer: Imaging Appearances and Pitfalls

Radiation therapy is part of a multimodality treatment approach to lung cancer. The radiologist must be aware of both the expected and the unexpected imaging findings of the post-radiation therapy patient, including the time course for development of post- radiation therapy pneumonitis and fibrosis. In this review, a brief discussion of radiation therapy techniques and indications is presented, followed by an image-heavy differential diagnostic approach. The review focuses on computed tomography imaging examples to help distinguish normal postradiation pneumonitis and fibrosis from alternative complications, such as infection, local recurrence, or radiation-induced malignancy.

Uncommon Causes of Interlobular Septal Thickening on CT Images and Their Distinguishing Features

Interlobular septa thickening (ILST) is a common and easily recognized feature on computed tomography (CT) images in many lung disorders. ILST thickening can be smooth (most common), nodular, or irregular. Smooth ILST can be seen in pulmonary edema, pulmonary alveolar proteinosis, and lymphangitic spread of tumors. Nodular ILST can be seen in the lymphangitic spread of tumors, sarcoidosis, and silicosis. Irregular ILST is a finding suggestive of interstitial fibrosis, which is a common finding in fibrotic lung diseases, including sarcoidosis and usual interstitial pneumonia. Pulmonary edema and lymphangitic spread of tumors are the commonly encountered causes of ILST. It is important to narrow down the differential diagnosis as much as possible by assessing the appearance and distribution of ILST, as well as other pulmonary and extrapulmonary findings. This review will focus on the CT characterization of the secondary pulmonary lobule and ILST. Various uncommon causes of ILST will be discussed, including infections, interstitial pneumonia, depositional/infiltrative conditions, inhalational disorders, malignancies, congenital/inherited conditions, and iatrogenic causes. Awareness of the imaging appearance and various causes of ILST allows for a systematic approach, which is important for a timely diagnosis. This study highlights the importance of a structured approach to CT scan analysis that considers ILST characteristics, associated findings, and differential diagnostic considerations to facilitate accurate diagnoses.

A Case of Vanishing Bronchus Syndrome in a Non-lung Transplant Patient

Vanishing bronchus syndrome (VBS) is the most severe form of bronchial stenosis. It has been described as a complication following a lung transplant (LT). We present a case of VBS in a patient with non-Hodgkin lymphoma in remission status post chemotherapy and radiation therapy and no history of a lung transplant.

Central airway squamous metaplasia following radiation therapy mimicking local tumour recurrence

Radiation therapy can result in injury to the lung parenchyma and central airways; the latter is less well documented in the literature. Here, we describe a 65-year-old Caucasian male, who developed focal endobronchial nodules and right main bronchial stenosis suggesting tumour recurrence, 32 months following curative intent concurrent chemoradiation therapy for Stage 3B squamous cell carcinoma of the lung. Computed tomography and positron emission tomography results are detailed. Flexible bronchoscopy with bronchial biopsies revealed squamous metaplasia rather than malignant tumour recurrence, with ongoing observation planned.

Validation of CT-based ventilation and perfusion biomarkers with histopathology confirms radiation-induced pulmonary changes in a porcine model

Imaging biomarkers can assess disease progression or prognoses and are valuable tools to help guide interventions. Particularly in lung imaging, biomarkers present an opportunity to extract regional information that is more robust to the patient's condition prior to intervention than current gold standard pulmonary function tests (PFTs). This regional aspect has particular use in functional avoidance radiation therapy (RT) in which treatment planning is optimized to avoid regions of high function with the goal of sparing functional lung and improving patient quality of life post-RT. To execute functional avoidance, detailed dose-response models need to be developed to identify regions which should be protected. Previous studies have begun to do this, but for these models to be clinically translated, they need to be validated. This work validates two metrics that encompass the main components of lung function (ventilation and perfusion) through post-mortem histopathology performed in a novel porcine model. With these methods validated, we can use them to study the nuanced radiation-induced changes in lung function and develop more advanced models.

Drug-Induced Interstitial Lung Diseases

Drug-induced interstitial lung disease (DI-ILD) is an increasingly common cause of morbidity and mortality as the list of culprit drugs continues to grow. Unfortunately, DI-ILD is difficult to study, diagnose, prove, and manage. This article attempts to raise awareness of the challenges in DI-ILD and discusses the current clinical landscape.

Long-Term Effects of Breast Cancer Therapy and Care: Calm after the Storm?

Breast cancer is still a lethal disease and the leading cause of death in women, undermining patients' survival and quality of life. Modern techniques of surgery and radiotherapy allow for the obtaining of good results in terms of survival, however they cause long-term side effects that persist over time, such as lymphedema and neuropathy. Similarly, the advent of new therapies such as endocrine therapy revolutionized breast cancer outcomes, but side effects are still present even in years of follow-up after cure. Besides the side effects of medical and surgical therapy, breast cancer is a real disruption in patients' lives considering quality of life-related aspects such as the distortion of body image, the psychological consequences of the diagnosis, and the impact on family dynamics. Therefore, the doctor-patient relationship is central to providing the best support both during treatment and afterwards. The aim of this review is to summarize the consequences of medical and surgical treatment on breast cancer patients and to emphasize the importance of early prevention of side effects to improve patients' quality of life.

The prognostic value of 18F-FDG PET/CT taken immediately after completion of radiotherapy for lung cancer treated with concurrent chemoradiotherapy: A pilot study

PURPOSE

The prognostic value of F-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) taken immediately after completion of radiotherapy in lung cancer patients is not well known. The purpose of this study is to assess the prognostic value of PET/CT taken immediately after completion of radiotherapy in lung cancer patients.

MATERIALS AND METHODS

Patients with primary lung cancer planned to undergo concurrent chemoradiotherapy were enrolled. Patients underwent PET/CT scans at 3 time points: before radiotherapy, within 24hours of completing radiotherapy (im-PET/CT), and 2-9 months after radiotherapy (post-PET/CT). Maximum standardized uptake value (SUV_max) was obtained. A post-PET/CT-SUV_max cut-off of 2.5 was determined as radiotherapy success.

RESULTS

Nineteen patients were enrolled. im-PET/CT-SUV_max for patients in the high post-PET/CT-SUV_max group was significantly higher than that of the low group (P=0.004). Receiver operator curve analysis indicated that im-PET/CT-SUV_max of 4.35 was an optimal cut-off value to discriminate between the two groups. Multivariable analysis showed that a high im-PET/CT-SUV_max was significantly associated with a high post-PET/CT-SUV_max (P=0.003).

CONCLUSION

PET/CT-SUV_max taken immediately following radiotherapy was associated with that evaluated 2-9 months after radiotherapy.

