Analysis of the variability among radiation oncologists in delineation of the postsurgical tumor bed based on 4D-CT

OBJECTIVE

This study investigated interobserver and intraobserver variability in radiation oncologists' definition of the tumor bed (TB) after breast-conserving surgery (BCS).

RESULTS

The TB volume, CVS and number of surgical clips were not significantly related to intraobserver variability. Moreover, no correlation was noted between CT slice thickness and interobserver variability (Δinter, DSCinter) in TB delineation, and no significant difference was noted among the three groups. The TB volume was negatively correlated with Δinter. DSCinter improved significantly with increased TB volume and decreased Δinter. DSCinter also increased significantly in patients with a CVS of 3 to 5 compared with patients with a CVS of 1 to 2. DSCinter was thus positively correlated with the CVS, with a correlation coefficient of 0.451. The use of 7 to 9 surgical clips neither decreased Δinter nor increased DSCinter.

MATERIALS AND METHODS

Five or more surgical clips were placed at the TB during lumpectomy. The TB was delineated on the end expiration scan. The data were stratified based on the cavity visualization score (CVS), CT slice thickness and surgical clip number. The Dice similarity coefficient (DSC) and inter(intra)observer variability (Δinter and Δintra) in different groups were evaluated and compared.

CONCLUSIONS

Inter(intra)observer variability in TB delineation was decreased for breast cancer patients implanted with 5 or more surgical clips in the cohort with a higher CVS and a larger TB. The use of more than 6 surgical clips did not significantly improve TB delineation, so 5 to 6 surgical clips are likely adequate to delineate the TB.

Effectiveness of Respiratory-gated Positron Emission Tomography/Computed Tomography for Radiotherapy Planning in Patients with Lung Carcinoma - A Systematic Review

AIMS

A systematic review of the literature evaluating the clinical use of respiratory-gated (four-dimensional; 4D) fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) compared with non-gated (three-dimensional; 3D) PET/CT for radiotherapy planning in lung cancer.

MATERIALS AND METHODS

A search of MEDLINE, Cochrane, Web of Science, SCOPUS and clinicaltrials.gov databases was undertaken for articles comparing 3D and 4D PET/CT tumour volume or 4D PET/CT for radiotherapy planning. PRISMA guidelines were followed.

RESULTS

Thirteen studies compared tumour volumes at 3D and 4D PET/CT; eight reported significantly smaller volumes (6.9-44.5%), three reported significantly larger volumes at 4D PET/CT (16-50%), one reported no significant difference and one reported mixed findings. Six studies, including two that reported differences in tumour volumes, compared target volumes or studied geographic misses. 4D PET/CT target volumes were significantly larger (19-40%) when compared with 3D PET/CT in all but one study, where they were smaller (3.8%). One study reported no significance in 4D PET/CT target volumes when compared with 4D CT, whereas another study reported significantly larger volumes (38.7%).

CONCLUSION

The use of 4D PET/CT leads to differences in target volume delineation compared with 3D PET/CT. These differences vary depending upon technique and the clinical impact currently remains uncertain. Correlation of pretreatment target volumes generated at 3D and 4D PET/CT with postsurgical histology would be ideal but technically challenging. Evaluation of patient outcomes based on 3D versus 4D PET/CT derived treatment volumes warrants further investigation.

Geriatric assessment may help decision-making in elderly patients with inoperable, locally advanced non-small-cell lung cancer

Background:

Although concurrent chemoradiotherapy (cCRT) increases survival in patients with inoperable, locally advanced non-small-cell lung cancer (NSCLC), there is no consensus on the treatment of elderly patients. The aim of this study was to determine the prognostic value of the comprehensive geriatric assessment (CGA) and its ability to predict toxicity in this setting.

Methods:

We enrolled 85 consecutive elderly (⩾75 years) participants, who underwent CGA and the Vulnerable Elders Survey (VES-13). Those classified as fit and medium-fit by CGA were deemed candidates for cCRT (platinum-based chemotherapy concurrent with thoracic radiation therapy), while unfit patients received best supportive care.

Results:

Fit (37%) and medium-fit (48%) patients had significantly longer median overall survival (mOS) (23.9 and 16.9 months, respectively) than unfit patients (15%) (9.3 months, log-rank P=0.01). In multivariate analysis, CGA groups and VES-13 were independent prognostic factors. Fit and medium-fit patients receiving cCRT (n=54) had mOS of 21.1 months (95% confidence interval: 16.2, 26.0). In those patients, higher VES-13 (⩾3) was associated with shorter mOS (16.33 vs 24.3 months, P=0.027) and higher risk of G3-4 toxicity (65 vs 32%, P=0.028).

Conclusions:

Comprehensive geriatric assessment and VES-13 showed independent prognostic value. Comprehensive geriatric assessment may help to identify elderly patients fit enough to be treated with cCRT.

