Exhaled nitric oxide predicts radiation pneumonitis in esophageal and lung cancer patients receiving thoracic radiation

Redox Interactions in Chemo/Radiation Therapy-induced Lung Toxicity; Mechanisms and Therapy Perspectives

Lung toxicity is a key limiting factor for cancer therapy, especially lung, breast, and esophageal malignancies. Radiotherapy for chest and breast malignancies can cause lung injury. However, systemic cancer therapy with chemotherapy may also induce lung pneumonitis and fibrosis. Radiotherapy produces reactive oxygen species (ROS) directly via interacting with water molecules within cells. However, radiation and other therapy modalities may induce the endogenous generation of ROS and nitric oxide (NO) by immune cells and some nonimmune cells such as fibroblasts and endothelial cells. There are several ROS generating enzymes within lung tissue. NADPH Oxidase enzymes, cyclooxygenase-2 (COX-2), dual oxidases (DUOX1 and DUOX2), and the cellular respiratory system in the mitochondria are the main sources of ROS production following exposure of the lung to anticancer agents. Furthermore, inducible nitric oxide synthase (iNOS) has a key role in the generation of NO following radiotherapy or chemotherapy. Continuous generation of ROS and NO by endothelial cells, fibroblasts, macrophages, and lymphocytes causes apoptosis, necrosis, and senescence, which lead to the release of inflammatory and pro-fibrosis cytokines. This review discusses the cellular and molecular mechanisms of redox-induced lung injury following cancer therapy and proposes some targets and perspectives to alleviate lung toxicity.

Gasotransmitters in the tumor microenvironment: Impacts on cancer chemotherapy (Review)

Nitric oxide, carbon monoxide and hydrogen sulfide are three endogenous gasotransmitters that serve a role in regulating normal and pathological cellular activities. They can stimulate or inhibit cancer cell proliferation and invasion, as well as interfere with cancer cell responses to drug treatments. Understanding the molecular pathways governing the interactions between these gases and the tumor microenvironment can be utilized for the identification of a novel technique to disrupt cancer cell interactions and may contribute to the conception of effective and safe cancer therapy strategies. The present review discusses the effects of these gases in modulating the action of chemotherapies, as well as prospective pharmacological and therapeutic interfering approaches. A deeper knowledge of the mechanisms that underpin the cellular and pharmacological effects, as well as interactions, of each of the three gases could pave the way for therapeutic treatments and translational research.

Fractional exhaled nitric oxide as a potential biomarker for radiation pneumonitis in patients with non-small cell lung cancer: A pilot study

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Weekly FeNO during radiotherapy can be useful in predicting radiation pneumonitis.

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6 months of clinical follow-up is necessary to detect delayed radiation pneumonitis.

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Pulmonary function tests are not predictable for radiation pneumonitis.

Introduction

The aim of the study was to investigate repetitive fractional exhaled nitric oxide (FeNO) measurements during high-dose radiation therapy (HDRT) and to evaluate the use of FeNO to predict symptomatic radiation pneumonitis (RP) in patients being treated for non-small cell lung cancer (NSCLC).

Materials and methods

A total of 50 patients with NSCLC referred for HDRT were enrolled. FeNO was measured at baseline, weekly during HDRT, one month- and every third month after HDRT for a one-year follow-up period. The mean FeNO_{(visit 0-6)} was calculated using the arithmetic mean of the baseline and weekly measurements during HDRT. Patients with grade ≥ 2 of RP according to the Common Terminology Criteria for Adverse Events (CTCAE) were considered symptomatic.

Results

A total of 42 patients completed HDRT and weekly FeNO measurements. Grade ≥ 2 of RP was diagnosed in 24 (57%) patients. The mean FeNO_{(visit 0-6)} ± standard deviation in patients with and without RP was 15.0 ± 7.1 ppb (95%CI: 12.0–18.0) and 10.3 ± 3.4 ppb (95%CI: 8.6–11.9) respectively with significant differences between the groups (p = 0.0169, 95%CI: 2.3–2.6). The leave-one-out cross-validated cut-off value of the mean FeNO_{(visit 0-6)} ≥ 14.8 ppb was predictive of grade ≥ 2 RP with a specificity of 71% and a positive predictive value of 78%.