COVID-19 Pneumonia and Lung Cancer: A Challenge for the Radiological Review of the Main Radiological Features, Differential Diagnosis and Overlapping Pathologies

The COVID-19 pneumonia pandemic represents the most severe health emergency of the 21st century and has been monopolizing health systems’ economic and human resources world-wide. Cancer patients have been suffering from the health systems’ COVID-19 priority management with evidence of late diagnosis leading to patients’ poor prognosis and late medical treatment. The radiologist plays a pivotal role as CT represents a non-invasive radiological technique which may help to identify possible overlap and differential diagnosis between COVID-19 pneumonia and lung cancer, which represents the most frequent cancer histology in COVID-19 patients. Our aims are: to present the main CT features of COVID-19 pneumonia; to provide the main differential diagnosis with lung cancer, chemotherapy-, immunotherapy-, and radiotherapy-induced lung disease; and to suggest practical tips and key radiological elements to identify possible overlap between COVID-19 pneumonia and lung cancer. Despite similarities or overlapping findings, the combination of clinics and some specific radiological findings, which are also identified by comparison with previous and follow-up CT scans, may guide differential diagnosis. It is crucial to search for typical COVID-19 pneumonia phase progression and typical radiological features on HRTC. The evidence of atypical findings such as lymphadenopathies and mediastinal and vessel invasion, as well as the absence of response to therapy, should arouse the suspicion of lung cancer and require contrast administration. Ground-glass areas and/or consolidations bound to radiotherapy fields or pneumonitis arising during and after oncological therapy should always arouse the suspicion of radiation-induced lung disease and chemo/immunotherapy-induced lung disease. The radiological elements we suggest for COVID-19 and lung cancer differential diagnosis may be used to develop AI protocols to guarantee an early and proper diagnosis and treatment to improve patients’ quality of life and life expectancy.

Clinical Value of Surveillance 18F-fluorodeoxyglucose PET/CT for Detecting Unsuspected Recurrence or Second Primary Cancer in Non-Small Cell Lung Cancer after Curative Therapy

Simple Summary

Non-small cell lung cancer (NSCLC) patients are at considerable risk of recurrence or second primary cancer (SPC) after curative therapy. The utility of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) surveillance to detect recurrent lesions in NSCLC patients without suspicion of recurrence has not been established. The aim of our retrospective study was to evaluate the diagnostic value of surveillance FDG PET/CT for detecting clinically unsuspected recurrence or SPC in patients with NSCLC after curative therapy. In a cohort of 2684 NSCLC patients after curative therapy, surveillance FDG PET/CT showed good diagnostic efficacy for detecting clinically unexpected recurrence or SPC. Furthermore, the diagnostic performance was improved in subgroups of patients with advanced stage prior to curative therapy, PET/CT scans performed within 3 years after curative-intent therapy, and curative surgery. Surveillance PET/CT can be more useful when performed soon after therapy in curative surgery recipients and those with an advanced disease stage considering its diagnostic efficacy and yield.

Abstract

We evaluated the diagnostic value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT surveillance for detecting clinically unsuspected recurrence or second primary cancer (SPC) in patients with non-small cell lung cancer (NSCLC) after curative therapy. A total of 4478 surveillance FDG PET/CT scans from 2864 NSCLC patients without suspicion of recurrence after curative therapy were reviewed retrospectively. In 274 of 2864 (9.6%) patients, recurrent NSCLC or SPC was found by surveillance PET/CT during clinical follow-up. Surveillance PET/CT scans showed sensitivity of 98.9% (274/277), specificity of 98.1% (4122/4201), accuracy of 98.2% (4396/4478), positive predictive value (PPV) of 77.6% (274/353), and negative predictive value of 99.9% (4122/4125). The specificity and accuracy in the curative surgery group were significantly higher than those in the curative radiotherapy group. PPV was significantly improved in subgroups of patients with advanced stage prior to curative therapy, PET/CT scans performed within 3 years after curative-intent therapy, and curative surgery. FDG PET/CT surveillance showed good diagnostic efficacy for detecting clinically unexpected recurrence or SPC in NSCLC patients after curative therapy. It can be more useful when performed soon after therapy in curative surgery recipients and those with an advanced disease stage considering its diagnostic efficacy and yield.

All for one, though not one for all: team players in normal tissue radiobiology

PURPOSE

As part of the special issue on 'Women in Science', this review offers a perspective on past and ongoing work in the field of normal (non-cancer) tissue radiation biology, highlighting the work of many of the leading contributors to this field of research. We discuss some of the hypotheses that have guided investigations, with a focus on some of the critical organs considered dose-limiting with respect to radiation therapy, and speculate on where the field needs to go in the future.

CONCLUSIONS

The scope of work that makes up normal tissue radiation biology has and continues to play a pivotal role in the radiation sciences, ensuring the most effective application of radiation in imaging and therapy, as well as contributing to radiation protection efforts. However, despite the proven historical value of preclinical findings, recent decades have seen clinical practice move ahead with altered fractionation scheduling based on empirical observations, with little to no (or even negative) supporting scientific data. Given our current appreciation of the complexity of normal tissue radiation responses and their temporal variability, with tissue- and/or organ-specific mechanisms that include intra-, inter- and extracellular messaging, as well as contributions from systemic compartments, such as the immune system, the need to maintain a positive therapeutic ratio has never been more urgent. Importantly, mitigation and treatment strategies, whether for the clinic, emergency use following accidental or deliberate releases, or reducing occupational risk, will likely require multi-targeted approaches that involve both local and systemic intervention. From our personal perspective as five 'Women in Science', we would like to acknowledge and applaud the role that many female scientists have played in this field. We stand on the shoulders of those who have gone before, some of whom are fellow contributors to this special issue.

Radiation-Induced Lung Injury-Current Perspectives and Management

Radiotherapy plays an important role in the treatment of localized primary malignancies involving the chest wall or intrathoracic malignancies. Secondary effects of radiotherapy on the lung result in radiation-induced lung disease. The phases of lung injury from radiation range from acute pneumonitis to chronic pulmonary fibrosis. Radiation pneumonitis is a clinical diagnosis based on the history of radiation, imaging findings, and the presence of classic symptoms after exclusion of infection, pulmonary embolism, heart failure, drug-induced pneumonitis, and progression of the primary tumor. Computed tomography (CT) is the preferred imaging modality as it provides a better picture of parenchymal changes. Lung biopsy is rarely required for the diagnosis. Treatment is necessary only for symptomatic patients. Mild symptoms can be treated with inhaled steroids while subacute to moderate symptoms with impaired lung function require oral corticosteroids. Patients who do not tolerate or are refractory to steroids can be considered for treatment with immunosuppressive agents such as azathioprine and cyclosporine. Improvements in radiation technique, as well as early diagnosis and appropriate treatment with high-dose steroids, will lead to lower rates of pneumonitis and an overall good prognosis.

