Radiation pneumonitis following combined modality therapy for lung cancer: analysis of prognostic factors

Gene Signatures for Latent Radiation-Induced Lung Injury Post X-ray Exposure in Mouse

Objective

To investigate the X-ray-specific sensitive genes and potential signaling pathways involved in the latent period of radiation-induced lung injury (RILI) in mouse models.

Method

Mice were randomized into groups for whole thoracic irradiation with a single fraction of 20 Gy X-ray or 12.5 Gy carbon heavy ion. Lungs were harvested 3 weeks after the irradiation, whole RNA was extracted and detected with the genome-wide transcriptional microarrays. Differentially expressed genes (DEGs) were calculated for each group and the X-ray-specific sensitive genes were determined, followed by the gene enrichment analysis of those DEGs exploring the potentially relevant signaling pathways and biological processes in latent RILI.

Results

Three weeks after irradiation, gene expression levels varied between groups. 76 up-regulated DEGs were determined with mice in the X-ray group and gene ontology enrichment analysis for biological process (GO-BP) obtained several processes which were associated with radiation reaction, mitotic, immune cell chemotaxis or metastasis, immune factors, p53 apoptosis, and tissue remodeling. KEGG signaling pathway enrichment analysis showed that those 76 up-regulated DEGs were enriched in p53, IL-17, FoXO, melanoma, and non-small-cell lung cancer signaling pathways. By comparing the DEGs in X-ray and heavy ion groups, X-ray-specific sensitive genes were determined, the top 10 genes were Adamts9, Aacs, Col6a2, Fdps, Mdk, Mcam, Stbd1, Lbh, Ak3, and Emid1. The expression level of the top 10 genes was found to be significantly higher in the X-ray group than in the control and heavy ion groups.

Conclusion

Our research determined the X-ray-specific sensitive gene set in mice lungs after exposure to radiation. The gene set could be used as a genetic marker to suggest the latency of RILI. The enrichment analysis results suggested that the relevant signaling pathways were potentially involved in the development of RILI. Further validation of those genes and signaling pathways is needed to confirm these findings.

CT radiomics-based long-term survival prediction for locally advanced non-small cell lung cancer patients treated with concurrent chemoradiotherapy using features from tumor and tumor organismal environment

Background

Definitive concurrent chemoradiotherapy (CCRT) is the standard treatment for locally advanced non-small cell lung cancer (LANSCLC) patients, but the treatment response and survival outcomes varied among these patients. We aimed to identify pretreatment computed tomography-based radiomics features extracted from tumor and tumor organismal environment (TOE) for long-term survival prediction in these patients treated with CCRT.

Methods

A total of 298 eligible patients were randomly assigned into the training cohort and validation cohort with a ratio 2:1. An integrated feature selection and model training approach using support vector machine combined with genetic algorithm was performed to predict 3-year overall survival (OS). Patients were stratified into the high-risk and low-risk group based on the predicted survival status. Pulmonary function test and blood gas analysis indicators were associated with radiomic features. Dynamic changes of peripheral blood lymphocytes counts before and after CCRT had been documented.

Results

Nine features including 5 tumor-related features and 4 pulmonary features were selected in the predictive model. The areas under the receiver operating characteristic curve for the training and validation cohort were 0.965 and 0.869, and were reduced by 0.179 and 0.223 when all pulmonary features were excluded. Based on radiomics-derived stratification, the low-risk group yielded better 3-year OS (68.4% vs. 3.3%, p < 0.001) than the high-risk group. Patients in the low-risk group had better baseline FEV1/FVC% (96.3% vs. 85.9%, p = 0.046), less Grade ≥ 3 lymphopenia during CCRT (63.2% vs. 83.3%, p = 0.031), better recovery of lymphopenia from CCRT (71.4% vs. 27.8%, p < 0.001), lower incidence of Grade ≥ 2 radiation-induced pneumonitis (31.6% vs. 53.3%, p = 0.040), superior tumor remission (84.2% vs. 66.7%, p = 0.003).

Conclusion

Pretreatment radiomics features from tumor and TOE could boost the long-term survival forecast accuracy in LANSCLC patients, and the predictive results could be utilized as an effective indicator for survival risk stratification. Low-risk patients might benefit more from radical CCRT and further adjuvant immunotherapy.

Trial registration:

retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13014-022-02136-w.

Symptomatic Radiation Pneumonitis in NSCLC Patients Receiving EGFR-TKIs and Concurrent Once-daily Thoracic Radiotherapy: Predicting the Value of Clinical and Dose-volume Histogram Parameters

BACKGROUND

The incidence of symptomatic radiation pneumonitis (RP) and its relationship with dose-volume histogram (DVH) parameters in non-small cell lung cancer (NSCLC) patients receiving epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) and concurrent once-daily thoracic radiotherapy (TRT) remain unclear. We aim to analyze the values of clinical factors and dose-volume histogram (DVH) parameters to predict the risk for symptomatic RP in these patients.

METHODS

Between 2011 and 2019, we retrospectively analyzed and identified 85 patients who had received EGFR-TKIs and once-daily TRT simultaneously (EGFR-TKIs group) and 129 patients who had received concurrent chemoradiotherapy (CCRT group). The symptomatic RP was recorded according to the Common Terminology Criteria for Adverse Event (CTCAE) criteria (grade 2 or above). Statistical analyses were performed using SPSS 26.0.

RESULTS

In total, the incidences of symptomatic (grade≥2) and severe RP (grade≥3) were 43.5% (37/85) and 16.5% (14/85) in EGFR-TKIs group vs 27.1% (35/129) and 10.1% (13/129) in CCRT group respectively. After 1:1 ratio between EGFR-TKIs group and CCRT group was matched by propensity score matching, chi-square test suggested that the incidence of symptomatic RP in the MATCHED EGFR-TKIs group was higher than that in the matched CCRT group (χ2=4.469, P=0.035). In EGFR-TKIs group, univariate and multivariate analyses indicated that the percentage of ipsilateral lung volume receiving ≥30 Gy (ilV30) [odds ratio (OR): 1.163, 95%CI: 1.036-1.306, P=0.011] and the percentage of total lung volume receiving ≥20 Gy (tlV20) (OR: 1.171, 95%CI: 1.031-1.330, P=0.015), with chronic obstructive pulmonary disease (COPD) or not (OR: 0.158, 95%CI: 0.041-0.600, P=0.007), were independent predictors of symptomatic RP. Compared to patients with lower ilV30/tlV20 values (ilV30 and tlV20<cut-off point values) and without COPD, patients with higher ilV30/tlV20 values (ilV30 and tlV20>cut-off point values) and COPD had a significantly higher risk for developing symptomatic RP, with a hazard ratio (HR) of 1.350 (95%CI: 1.190-1.531, P<0.001).

CONCLUSIONS

Patients receiving both EGFR-TKIs and once-daily TRT were more likely to develop symptomatic RP than patients receiving concurrent chemoradiotherapy. The ilV30, tlV20, and comorbidity of COPD may predict the risk of symptomatic RP among NSCLC patients receiving EGFR-TKIs and conventionally fractionated TRT concurrently.

Biological dosiomic features for the prediction of radiation pneumonitis in esophageal cancer patients

OBJECTIVE

The purpose of this study was to develop a model using dose volume histogram (DVH) and dosiomic features to predict the risk of radiation pneumonitis (RP) in the treatment of esophageal cancer with radiation therapy and to compare the performance of DVH and dosiomic features after adjustment for the effect of fractionation by correcting the dose to the equivalent dose in 2 Gy (EQD2).

MATERIALS AND METHODS

DVH features and dosiomic features were extracted from the 3D dose distribution of 101 esophageal cancer patients. The features were extracted with and without correction to EQD2. A predictive model was trained to predict RP grade ≥ 1 by logistic regression with L1 norm regularization. The models were then evaluated by the areas under the receiver operating characteristic curves (AUCs).

RESULT

The AUCs of both DVH-based models with and without correction of the dose to EQD2 were 0.66 and 0.66, respectively. Both dosiomic-based models with correction of the dose to EQD2 (AUC = 0.70) and without correction of the dose to EQD2 (AUC = 0.71) showed significant improvement in performance when compared to both DVH-based models. There were no significant differences in the performance of the model by correcting the dose to EQD2.

CONCLUSION

Dosiomic features can improve the performance of the predictive model for RP compared with that obtained with the DVH-based model.

