Feasibility of high-dose three-dimensional radiation therapy in the treatment of localised non-small-cell lung cancer

Detecting spatial susceptibility to cardiac toxicity of radiation therapy for lung cancer

Radiation therapy (RT) is a commonly used approach for treating lung cancer. Because the lungs are close to the heart, radiation dose may inevitably spill to the heart, causing heart damage and diminishing treatment outcomes. There is an urgent need to better understand how treatment outcomes are affected by radiation dose spilled to the heart in order to optimize RT planning. However, despite the fact that dose distribution on the heart is 3-D, most existing research collapses the 3-D dose map into a 1-D histogram to be linked with outcomes. This ignores the spatial information. We propose a novel method that automatically searches for subregions of the heart that are susceptible to radiation toxicity, called Toxicity-Susceptible Subregions (TSSs), based on the 3-D dose distribution. We apply the proposed method to a real-world dataset and find TSSs that harbor the sinoatrial node of the electronic conduction system of the heart. Damage of the sinoatrial node by radiation toxicity disrupts the crucial function of the heart, leading to shortening of the overall survival. Our finding suggests that protective strategies may be developed to spare the TSSs, and thus helping RT planning achieve optimal results in treating lung cancer patients.

Effect of Radiation Doses to the Heart on Survival for Stereotactic Ablative Radiotherapy for Early-stage Non-Small-cell Lung Cancer: An Artificial Neural Network Approach

INTRODUCTION

The cardiac radiation dose is an important predictor of cardiac toxicity and overall survival (OS) for patients with locally advanced non-small-cell lung cancer (NSCLC). However, radiation-induced cardiac toxicity among patients with early-stage NSCLC who have undergone stereotactic ablative radiotherapy (SABR) has been less well-characterized. Our objective was to assess the associations between cardiac radiation dosimetry and OS in patients with early-stage NSCLC undergoing SABR.

MATERIALS AND METHODS

From 2009 to 2014, 153 patients with early-stage NSCLC had undergone SABR at a single institution. The maximum dose, mean dose, V_10Gy, V_25Gy, and V_50Gy to 15 cardiac substructures and the whole heart were analyzed for their association with OS using the Kaplan-Meier method. An artificial neural network (ANN) analysis was performed to modulate confounding behaviors of dosimetric variables to predict for OS.

RESULTS

A total of 112 patients were included in the present analysis. The right ventricle (RV) V_10Gy most negatively predicted for OS, such that patients who had received a RV V_10Gy dose < 4% had significantly longer OS than patients who had received a RV V_10Gy does > 4% (5.3 years vs. 2.4 years). On ANN analysis, 74 input features, including cardiac dosimetry parameters, predicted for survival with a test accuracy of 64.7%. A repeat ANN analysis using dosimetry to dose neutral structure confirmed the predictive power of cardiac dosimetry.

CONCLUSION

Cardiac dosimetry to subvolumes of the heart was associated with decreased OS in patients with early-stage NSCLC undergoing SABR. These data support the importance of minimizing the radiation dose to cardiac substructures. Further prioritizing the heart as an organ at risk might be warranted. Additionally, cardiac follow-up should be considered.

Evaluation of the hybrid-dynamic conformal arc therapy technique for radiotherapy of lung cancer

Purpose

A hybrid-dynamic conformal arc therapy (HDCAT) technique consisting of a single half-rotated dynamic conformal arc beam and static field-in-field beams in two directions was designed and evaluated in terms of dosimetric benefits for radiotherapy of lung cancer.

Materials and Methods

This planning study was performed in 20 lung cancer cases treated with the VERO system (BrainLAB AG, Feldkirchen, Germany). Dosimetric parameters of HDCAT plans were compared with those of three-dimensional conformal radiotherapy (3D-CRT) plans in terms of target volume coverage, dose conformity, and sparing of organs at risk.

Results

HDCAT showed better dose conformity compared with 3D-CRT (conformity index: 0.74 ± 0.06 vs. 0.62 ± 0.06, p < 0.001). HDCAT significantly reduced the lung volume receiving more than 20 Gy (V₂₀: 21.4% ± 8.2% vs. 24.5% ± 8.8%, p < 0.001; V₃₀: 14.2% ± 6.1% vs. 15.1% ± 6.4%, p = 0.02; V₄₀: 8.8% ± 3.9% vs. 10.3% ± 4.5%, p < 0.001; and V₅₀: 5.7% ± 2.7% vs. 7.1% ± 3.2%, p < 0.001), V₄₀ and V₅₀ of the heart (V₄₀: 5.2 ± 3.9 Gy vs. 7.6 ± 5.5 Gy, p < 0.001; V₅₀: 1.8 ± 1.6 Gy vs. 3.1 ± 2.8 Gy, p = 0.001), and the maximum spinal cord dose (34.8 ± 9.4 Gy vs. 42.5 ± 7.8 Gy, p < 0.001) compared with 3D-CRT.

conclusions

HDCAT could achieve highly conformal target coverage and reduce the doses to critical organs such as the lung, heart, and spinal cord compared to 3D-CRT for the treatment of lung cancer patients.