Conclusions

The mean FeNO_{(visit 0-6)} in patients with symptomatic RP after HDRT for NSCLC was significantly higher than in patients without RP and may serve as a potential biomarker for RP.

Exhaled Nitric Oxide Is Useful in Symptomatic Radioactive Pneumonia: A Retrospective Study

The aim was to defect the exhaled nitric oxide (eNO) prediction value of symptomatic radioactive pneumonia (SRP). 64 cases of lung cancer or esophagus cancer, who had the primary radiotherapy (intensity-modulated radiation therapy), were included from 2015 June to 2016 January. During the following, the patients were divided: the symptomatic radiation pneumonia group (SRP, with the CTCAE v4.0 score > 2) and the asymptomatic radiation pneumonia group (ASRP, with CTCAE v4.0 score ≤ 1). All the patients were measured eNO before and at the end of thoracic radiotherapy and gain the posttherapy eNO value and the eNO ratio (posttherapy eNO value/pretherapy eNO value), then the predictive values of eNO toward SRP were measured using the receiver-operating characteristic (ROC). 17 cases were included in the SRP group and the other 47 were included in the ASRP group. The posttherapy eNO was 29.35 (19~60) bbp versus 20.646 (11~37) (P < 0.001), and the ratio was 1.669 (0.61~3.5) versus 0.920 (0.35~1.5) (P < 0.01) (symptomatic versus asymptomatic). ROC showed that the cutoff value of SRP was 19.5 bbp (posttherapy eNO, area under concentration-time curve (AUC) = 0.879) and 1.305 (eNO ratio, AUC = 0.774), which meant that posttherapy eNO and eNO ratio were useful in finding SRP.

Measurement of exhaled nitric oxide and serum surfactant protein D levels for monitoring radiation pneumonitis following thoracic radiotherapy

The present study aimed to examine the role of exhaled nitric oxide (eNO) and serum surfactant protein D (SP-D) level in the determination of radiation pneumonitis (RP) after thoracic radiotherapy (RT). The study included 34 treatments for 33 patients, including 16 three-dimensional conformal and 18 stereotactic body RT treatments. eNO levels were measured prior to RT, immediately subsequent to RT, every week during the RT course and at 1, 3, 6, 9 and 12 months following the treatment. The therapy reduced the eNO from 24.3±12.8 ppb prior to RT to 19.0±10.4 ppb immediately subsequent to RT (P=0.04). A total of 5 patients (14%) developed symptomatic RP of grade 2 or higher 3–5 months later, and exhibited an eNO elevation of 2.1±0.68-fold the minimum value, whereas the RP- group exhibited 1.4±0.6-fold elevation (P=0.02). The sensitivity of a cut-off of a 1.4-fold increase in the eNO ratio at the onset of RP was 100%; however, the specificity was 52%, and no predictive alterations to eNO levels were observed prior to the onset of RP. RT was associated with an elevated serum SP-D level at 3–6 months after RT. There was a statistically significant difference in the initial serum SP-D level between RP+ and RP- patients. In conclusion, obtaining the eNO ratio was a useful RP monitoring tool but did not predict RP occurrence in the present setting, whereas serum SP-D level may be a potential predictor for the detection of RP risk.

Anatomical, functional and metabolic imaging of radiation-induced lung injury using hyperpolarized MRI

MRI of hyperpolarized (129)Xe gas and (13)C-enriched substrates (e.g. pyruvate) presents an unprecedented opportunity to map anatomical, functional and metabolic changes associated with lung injury. In particular, inhaled hyperpolarized (129)Xe gas is exquisitely sensitive to changes in alveolar microanatomy and function accompanying lung inflammation through decreases in the apparent diffusion coefficient (ADC) of alveolar gas and increases in the transfer time (T(tr)) of xenon exchange from the gas and into the dissolved phase in the lung. Furthermore, metabolic changes associated with hypoxia arising from lung injury may be reflected by increases in lactate-to-pyruvate signal ratio obtained by magnetic resonance spectroscopic imaging following injection of hyperpolarized [1-(13)C]pyruvate. In this work, the application of hyperpolarized (129)Xe and (13)C MRI to radiation-induced lung injury (RILI) is reviewed and results of ADC, T(tr) and lactate-to-pyruvate signal ratio changes in a rat model of RILI are summarized. These results are consistent with conventional functional (i.e. blood gases) and histological (i.e. tissue density) changes, and correlate significantly with inflammatory cell counts (i.e. macrophages). Hyperpolarized MRI may provide an earlier indication of lung injury associated with radiotherapy of thoracic tumors, potentially allowing adjustment of treatment before the onset of severe complications and irreversible fibrosis.