Safety of cyclin-dependent kinase4/6 inhibitor combined with palliative radiotherapy in patients with metastatic breast cancer

Introduction

Cyclin-dependent kinase (CDK)4/6 inhibitor is a first-line therapy for metastatic ER+/HER2-breast cancer. However, there are limited data on safety of combined radiotherapy (RT) and CDK4/6 inhibition.

Methods

We conducted a retrospective study of women with metastatic breast cancer who received palliative RT within 14 days of CDK4/6 inhibitor use. The primary endpoint was toxicity per Common Terminology Criteria for Adverse Events v5. Secondary endpoints were pain response and local control based on clinical assessment and imaging.

Results

Thirty patients underwent 36 RT courses with palbociclib (n = 34 courses, 94.4%) or abemaciclib (n = 2, 5.6%). RT was delivered before, concurrently or after CDK4/6 inhibitors in 7 (19.4%), 8 (22.2%), and 21 (58.3%) of cases with median 3.5 days from RT to closest CDK4/6 inhibitor administration. Median RT dose was 30Gy (range 8–40.05Gy). Treated sites included brain (n = 5, 11.6%), spine (n = 19, 44.2%), pelvis (n = 9, 20.9%), other bony sites (n = 6, 14.0%) and others (n = 4, 9.3%). No acute grade ≥3 non-hematologic toxicity occurred. No increased hematologic toxicity was attributable to RT with grade 3 hematologic toxicities rates 16.7%, 0%, and 6.7% before, during, and 2 weeks after RT completion. All but one patient (29/30) achieved symptom relief. Local control rates were 94.4%, 91.7% at 6 and 12 months.

Conclusions

The use of RT within 2 weeks of CDK4/6 inhibitors had low acceptable toxicity and high efficacy, suggesting that it is safe for palliation of metastatic breast cancer.

•

CDK4/6 inhibitors with endocrine therapy is a preferred first line therapy for HR+, HER2-metastatic breast cancer.

•

Limited data exists on safety of combined radiotherapy and CDK4/6 inhibition in patients with metastatic breast cancer.

•

This retrospective cohort study included 30 patients who underwent palliative RT with combined CDK4/6 inhibitor use.

•

RT within 2 weeks of CDK4/6 inhibitor had low toxicity and high efficacy, supporting its safety in metastatic breast cancer.

Predicting the Risk of Radiation Pneumonitis and Pulmonary Function Changes after Breast Cancer Radiotherapy

Background

Radiotherapy plays an important role in the treatment of breast cancer. In the process of radiotherapy, the underling lung tissue receives higher doses from treatment field, which led to incidence of radiation pneumonitis.

Objective

The present study aims to evaluate the predictive factors of radiation pneumonitis and related changes in pulmonary function after 3D-conformal radiotherapy of breast cancer.

Material and Methods

In prospective basis study, thirty-two patients with breast cancer who received radiotherapy after surgery, were followed up to 6 months. Respiratory symptoms, lung radiologic changes and pulmonary function were evaluated. Radiation pneumonitis (RP) was graded according to common terminology criteria for adverse events (CTCAE) version 3.0. Dose-volume parameters, which included percentage of lung volume receiving dose of d Gy (V₅-V₅₀) and mean lung dose (MLD), were evaluated for RP prediction. Pulmonary function evaluated by spirometry test and changes of FEV1 and FVC parameters.

Results

Eight patients developed RP. Among the dose-volume parameters, V₁₀ was associated to RP incidence. When V₁₀<40% and V₁₀≥40% the incidences of RP were 5.26% and 61.54%, respectively. The FEV1 and FVC had a reduction 3 and 6 months after radiotherapy, while only FEV1 showed significant reduction. The FEV1 had more reduction in the patients who developed RP than patients without RP (15.25±3.81 vs. 9.2±0.93).

Conclusion

Pulmonary function parameters, especially FEV1, significantly decreased at 3 and 6 months after radiotherapy. Since most patients with breast cancer who developed RP did not show obvious clinical symptoms, so spirometry test is beneficial to identify patients with risk of radiation pneumonitis.

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.

Establishment and Verification of a Prediction Model for Symptomatic Radiation Pneumonitis in Patients with Esophageal Cancer Receiving Radiotherapy

BACKGROUND This study aimed to determine the value of the significant index in predicting symptomatic radiation pneumonitis (RP) in esophageal cancer patients, establish a nomogram prediction model, and verify the model. MATERIAL AND METHODS The patients enrolled were divided into 2 groups: a model group and a validation group. According to the logistic regression analysis, the independent predictors for symptomatic RP were obtained, and the nomogram prediction model was established according to these independent predictors. The consistency index (C-index) and calibration curve were used to evaluate the accuracy of the model, and the prediction ability of the model was verified in the validation group. Recursive partitioning analysis (RPA) was used for the risk stratification analysis. RESULTS The ratio of change regarding the pre-albumin at the end of treatment (P=0.001), platelet-to-lymphocyte ratio during treatment (P=0.027), and neutrophil-to-lymphocyte ratio at the end of treatment (P=0.001) were the independent predictors for symptomatic RP. The C-index of the nomogram model was 0.811. According to the risk stratification of RPA, the whole group was divided into 3 groups: a low-risk group, a medium-risk group, and a high-risk group. The incidence of symptomatic RP was 0%, 16.9%, and 57.6%, respectively. The receiver operating characteristic curve also revealed that the nomogram model has good accuracy in the validation group. CONCLUSIONS The developed nomogram and corresponding risk classification system have superior prediction ability for symptomatic RP and can predict the occurrence of RP in the early stage.

Higher Dose Volumes May Be Better for Evaluating Radiation Pneumonitis in Lung Proton Therapy Patients Compared With Traditional Photon-Based Dose Constraints

Purpose

The dosimetric parameters used clinically to reduce the likelihood of radiation pneumonitis (RP) for lung cancer radiation therapy have traditionally been V20Gy ≤ 30% to 35% and mean lung dose ≤ 20 to 23 Gy; however, these parameters are derived based on studies from photon therapy. The purpose of this study is to evaluate whether such dosimetric predictors for RP are applicable for locally advanced non-small cell lung cancer (LA-NSCLC) patients treated with proton therapy.

Methods and Materials

In the study, 160 (78 photon, 82 proton) patients with LA-NSCLC treated with chemoradiotherapy between 2011 and 2016 were retrospectively identified. Forty (20 photon, 20 proton) patients exhibited grade ≥2 RP after therapy. Dose volume histograms for the uninvolved lung were extracted for each patient. The percent lung volumes receiving above various dose levels were obtained in addition to V20Gy and D_mean. These dosimetric parameters and patient characteristics were evaluated with univariate and multivariate logistic regression tests. Receiver operating characteristic curves were generated to obtain the optimal dosimetric constraints through analyzing RP and non-RP sensitivity and specificity values.

Results

The multivariate analysis showed V40Gy and D_mean to be statistically significant for proton and photon patients, respectively. V35Gy to V50Gy were strongly correlated to V40Gy for proton patients. Based on the receiver operating characteristic curves, V35Gy to V50Gy had the highest area under the curve compared with other dose levels for proton patients. A potential dosimetric constraint for RP predictor in proton patients is V40Gy ≤ 23%.

Conclusions

In addition to V20Gy and D_mean, the lung volume receiving higher doses, such as V40Gy, may be used as an additional indicator for RP in LA-NSCLC patients treated with proton therapy.

The dose-response characteristics of four NTCP models: using a novel CT-based radiomic method to quantify radiation-induced lung density changes

Multiple competing normal tissue complication probability (NTCP) models have been proposed for predicting symptomatic radiation-induced lung injury in human. In this paper we tested the efficacy of four common NTCP models applied quantitatively to sub-clinical X-ray computed tomography (CT)-density changes in the lung following radiotherapy. Radiotherapy planning datasets and follow-up chest CTs were obtained in eight patients treated for targets within the lung or hilar region. Image pixel-wise radiation dose exposure versus change in observable CT Hounsfield units was recorded for early (2-5 months) and late (6-9 months) time-points. Four NTCP models, Lyman, Logistic, Weibull and Poisson, were fit to the population data. The quality of fits was assessed by five statistical criteria. All four models fit the data significantly (p < 0.05) well at early, late and cumulative time points. The Lyman model fitted best for early effects while the Weibull Model fitted best for late effects. No significant difference was found between the fits of the models and with respect to parameters D₅₀ and γ₅₀. The D₅₀ estimates were more robust than γ₅₀ to image registration error. For analyzing population-based sub-clinical CT pixel intensity-based dose response, all four models performed well.