Anatomic, functional and molecular imaging in lung cancer precision radiation therapy: treatment response assessment and radiation therapy personalization

This article reviews key imaging modalities for lung cancer patients treated with radiation therapy (RT) and considers their actual or potential contributions to critical decision-making. An international group of researchers with expertise in imaging in lung cancer patients treated with RT considered the relevant literature on modalities, including computed tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET). These perspectives were coordinated to summarize the current status of imaging in lung cancer and flag developments with future implications. Although there are no useful randomized trials of different imaging modalities in lung cancer, multiple prospective studies indicate that management decisions are frequently impacted by the use of complementary imaging modalities, leading both to more appropriate treatments and better outcomes. This is especially true of ¹⁸F-fluoro-deoxyglucose (FDG)-PET/CT which is widely accepted to be the standard imaging modality for staging of lung cancer patients, for selection for potentially curative RT and for treatment planning. PET is also more accurate than CT for predicting survival after RT. PET imaging during RT is also correlated with survival and makes response-adapted therapies possible. PET tracers other than FDG have potential for imaging important biological process in tumors, including hypoxia and proliferation. MRI has superior accuracy in soft tissue imaging and the MRI Linac is a rapidly developing technology with great potential for online monitoring and modification of treatment. The role of imaging in RT-treated lung cancer patients is evolving rapidly and will allow increasing personalization of therapy according to the biology of both the tumor and dose limiting normal tissues.

MODEL-BASED COST-EFFECTIVENESS OF CONVENTIONAL AND INNOVATIVE CHEMO-RADIATION IN LUNG CANCER

INTRODUCTION

Optimizing radiotherapy with or without chemotherapy through advanced imaging and accelerated radiation schemes shows promising results in locally advanced non-small-cell lung cancer (NSCLC). This study compared the cost-effectiveness of positron emission tomography-computed tomography based isotoxic accelerated sequential chemo-radiation (SRT2) and concurrent chemo-radiation with daily low-dose cisplatin (CRT2) with standard sequential (SRT1) and concurrent chemo-radiation (CRT1).

METHODS

We used an externally validated mathematical model to simulate the four treatment strategies. The model was built using data from 200 NSCLC patients treated with curative sequential chemo-radiation. For concurrent strategies, data from a meta-analysis and a single study were included in the model. Costs, utilities, and resource use estimates were obtained from literature. Primary outcomes were the incremental cost-effectiveness and cost-utility ratio (ICUR) of each strategy. Scenario analyses were carried out to investigate the impact of uncertainty.

RESULTS

Total undiscounted costs and quality-adjusted life-years (QALYs) for SRT1, CRT1, SRT2, and CRT2 were EUR 17,288, EUR 18,756, EUR 19,072, EUR 17,360 and QALYs 1.10, 1.15, 1.40, and 1.40, respectively. Compared with SRT1, the ICURs were EUR 38,024/QALY for CRT1, EUR 6,249/QALY for SRT2, and EUR 346/QALY for CRT2. CRT2 was highly cost-effective compared with SRT1. Moreover, CRT2 was more effective and less costly than CRT1 and SRT2. Therefore, these strategies were dominated by CRT2.

CONCLUSION

Optimized sequential and concurrent chemo-radiation strategies are more effective and cost-effective than the current conventional sequential and concurrent strategies. Concurrent chemo-radiation with a daily low dose cisplatin regimen is the most cost-effective treatment option for locally advanced inoperable NSCLC patients.

New prospective 4D-CT for mitigating the effects of irregular respiratory motion

Artifact caused by irregular respiration is a major source of error in 4D-CT imaging. We propose a new prospective 4D-CT to mitigate this source of error without new hardware, software or off-line data-processing on the GE CT scanner. We utilize the cine CT scan in the design of the new prospective 4D-CT. The cine CT scan at each position can be stopped by the operator when an irregular respiration occurs, and resumed when the respiration becomes regular. This process can be repeated at one or multiple scan positions. After the scan, a retrospective reconstruction is initiated on the CT console to reconstruct only the images corresponding to the regular respiratory cycles. The end result is a 4D-CT free of irregular respiration. To prove feasibility, we conducted a phantom and six patient studies. The artifacts associated with the irregular respiratory cycles could be removed from both the phantom and patient studies. A new prospective 4D-CT scanning and processing technique to mitigate the impact of irregular respiration in 4D-CT has been demonstrated. This technique can save radiation dose because the repeat scans are only at the scan positions where an irregular respiration occurs. Current practice is to repeat the scans at all positions. There is no cost to apply this technique because it is applicable on the GE CT scanner without new hardware, software or off-line data-processing.

European Organization for Research and Treatment of Cancer (EORTC) recommendations for planning and delivery of high-dose, high precision radiotherapy for lung cancer

PURPOSE

To update literature-based recommendations for techniques used in high-precision thoracic radiotherapy for lung cancer, in both routine practice and clinical trials.

METHODS

A literature search was performed to identify published articles that were considered clinically relevant and practical to use. Recommendations were categorised under the following headings: patient positioning and immobilisation, Tumour and nodal changes, CT and FDG-PET imaging, target volumes definition, radiotherapy treatment planning and treatment delivery. An adapted grading of evidence from the Infectious Disease Society of America, and for models the TRIPOD criteria, were used.

RESULTS

Recommendations were identified for each of the above categories.