Radiation-induced heart disease in lung cancer radiotherapy: A dosimetric update

BACKGROUND

Radiation-induced heart disease (RIHD), which affects the patients' prognosis with both acute and late side effects, has been published extensively in the radiotherapy of breast cancer, lymphoma and other benign diseases. Studies on RIHD in lung cancer radiotherapy, however, are less extensive and clear even though the patients with lung cancer are delivered with higher doses to the heart during radiation treatment.

METHODS

In this article, after extensive literature search and analysis, we reviewed the current evidence on RIHD in lung cancer patients after their radiation treatments and investigated the potential risk factors for RIHD as compared to other types of cancers.

RESULT

Cardiac toxicity has been found highly relevant in lung cancer radiotherapy. So far, the crude incidence of cardiac complications in the lung cancer patients after radiotherapy has been up to 33%.

CONCLUSION

The dose to the heart, the lobar location of tumor, the treatment modality, the history of heart and pulmonary disease and smoking were considered as potential risk factors for RIHD in lung cancer radiotherapy. As treatment techniques improve over the time with better prognosis for lung cancer survivors, an improved prediction model can be established to further reduce the cardiac toxicity in lung cancer radiotherapy.

Cardiac Exposure in the Dynamic Conformal Arc Therapy, Intensity-Modulated Radiotherapy and Volumetric Modulated Arc Therapy of Lung Cancer

Purpose

To retrospectively evaluate the cardiac exposure in three cohorts of lung cancer patients treated with dynamic conformal arc therapy (DCAT), intensity-modulated radiotherapy (IMRT), or volumetric modulated arc therapy (VMAT) at our institution in the past seven years.

Methods and Materials

A total of 140 lung cancer patients were included in this institutional review board approved study: 25 treated with DCAT, 70 with IMRT and 45 with VMAT. All plans were generated in a same commercial treatment planning system and have been clinically accepted and delivered. The dose distribution to the heart and the effects of tumor laterality, the irradiated heart volume and the beam-to-heart distance on the cardiac exposure were investigated.

Results

The mean dose to the heart among all 140 plans was 4.5 Gy. Specifically, the heart received on average 2.3, 5.2 and 4.6 Gy in the DCAT, IMRT and VMAT plans, respectively. The mean heart doses for the left and right lung tumors were 4.1 and 4.8 Gy, respectively. No patients died with evidence of cardiac disease. Three patients (2%) with preexisting cardiac condition developed cardiac disease after treatment. Furthermore, the cardiac exposure was found to increase linearly with the irradiated heart volume while decreasing exponentially with the beam-to-heart distance.

Conclusions

Compared to old technologies for lung cancer treatment, modern radiotherapy treatment modalities demonstrated better heart sparing. But the heart dose in lung cancer radiotherapy is still higher than that in the radiotherapy of breast cancer and Hodgkin’s disease where cardiac complications have been extensively studied. With strong correlations of mean heart dose with beam-to-heart distance and irradiated heart volume, cautions should be exercised to avoid long-term cardiac toxicity in the lung cancer patients undergoing radiotherapy.

Pulmonary artery invasion, high-dose radiation, and overall survival in patients with non-small cell lung cancer

PURPOSE

To investigate whether high-dose radiation to the pulmonary artery (PA) affects overall survival (OS) in patients with non-small cell lung cancer (NSCLC).

METHODS AND MATERIALS

Patients with medically inoperable/unresectable NSCLC treated with definitive radiation therapy in prospective studies were eligible for this study. Pulmonary artery involvement was defined on the basis of pretreatment chest CT and positron emission tomography/CT fusion. Pulmonary artery was contoured according to the Radiation Therapy Oncology Group protocol 1106 atlas, and dose-volume histograms were generated.

RESULTS

A total of 100 patients with a minimum follow-up of 1 year for surviving patients were enrolled: 82.0% underwent concurrent chemoradiation therapy. Radiation dose ranged from 60 to 85.5 Gy in 30-37 fractions. Patients with PA invasion of grade ≤2, 3, 4, and 5 had 1-year OS and median survival of 67% and 25.4 months (95% confidence interval [CI] 15.7-35.1), 62% and 22.2 months (95% CI 5.8-38.6), 90% and 35.8 months (95% CI 28.4-43.2), and 50% and 7.0 months, respectively (P=.601). Two of the 4 patients with grade 5 PA invasion died suddenly from massive hemorrhage at 3 and 4.5 months after completion of radiation therapy. Maximum and mean doses to PA were not significantly associated with OS. The V45, V50, V55, and V60 of PA were correlated significantly with a worse OS (P<.05). Patients with V45 >70% or V60 >37% had significantly worse OS (13.3 vs 37.9 months, P<.001, and 13.8 vs 37.9 months, P=.04, respectively).