Evaluation of the Efficacy and Safety of the Herbal Formula PM014 in a Cisplatin- and Paclitaxel-Treated Tumor-Bearing Mouse Model

PM014 (HL301) is a standardized herbal mixture derived from a traditional Korean medicine, Chung-Sang-Bo-Ha-Tang. Previously, we reported that PM014 treatment significantly suppressed pulmonary fibrosis, one of the frequent adverse effects of anticancer therapy in lung cancer. Before the clinical application of PM014 in anticancer therapy, the safety and efficacy of PM014 in combination with conventional anticancer drugs should be addressed to determine whether PM014 can be used in lung cancer. Lewis lung cancer–bearing mice were injected with 10 mg/kg of cisplatin or paclitaxel on day 5. Starting on day 7, the mice were administered 200 mg/kg PM014 every 2 days. On day 15, all mice were assessed by biochemical and histological analyses. PM014 did not block the antitumor activity of cisplatin and paclitaxel. Coadministration of PM014 and antitumor agents did not elevate the aspartate transaminase/alanine transaminase ratio or the blood urea nitrogen/creatinine ratio. Histopathological analysis also showed that PM014 did not induce hepatic or renal injury. Moreover, PM014 had no apparent inhibitory effects on drug metabolizing enzymes, indicating that PM014 did not alter the pharmacokinetics of chemotherapeutic drugs. Overall, these data show the safety and compatibility of combination therapy of PM014 and chemotherapies for the treatment of lung cancer.

Effects of exercise therapy in cancer patients undergoing radiotherapy treatment: a narrative review

Despite its beneficial effects, radiotherapy still results in a range of side effects that negatively impact quality of life of patients. Exercise has been shown to counteract the side effects induced by cancer treatment. This narrative review aims to provide an up-to-date review of the effects of an exercise intervention in cancer patients during radiotherapy. A literature search was performed on PubMed to identify original articles that evaluated the effects of an exercise programme to alleviate treatment-related side effects in cancer patients undergoing radiotherapy with or without other cancer treatments. Benefits related to exercise training have been shown in breast, prostate, rectal, lung, head and neck cancer patients undergoing radiotherapy. Therefore, exercise should be considered as a concurrent treatment alongside radiotherapy to alleviate treatment-related side effects and facilitate effective recovery. Due to the onset and progress of treatment-related side effects throughout radiotherapy, a regular clinical evaluation seems strongly advisable in order to continuously adapt the exercise programme depending on symptoms and side effects. An exercise professional is needed to personalize exercise training based on the medical condition and tailor it throughout the intervention according to progress and the patient’s medical status. Future studies are needed to confirm the potential benefits of exercises observed on treatment-related side effects. Furthermore, because of the narrative design of this study, a systematic review is required to evaluate the strength of the evidence reported.

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

OBJECTIVE

Investigate the spectrum of radiographic patterns of radiation pneumonitis (RP) in lung cancer patients and identify imaging markers for high-grade RP and RP-related death.

METHODS

Eighty-two patients with lung cancer treated with conventional chest radiotherapy who had symptomatic RP were identified from the radiation oncology database. The imaging features of RP were studied for association with high-grade RP (Grade ≥3) and RP-related death (Grade 5).

RESULTS

RP was Grade 2 in 60 (73%), Grade 3 in 15 (18%), and Grade 5 in 7 patients (9%). Lower performance status (p = 0.04), squamous cell histology (p = 0.03), and FEV1 ≤ 2 (p = 0.009) were associated with high-grade pneumonitis. Older age (p = 0.03) and squamous cell histology (p = 0.03) were associated with RP-related death. The CT findings included ground-glass and reticular opacities in all patients, with traction bronchiectasis in 77 (94%) and consolidation in 74 (90%). The most common radiographic pattern of RP was cryptogenic organizing pneumonia (COP) pattern (n = 54), followed by acute interstitial pneumonia (AIP)/acute respiratory distress syndrome (ARDS) pattern (n = 10). Higher extent of lung involvement, diffuse distribution, and AIP/ARDS pattern were associated with high-grade pneumonitis and RP-related death. AIP/ARDS pattern was a significant factor for high-grade pneumonitis (OR:12.62, p = 0.01) in multivariable analyses adjusting for clinical variables.

CONCLUSION

COP pattern was the most common radiographic pattern for symptomatic RP in lung cancer patients. AIP/ARDS pattern was significantly associated with high-grade RP and RP-related deaths, and was an independent marker for high-grade RP. The recognition of the radiographic patterns of RP can help to effectively contribute to patient management.

Preclinical Model of Stereotactic Ablative Lung Irradiation Using Arc Delivery in the Mouse: Effect of Beam Size Changes and Dose Effect at Constant Collimation

PURPOSE

Stereotactic body radiation therapy is a therapeutic option offered to high surgical risk patients with lung cancer. Focal lung irradiation in mice is a new preclinical model to help understand the development of lung damage in this context. Here we developed a mouse model of lung stereotactic therapy using arc delivery and monitored the development of lung damage while varying the beam size and dose delivered.

METHODS AND MATERIALS

C57BL/6JRj mice were exposed to 90 Gy focal irradiation on the left lung using 1-mm diameter, 3 × 3 mm², 7 × 7 mm², or 10 × 10 mm² beam collimation for beam size effect and using 3 × 3 mm² beam collimation delivering 20 to 120 Gy for dose effect. Long-term lung damage was monitored with micro-computed tomography imaging with anatomopathologic and gene expression measurements in the injured patch and the ipsilateral and contralateral lungs.

RESULTS

Both 1-mm diameter and 3 × 3 mm² beam collimation allow long-term studies, but only 3-mm beam collimation generates lung fibrosis when delivering 90 Gy. Dose-effect studies with constant 3-mm beam collimation revealed a dose of 60 Gy as the minimum to obtain lung fibrosis 6 months postexposure. Lung fibrosis development was associated with club cell depletion and increased type II pneumocyte numbers. Lung injury developed with ipsilateral and contralateral consequences such as parenchymal thickening and gene expression modifications.

CONCLUSIONS

Arc therapy allows long-term studies and dose escalation without lethality. In our dose-delivery conditions, dose-effect studies revealed that 3 × 3 mm² beam collimation to a minimum single dose of 60 Gy enables preclinical models for the assessment of lung injury within a 6-month period. This model of lung tissue fibrosis in a time length compatible with mouse life span may offer good prospects for future mechanistic studies.

Risk factors of grade ≥ 2 radiation pneumonitis after gemcitabine induction chemotherapy for patients with non-small cell lung cancer

Objectives

To observe the risk factors affecting the occurrence of RP after gemcitabine-based induction chemotherapy.

Methods

Between January 2010 and December 2017, patients with NSCLC received gemcitabine or docetaxel chemotherapy, followed by radiotherapy at Zhejiang cancer hospital were enrolled in this study. Patients were treated with gemcitabine or docetaxel induction chemotherapy, followed by radiotherapy or concurrent chemoradiotherapy. Acute radiation pneumonitis was scored post chemoradiotherapy.

Results

One hundred and eighty-four patients with NSCLC were included in the gemcitabine group and 144 in the docetaxel group. The gemcitabine group experienced a higher incidence of grade ≥ 2 RP, compared with docetaxel group (25.5% Vs. 13.2%, P = 0.005). The optimal cutoff values of lung V₅, V₂₀, V₃₀ and MLD were set at 44% (AUC [area under the curve] = 0.593), 24% (AUC = 0.607), 14.2% (AUC = 0.622) and 1226 cGy (AUC = 0.626). On multivariate analysis, only lung V₃₀ was identified as a predictor for grade ≥ 2 RP (P = 0.03). The grade ≥ 2 RP rate was only 9.4% for the low-risk group (Lung V₅ ≤ 44%, V₂₀ ≤ 24%, V₃₀ ≤ 14.2%, and MLD ≤ 1226 cGy) in patients received gemcitabine induction chemotherapy.

Conclusions

Gemcitabine chemotherapy before thoracic radiotherapy in NSCLC patients was related to a higher incidence of grade ≥ 2 RP, compared with docetaxel chemotherapy. The Lung dose-volume variable V₃₀ was the best predictor of grade ≥ 2 RP.