CONCLUSION

Recommendations for the clinical implementation of high-precision conformal radiotherapy and stereotactic body radiotherapy for lung tumours were identified from the literature. Techniques that were considered investigational at present are highlighted.

Robotic assisted lobectomy for locally advanced lung cancer

Some series report the use of video-assisted thoracic surgery (VATS) in patients with locally advanced non-small cell lung cancer (NSCLC) but, few studies describe the use of the robotic approach specifically for locally advanced disease. One potential advantage of the robotic approach over traditional VATS is the increased radicality. While the benefit of the robotic approach over open thoracotomy is directly related to reduced surgical trauma and the improved tolerability in fragile patients that have received induction treatment. In case of occult N2 disease, robotic assisted surgery can translate into a quicker recovery with improved compliance with adjuvant treatments following surgery. Technical details are reported and described. The robotic instrument technology allows sharp and controlled dissection compared to the typical blunt sweeping methods used in most VATS lobectomy techniques. The authors believe that robotic technology favors a more radical resection in the case of complex locally advanced tumors. Robotic technology has some limitations that have affected adoption such as significant capital and maintenance costs, reduced operating room efficiencies, and a steep learning curve.

Pulmonary Function Changes After Radiotherapy for Lung or Esophageal Cancer: A Systematic Review Focusing on Dose-Volume Parameters

BACKGROUND

Despite technical developments in treatment delivery, radiation-induced lung toxicity (RILT) remains a crucial problem in thoracic radiotherapy. Clinically based RILT scores have their limitations, and more objective measures such as pulmonary functions tests (PFTs) might help to improve treatment strategies.

PURPOSE

To summarize the available evidence about the effect of dose to the lung in thoracic radiotherapy on forced expiratory volume in one second (FEV1) and diffusion capacity (DLCO) in patients with lung and esophageal cancer treated with curative intent.

MATERIAL AND METHODS

A systematic review following the PRISMA guidelines was performed, using MEDLINE and including clinical studies using (chemo)radiotherapy (CRT) or stereotactic ablative radiotherapy (SABR) for lung or CRT for esophageal cancer that reported both lung dose-volume histogram (DVH) parameters and changes in PFT results. Search terms included lung and esophageal neoplasms, respiratory function tests, and radiotherapy.

RESULTS

Fifteen studies met the inclusion criteria. Seven out of 13 studies on lung cancer reported significant declines (defined as a p value < .05) in PFT results. Both esophageal studies reported significant DLCO declines. One SABR study found a correlation between low lung-dose parameters and FEV1 decline. Relations between decline of FEV1 (three studies) or decline of DLCO (five studies), respectively, and DVH parameters were found in eight studies analyzing CRT. Furthermore, a heterogeneous range of clinical risk factors for pulmonary function changes were reported in the selected studies.

CONCLUSIONS

There is evidence that pulmonary function declines after RT in a dose-dependent manner, but solid data about lung DVH parameters predicting changes in PFT results are scarce. A major disadvantage was the wide variety of methods used, frequently lacking multivariable analyses. Studies using prospective high-quality data, analyzed with appropriate statistical methods, are needed. The Oncologist 2017;22:1257-1264 IMPLICATIONS FOR PRACTICE: Radiation-induced lung toxicity remains crucial in thoracic radiotherapy. To prevent this toxicity in the future and individualize patient treatment, objective measures of pulmonary toxicity are needed. Pulmonary function tests may provide such objective measures. This systematic review, included all available clinical studies using external beam radiotherapy for lung or esophageal cancer reporting pulmonary function combined with dose-volume histogram parameters. There is preliminary evidence that pulmonary function declines post radiotherapy in a dose-dependent manner. Data quality and analyses were generally limited. Analyses of high-quality data are therefore urgently needed to improve individualization of advanced radiation therapy.

[Stereotactic lung radiotherapy: Technical setting up on Novalis Tx® and single centre prospective study of the 100 first malignant pulmonary nodules treated at centre Jean-Perrin]

PURPOSE

Description of the treatment technique of stereotactic lung radiotherapy on Novalis Tx^® and prospective study of the first 100 pulmonary nodules treated at centre Jean-Perrin (France).

MATERIAL AND METHODS

From October 2012 to December 2015, 100 inoperable pulmonary nodules (62 stage I non-small-cell lung cancer and 38 metastases) of 90 patients with a mean age of 68.2 years (range: 46-89 years) were prospectively treated with dynamic arctherapy on Novalis Tx^®. Mean gross tumour and planning target volumes were respectively 6.9 cm³ (range: 0.2-31.4 cm³) and 38.7 cm³ (range: 1.7-131 cm³), which correspond to diameters equal to 2.3cm and 4.2cm. Prescribed doses to the 80% isodose line were 54Gy in three fractions for peripheral non-small-cell lung cancer, 50Gy in five fractions for central non-small-cell lung cancer and 45Gy in three fractions for lung metastases. Clinical and radiological follow-up was done every three months with RECIST criteria for efficacy and NCI-CTCAE v4 scale for toxicity. Median follow-up was 12.5 months.