CONCLUSIONS

Grade 5 PA invasion and PA volume receiving more than 45-60 Gy may be associated with inferior OS in patients with advanced NSCLC treated with concurrent chemoradiation.

[Interstitial lung disease associated with lung cancer treatment]

间质性肺病是肺癌相关治疗引起的严重副反应之一，因诊断的复杂性及病情的多变性往往不能及时诊治甚至危及患者的生命，严重影响患者的预后。放、化疗及靶向治疗导致间质性肺炎的机制及相关因素尚不完全清楚。因此，如何减少、早期发现及诊治肺癌相关治疗引起的间质性肺病成为今后肺癌治疗过程中不可忽略的一个问题。

[Single French centre retrospective analysis of local control after high dose radiotherapy with or without chemotherapy and local control for Pancoast tumours]

PURPOSE

Superior sulcus non-small cell lung cancer represents less than 5% of all lung cancers and is a challenge for the physicians because of clinical presentation, treatments related toxicities and poor prognosis. The aim of this preliminary retrospective report is to present outcomes of patients affected by a superior sulcus non-small cell lung cancer, treated by high dose radiotherapy (>60 Gy) with or with our chemotherapy.

PATIENTS AND METHODS

All adult inoperable or unresectable patients (≥18 years) with a clinical and radiological diagnosis of superior sulcus non-small cell lung cancer treated in our department by radiotherapy with or without chemotherapy were retrospectively analysed. Primary endpoint was the local control. Overall survival, metastasis free survival and toxicity rates were also analysed and reported.

RESULTS

From January 1999 to June 2009, 12 patients were treated by exclusive high-dose radiochemotherapy. Median age was 53 years (range: 33-64 years); mean follow-up time was 20 months (range: 2-75 months). Mean local control, overall survival and metastasis free survival were 20.2, 22 and 20 months, respectively. At the time of this analysis, seven patients died of cancer and three of them presented only a metastatic disease progression. One patient died of acute cardiac failure 36 months after the end of radiochemotherapy and was disease free. Treatment was well tolerated and any acute and/or late G3-4 toxicity was recorded (NCI-CTC v 3.0 score).

CONCLUSION

This analysis confirms the interest of exclusive high-dose radiochemotherapy in treating inoperable superior sulcus non-small cell lung cancer patients, in achieving good local control and overall survival rates.

Single fraction radiosurgery using Rapid Arc for treatment of intracranial targets

Background

Stereotactic-Radio-Surgery (SRS) using Conformal-Arc-Therapy (CAT) is a well established irradiation technique for treatment of intracranial targets. Although small safety margins are required because of very high accuracy of patient positioning and exact online localisation, there are still disadvantages like long treatment time, high number of monitor units (MU) and covering of noncircular targets. This planning study analysed whether Rapid Arc (RA) with stereotactic localisation for single-fraction SRS can solve these problems.

Methods

Ten consecutive patients were treated with Linac-based SRS. Eight patients had one or more brain metastases. The other patients presented a symptomatic vestibularis schwannoma and an atypic meningeoma. For all patients, two plans (CAT/RA) were calculated and analysed.

Results

Conformity was higher for RA with additional larger low-dose areas. Furthermore, RA reduced the number of MU and the treatment time for all patients. Dose to organs at risk were equal or slightly higher using RA in comparison to CAT.

Conclusions

RA provides a new alternative for single-fraction SRS irradiation combining advantages of short treatment time with lower number of MU and better conformity in addition to accuracy of stereotactic localisation in selected cases with uncomplicated clinical realization.

Cardiac toxicity in association with chemotherapy and radiation therapy in a large cohort of older patients with non-small-cell lung cancer

BACKGROUND

The study's objective was to investigate the risks of developing cardiac disorders following the administration of chemotherapy and radiation therapy in patients with non-small-cell lung cancer (NSCLC).

METHODS

The study consisted of 34 209 patients aged > or =65 years with American Joint Committee on Cancer stages I-IV NSCLC identified from the Surveillance, Epidemiology, and End Result-Medicare linked database (1991-2002) who were free of cardiac disorders at NSCLC diagnosis.

RESULTS

There were significant associations between the use of chemotherapy/radiation and the risks of developing ischemic heart disease, conduction disorders, cardiac dysfunction, and heart failure. The absolute risks for cardiac dysfunction increased with the administration of chemotherapy-only and radiation-only, and incrementally with chemoradiation. Men, blacks, older patients, those with higher comorbidity scores, and advanced disease were at higher risk. The risk for ischemic heart disease increased when radiation/chemoradiation were rendered to the left lung and both lungs and for cardiac dysfunction, radiation administered to the left lung.

CONCLUSIONS

There were significant associations especially for cardiac dysfunction with use of chemotherapy/radiation therapy and risks of developing cardiac toxicity in NSCLC patients. The risks of treatment-associated cardiac toxicity, specifically ischemic heart disease and cardiac dysfunction, were greatest among those with left-sided lung tumors.