Radiation-Induced Lung Injury (RILI)

Radiation pneumonitis (RP) and radiation fibrosis (RF) are two dose-limiting toxicities of radiotherapy (RT), especially for lung, and esophageal cancer. It occurs in 5-20% of patients and limits the maximum dose that can be delivered, reducing tumor control probability (TCP) and may lead to dyspnea, lung fibrosis, and impaired quality of life. Both physical and biological factors determine the normal tissue complication probability (NTCP) by Radiotherapy. A better understanding of the pathophysiological sequence of radiation-induced lung injury (RILI) and the intrinsic, environmental and treatment-related factors may aid in the prevention, and better management of radiation-induced lung damage. In this review, we summarize our current understanding of the pathological and molecular consequences of lung exposure to ionizing radiation, and pharmaceutical interventions that may be beneficial in the prevention or curtailment of RILI, and therefore enable a more durable therapeutic tumor response.

Genetic variants of SP-D confer susceptibility to radiation pneumonitis in lung cancer patients undergoing thoracic radiation therapy

Background

Surfactant protein D (SP‐D) is an innate immunity molecule in the alveoli. However, the associations between genetic variants of SP‐D and radiation pneumonitis (RP) have never been investigated.

Methods

The Linkage disequilibrium of SP‐D and tagSNPs were analyzed by using Haploview 4.1. Eight tagSNPs were genotyped among 396 lung cancer patients who received thoracic radiation therapy with follow–up time (median [P25, P75]: 11[6, 18]) using improved multiplex ligation detection reaction (iMLDR). The associations between clinical characteristics, tagSNP alleles, genotypes, haplotypes and onset time of grade ≥2 or ≥3 RP were evaluated by using univariate and multivariate Cox proportional hazard regression model.

Results

Three tagSNPs of SP‐D (rs1998374, rs911887 and rs2255326) were significantly associated with grade ≥2 RP in multivariate analysis with multiple testing (Q test). The rs199874 had a protective effect for grade ≥2 RP in the dominant model (Hazard ratio (HR), 0.575; 95% confidence interval (CI), 0.378‐0.875). The homozygous mutant genotype for rs911887 had risk effect for grade ≥2 RP (HR, 2.209; 95% CI, 1.251‐3.902). The A mutant allele of rs2255326 also showed an elevated risk for grade ≥2 RP (HR, 1.777; 95% CI, 1.283‐2.461) and this risk effect was still significant in the recessive genetic model (HR, 3.320; 95% CI, 1.659‐6.644) and dominant genetic model (HR, 1.773; 95% CI, 1.166‐2.696). Compared to the lung cancer patients bearing the most common haplotype C‐G‐T, the patients bearing the haplotype T‐A‐C (rs1998374‐rs2255326‐rs911887) showed a significant risk of both grade ≥2 RP (HR, 1.885; 95% CI, 1.284‐2.765) and grade ≥3 RP (HR, 2.256; 95% CI, 1.248‐4.080).

Conclusions

Genetic variants of SP‐D were associated with risk of RP development in lung cancer patients receiving thoracic radiotherapy.

Determining RBE for development of lung fibrosis induced by fractionated irradiation with carbon ions utilizing fibrosis index and high-LET BED model

BACKGROUND AND PURPOSES

Carbon ion radiotherapy (CIRT) with raster scanning technology is a promising treatment for lung cancer and thoracic malignancies. Determining normal tissue tolerance of organs at risk is of utmost importance for the success of CIRT. Here we report the relative biological effectiveness (RBE) of CIRT as a function of dose and fractionation for development of pulmonary fibrosis using well established fibrosis index (FI) model.

MATERIALS AND METHODS

Dose series of fractionated clinical quality CIRT versus conventional photon irradiation to the whole thorax were compared in C57BL6 mice. Quantitative assessment of pulmonary fibrosis was performed by applying the FI to computed tomography (CT) data acquired 24-weeks post irradiation. RBE was calculated as the ratio of photon to CIRT dose required for the same level of FI. Further RBE predictions were performed using the derived equation from high-linear energy transfer biologically effective dose (high-LET BED) model.

RESULTS

The averaged lung fibrosis RBE of 5-fraction CIRT schedule was determined as 2.75 ± 0.55. The RBE estimate at the half maximum effective dose (RBE_ED50) was estimated at 2.82 for clinically relevant fractional sizes of 1-6 Gy. At the same dose range, an RBE value of 2.81 ± 0.40 was predicted by the high-LET BED model. The converted biologically effective dose (BED) of CIRT for induction of half maximum FI (BED_ED50) was identified to be 58.12 Gy_3.95. In accordance, an estimated RBE of 2.88 was obtained at the BED_ED50 level. The LQ model radiosensitivity parameters for 5-fraction was obtained as α_H = 0.3030 ± 0.0037 Gy^-1 and β_H = 0.0056 ± 0.0007 Gy^-2.

CONCLUSION

This is the first report of RBE estimation for CIRT with the endpoint of pulmonary fibrosis in-vivo. We proposed in present study a novel way to mathematically modeling RBE by integrating RBE_max and α/β_L based on conventional high-LET BED conception. This model well predicted RBE in the clinically relevant dose range but is sensitive to the uncertainties of α/β estimates from the reference photon irradiation (α/β_L). These findings will assist to eliminate current uncertainties in prediction of CIRT induced normal tissue complications and builds a solid foundation for development of more accurate in-vivo data driven RBE estimates.

Identification of molecular signatures involved in radiation-induced lung fibrosis

In radiotherapy, radiation (IR)-induced lung fibrosis has severe and dose-limiting side effects. To elucidate the molecular effects of IR fibrosis, we examined the fibrosis process in irradiated mouse lung tissues. High focal IR (90 Gy) was exposed to a 3-mm volume of the left lung in C57BL6 mice. In the diffused irradiation, 20 Gy dose delivered with a 7-mm collimator almost covered the entire left lung. Histological examination for lung tissues of both irradiated and neighboring regions was done for 4 weeks after irradiation. Long-term effects (12 months) of 20Gy IR were compared on a diffuse region of the left lung and non-irradiated right lung. Fibrosis was initiated as early as 2 weeks after IR in the irradiated lung region and neighboring region. Upregulation of gtse1 in both 90Gy-irradiated and neighboring regions was observed. Upregulation of fgl1 in both 20Gy diffused irradiated and non-irradiated lungs was identified. When gtse1 or flg1 was knock-downed, TGFβ or IR-induced epithelial-mesenchymal transition was inhibited, accompanied with the inhibition of cellular migration, suggesting fibrosis responsible genes. Immunofluorescence analysis using mouse fibrotic lung tissues suggested that fibrotic regions showed increased expressions of Gtse1 and Fgl1, indicating novel molecular signatures of gtse1and fgl1 for IR-induced lung fibrosis. Even though their molecular mechanisms and IR doses or irradiated volumes for lung fibrosis may be different, these genes may be novel targets for understanding IR-induced lung fibrosis and in treatment strategies. KEY MESSAGES: Upregulation of gtse1 by 90Gy focal irradiation and upregulation of fgl1 by 20Gy diffused irradiation are identified in mouse lung fibrosis model. Gtse1 and Fgl1 are involved in radiation or TGFβ-induced epithelial-mesenchymal transition. Radiation-induced fibrotic regions of mouse lungs showed increased expressions of Gtse1 and Fgl1. Gtse1 and Fgl1 are suggested to be novel targets for radiation-induced lung fibrosis.

Oral administration of herbal medicines for radiation pneumonitis in lung cancer patients: A systematic review and meta-analysis

BACKGROUND

Radiation pneumonitis is a common and serious complication of radiotherapy. Many published randomized controlled studies (RCTs) reveal a growing trend of using herbal medicines as adjuvant therapy to prevent radiation pneumonitis; however, their efficacy and safety remain unexplored.

OBJECTIVE

The aim of this systematic review is to evaluate the efficacy and safety of herbal medicines as adjunctive therapy for the prevention of radiation pneumonitis in patients with lung cancer who undergo radiotherapy.

METHODS

We searched the following 11 databases: three English medical databases [MEDLINE (PubMed), EMBASE, The Cochrane Central Register of Controlled Trials (CENTRAL)], five Korean medical databases (Korean Studies Information, Research information Service System, KoreaMed, DBPIA, National Digital Science Library), and three Chinese medical databases [the China National Knowledge Database (CNKI), Journal Integration Platform (VIP), and WanFang Database]. The primary outcome was the incidence of radiation pneumonitis. The risk of bias was assessed using the Cochrane risk-of-bias tool.

RESULTS

Twenty-two RCTs involving 1819 participants were included. The methodological quality was poor for most of the studies. Meta-analysis showed that herbal medicines combined with radiotherapy significantly reduced the incidence of radiation pneumonitis (n = 1819; RR 0.53, 95% CI 0.45-0.63, I2 = 8%) and the incidence of severe radiation pneumonitis (n = 903; RR 0.22, 95% CI 0.11-0.41, I2 = 0%). Combined therapy also improved the Karnofsky performance score (n = 420; WMD 4.62, 95% CI 1.05-8.18, I2 = 82%).