The role of melatonin on radiation-induced pneumonitis and lung fibrosis: A systematic review

PURPOSE

Pneumonitis and lung fibrosis, as the most common compliances of lung irradiation, can affect the quality of life. The use of radio-protective agents can ameliorate these injuries. This study aimed to review the potential protective role of melatonin in the treatment of radiation-induced Pneumonitis and lung fibrosis.

METHODS

The current systematic study was conducted based on PRISMA guidelines to identify relevant literature on " the effect of melatonin on radiation-induced pneumonitis and lung fibrosis" in the electronic databases of Web of Science, Embase, PubMed, and Scopus up to January 2021. Eighty-one articles were screened in accordance with the inclusion and exclusion criteria of the study. Finally, eight articles were included in this systematic review.

RESULTS

The finding showed that the lung irradiation-induced pneumonitis and lung fibrosis. The co-treatment with melatonin could alleviate these compliances through its anti-oxidant and anti-inflammatory actions. Melatonin through upregulation of some enzymes such as catalase, superoxide dismutase, glutathione, NADPH oxidases 2 and 4, dual oxidases 1 and 2, and also downregulation of malondialdehyde reduced oxidative stress following lung radiation. Moreover, melatonin through its anti-inflammatory effects, can attenuate the increased levels of nuclear factor kappa B, tumor necrosis factor alpha, transforming growth factor beta 1, SMAD2, interleukin (IL)-4, IL-4 receptor-a1 (IL4ra1), and IL-1 beta following lung radiation. The histological damages induced by ionizing radiation were also alleviated by co-treatment with melatonin.

CONCLUSION

According to the obtained results, it was found that melatonin can have anti-pneumonitis and anti-fibrotic following lung irradiation.

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.

Recognizing Radiation Therapy-related Complications in the Chest

Radiation therapy is one of the cornerstones for the treatment of thoracic malignancies. Although advances in radiation therapy technology have improved the delivery of radiation considerably, adverse effects are still common. Postirradiation changes affect the organ or tissue treated and the neighboring structures. Advances in external-beam radiation delivery techniques and how these techniques affect the expected thoracic radiation-induced changes are described. In addition, how to distinguish these expected changes from complications such as infection and radiation-induced malignancy, and identify treatment failure, that is, local tumor recurrence, is reviewed. ^©RSNA, 2019.

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

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

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

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

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

Predictors of Respiratory Decline Following Stereotactic Ablative Radiotherapy to Multiple Lung Tumors

INTRODUCTION

Stereotactic ablative radiotherapy (SABR) is highly effective at controlling early stage primary lung cancer and lung metastases. Although previous studies have suggested that treating multiple lung tumors with SABR is safe, post-treatment changes in respiratory function have not been analyzed in detail.

PATIENTS AND METHODS

We retrospectively identified patients with 2 or more primary lung cancers or lung metastases treated with SABR and analyzed clinical outcomes and predictors of toxicity. We defined a composite respiratory decline endpoint to include increased oxygen requirement, increased dyspnea scale, or death from respiratory failure not owing to disease progression.

RESULTS

A total of 86 patients treated with SABR to 203 lung tumors were analyzed. A total of 21.8% and 41.8% of patients developed composite respiratory decline at 2 and 4 years, respectively. When accounting for intrathoracic disease progression, 12.7% of patients developed composite respiratory decline at 2 years. Of the patients, 7.9% experienced grade 2 or greater radiation pneumonitis. No patient- or treatment-related factor predicted development of respiratory decline. The median overall survival was 46.9 months, and the median progression-free survival was 14.8 months. The cumulative incidence of local failure was 9.7% at 2 years.

CONCLUSION

Although our results confirm that SABR is an effective treatment modality for patients with multiple lung tumors, we observed a high rate of respiratory decline after treatment, which may be owing to a combination of treatment and disease effects. Future studies may help to determine ways to avoid pulmonary toxicity from SABR.

Hypofractionated radiotherapy in nine dogs with unresectable solitary lung adenocarcinoma

Although lung lobectomy is the most common treatment option for dogs with solitary lung tumors, surgery often cannot be performed at the time of diagnosis. In this retrospective, case series study, we described the effects of hypofractionated radiotherapy for tumor mass reduction in nine dogs with solitary lung adenocarcinoma that were later considered for surgical resection, and we assessed the tolerability of the radiation protocol. Tumors were deemed unresectable by the attending veterinarian. The dose prescription was 7.0-12.0 Gy/fraction in four to seven fractions, administered weekly for a total dose of 40-50 Gy. Treatment planning prioritized normal tissue dose constraints. The median interval between the last radiotherapy session and maximum tumor size reduction was 56 (range: 26-196) days, with six and three dogs exhibiting a partial response and stable disease, respectively. Although acute and late radiation-induced toxicity to the skin and/or lungs developed in all nine dogs, it was self-limiting or improved with short-term anti-inflammatory treatment. Tumor progression after initial size reduction was confirmed in three dogs at 62, 126, and 175 days, respectively, after the last radiotherapy session. Seven of the nine dogs underwent lobectomy a median of 68 days after radiotherapy when tumors were in partial response or stable disease or at the time of progression, and five received systemic chemotherapy concurrent with or after radiotherapy. These findings suggest that hypofractionated radiotherapy for canine solitary lung adenocarcinoma is useful when the tumor is large or when surgery cannot be performed immediately after diagnosis.

Radiation-induced lung toxicity in mice irradiated in a strong magnetic field

Strong magnetic fields affect radiation dose deposition in MRI-guided radiation therapy systems, particularly at interfaces between tissues of differing densities such as those in the thorax. In this study, we evaluated the impact of a 1.5 T magnetic field on radiation-induced lung damage in C57L/J mice. We irradiated 140 mice to the whole thorax with parallel-opposed Co-60 beams to doses of 0, 9.0, 10.0, 10.5, 11.0, 12.0, or 13.0 Gy (20 mice per dose group). Ten mice per dose group were irradiated while a 1.5 T magnetic field was applied transverse to the radiation beam and ten mice were irradiated with the magnetic field set to 0 T. We compared survival and noninvasive assays of radiation-induced lung damage, namely respiratory rate and metrics derived from thoracic cone-beam CTs, between the two sets of mice. We report two main results. First, the presence of a transverse 1.5 T field during irradiation had no impact on survival of C57L/J mice. Second, there was a small but statistically significant effect on noninvasive assays of radiation-induced lung damage. These results provide critical safety data for the clinical introduction of MRI-guided radiation therapy systems.