Genetic variants in inducible nitric oxide synthase gene are associated with the risk of radiation-induced lung injury in lung cancer patients receiving definitive thoracic radiation

BACKGROUND AND PURPOSE

Nitric oxide (NO), mainly synthesized by inducible nitric oxide synthase (NOS2) in pathological conditions, plays an important role in cytotoxicity, inflammation and fibrosis. Elevations in exhaled NO after thoracic radiation have been reported to predict radiation-induced lung injury (RILI). This study examined whether genetic variations in NOS2 gene is associated with the risk of RILI.

MATERIAL AND METHODS

A cohort of 301 patients between 2009 and 2011 were genotyped for 21 single nucleotide polymorphisms (SNPs) in the NOS2 gene by the Sequenom MassArray system. Kaplan-Meier cumulative probability was used to assess RILI risk and Cox proportional hazards analyses were performed to evaluate the effect of NOS2 genotypes on RILI.

RESULTS

Multivariate analysis found that three SNPs (rs2297518, rs1137933 and rs16949) in NOS2 were significantly associated with risk of RILI⩾2 (P value=0.001, 0.000092, 0.001, respectively) after adjusting for other covariates. Their associations were independent of radiation dose and mean lung dose. Further haplotype analysis indicated that the ATC haplotype of three SNPs is associated with reducing the risk of developing RILI.

CONCLUSION

Our results demonstrate that genetic variants of NOS2 may serve as a reliable predictor of RILI in lung cancer patients treated with thoracic radiation.

Pre-radiotherapy FDG PET predicts radiation pneumonitis in lung cancer

BACKGROUND

A retrospective analysis is performed to determine if pre-treatment [18 F]-2-fluoro-2-deoxyglucose positron emission tomography/computed tomography (FDG PET/CT) image derived parameters can predict radiation pneumonitis (RP) clinical symptoms in lung cancer patients.

METHODS AND MATERIALS

We retrospectively studied 100 non-small cell lung cancer (NSCLC) patients who underwent FDG PET/CT imaging before initiation of radiotherapy (RT). Pneumonitis symptoms were evaluated using the Common Terminology Criteria for Adverse Events version 4.0 (CTCAEv4) from the consensus of 5 clinicians. Using the cumulative distribution of pre-treatment standard uptake values (SUV) within the lungs, the 80th to 95th percentile SUV values (SUV(80) to SUV(95) were determined. The effect of pre-RT FDG uptake, dose, patient and treatment characteristics on pulmonary toxicity was studied using multiple logistic regression.

RESULTS

The study subjects were treated with 3D conformal RT (n=23), intensity modulated RT (n=64), and proton therapy (n=13). Multiple logistic regression analysis demonstrated that elevated pre-RT lung FDG uptake on staging FDG PET was related to development of RP symptoms after RT. A patient of average age and V(30) with SUV(95)=1.5 was an estimated 6.9 times more likely to develop grade ≥ 2 radiation pneumonitis when compared to a patient with SUV(95)=0.5 of the same age and identical V(30). Receiver operating characteristic curve analysis showed the area under the curve was 0.78 (95% CI=0.69 - 0.87). The CT imaging and dosimetry parameters were found to be poor predictors of RP symptoms.

CONCLUSIONS

The pretreatment pulmonary FDG uptake, as quantified by the SUV(95), predicted symptoms of RP in this study. Elevation in this pre-treatment biomarker identifies a patient group at high risk for post-treatment symptomatic RP.