CONCLUSION

There is some encouraging evidence that oral administration of herbal medicines combined with radiotherapy may benefit patients with lung cancer by preventing or minimizing radiation pneumonitis. However, due to the poor methodological quality of the identified studies, definitive conclusion could not be drawn. To confirm the merits of this approach, further rigorously designed large scale trials are warranted.

Is severe emphysema, as defined by quantitative CT measurement, a negative risk factor of radiation fibrosis?

OBJECTIVE

To investigate whether patients with emphysema, as evaluated by quantitative CT image measurement, are at risk of developing radiation pneumonitis (RP) after radiotherapy (RT) for non-small cell lung cancer (NSCLC).

METHODS

Between March 2011 and June 2015, 68 consecutive patients with Stage I NSCLC treated with a RT dose of 75 Gy given in 30 fractions were enrolled. The median age was 79 years and there were 45 males and 23 females. The number of patients with T₁ and T₂ were 49 and 19, respectively. The severity of emphysema was evaluated by the percentages of the low attenuation area (LAA) of ≤-860 or -950 Hounsfield unit (HU) and average HU in the whole lung.

RESULTS

The mean difference percentages of LAA of ≤-860 (p = 0.0004) or -950 HU (p = 0.005) and average HU (p = 0.001) in patients with RP were significantly lower than those in patients without RP. The area under curve (AUC) of average HU was significantly higher than AUC of LAA of ≤-860 (p < 0.0001) or -950 HU (p < 0.0001). The RP rate after RT was significantly lower when the average HU values were ≤-850 HU (p = 0.0003).

CONCLUSION

Patients with emphysema evaluated by average HU (≤-850 HU) in the whole lung were found to be at low risk of RP after RT. Advances in Knowledge: Quantitative measurement of average HU from CT images was predicted of RP after RT.

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.

Potentially Functional Variants of ATG16L2 Predict Radiation Pneumonitis and Outcomes in Patients with Non-Small Cell Lung Cancer after Definitive Radiotherapy

INTRODUCTION

Autophagy not only plays an important role in the progression of cancer but is also involved in tissue inflammatory response. However, few published studies have investigated associations between functional genetic variants of autophagy-related genes and radiation pneumonitis (RP) as well as clinical outcomes in patients with NSCLC after definitive radiotherapy.

METHODS

We genotyped nine potentially functional single-nucleotide polymorphisms (SNPs) in four autophagy-related genes (autophagy related 2B gene [ATG2B], autophagy related 10 gene [ATG10], autophagy related 12 gene [ATG12], and autophagy related 16 like 2 gene [ATG16L2]) in 393 North American patients with NSCLC treated by definitive radiotherapy and assessed their associations with RP, local recurrence-free survival (LRFS), progression-free survival (PFS), and overall survival (OS) in multivariable Cox proportional hazard regression analyses.

RESULTS

We found that patients with the ATG16L2 rs10898880 CC variant genotype had a better LRFS, PFS, and OS (adjusted hazard ratio = 0.59, 0.64, and 0.64; 95% confidence interval: 0.45-0.79, 0.48-0.84, and 0.48-0.86; p = 0.0004, 0.002, and 0.003, respectively), but a greater risk for development of severe RP (adjusted hazard ratio = 1.80, 95% confidence interval: 1.04-3.12, p = 0.037) than did patients with AA/AC genotypes. Further functional analyses suggested that the ATG16L2 rs10898880 C variant allele modulated expression of the ATG16L2 gene.

CONCLUSION

This is the first report that one potentially functional SNP rs10898880 in ATG16L2 may be a predictor of RP, LRFS, PFS, and OS in patients with NSCLC after definitive radiotherapy. Additional larger, prospective studies are needed to confirm these findings.

Which is the optimal threshold for defining functional lung in single-photon emission computed tomography lung perfusion imaging of lung cancer patients?

PURPOSE

The aim of this study was to investigate the optimal threshold for the functional lung (FL) definition of single-photon emission computed tomography (SPECT) lung perfusion imaging.

PATIENTS AND METHODS

Forty consecutive stage III non-small-cell lung cancer patients underwent SPECT lung perfusion scans and PET/CT scans for treatment planning, and the images were coregistered. Total lung and perfusion lung volumes corresponding to 10, 20, …, 60% of the maximum SPECT count were segmented automatically. The SPECT-weighted mean lung dose (SWMDx%) and the percentage of FL volume receiving more than 20 Gy (Fx%V20) of different thresholds were investigated using SPECT-weighted dose-volume histograms. Receiver-operator characteristic curves were used to identify SWMD and FV20 of different thresholds in predicting the incidence of radiation pneumonitis (RP).

RESULTS

Eleven (27.5%) patients developed RP (grades 1, 2, 3, and 4 were 10.0, 7.5, 7.5, and 2.5%, respectively) after treatment. The largest area under the receiver-operator characteristic curve was 0.881 for the ability of SWMD to predict RP with 20% as the threshold and 0.928 for the ability of FV20 with 20% as the threshold.

CONCLUSION

The SWMD20% and FV20 of FL using 20% of the maximum SPECT count as the threshold may be better predictors for the risk of RP.

Association between ATM gene polymorphisms, lung cancer susceptibility and radiation-induced pneumonitis: a meta-analysis

BACKGROUND

Previous studies have suggested that DNA double-strand break (DSB) repair is an important protective pathway after damage. The ataxia telangiectasia mutated (ATM) gene plays an important role in the DNA DSB repair pathway. DNA damage is a major cytotoxic effect that can be caused by radiation, and the ability to repair DNA after damage varies among different tissues. Impaired DNA repair pathways are associated with high sensitivity to radiation exposure. Hence, ATM gene polymorphisms are thought to influence the risk of cancer and radiation-induced pneumonitis (RP) risk in cancer patients treated with radiotherapy. However, the results of previous studies are inconsistent. We therefore conducted this comprehensive meta-analysis.

METHODS

A systematic literature search was performed in the PubMed, Embase, China National Knowledge Internet (CNKI) and Wanfang databases to identify studies that investigated the association between the ATM gene polymorphisms and both lung cancer and RP radiotherapy-treated lung cancer (the last search was conducted on Dec.10, 2015). The odds ratio (OR) and 95% confidence interval (CI) were used to investigate the strength of these relationships. Funnel plots and Begg's and Egger's tests were conducted to assess the publication bias. All analyses were performed in STATA 13.0 software.

RESULTS

Ten eligible case-control studies (4731 cases and 5142 controls) on lung cancer susceptibility and four (192 cases and 772 controls) on RP risk were included. The results of the overall and subgroup analyses indicated that in the ATM gene, the rs189037 (-111G > A, -4519G > A), rs664677 (44831C > T, 49238C > T) and rs664143 (131,717 T > G) polymorphisms were significantly associated with lung cancer susceptibility (OR = 1.21, 95% CI = 1.04-1.39, P = 0.01; OR = 1.26, 95% CI = 1.06-1.49, P = 0.01; OR = 1.43, 95% CI = 1.15-1.78, P < 0.01). Additionally, the rs189037 variant was significantly associated with RP risk (OR = 1.74, 95% CI = 1.02-2.97, P = 0.04). No publication bias was found in the funnel plots, Begg's tests or Egger's tests.

CONCLUSIONS

The results indicate that the ATM rs189037, rs664677 and rs664143 gene polymorphisms are risk factors for lung cancer, while the ATM rs189037 variant was significantly associated with RP risk.

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.

Subjective Global Assessment (SGA) Score Could Be a Predictive Factor for Radiation Pneumonitis in Lung Cancer Patients With Normal Pulmonary Function Treated by Intensity-Modulated Radiation Therapy and Concurrent Chemotherapy

INTRODUCTION

To investigate the relationship between malnutrition and the severity of radiation pneumonitis (RP) in patients with lung cancer with normal baseline pulmonary function and lungs' V20 < 35% treated by intensity-modulated radiation therapy (IMRT) and concurrent chemotherapy.

MATERIALS AND METHODS

A total of 150 patients with lung cancer who received definitive IMRT (≥ 60 Gy) and concurrent chemotherapy were enrolled. In the condition of normal baseline pulmonary function and strict constraints of the irradiation dose to normal lung tissues, we recorded Eastern Cooperative Oncology Group score; concurrent chemotherapy; clinical stage; the level of albumin (ALB), hemoglobin, and C-reactive protein; Subjective Global Assessment (SGA) scores; radiation esophagitis grade; V20 of lungs; and mean lung dose. These factors were correlated with RP using univariate and multivariate regression analyses.