18F-FDG PET/CT in Patients with Parenchymal Changes Attributed to Radiation Pneumonitis

Objectives:

Radiation pneumonitis (RP) can be an adverse complication of radiotherapy (RT) and can limit the application of the already planned radiation dose. It is often associated with RT of lung carcinoma and is occasionally caused by radiation therapy of breast carcinoma and lymphomas located in the mediastinum. Positron emission tomography/computed tomography (PET/CT) emerges lately as a prospective modality for early diagnostics of RP. The aim of this study was to summarize the initial data from diagnostic application of PET/CT in patients suspicious of RP and to derive criteria, which can help differentiate RP from early recurrence of the disease and/or residual tumor.

Methods:

The current study included 23 patients who had metabolic (PET) and anatomical (CT) changes consistent with RP. We additionally defined metabolic activity (SUV_max) in the lung parenchyma of 20 patients without RT.

Results:

All patients had increased metabolic activity in the lung parenchyma involved in the irradiated area with a mean SUV_max 3.45 (ranging between 1 and 7.1). The control group had a physiological background metabolic activity-SUV_max 0.61 +/- 0.11.

Conclusion:

Metabolic changes in patients suspicious of RP involved diffusely increased metabolic activity coinciding with the anatomical changes in the irradiated area. Three out of 23 patients had a proven recurrence of the primary neoplastic process in the irradiated area. The metabolic changes in those patients involved an increase in metabolic activity at follow-up or lack of tendency towards normalization after chemotherapy, which implied the existence of viable tumor cells. Our initial experience in the diagnostic application of ¹⁸F-FDG PET/CT in patients suspicious of RP allows us to summarize the following: PET/CT is a reliable imaging modality in the diagnostics of RP. Through its sequential use, we can differentiate inflammatory changes related to RP from early recurrence of the primary neoplastic process.

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

PURPOSE

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

Lung Cancer: Posttreatment Imaging: Radiation Therapy and Imaging Findings

Over the last few decades, advances in radiation therapy technology have markedly improved radiation delivery. Advancements in treatment planning with the development of image-guided radiotherapy and techniques such as proton therapy, allow precise delivery of high doses of radiation conformed to the tumor. These advancements result in improved locoregional control while reducing radiation dose to surrounding normal tissue. The radiologic manifestations of these techniques can differ from radiation induced lung disease seen with traditional radiation therapy. Awareness of these radiologic manifestations and correlation with radiation treatment plans are important to differentiate expected radiation induced lung injury from recurrence, infection and drug toxicity.

Unusual Complication after Radiotherapy for Breast Cancer Bronchiolitis Obliterans Organizing Pneumonia Case Report and Review of the Literature

Breast-conserving surgery and postoperative radiotherapy play an important role in the treatment of early breast cancer. Bronchiolitis obliterans with organizing pneumonia (BOOP) is an uncommon syndrome reported to be one of the complications of adjuvant radiotherapy. We report the case of a 71-year-old woman who developed cough, dyspnea and fever three weeks after radiation therapy to the left breast for breast carcinoma. Chest X-ray and computed tomography scan demonstrated alveolar opacities within both lungs. Antibiotic therapy against any probable septic pathology did not improve the symptoms, while corticosteroid treatment resulted in rapid clinical improvement together with regression of the pulmonary opacities. Irradiation was thought to be the cause of the migratory pneumonitis, hence this case was clinically diagnosed as radiation-induced migratory pneumonitis similar to BOOP, without lung biopsy. The present case suggests that one should be mindful of this disease when treating patients with a history of irradiation to the breast. BOOP promptly responds to systemic corticosteroid therapy with rapid improvement of symptoms and regression of the pulmonary opacities.

Lung density change after SABR: A comparative study between tri-Co-60 magnetic resonance-guided system and linear accelerator

Radiation-induced lung damage is an important treatment-related toxicity after lung stereotactic ablative radiotherapy (SABR). After implementing a tri-⁶⁰Co magnetic-resonance image guided system, ViewRay^TM, we compared the associated early radiological lung density changes to those associated with a linear accelerator (LINAC). Eight patients treated with the tri-⁶⁰Co system were matched 1:1 with patients treated with LINAC. Prescription doses were 52 Gy or 60 Gy in four fractions, and lung dose-volumetric parameters were calculated from each planning system. The first two follow-up computed tomography (CT) were co-registered with the planning CT through deformable registration software, and lung density was measured by isodose levels. Tumor size was matched between the two groups, but the planning target volume of LINAC was larger than that of the tri-⁶⁰Co system (p = 0.036). With regard to clinically relevant dose-volumetric parameters in the lungs, the ipsilateral lung mean dose, V_10Gy and V_20Gy were significantly poorer in tri-⁶⁰Co plans compared to LINAC plans (p = 0.012, 0.036, and 0.017, respectively). Increased lung density was not observed in the first follow-up scan compared to the planning scan. A significant change of lung density was shown in the second follow-up scan and there was no meaningful difference between the tri-⁶⁰Co system and LINAC for all dose regions. In addition, no patient developed clinical radiation pneumonitis until the second follow-up scan. Therefore, there was no significant difference in the early radiological lung damage between the tri-⁶⁰Co system and LINAC for lung SABR despite of the inferior plan quality of the tri-⁶⁰Co system compared to that of LINAC. Further studies with a longer follow-up period are needed to confirm our findings.

Patient-reported lung symptoms as an early signal of impending radiation pneumonitis in patients with non-small cell lung cancer treated with chemoradiation: an observational study

PURPOSE

Clinician ratings of concurrent chemoradiation (CRT)-induced radiation pneumonitis (RP) in patients with non-small cell lung cancer (NSCLC) are based on both imaging and patient-reported lung symptoms. We compared the value of patient-reported outcomes versus normal-lung uptake of ¹⁸F-fluoro-2-deoxyglucose in positron emission computed tomography (FDG PET/CT) during the last week of treatment, for indicating the development of grade ≥ 2 RP within 4 months of CRT completion.

METHODS

132 patients with NSCLC-reported RP-related symptoms (coughing, shortness of breath) repeatedly using the validated MD Anderson Symptom Inventory lung cancer module. Of these patients, 68 had FDG PET/CT scans that were analyzed for normal-lung mean standardized FDG uptake values (SUV_mean) before, during, and up to 4 months after CRT. Clinicians rated RP using CTCAE version 3. Logistic regression models examined potential predictors for developing CTCAE RP ≥ 2.