Mapping metabolic changes associated with early Radiation Induced Lung Injury post conformal radiotherapy using hyperpolarized ¹³C-pyruvate Magnetic Resonance Spectroscopic Imaging

PURPOSE

Radiation Pneumonitis (RP) limits radiotherapy. Detection of early metabolic changes in the lungs associated with RP may provide an opportunity to adjust treatment before substantial toxicities occur. In this work, regional lactate-to-pyruvate signal ratio (lac/pyr) was quantified in rat lungs and heart following administration of hyperpolarized (13)C-pyruvate magnetic resonance imaging (MRI) at day 5, 10, 15 and 25-post conformal radiotherapy. These results were also compared to histology and blood analyses.

METHODS

The lower right lungs of 12 Sprague Dawley rats were irradiated in 2 fractions with a total dose of 18.5 Gy using a modified micro-CT system. Regional lactate and pyruvate data were acquired from three irradiated and three age-matched healthy rats at each time point on days 5, 10, 15 and 25-post radiotherapy. Arterial blood was collected from each animal prior to the (13)C-pyruvate injection and was analyzed for blood lactate concentration and arterial oxygen concentration (paO₂). Macrophage count was computed from the histology of all rat lungs.

RESULTS

A significant increase in lac/pyr was observed in both right and left lungs of the irradiated cohort compared to the healthy cohort for all time points. No increase in lac/pyr was observed in the hearts of the irradiated cohort compared to the hearts of the healthy cohorts. Blood lactate concentration and paO2 did not show a significant change between the irradiated and the healthy cohorts. Macrophage count in both right and left lungs was elevated for the irradiated cohort compared to the healthy cohort.

CONCLUSIONS

Metabolic changes associated with RP may be mapped as early as five days post conformal radiotherapy. Over the small sample size in each cohort, elevated macrophage count, consistent with early phase of inflammation was highly correlated to increases in lac/pyr in both the irradiated and unirradiated lungs. Further experiments with larger sample size may improve the confidence of this finding.

Quantitative assessment of global lung inflammation following radiation therapy using FDG PET/CT: a pilot study

PURPOSE

Radiation pneumonitis is the most severe dose-limiting complication in patients receiving thoracic radiation therapy. The aim of this study was to quantify global lung inflammation following radiation therapy using FDG PET/CT.

METHODS

We studied 20 subjects with stage III non-small-cell lung carcinoma who had undergone FDG PET/CT imaging before and after radiation therapy. On all PET/CT studies, the sectional lung volume (sLV) of each lung was calculated from each slice by multiplying the lung area by slice thickness. The sectional lung glycolysis (sLG) was calculated by multiplying the sLV and the lung sectional mean standardized uptake value (sSUVmean) on each slice passing through the lung. The lung volume (LV) was calculated by adding all sLVs from the lung, and the global lung glycolysis (GLG) was calculated by adding all sLGs from the lung. Finally, the lung SUVmean was calculated by dividing the GLG by the LV. The amount of inflammation in the lung parenchyma directly receiving radiation therapy was calculated by subtracting tumor measurements from GLG.

RESULTS

In the lung directly receiving radiation therapy, the lung parenchyma SUVmean and global lung parenchymal glycolysis were significantly increased following therapy. In the contralateral lung (internal control), no significant changes were observed in lung SUVmean or GLG following radiation therapy.

CONCLUSION

Global lung parenchymal glycolysis and lung parenchymal SUVmean may serve as potentially useful biomarkers to quantify lung inflammation on FDG PET/CT following thoracic radiation therapy.

Development of radiation pneumopathy and generalised radiological changes after radiotherapy are independent negative prognostic factors for survival in non-small cell lung cancer patients

BACKGROUND AND PURPOSE

To investigate the risk factors for radiation pneumopathy (RP) and survival rate of non-small cell lung cancer patients with RP and generalised interstitial lung changes (gen-ILC).

MATERIAL AND METHODS

A total of 147 consecutive patients receiving curative radiotherapy were analysed. RP was graded according to Common Terminology Criteria for Adverse Events v. 3. Computed tomography images were assessed for the presence of gen-ILC after radiotherapy. Univariate and multivariate analyses were performed to identify significant factors.