RESULTS

Of 150 patients, 12 patients (8.0%) developed Grade 3 to 5 RP, 37 (24.6%) patients developed grade 3 to 5 esophageal toxicity. In univariate analysis, ALB level (P = .002), radiation esophagitis (P < .001), and SGA score (P < .001) were significantly associated with RP. Multivariate analysis revealed that SGA (P < .001) was the independent predictor of RP.

CONCLUSIONS

SGA could be a predictor for RP in patients with lung cancer treated with definitive IMRT and concurrent chemotherapy.

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.

Update of a Prospective Study of Stereotactic Body Radiation Therapy for Post-Chemoradiation Residual Disease in Stage II/III Non-Small Cell Lung Cancer

PURPOSE

To report long-term outcomes (risk of late toxicities, local control, and survival) of dose escalation by stereotactic radiation therapy boost to residual fluorodeoxyglucose positron emission tomography-positive residual disease after chemoradiation (CRT) in stage III non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

Patients with stage IIB/III NSCLC underwent computed tomography or positron emission tomography-computed tomography screening approximately 1 month after completion of CRT. Limited residual disease (≤5 cm) within the site of the primary tumor received a stereotactic radiation therapy boost of either 10 Gy × 2 fractions or 6.5 Gy × 3 fractions to the primary tumor, to achieve a total Biologically Equivalent Dose >100 Gy.

RESULTS

Thirty-seven patients received protocol therapy. With a median follow-up of 25.2 months, the crude local control rate for the entire group was 78% (n=29), but 10 patients (29%) and 24 patients (65%) developed regional and metastatic disease, respectively. At last follow-up, 5 patients (13.5%) remain alive, all with no evidence of disease, whereas 27 (73%) died of disease and the remaining 5 (13.5%) died of other causes. Median overall survival (OS) for the entire group was 25.2 months. Predictors for grade 3 pneumonitis included age and mean lung dose. Poorer median OS was associated with histology: median OS 15.6 months for squamous cell versus 34.8 months for other histologies (large cell neuroendocrine tumors excluded) (P=.04). The median progression-free survival was 6 months, with IIIB disease having significantly worse median progression-free survival (stages IIB/IIA being 9.4 months, vs 4.7 months for stage IIIB [P=.03]).

CONCLUSIONS

Stereotactic radiation therapy boost after CRT is a safe treatment resulting in improvements in local control for locally advanced NSCLC. No additional late toxicities were seen. Possible improvement in OS was found, but further study in a larger prospective trial is needed.

Assessment of pulmonary 18F-FDG-PET uptake and cytokine profiles in non-small cell lung cancer patients treated with radiotherapy and erlotinib

Purpose

To investigate effects of radiotherapy (RT) and erlotinib on pulmonary glucose uptake using 2-deoxy-2-(18F)fluoro-D-glucose (¹⁸F-FDG) positron emission tomography (PET) during and after treatment of non-small cell lung cancer (NSCLC) and to identify associations between serum cytokine levels and lung glucose uptake.

Material and methods

Twenty-seven patients with advanced NSCLC, receiving RT alone or concomitant RT and erlotinib therapy, were examined by ¹⁸F-FDG PET before, during, and after treatment. A total of 57 ¹⁸F-FDG PET scans were analyzed. Pulmonary ¹⁸F-FDG uptake and radiotherapy dose mapping were used to acquire dose-response curves for each patient, where subsequent linear regression gave a glucose uptake level in the un-irradiated parts of the lungs (SUV₀) and a response slope (ΔSUV). Serum cytokine levels at corresponding time points were assessed using a multiplex bioassay. Correlations between the most robust cytokines and lung ¹⁸F-FDG dose response parameters were further investigated.

Results

From the dose response analysis, SUV₀ at post-therapy was significantly higher (P < 0.001) than at mid- and pre-therapy (45% and 58%, respectively) for the group receiving RT + erlotinib. Also, SUV₀ at post-therapy was higher for patients receiving RT + erlotinib compared to RT alone (42%; P < 0.001). No differences in ΔSUV were seen with treatments or time. SUV₀ was positively associated (r = 0.47, P = 0.01) with serum levels of the chemokine C-C motif ligand 21 (CCL21) for patients receiving RT + erlotinib.

Conclusions

Concomitant RT and erlotinib causes an elevation in pulmonary ¹⁸F-FDG uptake post treatment compared to RT alone. Pulmonary glucose uptake is associated with an upregulation of a chemokine (CCL21) involved in inflammatory reactions.

The effect of the TLR9 ligand CpG-oligodeoxynucleotide on the protective immune response to radiation-induced lung fibrosis in mice

CpG-oligodeoxynucleotide (CpG-ODN) is not only reported to protect against airway hyper responsiveness but is also known as a potent vaccine adjuvant for anti-tumor therapy. Little is known about the effect of CpG-ODN in mice with radiation-induced lung fibrosis (RILF), a common late stage form of tissue damage that occurs after thorax radiotherapy (RT). Here, we evaluated the immunomodulatory effects of CpG-ODN on the development of RILF. Mice were divided into four groups: (1) RT, single dose of 12Gy to the whole thorax; (2) CpG, only intraperitoneal injection of CpG-ODN for total 5 weeks; (3) RT+CpG, irradiation plus CpG-ODN treatment before and after irradiation for total 5 weeks; and (4) control (CTL): No RT or CpG-ODN treatment. In this study, we found that CpG-ODN treatment attenuated lung fibrosis and collagen deposition by increasing the number of M1 macrophagocytes, levels of Type-2 cytokines and TGF-β. CpG-ODN administration up-regulated the expression of TLR9 and STAT1 phosphorylation and reversed the expression of Type-2 immune response key transcription factor GATA-3. Activation of the JAK-STAT1 signaling pathway further enhanced M1 macrophage differentiation and Type-1 cytokine production. This study reveals the mitigating effect of early exposure to CpG-ODN on lung injury caused by irradiation in mice. The potential mechanism of action may be related to enhancement of Type-1 immunity. In conclusion, CpG-ODN may be a potential therapeutic target to treat RILF.

Correlation between pneumonitis risk in radiation oncology and lung density measured with X-ray computed tomography

BACKGROUND

The risk of toxicity with radiation oncology for lung cancer limits the maximal radiation dose that can be delivered to thoracic tumors. This study aims at investigating the correlation between normal tissue complication probability (NTCP) and physical lung density by analyzing the computed tomography (CT) scan imaging used for radiotherapy dose planning.

METHODS

Data from CT of lung cancer patients (n=10), treated with three dimensional radiotherapy, were selected for this study. The dose was calculated using analytical anisotropic algorithm (AAA). Dose volume histograms (DVH) for healthy lung (lung excluding targets) were calculated. The NTCP for lung radiation induced pneumonitis was computed using initial radiobiological parameters from Lyman-Kutcher and Burman (LKB) model and readjusted parameters for AAA, with α/β=3. The correlation coefficient "rho" was calculated using Spearman's rank test. The bootstrap method was used to estimate the 95% confidence interval (95% CI). Wilcoxon paired test was used to calculate P values.

RESULTS

Bootstrapping simulation revealed significant difference between NTCP computed with the initial radiobiological parameters and that computed with the parameters readjusted for AAA (P=0.03). The results of simulations based on 1,000 replications showed no correlation for NTCP with density, with "rho" <0.3.

CONCLUSIONS

For a given set of patients, we assessed the correlation between NTCP and lung density using bootstrap analysis. The lack of correlation could result either from a very accurate dose calculation, by AAA, whatever the lung density yielding a NTCP result only dependant of the dose and not any more of the density; or to the very limited range of natural variation of relative electronic density (0.15 to 0.20) observed in this small series of patients. Another important parameter is the bootstrap simulation with 1,000 random samplings may have underestimated the correlation, since the initial data (n=10) showed a weak correlation.