RESULTS

Complete response was observed in 23.8% of cases. Local control rates were 100% and 90.7% respectively at 12 and 24 months, with 96% at 24 months for stage I non-small-cell lung cancer. Overall survival rates of patients with stage I non-small-cell lung cancer were 77.4% and 73.5% at 12 and 24 months (median overall survival was 32 months). Diffusing capacity of the lungs for carbon monoxide corrected for alveolar volume below 40% was significantly associated to a poor prognostic factor on univariate analysis (P=0.00013). At least three deaths were due to an acute respiratory failure, which correspond to about 4.8% of grade 5 radiation pneumonitis. Overall survival rate for metastatic patients were 95.2% and 59.5% respectively at 12 and 24 months (median overall survival was 25 months); 23.3% of grade 2 or less radiation pneumonitis, 7.8% of grade 2 or less radiation dermatitis, 2.2% of asymptomatic ribs fracture and 3.3% of chest pains were observed.

CONCLUSION

Stereotactic lung radiotherapy is an effective treatment for inoperable stage I non-small-cell lung cancer and lung oligometastases of well informed and selected patients. Initial respiratory state, and especially the diffusing capacity of the lungs for carbon monoxide corrected for alveolar volume, seems to be important for tolerance.

The Role of Radiotherapy in Epidermal Growth Factor Receptor Mutation-positive Patients with Oligoprogression: A Matched-cohort Analysis

AIMS

Almost all patients with epidermal growth factor receptor (EGFR) mutations will develop resistance to first-line EGFR tyrosine kinase inhibitors (TKIs). The management of oligoprogression on EGFR TKI is controversial. Irradiating progressing tumours may potentially eradicate the resistant clone and allow continuation of EGFR TKI, but the clinical data remain sparse. We aimed to assess the effect of radiotherapy on survival outcomes in patients with oligoprogression in a matched-cohort study.

MATERIALS AND METHODS

This was a retrospective matched-cohort study comparing patients with EGFR mutation-positive stage IV non-small cell lung cancer receiving radiotherapy versus chemotherapy for progression. Patients in the radiotherapy group received radiotherapy (mainly stereotactic ablative radiotherapy) for oligoprogression, whereas the chemotherapy group received only systemic chemotherapy upon progression. Key prognostic factors including gender, age, performance status, time to first progression and mutation subtypes were matched.

RESULTS

Twenty-five patients with oligoprogression (radiotherapy group) were identified, and a matched chemotherapy group with the same number of patients was generated. The median duration of follow-up was 24.3 and 34 months for the radiotherapy and chemotherapy groups, respectively. The median overall survival of the radiotherapy group was significantly longer than the chemotherapy group, 28.2 versus 14.7 months (P = 0.026). The median progression-free survival (PFS) was 7.0 and 4.1 months after radiotherapy and chemotherapy, respectively (P = 0.0017). The use of radiotherapy was an independent predictive factor of overall survival and PFS in multivariate analysis. Only one patient had ≥grade 3 toxicity after radiotherapy. The frequency of secondary T790M mutation and subsequent Osimertinib exposure were similar in both groups.

CONCLUSION

Radiotherapy may effectively extend EGFR TKI therapy for patients with oligoprogression on TKI. Improved PFS and overall survival were observed, although potential biases should not be overlooked. Further randomised studies are warranted.

A comprehensive dosimetric study on switching from a Type-B to a Type-C dose algorithm for modern lung SBRT

BACKGROUND

Type-C dose algorithms provide more accurate dosimetry for lung SBRT treatment planning. However, because current dosimetric protocols were developed based on conventional algorithms, its applicability for the new generation algorithms needs to be determined. Previous studies on this issue used small sample sizes and reached discordant conclusions. Our study assessed dose calculation of a Type-C algorithm with current dosimetric protocols in a large patient cohort, in order to demonstrate the dosimetric impacts and necessary treatment planning steps of switching from a Type-B to a Type-C dose algorithm for lung SBRT planning.

METHODS

Fifty-two lung SBRT patients were included, each planned using coplanar VMAT arcs, normalized to D95% = prescription dose using a Type-B algorithm. These were compared against three Type-C plans: re-calculated plans (identical plan parameters), re-normalized plans (D95% = prescription dose), and re-optimized plans. Dosimetric endpoints were extracted and compared among the four plans, including RTOG dosimetric criteria: (R100%, R50%, D2cm, V105%, and lung V20), PTV Dmin, Dmax, Dmean, V% and D90%, PTV coverage (V100%), homogeneity index (HI), and Paddick conformity index (PCI).

RESULTS

Re-calculated Type-C plans resulted in decreased PTV Dmin with a mean difference of 5.2% and increased Dmax with a mean difference of 3.1%, similar or improved RTOG dose compliance, but compromised PTV coverage (mean D95% and V100% reduction of 2.5 and 8.1%, respectively). Seven plans had >5% D95% reduction (maximum reduction = 16.7%), and 18 plans had >5% V100% reduction (maximum reduction = 60.0%). Re-normalized Type-C plans restored target coverage, but yielded degraded plan conformity (average PCI reduction 4.0%), and RTOG dosimetric criteria deviation worsened in 11 plans, in R50%, D2cm, and R100%. Except for one case, re-optimized Type-C plans restored RTOG compliance achieved by the original Type-B plans, resulting in similar dosimetric values but slightly higher target dose heterogeneity (mean HI increase = 13.2%).