RESULTS

Median follow-up was 16.2 months (range 1.4-58.6). Radiological changes after radiotherapy were confined to high dose irradiation volume in 111 patients, while 31 patients developed gen-ILC. Dosimetric parameters and level of C-reactive protein before radiotherapy were significantly associated with severe RP. Development of gen-ILC (p=0.008), as well as severe RP (p=0.03) had significant negative impact on patients' survival. These two factors remained significant in the multivariate analysis.

CONCLUSIONS

Severe radiation pneumopathy and generalised radiographic changes were significant independent prognostic factors for survival. More studies on pathophysiology of radiation induced damage are necessary to fully understand the mechanisms behind it.

Can exhaled NO fraction predict radiotherapy-induced lung toxicity in lung cancer patients?

Background

A large increase in nitric oxide fraction (FeNO) after radiotherapy (RT) for lung cancer may predict RT-induced lung toxicity.

Methods

In this study, we assessed the relationships between FeNO variations and respiratory symptoms, CT scan changes or dose volume histogram (DVH) parameters after RT. We measured FeNO before RT, 4, 5, 6, 10 weeks, 4 and 7.5 months after RT in 65 lung cancer patients.

Results

Eleven lung cancer patients (17%) complained of significant respiratory symptoms and 21 (31%) had radiation pneumonitis images in >1/3 of the irradiated lung after RT. Thirteen patients (20%) showed increases in FeNO >10 ppb. The sensitivity and specificity of a >10 ppb FeNO increase for the diagnosis of RT-associated respiratory symptoms were 18% and 83%, respectively. There was no correlation between DVH parameters or CT scan changes after RT and FeNO variations. Three patients (5%) showed intriguingly strong (2 or 3-fold, up to 55 ppb) and sustained increases in FeNO at 4 and 5 weeks, followed by significant respiratory symptoms and/or radiation-pneumonitis images.

Conclusion

Serial FeNO measurements during RT had a low ability to identify lung cancer patients who developed symptoms or images of radiation pneumonitis. However, three patients presented with a particular pattern which deserves to be investigated.

[18F]-FDG uptake dose-response correlates with radiation pneumonitis in lung cancer patients

PURPOSE

To quantify the post-radiotherapy 2-[(18)F]-fluoro-2-deoxyglucose (FDG) pulmonary uptake dose-response in lung cancer patients and determine its relationship with radiation pneumonitis symptoms.

METHODS AND MATERIALS

The data from 24 patients treated for lung cancer with thoracic radiotherapy who received restaging PET/CT imaging between 4 and 12 weeks after radiotherapy completion were evaluated. Their radiation dose distribution was registered with the post-treatment restaging PET/CT. Using histogram analysis, the voxel average FDG-PET uptake vs. radiation dose was obtained for each case and linear regression was performed. The resulting slope, the pulmonary metabolic radiation response (PMRR), was used to characterize the dose-response. The Common Toxicity Criteria version 3 was used to score clinical pulmonary toxicity symptoms. Receiver operating characteristic (ROC) curves were used to determine the level of FDG uptake vs. dose, MLD, V(5), V(10), V(20), and V(30) that can best predict symptomatic and asymptomatic patients.

RESULTS

The median time between radiotherapy completion and FDG-PET imaging was 59 days (range, 26-70 days). The median of the mean SUV from lung that received 0-5 Gy was 1.00 (range, 0.37-1.48), 5-10 Gy was 1.01 (range, 0.37-1.77), 10-20 Gy was 1.04 (0.42-1.53), and >20 Gy was 1.29 (range, 0.41-8.01). Using the dose range of 0 Gy to the maximum dose minus 10 Gy, hierarchical linear regression model of the radiation dose and normalized FDG uptake per case found an adequate fit with the linear model. Pneumonitis scores were: Grade 0 for 13, Grade 1 for 5, Grade 2 for 6, and Grade 3, 4 or 5 for none. Using a PMRR threshold of 0.017 yields an associated true positive rate of 0.67 and false positive rate of 0.15 with average error of 30%. A V(5) threshold of 57.6 gives an associated true positive rate of 0.67 and false positive rate of 0.05 with a 20% average error.

CONCLUSION

The metabolic radiation pneumonitis dose-response was evaluated from post-treatment FDG-PET/CT imaging. Statistical modeling found a linear relationship. The FDG uptake dose-response and V(5) correlated with symptomatic radiation pneumonitis.