RESULTS

For the entire sample, patient-rated RP-related symptoms during the last week of CRT correlated with clinically meaningful CTCAE RP ≥ 2 post-CRT (OR 2.74, 95% CI 1.25-5.99, P = 0.012), controlled for sex, age, mean lung radiation dose, comorbidity, and baseline symptoms. Moderate/severe patient-rated RP-related symptom score (≥ 4 on a 0-10 scale, P = 0.001) and normal-lung FDG uptake (SUV_mean > 0.78, P = 0.002) in last week of CRT were equally strong predictors of post-CRT CTCAE RP ≥ 2 (C-index = 0.78, 0.77).

CONCLUSIONS

During the last week of CRT, routine assessment of moderate-to-severe RP-related symptoms provides a simple way to identify patients with NSCLC who may be at risk for developing significant post-CRT RP, especially when PET/CT images of normal-lung FDG uptake are not available.

Imaging of Radiation Treatment of Lung Cancer

Radiation therapy is an important modality in the treatment of patients with lung cancer. Recent advances in delivering radiotherapy were designed to improve loco-regional tumor control by focusing higher doses on the tumor. More sophisticated techniques in treatment planning include 3-dimensional conformal radiation therapy, intensity-modulated radiotherapy, stereotactic body radiotherapy, and proton therapy. These methods may result in nontraditional patterns of radiation injury and various radiologic appearances that can be mistaken for recurrence, infection and other lung diseases. Knowledge of radiological manifestations, awareness of new radiation delivery techniques and correlation with radiation treatment plans are essential in order to correctly interpret imaging in these patients.

Analysis of predictive parameters for the development of radiation-induced pneumonitis

INTRODUCTION:

Prevention and effective treatment of radiation-induced pneumonitis (RP) could facilitate greater use of radiation therapy (RT) for lung cancer. The purpose of this study was to determine clinical parameters useful for early prediction of RP.

METHODS:

Blood sampling, pulmonary function testing, chest computed tomography, and bronchoalveolar lavage (BAL) were performed in patients with pathologically confirmed lung cancer who had completed ≥60 Gy of RT, at baseline, shortly after RT, and at 1 month posttreatment.

RESULTS:

By 3 months post-RT, 11 patients developed RP (RP group) and the remaining 11 patients did not (NRP group). RT significantly increased total cell counts and alveolar macrophages in BAL of the NRP group, whereas lymphocyte count was increased in both groups. Matrix metallopeptidase-9 (MMP-9) increased and vascular endothelial growth factor decreased significantly in the BAL fluid (BALF) of the RP group following RT. Serum surfactant protein D (SP-D) increased significantly in the NRP group. SP-D in BALF from the RP group increased significantly with a subsequent increase in serum SP-D. Pulmonary dilution decreased similarly in both groups of patients.

CONCLUSIONS:

Increased SP-D in BALF, rather than that in serum, could be useful biomarkers in predicting RP. The MMP-9 in BALF might play a role in the pathogenesis of RP. Pulmonary dilution test may not be predictive of the development of RP.

New Clinical Features and Dosimetric Predictor Identification for Symptomatic Radiation Pneumonitis after Tangential Irradiation in Breast Cancer Patients

Background: Tangential irradiation is the most popular postoperative radiotherapy technique for breast cancer. However, irradiation has been related to symptomatic radiation pneumonitis (SRP), which decreases the quality of life of patients. This study investigated the clinical features and dosimetric parameters related to SRP of the ipsilateral lung to identify risk factors for SRP in breast cancer patients after three-dimensional conformal radiation therapy (3D-CRT) with tangential fields. Material and Methods: A total of 515 breast cancer patients were evaluated and divided into two groups: the local-regional irradiation group (259 patients) and the simple local irradiation group (256 patients). Clinical symptoms were registered and patient data collected. The relationship between the incidence of SRP and dosimetric parameters for the ipsilateral lung was assessed within 6 months after 3D-CRT. Dosimetric parameters were compared using t tests. The dosimetric predictors for SRP were estimated using a logistic regression model and receiver operating characteristic curve analysis. Results: In total, 19 patients (3.7%) developed grade 2 SRP. In the local-regional irradiation group, the probability of SRP in the lung body was greater than that in the lung apex (3.9% vs. 1.5%). V20 and V30 were independent predictors for SRP in the local-regional irradiation group (odds ratio = 1.152 and 1.439, both p = 0.030), whereas only V20 was an independent predictor of SRP in the simple local irradiation group (odds ratio = 1.351, p = 0.001). With 39.8% as the optimal threshold for V20 and 25.7% for V30 for local-regional irradiation, SRP could be predicted with an accuracy of 80.3% and 79.9%, a sensitivity of 61.5% and 69.2%, and a specificity of 81.3% and 80.5%, respectively. With 20.2% as the optimal V20 threshold for simple local irradiation, SRP could be predicted with an accuracy of 88.7%, a sensitivity of 83.3% and a specificity of 89.6%. Conclusions: SRP has become a rare complication with mild symptoms and occurs mainly in the lung body. V20 and V30 may be useful dosimetric predictors to evaluate SRP risk of the ipsilateral lung in breast cancer.

Modeling DNA damage-induced pneumopathy in mice: insight from danger signaling cascades

Radiation-induced pneumonitis and fibrosis represent severe and dose-limiting side effects in the radiotherapy of thorax-associated neoplasms leading to decreased quality of life or - as a consequence of treatment with suboptimal radiation doses - to fatal outcomes by local recurrence or metastatic disease. It is assumed that the initial radiation-induced damage to the resident cells triggers a multifaceted damage-signalling cascade in irradiated normal tissues including a multifactorial secretory program. The resulting pro-inflammatory and pro-angiogenic microenvironment triggers a cascade of events that can lead within weeks to a pronounced lung inflammation (pneumonitis) or after months to excessive deposition of extracellular matrix molecules and tissue scarring (pulmonary fibrosis).The use of preclinical in vivo models of DNA damage-induced pneumopathy in genetically modified mice has helped to substantially advance our understanding of molecular mechanisms and signalling molecules that participate in the pathogenesis of radiation-induced adverse late effects in the lung. Herein, murine models of whole thorax irradiation or hemithorax irradiation nicely reproduce the pathogenesis of the human disease with respect to the time course and the clinical symptoms. Alternatively, treatment with the radiomimetic DNA damaging chemotherapeutic drug Bleomycin (BLM) has frequently been used as a surrogate model of radiation-induced lung disease. The advantage of the BLM model is that the symptoms of pneumonitis and fibrosis develop within 1 month.Here we summarize and discuss published data about the role of danger signalling in the response of the lung tissue to DNA damage and its cross-talk with the innate and adaptive immune systems obtained in preclinical studies using immune-deficient inbred mouse strains and genetically modified mice. Interestingly we observed differences in the role of molecules involved in damage sensing (TOLL-like receptors), damage signalling (MyD88) and immune regulation (cytokines, CD73, lymphocytes) for the pathogenesis and progression of DNA damage-induced pneumopathy between the models of pneumopathy induced by whole thorax irradiation or treatment with the radiomimetic drug BLM. These findings underline the importance to pursue studies in the radiation model(s) if we are to unravel the mechanisms driving radiation-induced adverse late effects.A better understanding of the cross-talk of danger perception and signalling with immune activation and repair mechanisms may allow a modulation of these processes to prevent or treat radiation-induced adverse effects. Vice-versa an improved knowledge of the normal tissue response to injury is also particularly important in view of the increasing interest in combining radiotherapy with immune checkpoint blockade or immunotherapies to avoid exacerbation of radiation-induced normal tissue toxicity.