Radiation-induced lung fibrosis in a tumor-bearing mouse model is associated with enhanced Type-2 immunity

Lung fibrosis may be associated with Type-2 polarized inflammation. Herein, we aim to investigate whether radiation can initiate a Type-2 immune response and contribute to the progression of pulmonary fibrosis in tumor-bearing animals. We developed a tumor-bearing mouse model with Lewis lung cancer to receive either radiation therapy alone or radiation combined with Th1 immunomodulator unmethylated cytosine-phosphorothioate-guanine containing oligodeoxynucleotide (CpG-ODN). The Type-2 immune phenotype in tumors and the histological grade of lung fibrosis were evaluated in mice sacrificed three weeks after irradiation. Mouse lung tissues were analyzed for hydroxyproline and the expression of Type-1/Type-2 key transcription factors (T-bet/GATA-3). The concentration of Type-1/Type-2 cytokines in serum was measured by cytometric bead array. Lung fibrosis was observed to be more serious in tumor-bearing mice than in normal mice post-irradiation. The fibrosis score in irradiated tumor-bearing mice on Day 21 was 4.33 ± 0.82, which was higher than that of normal mice (2.00 ± 0.63; P < 0.05). Hydroxyproline and GATA-3 expression were increased in the lung tissues of tumor-bearing mice following irradiation. CpG-ODN attenuated fibrosis by markedly decreasing GATA-3 expression. Serum IL-13 and IL-5 were elevated, whereas INF-γ and IL-12 expression were decreased in irradiated tumor-bearing mice. These changes were reversed after CpG-ODN treatment. Thus, Type-2 immunity in tumors appeared to affect the outcome of radiation damage and might be of interest for future studies on developing approaches in which Type-1-related immunotherapy and radiotherapy are used in combination.

Transforming growth factor-beta-1 is a serum biomarker of radiation-induced pneumonitis in esophageal cancer patients treated with thoracic radiotherapy: preliminary results of a prospective study

OBJECTIVE

To examine the relationship between cytokine levels of transforming growth factor-beta-1 (TGF-β1), interleukin-1 beta (IL-1β), and angiotensin-converting enzyme (ACE) in the plasma of esophageal carcinoma patients and radiation-induced pneumonitis (RP).

MATERIALS AND METHODS

Sixty-three patients with esophageal carcinoma were treated with three-dimensional conformal radiotherapy (RT) using the Elekta Precise treatment planning system with a prescribed dose of 50-70 Gy. Dose-volume histograms were collected from three-dimensional conformal RT to determine the volume percentage of the lung received V5, V10, V20, and the normal tissue complication probability. RP was diagnosed based on computed tomography imaging, respiratory symptoms, and signs. The severity of radiation-induced lung toxicity was determined using the Lent-Soma scale defined by the Radiation Therapy Oncology Group. Plasma samples obtained before RT, during RT (at 40 Gy), and at 1 day, 1 month, and 3 months after RT were assayed for TGF-β1, IL-1β, and ACE levels by enzyme-linked immunosorbent assay.

RESULTS

From the 63 patients, 17 (27%) developed RP, and 13 (21%) had RP of grade I and four (6%) had grade II or higher. We found plasma TGF-β1 levels were elevated in the patients that had RP when compared with the other 46 patients who did not have RP. The plasma IL-1β levels were not changed. The ACE levels were significantly lower in the 17 patients with RP compared to the 46 patients without RP throughout the RT. As expected, RP is associated with a higher dose of irradiation (>60 Gy); no other factors, including dose-volume histogram, age, sex, smoking status, location of tumor, and methods of treatment, are associated with RP.

CONCLUSION

Elevated plasma TGF-β1 levels can be used as a marker for RP.

Accelerated radiotherapy and concurrent chemotherapy for patients with contralateral central or mediastinal lung cancer relapse after pneumonectomy

BACKGROUND

Treatment options are very limited for patients with lung cancer who experience contralateral central or mediastinal relapse following pneumonectomy. We present results of an accelerated salvage chemoradiotherapy regimen.

METHODS

Patients with localized contralateral central intrapulmonary or mediastinal relapse after pneumonectomy were offered combined chemoradiotherapy including concurrent weekly cisplatin (25 mg/m(2)) and accelerated radiotherapy [accelerated fractionated (AF), 60 Gy, 8×2 Gy per week] to reduce time for repopulation. Based on 4D-CT-planning, patients were irradiated using multifield intensity-modulated radiotherapy (IMRT) or helical tomotherapy.

RESULTS

Between 10/2011 and 12/2012, seven patients were treated. Initial stages were IIB/IIIA/IIIB: 3/1/3; histopathological subtypes scc/adeno/large cell: 4/1/2. Tumour relapses were located in mediastinal nodal stations in five patients with endobronchial tumour in three patients. The remaining patients had contralateral central tumour relapses. All patients received 60 Gy (AF), six patients received concurrent chemotherapy. Median dose to the remaining contralateral lung, esophagus, and spinal cord was 6.8 (3.3-11.4), 8.0 (5.1-15.5), and 7.6 (2.8-31.2) Gy, respectively. With a median follow-up of 29 [17-32] months, no esophageal or pulmonary toxicity exceeding grade 2 [Common terminology criteria for adverse events (CTC-AE) v. 3] was observed. Median survival was 17.2 months, local in-field control at 12 months 80%. Only two local recurrences were observed, both in combination with out-field metastases.

CONCLUSIONS

This intensified accelerated chemoradiotherapy schedule was safely applicable and offers a curative chance in these pretreated frail lung cancer patients.

Focus on treatment complications and optimal management: radiation oncology

BACKGROUND

Esophagitis and pneumonitis are the most important treatment complications and dose-limiting toxicities in non-small cell lung cancer (NSCLC) patients treated with radiotherapy (RT) alone or combined modality therapy.

METHODS

A literature research was performed to identify published articles relating clinical and dosimetric parameters associated with significant radiation pneumonitis (RP) and esophagitis in NSCLC patients treated with three-dimensional conformal RT.

RESULTS

Possible clinical parameters associated with acute and or late esophagitis are concurrent chemoradiation, hyperfractionated and accelerated radiation regimens, dysphagia and neutropenia during treatment. Mean dose <34 Gy is currently used as standard dosimetric recommendation. Addition of chemotherapy and hyperfractionation are also associated with the risk of pneumonitis. Both the V20 and the mean lung dose are used as dosimetric parameter to correlate with the risk of high-grade radiation pneumonitis.

CONCLUSIONS

A variety of clinical and dosimetric parameters have been associated with acute and late toxicity. Treatment consist mainly in symptomatic relieve. Further research is necessary, as many studies led to different and sometimes even contradictory results.

Intravenous delivery of adipose-derived mesenchymal stromal cells attenuates acute radiation-induced lung injury in rats

BACKGROUND AIMS

Radiation-induced lung injury (RILI) commonly occurs in patients with thoracic cancer. However, an effective treatment option has not yet been established. Adipose-derived mesenchymal stromal cells (Ad-MSCs) have significant potential for clinical use, but their role in RILI is currently unknown. We aimed to evaluate the therapeutic capacity of Ad-MSCs to heal acute RILI in rats.

METHODS

Sprague-Dawley rats were used in this study. Rat Ad-MSCs were delivered through the tail veins of rats 2 h after thorax irradiation. Lung histopathologic findings, pulmonary levels of inflammatory cytokines (interleukin [IL]-1, IL-6, IL-10 and tumor necrosis factor-α), pro-fibrotic factors (transforming growth factor [TGF]-β1, connective tissue growth factor, α-smooth muscle actin and type 1 collagen), pro- or anti-apoptotic mediators (Bcl-2, Bax and caspase-3) and the multifunctional factor hepatocyte growth factor were evaluated after Ad-MSC transplant.

RESULTS

Intravenous delivery of Ad-MSCs attenuated acute RILI. Further studies showed that Ad-MSCs had anti-inflammation and anti-fibrotic effects and maintained lung epithelium integrity, as indicated by reduced serum levels of the pro-inflammatory cytokines IL-1, IL-6 and tumor necrosis factor-α, increased levels of the anti-inflammatory cytokine IL-10, and downregulated transforming growth factor -β1, α-smooth muscle actin and type 1 collagen levels in irradiated lung tissues. Ad-MSCs also regulated the expression of pro- and anti-apoptotic mediators (Bcl-2, Bax and caspase-3) to protect lung cells from apoptosis.

CONCLUSIONS

Intravenous Ad-MSC delivery attenuated acute RILI through anti-inflammation, anti-fibrosis and anti-apoptosis mechanisms.