CONCLUSIONS

Type-B SBRT lung plans considerably overestimate target coverage for some patients, necessitating Type-C re-normalization or re-optimization. Current RTOG dosimetric criteria appear to remain appropriate.

The role of dosimetry audit in lung SBRT multi-centre clinical trials

Stereotactic Body Radiotherapy (SBRT) in the lung is a challenging technique which requires high quality clinical trials to answer the un-resolved clinical questions. Quality assurance of these clinical trials not only ensures the safety of the treatment of the participating patients but also minimises the variation in treatment, thus allowing the lowest number of patient treatments to answer the trial question. This review addresses the role of dosimetry audits in the quality assurance process and considers what can be done to ensure the highest accuracy of dose calculation and delivery and it's assessment in multi-centre trials.

Clinical Outcomes of 130 Patients with Primary and Secondary Lung Tumors treated with Cyberknife Robotic Stereotactic Body Radiotherapy

Background

Authors report clinical outcomes of patients treated with robotic stereotactic body radiotherapy (SBRT) for primary, recurrent and metastatic lung lesions.

Patients and methods

130 patients with 160 lesions were treated with Cyberknife SBRT, including T1-3 primary lung cancers (54%), recurrent tumors (22%) and pulmonary metastases (24%). The mean biologically equivalent dose (BED_10Gy) was 151 Gy (72–180 Gy). Median prescribed dose for peripheral and central lesions was 3×20 Gy and 3×15 Gy, respectively. Local control (LC), overall survival (OS), and cause-specific survival (CSS) rates, early and late toxicities are reported. Statistical analysis was performed to identify factors influencing local tumor control.

Results

Median follow-up time was 21 months. In univariate analysis, higher dose was associated with better LC and a cut-off value was detected at BED_10Gy ≤ 112.5 Gy, resulting in 1-, 2-, and 3-year actuarial LC rates of 93%, vs 73%, 80% vs 61%, and 63% vs 54%, for the high and low dose groups, respectively (p = 0.0061, HR = 0.384). In multivariate analysis, metastatic origin, histological confirmation and larger Planning Target Volume (PTV) were associated with higher risk of local failure. Actuarial OS and CSS rates at 1, 2, and 3 years were 85%, 74% and 62%, and 93%, 89% and 80%, respectively. Acute and late toxicities ≥ Gr 3 were observed in 3 (2%) and 6 patients (5%), respectively.

Conclusions

Our favorable LC and survival rates after robotic SBRT, with low rates of severe toxicities, are coherent with the literature data in this mixed, non-selected study population.

From chemotherapy to target therapies associated with radiation in the treatment of NSCLC: a durable marriage?

INTRODUCTION

The integration between radiotherapy and drugs, from chemotherapy to recently available target therapies, continues to have a relevant role in the treatment of locally advanced and metastatic Non-small cell lung cancer (NSCLC). Aim of the present review is to evaluate the promising and emerging application of the best interaction between new drugs and new modalities of radiotherapy. Areas covered: We searched Medline, Google Scholar, PubMed, ProQuest Dissertation, and Theses databases for reports published in English. A study was included when it reported on cancer-related radiotherapy and included patients with NSCLC treated with chemo and/or target therapies. Review articles were excluded from the analysis. Expert commentary: Chemo-radiotherapy still represents the standard of choice in locally advanced NSCLC, while to date the addition of target therapies to chemo-radiotherapy did not demonstrate any robust advantage in this stage of disease. Considering the absence of randomized controlled trials, the role of target therapies in early stage adjuvant NSCLC is not yet recommended in clinical practice. On the contrary, in the setting of oligometastatic and oligoprogressive disease, new molecules demonstrated to be safe and effective, opening to a promising and emerging application of the best interaction between new drugs and new modalities of radiotherapy.

Radio(chemo)therapy in locally advanced nonsmall cell lung cancer

Definitive radiochemotherapy is the standard treatment for many patients with locally advanced nonsmall cell lung cancer (NSCLC). Treatment outcomes have improved over the last decades. Several treatment regimens have been shown effective and safe. This review summarises the results of significant studies between 1996 and 2015 on concomitant and sequential radiochemotherapy regimens and radiation dose per fraction. Beside therapy regimens, optimised radiotherapy planning is indispensable to improve outcome and minimise radiation-induced toxicity. An insight into the rationale of radiotherapy planning for stage III NSCLC is also provided.

Concomitant radiochemotherapy is an established standard treatment for locally advanced nonsmall cell lung cancerhttp://ow.ly/TTkkc

Involved field radiotherapy (IFRT) versus elective nodal irradiation (ENI) for locally advanced non-small cell lung cancer: a meta-analysis of incidence of elective nodal failure (ENF)

Background and purpose

The use of involved field radiotherapy (IFRT) has generated concern about the increasing incidence of elective nodal failure (ENF) in contrast to elective nodal irradiation (ENI). This meta-analysis aimed to provide more reliable and up-to-date evidence on the incidence of ENF between IFRT and ENI.