Association of lung fluorodeoxyglucose uptake with radiation pneumonitis after concurrent chemoradiation for non-small cell lung cancer

Background

Increased uptake of fluorodeoxyglucose (FDG) by lung tissue could reflect inflammatory changes related to radiation pneumonitis (RP). In this secondary analysis of a clinical trial, we examined potential associations between posttreatment lung FDG uptake and RP severity in patients with non-small cell lung cancer (NSCLC) for up to 12 months after concurrent chemoradiation (CRT).

Methods

Subjects were 152 patients with NSCLC who had received concurrent CRT as part of the prospective trial NCT00915005. The following lung FDG variables were evaluated after CRT: maximum, mean, and peak standardized uptake values (SUVmax, SUVmean, SUVpeak) and global lung glycolysis (GLG; lung SUVmean × lung volume). RP severity was scored with the Common Terminology Criteria for Adverse Events v3.0.

Results

Significant associations were noted between PET findings and RP severity at 1–6 months (all P < 0.05), but not at 7–12 months after therapy (all P > 0.05). Lung FDG uptake at 1–3 months after treatment predicted later development of grade ≥2 RP (all P < 0.05), with cutoff values as follows: 4.54 for SUVmax, 3.69 for SUVpeak, 0.78 for SUVmean, and 2295 for GLG.

Conclusions

Lung FDG uptake correlated significantly with RP severity during the first 6 months after CRT. The cutoff values seem clinically meaningful for identifying patients at risk of developing RP after such therapy.

Pulmonary injury associated with radiation therapy - Assessment, complications and therapeutic targets

Pulmonary injury is more common in patients undergoing radiation therapy for lungs and other thoracic malignancies. Recently with the use of most-advanced technologies powerful doses of radiation can be delivered directly to tumor site with exquisite precision. The awareness of technical and clinical parameters that influence the chance of radiation induced lung injury is important to guide patient selection and toxicity minimization strategies. At the cellular level, radiation activates free radical production, leading to DNA damage, apoptosis, cell cycle changes, and reduced cell survival. Preclinical research shows the potential for therapies targeting transforming growth factor-β (TGF-B), Toll like receptor (TLRs), Tumour necrosis factor-alpha (TNF-alpha), Interferon gamma (IFN-γ) and so on that may restore lung function. At present Amifostine (WR-2721) is the only approved broad spectrum radioprotector in use for patients undergoing radiation therapy. Newer techniques also offer the opportunity to identify new biomarkers and new targets for interventions to prevent or ameliorate these late effects of lung damage.

Interstitial Lung Diseases

The term interstitial lung diseases (ILD) comprises a diverse group of diseases that lead to inflammation and fibrosis of the alveoli, distal airways, and septal interstitium of the lungs. The ILD consist of disorders of known cause (e.g., collagen vascular diseases, drug-related diseases) as well as disorders of unknown etiology. The latter include idiopathic interstitial pneumonias (IIPs), and a group of miscellaneous, rare, but nonetheless interesting, diseases. In patients with ILD, MDCT enriches the diagnostic armamentarium by allowing volumetric high-resolution scanning, i.e., continuous data acquisition with thin collimation and a high spatial frequency reconstruction algorithm. CT is a key method in the identification and management of patients with ILD. It not only improves the detection and characterization of parenchymal abnormalities, but also increases the accuracy of diagnosis. The spectrum of morphologic characteristics that are indicative of interstitial lung disease is relatively limited and includes the linear and reticular pattern, the nodular pattern, the increased attenuation pattern (such as ground-glass opacities and consolidation), and the low attenuation pattern (such as emphysema and cystic lung diseases). In the correct clinical context, some patterns or combination of patterns, together with the anatomic distribution of the abnormality, i.e., from the lung apex to the base, or peripheral subpleural versus central bronchovascular, can lead the interpreter to a specific diagnosis. However, due to an overlap of the CT morphology between the various entities, the final diagnosis of many ILD requires close cooperation between clinicians and radiologists and complementary lung biopsy is recommended in many cases.

Inhibition of Radiation-Induced Oxidative Damage in the Lung Tissue: May Acetylsalicylic Acid Have a Positive Role?

The lung is relatively sensitive to irradiation. It is shown that acetylsalicylic acid (ASA) might reduce oxidative injury and that it has a place in protection from cancer. The aim of this study is to evaluate the potential radioprotective effects of ASA. Whole-body irradiation (6 Gy, single dose) was applied to the rats. Glutathione (GSH), malondialdehyde (MDA), myeloperoxidase (MPO), and nitric oxide (NO) levels in the lung tissue were measured. Control (C), Radiation (R), Radiation + ASA (R + ASA; received irradiation and 25 mg/kg of ASA intraperitoneally (i.p.)), and Radiation + Amifostine (R + WR-2721; received irradiation and 200 mg/kg of WR-2721 i.p.) groups were used. The MPO levels decreased statistically significantly in the group administered ASA. Histopathologically, a radioprotective effect of ASA was more evident in the R + ASA group. ASA is an agent which has not been used as a radioprotector in the clinic yet, and it is worth supporting with more advanced studies.

Imaging after radiation therapy of thoracic tumors

Radiation-induced lung disease (RILD) is frequent after therapeutic irradiation of thoracic malignancies. Many technique-, treatment-, tumor- and patient-related factors influence the degree of injury sustained by the lung after irradiation. Based on the time interval after the completion of the treatment RILD presents as early and late features characterized by inflammatory and fibrotic changes, respectively. They are usually confined to the radiation port. Though the typical pattern of RILD is easily recognized after conventional two-dimensional radiation therapy (RT), RILD may present with atypical patterns after more recent types of three- or four-dimensional RT treatment. Three atypical patterns are reported: the modified conventional, the mass-like and the scar-like patterns. Knowledge of the various features and patterns of RILD is important for correct diagnosis and appropriate treatment. RILD should be differentiated from recurrent tumoral disease, infection and radiation-induced tumors. Due to RILD, the follow-up after RT may be difficult as response evaluation criteria in solid tumours (RECIST) criteria may be unreliable to assess tumor control particularly after stereotactic ablation RT (SABR). Long-term follow-up should be based on clinical examination and morphological and/or functional investigations including CT, PET-CT, pulmonary functional tests, MRI and PET-MRI.