Pulmonary Effects of Antineoplastic Therapy

Pulmonary toxicity is common after cancer therapy and can result from all therapeutic modalities. The consequential decrease in lung function ranges in severity from subclinical to life-threatening or even fatal and can manifest in the acute setting or many years after completion of therapy. Radiation effects are due to direct insult to the pulmonary parenchyma and, for younger children, impaired thoracic musculoskeletal development. Radiation pneumonitis can occur in the acute/subacute setting, as well as fibrosis with comprised gas exchange as a late effect of direct lung irradiation; thoracic wall malformation can cause restriction of function as a chronic sequela. The pulmonary effects of cytotoxic drugs usually present as acute effects, but there is the potential for significant late morbidity and mortality. Of course, surgical interventions can also cause both acute and/or late pulmonary effects as well, depending on the specific procedure. Although treatment approaches for the management of pediatric cancers are continually adapted to provide optimal therapy while minimizing toxicities, to a varying degree all therapies have the potential for both acute and late pulmonary toxicity. Of note, the cumulative incidence of pulmonary complications rises with increasing time since diagnosis, which suggests that adult survivors of childhood cancer require lifelong monitoring and management of potential new-onset pulmonary morbidity as they age. Knowledge of cytotoxic therapies and an understanding of lung physiology and how it may be altered by therapy facilitate appropriate clinical care and monitoring of long-term survivors.

A polymorphism in the DNA repair domain of APEX1 is associated with the radiation-induced pneumonitis risk among lung cancer patients after radiotherapy

OBJECTIVE

To examine the association of tag single nucleotide polymorphisms (tagSNPs) (rs1130409, rs1760944, rs2307486 and rs3136817) in APEX1 with the risk of severe radiation-induced pneumonitis (RP) after radiotherapy among Han Chinese patients with lung cancer.

METHODS

A total of 168 patients with lung cancer who were receiving radiotherapy were prospectively recruited. RP was evaluated according to the Radiation Therapy Oncology Group. A case-control study was performed. The case group included patients with RP grade of ≥3, while the control group comprised patients with RP grades <3. Four tagSNPs of APEX1 were genotyped in 126 patients with complete follow-up by multi-SNaPshot® (Genesky Biotechnologies Inc., Shanghai, China) genotyping assays. RESULTS were assessed by a logistic regression model for RP risk and Mantal-Cox log-rank test for the cumulative RP probability by the genotypes.

RESULTS

rs1130409 was associated with severe RP. GT genotype of rs1130409 was significantly higher in patients with RP than in those of the control group [68.8% vs 41.8%; p = 0.025; resulting odds ratio (OR), 5.98]. Patients with lung cancer bearing the G allele had a 5.83-fold higher risk of RP than those with the wild TT genotype [OR = 5.83; 95% confidence interval (CI), 1.27-26.90; p = 0.024], and this was further confirmed by the binary regression adjusted by some confounding factors, including Karnofsky performance scale, concurrent chemotherapy-radiotherapy and lung volume receiving >30 Gy (OR = 6.96; 95% CI, 1.36-35.77; p = 0.02). rs1130409 was also associated with the time to occurrence of severe RP (p = 0.04). Three-dimensional model APEX1 protein showed that rs1130409 is located in the random coil structure corresponding to the DNA repair function region.

ADVANCES IN KNOWLEDGE

rs1130409 of APEX1 can be a predictor of RP grades ≥3 among patients with lung cancer.

Genetic variants of the LIN28B gene predict severe radiation pneumonitis in patients with non-small cell lung cancer treated with definitive radiation therapy

BACKGROUND

LIN28 is an RNA-binding protein that not only plays key roles in multiple cellular developmental processes and tumourigenesis, but also is involved in tissue inflammatory response. However, no published study has investigated associations between genetic variants in LIN28 and radiation-induced pneumonitis (RP) in patients with non-small cell lung cancer (NSCLC) treated with definitive radiation therapy.

METHODS

We genotyped eight potentially functional single nucleotide polymorphisms (SNPs) of LIN28A (rs11247946 T>C, rs3811464 C>T, rs11581746 T>C, and rs12728900 G>A) and LIN28B (rs314280 G>A, rs12194974 G>A, rs17065417 A>C and rs314276 C>A) in 362 patients with NSCLC, who received definitive radio(chemo)therapy. The associations between RP risk and genotypes were assessed by hazards ratio (HR) in Cox proportional hazards regression analysis with time to event considered with and without adjustment for potential confounders.

RESULTS

Multivariate analyses found that patients carrying LIN28B rs314280 AG and AA/AG or rs314276 AC and AA/AC genotypes had a higher risk of grade ⩾3 RP (for rs314280 AG and AA/AG versus GG, adjusted HR=2.97 and 2.23, 95% confidence interval (CI)=1.32-6.72 and 1.01-4.94, P=0.009 and 0.048, respectively; for rs314276 AC and AA/AC versus CC, adjusted HR=2.30 and 2.00, 95% CI=1.24-4.28 and 1.11-3.62, and P=0.008 and 0.022, respectively). Further stratified analyses showed a more consistent and profound risk in the subgroups of age <65years, males, stage III/IV, ever smokers, having radio-chemotherapy and mean lung dose (MLD) ⩾19.0Gy.

CONCLUSION

Genetic variants of LIN28B, but not LIN28A, may be biomarkers for susceptibility to severe RP in NSCLC patients. Large, prospective studies are needed to confirm our findings.

Characteristics of primary and secondary hepatic malignancies associated with hepatopulmonary shunting

PURPOSE

To identify liver tumor characteristics associated with low (<10%), intermediate (10%-20%), and high (>20%) lung shunt fraction (LSF) at technetium 99m ((99m)Tc) macroaggregated albumin (MAA) imaging performed before yttrium 90 ((90)Y) radioembolization (RE).

MATERIALS AND METHODS

In this single-center retrospective study, 141 patients (70 with hepatocellular carcinoma [HCC], 71 with other tumors; 95 men, 45 women; median age, 61 years) underwent mapping arteriography with (99m)Tc-MAA LSF calculation before (90)Y RE from 2006 to 2012. Tumor characteristics, including tumor type, index lesion size and morphologic structure (circumscribed, infiltrative), focality (solitary oligonodular, multinodular), disease distribution (unilobar, bilobar), tumor burden (≤50%, 50%), portal vein invasion (present, absent), and arterioportal shunting (present, absent) were correlated with (99m)Tc-MAA imaging-calculated LSFs at univariate and multivariate analysis.

RESULTS

Median LSF was 8.4% (HCC, 9.0%; other tumors, 8.3%). LSF greater than 20% occurred in 14% of HCCs, but only in 3% of other tumors (P = .004). For HCC, tumor morphologic structure (P = .022), tumor burden (P < .001), main portal vein invasion (P = .033), and arterioportal shunting (P < .001) were significantly associated with different LSF categories at univariate analysis; infiltrative morphologic structure, tumor burden greater than 50%, portal vein invasion, and shunting had confirmed association with high LSF at multivariate analysis. For other liver tumors, tumor size (P = .001) and tumor burden (P = .003) were significantly associated with different LSF categories at univariate analysis. Multivariate confirmation was precluded by small sample size. Patients underwent a median of one (90)Y RE session (range, one to six), with median per-treatment and cumulative lung doses of 6.0 Gy and 8.5 Gy, respectively.

CONCLUSION

LSF greater than 20% periodically occurs in HCC but is uncommon in other liver tumors. Specific tumor characteristics are associated with LSF greater than 20% and may indicate need for interventions to reduce LSF.

Predictive factors for radiation pneumonitis in lung cancer treated with helical tomotherapy

Purpose

Predictive factors for radiation pneumonitis (RP) after helical tomotherapy (HT) may differ from those after linac-based radiotherapy. In this study, we identified predictive factors for RP in patients with lung cancer treated with HT.

Materials and Methods

We retrospectively analyzed clinical, treatment-related and dosimetric factors from 31 patients with lung cancer treated with HT. RP was graded according to Common Terminology Criteria for Adverse Events version 4.0 and grade ≥2 RP was defined as a RP event. We used Kaplan-Meier methods to compute the actuarial incidence of RP. For univariate and multivariate analysis, the log-rank test and the Cox proportional regression hazard model were used. We generated receiver-operating characteristics (ROC) curves to define the cutoff values for significant parameters.

Results

The median follow-up duration was 6.6 months (range, 1.6 to 38.5 months). The 2-, 4-, and 6-month actuarial RP event rates were 13.2%, 58.5%, and 67.0%, respectively. There was no grade 4 or more RP. Ipsilateral V5, V10, V15, and contralateral V5 were related with RP event on univariate analysis. By multivariate analysis, ipsilateral V10 was factor most strongly associated with RP event. On the ROC curve, the cutoff values of ipsilateral V5, V10, V15, and contralateral V5 were 67.5%, 58.5%, 50.0%, and 55.5%, respectively.

Conclusion

In our study, ipsilateral V5, V10, V15, and contralateral V5 were significant predictive factors for RP after HT.