Materials and methods

We searched three databases for eligible studies where locally advanced non-small cell lung cancer (NSCLC) patients received IFRT or ENI. Outcome of interest was the incidence of ENF. The fixed-effects model was used to pool outcomes across the studies.

Results

There were 3 RCTs and 3 cohort studies included with low risk of bias. There was no significant difference in incidence of ENF between IFRT and ENI either among RCTs (RR = 1.38, 95 % CI: 0.59–3.25, p = 0.46) or among cohort studies (RR = 0.99, 95 % CI: 0.46–2.10, p = 0.97). There was also no significant difference in incidence of ENF between IFRT and ENI when RCTs and cohort studies were combined (RR = 1.15, 95 % CI: 0.65–2.01, p = 0.64). I² of test for heterogeneity was 0 %.

Conclusion

This meta-analysis provides more reliable and stable evidence that there is no significant difference in incidence of ENF between IFRT and ENI.

Electronic supplementary material

The online version of this article (doi:10.1186/s13014-016-0698-3) contains supplementary material, which is available to authorized users.

The Impact of Diffusion-Weighted MRI on the Definition of Gross Tumor Volume in Radiotherapy of Non-Small-Cell Lung Cancer

Objective

The study was designed to evaluate diffusion-weighted magnetic resonance imaging (DWI) vs. PET-CT of the thorax in the determination of gross tumor volume (GTV) in radiotherapy planning of non-small-cell lung cancer (NSCLC).

Materials and Methods

Eligible patients with NSCLC who were supposed to receive definitive radio(chemo)therapy were prospectively recruited. For MRI, a respiratory gated T2-weighted sequence in axial orientation and non-gated DWI (b = 0, 800, 1,400 and apparent diffusion coefficient map [ADC]) were acquired on a 1.5 Tesla scanner. Primary tumors were delineated on FDG-PET/CT (stGTV) and DWI images (dwGTV). The definition of stGTV was based on the CT and visually adapted to the FDG-PET component if indicated (e.g., in atelectasis). For DWI, dwGTV was visually determined and adjusted for anatomical plausibility on T2w sequences. Beside a statistical comparison of stGTV and dwGTB, spatial agreement was determined with the “Hausdorff-Distance” (HD) and the “Dice Similarity Coefficient” (DSC).

Results

Fifteen patients (one patient with two synchronous NSCLC) were evaluated. For 16 primary tumors with UICC stages I (n = 4), II (n = 3), IIIA (n = 2) and IIIB (n = 7) mean values for dwGTV were significantly larger than those of stGTV (76.6 ± 84.5 ml vs. 66.6 ± 75.2 ml, p<0.01). The correlation of stGTV and dwGTV was highly significant (r = 0.995, p<0.001). Yet, some considerable volume deviations between these two methods were observed (median 27.5%, range 0.4–52.1%). An acceptable agreement between dwGTV and stGTV regarding the spatial extent of primary tumors was found (average HD: 2.25 ± 0.7 mm; DC 0.68 ± 0.09).

Conclusion

The overall level of agreement between PET-CT and MRI based GTV definition is acceptable. Tumor volumes may differ considerably in single cases. DWI-derived GTVs are significantly, yet modestly, larger than their PET-CT based counterparts. Prospective studies to assess the safety and efficacy of DWI-based radiotherapy planning in NSCLC are warranted.

[Role of functional imaging in the definition of target volumes for lung cancer radiotherapy]

Functional imaging with positron emission tomography (PET) is interesting to optimize lung radiotherapy planning, and probably to deliver a heterogeneous dose or adapt the radiation dose during treatment. Only fluorodeoxyglucose (FDG) PET-computed tomography (CT) is validated for staging lung cancer and planning radiotherapy. The optimal segmentation methods remain to be defined as well as the interest of "dose painting" from pre-treatment PET (metabolism: FDG) or hypoxia (fluoromisonidazole: FMISO) and the interest of replanning based on pertherapeutic PET.

A critical review of recent developments in radiotherapy for non-small cell lung cancer

Lung cancer is the leading cause of cancer mortality, and radiotherapy plays a key role in both curative and palliative treatments for this disease. Recent advances include stereotactic ablative radiotherapy (SABR), which is now established as a curative-intent treatment option for patients with peripheral early-stage NSCLC who are medically inoperable, or at high risk for surgical complications. Improved delivery techniques have facilitated studies evaluating the role of SABR in oligometastatic NSCLC, and encouraged the use of high-technology radiotherapy in some palliative settings. Although outcomes in locally advanced NSCLC remain disappointing for many patients, future progress may come about from an improved understanding of disease biology and the development of radiotherapy approaches that further reduce normal tissue irradiation. At the moment, the benefits, if any, of radiotherapy technologies such as proton beam therapy remain unproven. This paper provides a critical review of selected aspects of modern radiotherapy for lung cancer, highlights the current limitations in our understanding and treatment approaches, and discuss future treatment strategies for NSCLC.