Oral vinorelbine and cisplatin with concomitant radiotherapy in stage III non-small-cell lung cancer: an open-label phase II multicentre trial (COVeRT study)

Chemoradiotherapy regimens for stage III non-small-cell lung cancer (NSCLC) require ongoing evaluation. This South Australian multicentre prospective phase II study evaluated the safety, activity and outcomes of combination oral vinorelbine and cisplatin administered concurrently with radiotherapy for stage III NSCLC. Consecutive eligible patients received two cycles of oral vinorelbine 50 mg/m day 1 (D1), day 8 (D8) and intravenous cisplatin 50 mg/m D1 and D8 in a 21-day cycle. Chemotherapy was administered concurrently with radiotherapy at 60 Gy in 30 fractions, 2 Gy/fraction to the isocentre, all fields treated daily, 5 days a week over 6 weeks using 10 MV photons and three-dimensional conformal radiotherapy. The primary endpoint was to evaluate the progression-free survival (PFS). The secondary end points were safety, response rates and overall survival (OS). Forty-three eligible patients with stage III NSCLC - comprising 21 squamous cell carcinoma, 18 adenocarcinoma and four large cell carcinoma - were studied. Four patients did not complete the treatment. By intention-to-treat analysis, 25% showed a partial response and 65% had stable disease. None achieved a complete response. Of the 39 patients who completed protocol-specified treatment, 11 (28%) showed a partial response and 28 (72%) had stable disease. The median PFS was 25.2 months and the median OS was 48.3 months. Toxicities were manageable and generally mild, with the majority being either grade 1 (n=38) or grade 2 (n=21). Toxicities were mainly of oesophagitis, pneumonitis, fatigue, nausea and dysphagia. Two cycles of chemotherapy with oral vinorelbine and cisplatin administered concurrently with radical radiation had an acceptable toxicity profile and was active in inoperable stage III NSCLC. PFS and OS outcomes were encouraging. This regimen warrants further investigation.

Time, Dose, and Volume Responses in a Mouse Pulmonary Injury Model Following Ablative Irradiation

PURPOSE

We aimed to determine the time, dose, and volume responses in a mouse pulmonary injury model following ablative dose focal irradiation (ADFIR) in order to better understand normal lung injury.

METHODS AND MATERIALS

ADFIR was administered to the left lung of mice using a small animal micro-irradiator. Histopathological evaluation and micro-computed tomography (micro-CT) analyses were performed at 1, 2, 6, and 12 weeks after irradiation. Dose responses were tested at doses of 0-90 Gy in C57BL/6 and C3H/HeJCr mice at 6 weeks after irradiation. The volume effect was evaluated with 1-, 3-, and 5-mm diameter collimators at 1-4 weeks after 90-Gy irradiation.

RESULTS

ADFIR caused gross local lung injury of the inflated lung in just 1 week, with extensive hyaline material visible in the irradiated area. The fibrosing process was initiated as early as 2 weeks after irradiation. C3H and C57 mice did not show significant differences in dose response. Six weeks after irradiation, the radiation dose-response curve had a sigmoidal shape, where the lag, log, and stationary phases occurred at <40, 50-70, and >80 Gy, respectively. ADFIR induced substantial volume-dependent structural and functional damage to the lungs, and the volume changes of lung consolidation on micro-CT correlated inversely with lung fibrosis over time.

CONCLUSIONS

We determined the time, dose, and volume responses in our established small animal model, and found that lung injury was substantially accelerated and phenotypically different from that of prior studies using non-ablative hemi-thorax and complete thorax irradiation schemes.

Radiation Effects in the Mediastinum and Surroundings: Imaging Findings and Complications

Radiotherapy is one of the cornerstones for treatment of patients with cancer. Although advances in radiotherapy technology have considerably improved radiation delivery, potential adverse effects are still common. Postradiation changes to the mediastinum can include different structures such as the heart, great vessels, and esophagus. The purpose of the article was to illustrate the expected variety of changes to the mediastinum and adjacent lung resulting from external beam radiotherapy and radiotherapy-induced complications to the mediastinum and to discuss different radiotherapy delivery techniques.

Quantitative evaluation of radiation-induced lung injury with hyperpolarized xenon magnetic resonance

PURPOSE

To demonstrate the feasibility of quantitative and comprehensive global evaluation of pulmonary function and microstructural changes in rats with radiation-induced lung injury (RILI) using hyperpolarized xenon MR.

METHODS

Dissolved xenon spectra were dynamically acquired using a modified chemical shift saturation recovery pulse sequence in five rats with RILI (bilaterally exposed by 6-MV x-ray with a dose of 14 Gy 3 mo. prior to MR experiments) and five healthy rats. The dissolved xenon signals were quantitatively analyzed, and the pulmonary physiological parameters were extracted with the model of xenon exchange.

RESULTS

The obtained pulmonary physiological parameters and the ratio of (129) Xe signal in red blood cells (RBCs) versus barrier showed a significant difference between the groups. In RILI rats versus controls, the exchange time increased from 44.5 to 112 ms, the pulmonary capillary transit time increased from 0.51 to 1.48 s, and the ratio of (129) Xe spectroscopic signal in RBCs versus barrier increased from 0.294 to 0.484.

CONCLUSION

Hyperpolarized xenon MR is effective for quantitative and comprehensive global evaluation of pulmonary function and structural changes without the use of radiation. This may open the door for its use in the diagnosis of lung diseases that are related to gas exchange. Magn Reson Med 76:408-416, 2016. © 2015 Wiley Periodicals, Inc.

Migratory eosinophilic alveolitis caused by radiation therapy

Although radiation pneumonitis is usually confined to irradiated areas, some studies have reported that radiation-induced lymphocytic alveolitis can also spread to the non-irradiated lung. However, there have been few reports of radiation-induced eosinophilic alveolitis. We report the case of a 27-year-old female with radiation pneumonitis, occurring 4 months after radiation therapy for cancer of the left breast. Clinical and radiological relapse followed withdrawal of corticosteroids. Examination of bronchoalveolar lavage (BAL) in patchy airspace consolidations revealed increased eosinophil counts. Finally, clinical and radiological signs resolved rapidly after reintroduction of corticosteroids. Eosinophilic alveolitis may be promoted by radiation therapy. In the present case report, possible mechanisms for radiation-induced eosinophilic alveolitis are also reviewed.