Selective mediastinal node irradiation in non-small cell lung cancer in the IMRT/VMAT era: How to use E(B)US-NA information in addition to PET-CT for delineation?

BACKGROUND

FDG-PET-CT-based selective lymph node (LN) irradiation is standard using 3D-conformal techniques for locally advanced NSCLC. With newer techniques (intensity-modulated/volumetric-arc therapy (IMRT/VMAT)), the dose to non-involved adjacent LN decreases, which raises the question whether FDG-PET-CT-delineation is still safe. We therefore evaluated the impact of adding linear endosonography with needle aspiration (E(B)US-NA) to FDG-PET-CT in selective nodal irradiation.

METHODS

Based on literature data on sensitivity and specificity of E(B)US-NA in FDG-PET-CT-staged NSCLC, false negative (FN) rates for different constellations of CT, PET and E(B)US-NA were calculated. The algorithm was tested on consecutive patients with N2/N3 disease referred for radiotherapy in Leuven and Maastricht.

RESULTS

An algorithm determining when to include LN in the GTV is proposed, based on data from 5 meta-analyses. Adding E(B)US-NA to FDG-PET-CT decreases the FN-rate, but for PET-positive and E(B)US-negative LN, FN rates are still 14-16%. In Leuven 520 LN were analyzed, in Maastricht 364 LN; with E(B)US-NA a geographical miss was avoided in 2 (2/40=5%) and 1 (1/28=4%) patients, respectively.

CONCLUSIONS

E(B)US-NA in addition to FDG-PET-CT for mediastinal staging decreases the risk of a geographical miss with 4-5%. The impact of this small decrease on survival is unknown. The proposed algorithm may guide the radiation oncologist when to include LN in the nodal GTV.

A treatment-planning comparison of three beam arrangement strategies for stereotactic body radiation therapy for centrally located lung tumors using volumetric-modulated arc therapy

The purpose of this study was to determine appropriate beam arrangement for volumetric-modulated arc therapy (VMAT)-based stereotactic body radiation therapy (SBRT) in the treatment of patients with centrally located lung tumors. Fifteen consecutive patients with centrally located lung tumors treated at our institution were enrolled. For each patient, three VMAT plans were generated using two coplanar partial arcs (CP VMAT), two non-coplanar partial arcs (NCP VMAT), and one coplanar full arc (Full VMAT). All plans were designed to deliver 70 Gy in 10 fractions. Target coverage and sparing of organs at risk (OARs) were compared across techniques. PTV coverage was almost identical for all approaches. The whole lung V10Gy was significantly lower with CP VMAT plans than with NCP VMAT plans, whereas no significant differences in the mean lung dose, V5Gy, V20Gy or V40Gy were observed. Full VMAT increased mean contralateral lung V5Gy by 12.57% and 9.15% when compared with NCP VMAT and CP VMAT, respectively. Although NCP VMAT plans best achieved the dose-volume constraints for mediastinal OARs, the absolute differences in dose were small when compared with CP VMAT. These results suggest that partial-arc VMAT may be preferable to minimize unnecessary exposure to the contralateral lung, and use of NCP VMAT should be considered when the dose-volume constraints are not achieved by CP VMAT.

Therapeutic options following pneumonectomy in non-small cell lung cancer

INTRODUCTION

Pneumonectomy can be considered the most appropriate treatment for lung cancer that cannot be removed by lesser resection on.

AREAS COVERED

Therapeutic options following pneumonectomy may be required at least in 3 different scenarios: 1) an early approach due to acute surgical complications 2) a late approach due to chronic surgical complications 3) an integrated radio-chemotherapeutic adjuvant approach for advanced stages. In this review we focused on these three settings with particular emphasis to surgical approach as well as to alternative options. Expert commentary: Pneumonectomy itself does not preclude postoperative additional treatments, if needed, to maximize oncological results and to manage potential short or long term complications. However, as pneumonectomy puts a significant physiological stress on the respiratory and circulatory systems, the benefits and risks of pneumonectomy should be compared with those of alternative, non-resectional treatment modalities.

Limiting the risk of cardiac toxicity with esophageal-sparing intensity modulated radiotherapy for locally advanced lung cancers

BACKGROUND

Intensity modulated radiotherapy (IMRT) is routinely utilized in the treatment of locally advanced non-small cell lung cancer (NSCLC). RTOG 0617 found that overall survival was impacted by increased low (5 Gy) and intermediate (30 Gy) cardiac doses. We evaluated the impact of esophageal-sparing IMRT on cardiac doses with and without the heart considered in the planning process and predicted toxicity compared to 3D-conventional radiotherapy (3DCRT).

METHODS

Ten consecutive patients with N2 Stage III NSCLC treated to 60 Gy in 30 fractions, between February 2012 and September 2014, were evaluated. For each patient, 3DCRT and esophageal-sparing IMRT plans were generated. IMRT plans were then created with and without the heart considered in the optimization process. To compare plans, the dose delivered to 95% and 99% of the target (D95% and D99%), and doses to the esophagus, lung and heart were compared by determining the volume receiving X dose (VXGy) and the normal tissue complication probability (NTCP) calculated.