Radioprotective effect of melatonin on radiation-induced lung injury and lipid peroxidation in rats

Objective

Free radicals generated by ionizing radiation attack various cellular components such as lipids. The lung is a very radiosensitive organ and its damage is a doselimiting factor in radiotherapy treatments. Melatonin (MLT), the major product of the pineal gland acts as a radioprotective agent. This study aims to investigate the radioprotective effects of MLT on malondialdehyde (MDA) levels and histopathological changes in irradiated lungs.

Materials and Methods

In this experimental study, a total of 62 rats were divided into five groups. Group 1 received no MLT and radiation (unT), group 2 received oral MLT (oM), group 3 received oral MLT and their thoracic areas were irradiated with 18 Gy (oMR), group 4 received MLT by intraperitoneal (i.p.) injection and their thoracic areas were irradiated with 18 Gy (ipM-R), group 5 received only 18 Gy radiation in the thoracic area (R). Following radiotherapy, half of the animals in each group were sacrificed at 48 hours for evaluation of lipid peroxidation and early phase lung injuries. Other animals were sacrificed in the eighth week of the experiment for evaluation of the presence of late phase radiation induced lung injuries.

Results

Pre-treatment of rats with either i.p injection (p<0.05) and oral administration of MLT (p<0.001) significantly reduced MDA levels in red blood cell (RBC) samples compared to the R group. Furthermore, i.p. injection of MLT decreased MDA levels in plasma and tissue (p<0.05). In the early phase of lung injury, both administration of MLT significantly increased lymphocyte (p<0.05) and macrophage frequency (p<0.001). MLT reduced the lung injury index in the lungs compared to the R group (p<0.05).

Conclusion

The result of this study confirms the radioprotective effect of MLT on lipid peroxidation, and in both early and late phases of radiation induced lung injuries in an animal model.

Clear vision through the haze: a practical approach to ground-glass opacity

Ground-glass opacity (GGO) is a common, nonspecific imaging finding on chest computed tomography that may occur in a variety of pulmonary diseases. GGO may be the result of partial filling of alveolar spaces, thickening of the alveolar walls or septal interstitium, or a combination of partial filling of alveolar spaces and thickening of the alveolar walls and septal interstitium at the histopathologic level. Diseases that commonly manifest on chest computed tomography as GGO include pulmonary edema, alveolar hemorrhage, nonspecific interstitial pneumonia, hypersensitivity pneumonitis, and pulmonary alveolar proteinosis. Generating an extensive list of possible causes of GGO in radiologic reports would not be helpful to referring physicians. Preferably, a more concise and focused list of differential diagnostic possibilities may be constructed using a systematic approach to further classify GGO based on morphology, distribution, and ancillary imaging findings, such as the presence of cysts, traction bronchiectasis, and air trapping. Correlation with clinical history, such as the chronicity of symptoms, the patient's immune status, and preexisting medical conditions is vital. By thorough analysis of imaging patterns and consideration of relevant clinical information, the radiologist can generate a succinct and useful imaging differential diagnosis when confronted with the nonspecific finding of GGO.

miR-15b/16-2 regulates factors that promote p53 phosphorylation and augments the DNA damage response following radiation in the lung

MicroRNAs (miRNAs) are regulatory RNAs frequently dysregulated in disease and following cellular stress. Investigators have described changes in miR-15b expression following exposure to several stress-inducing anticancer agents, including ionizing radiation (IR), etoposide, and hydrogen peroxide. However, the role for miR-15b as a mediator of cellular injury in organs such as the lung has yet to be explored. In this study, we examined miR-15b expression patterns as well as its potential role in DNA damage and repair in the setting of IR exposure. We showed that miR-15b is up-regulated in a dose- and time-dependent manner in human bronchial epithelial cells following IR. miR-15b expression was highest after 2 h of IR and decreased gradually. Survival rates following IR were also higher in miR-15b/16-2-overexpressing cells. Cell cycle arrest in G2/M phase and an increased DNA repair response were observed in IR-exposed miR-15b/16-2 stable cells. We observed an up-regulation of components of the ataxia telangiectasia mutated (ATM)/Chek1/p53 pathway in miR-15b/16-2-overexpressing cells after IR. Moreover, a pathway-based PCR expression array of genes demonstrated that miR-15b/16-2 overexpression significantly induced the expression of genes involved in ATM/ataxia telangiectasia and Rad-3-related (ATR) signaling, apoptosis, the cell cycle, and DNA repair pathways. Here we demonstrated a novel biological link between miR-15b and DNA damage and cellular protection in lung cells. We identified Wip1 (PPM1D) as a functional target for miR-15b and determined that miR-15b induction of the DNA damage response is partially dependent upon suppression of Wip1. Our study suggests that miR-15b/Wip1 could be a potential therapeutic target in radiation-induced lung disease.

New era of radiotherapy: an update in radiation-induced lung disease

Over the last few decades, advances in radiotherapy (RT) technology have improved delivery of radiation therapy dramatically. Advances in treatment planning with the development of image-guided radiotherapy and in techniques such as proton therapy, allows the radiation therapist to direct high doses of radiation to the tumour. These advancements result in improved local regional control while reducing potentially damaging dosage to surrounding normal tissues. It is important for radiologists to be aware of the radiological findings from these advances in order to differentiate expected radiation-induced lung injury (RILD) from recurrence, infection, and other lung diseases. In order to understand these changes and correlate them with imaging, the radiologist should have access to the radiation therapy treatment plans.

Breast cancer subtypes: response to radiotherapy and potential radiosensitisation

Radiotherapy (RT) is of critical importance in the locoregional management of early breast cancer. Over 50% of patients receive RT at some time during the treatment of their disease, equating to over 500 000 patients worldwide receiving RT each year. Unfortunately, not all patients derive therapeutic benefit and some breast cancers are resistant to treatment, as evidenced by distant metastatic spread and local recurrence. Prediction of individual responses to RT may allow a stratified approach to this treatment permitting those patients with radioresistant tumours to receive higher doses of RT (total and/or tumour cavity boost doses) and/or radiosensitising agents to optimise treatment. Also, for those patients unlikely to respond at all, it would prevent harmful side effects occurring for no therapeutic gain. More selective targeting would better direct National Health Service resources, ease the burden on heavily used treatment RT machines and reduce the economic cost of cancer treatment. Unfortunately, there are no robust and validated biomarkers for predicting RT outcome. We review the available literature to determine whether classification of breast cancers according to their molecular profile may be used to predict successful response to, or increased morbidity from, RT. Class-specific biomarkers for targeting by radiosensitising agents are also discussed.