RESULTS

IMRT reduced maximum esophagus dose to below 60 Gy in all patients and produced significant reductions to V50Gy, V40Gy and esophageal NTCP. The cost of this reduction was a non-statistically, non-clinically significant increase in low dose (5 Gy) lung exposure that did not worsen lung NTCP. IMRT plans produced significant cardiac sparing, with the amount of improvement correlating to the amount of heart overlapping with the target. When included in plan optimization, for selected patients further sparing of the heart and improvement in heart NTCP was possible.

CONCLUSIONS

Esophageal-sparing IMRT can significantly spare the heart even if it is not considered in the optimization process. Further sparing can be achieved if plan optimization constrains low and intermediate heart doses, without compromising lung doses.

Phase II Trial of SBRT for Stage I NSCLC: Survival, Local Control, and Lung Function at 36 Months

OBJECTIVES

The long-term impact of stereotactic body radiotherapy (SBRT) on respiratory function in patients with inoperable non-small cell lung cancer (NSCLC) has not been well studied. The aim of this phase II trial was to assess local control, survival, and lung function at 36 months after treatment.

METHODS

From July 2008 to February 2012, 42 patients in whom inoperable NSCLC with peripheral lesions was diagnosed were consecutively enrolled. Lung function testing included measurement of forced expiratory vital capacity, forced expiratory volume in 1 second, and diffusing capacity for carbon monoxide. All lung function parameters were registered at baseline and evaluated prospectively after SBRT every 6 months for 2 years and annually thereafter.

RESULTS

Of the 42 initial patients, four were excluded. At 36 months after SBRT, 22 patients were still evaluable (12 deaths and four patients lost to follow-up). At 36 months, the rate of local control was 94%. At 1, 2, and 3 years, respectively, overall survival rates were 92%, 75%, and 66%. Median overall survival was 57 months. Grade (G) 3 acute toxicity was observed in four patients (10%). Chronic G1 toxicity was observed in all 38 cases (100%), with the most common type being pneumonitis (26 patients [68%]). The mean lung function parameters at baseline and at 36 months after treatment were as follows: forced expiratory vital capacity 83% versus 79%; forced expiratory volume in 1 second 62% versus 57%; and diffusing capacity for carbon monoxide 54% versus 54%. These changes were not significant.

CONCLUSIONS

In this trial, local control and survival rates after SBRT were very good. Treatment with SBRT had no significant impact on lung function at 36 months. These findings provide further support for the use of SBRT as a radical treatment for NSCLC. Lung toxicity is minimal, even in patients with poor pulmonary function before treatment.

Stereotactic body radiotherapy for lung cancer: how much does it really cost?

INTRODUCTION

Despite the lack of randomized evidence, stereotactic body radiotherapy (SBRT) is being accepted as superior to conventional radiotherapy for patients with T1-2N0 non-small-cell lung cancer in the periphery of the lung and unfit or unwilling to undergo surgery. To introduce SBRT in a system of coverage with evidence development, a correct financing had to be determined.

METHODS

A time-driven activity-based costing model for radiotherapy was developed. Resource cost calculation of all radiotherapy treatments, standard and innovative, was conducted in 10 Belgian radiotherapy centers in the second half of 2012.

RESULTS

The average cost of lung SBRT across the 10 centers (6221&OV0556;) is in the range of the average costs of standard fractionated 3D-conformal radiotherapy (5919&OV0556;) and intensity-modulated radiotherapy (7379&OV0556;) for lung cancer. Hypofractionated 3D-conformal radiotherapy and intensity-modulated radiotherapy schemes are less costly (3993&OV0556; respectively 4730&OV0556;). The SBRT cost increases with the number of fractions and is highly dependent of personnel and equipment use. SBRT cost varies more by centre than conventional radiotherapy cost, reflecting different technologies, stages in the learning curve and a lack of clear guidance in this field.

CONCLUSIONS

Time-driven activity-based costing of radiotherapy is feasible in a multicentre setup, resulting in real-life resource costs that can form the basis for correct reimbursement schemes, supporting an early yet controlled introduction of innovative radiotherapy techniques in clinical practice.

The effect of beam arrangements and the impact of non-coplanar beams on the treatment planning of stereotactic ablative radiation therapy for early stage lung cancer

INTRODUCTION

The aim of this study was to compare various coplanar and non-coplanar 3-dimensional conformal radiation therapy (3DCRT) beam arrangements for the delivery of stereotactic ablative radiation therapy (SABR) to patients with early stage lung cancer, based on the dosimetric criteria from the Radiation Therapy Oncology Group (RTOG) 1021 protocol.

METHODS

Ten medically inoperable lung cancer patients eligible for SABR were re-planned using three different coplanar and three different non-coplanar beam arrangements. The plans were compared by assessing planning target volume (PTV) coverage, doses to normal tissues, the high-dose conformity (conformity index) and intermediate dose spillage as defined by the D2cm, (the dose at any point 2 cm away from the PTV), and the R50% (the ratio of the volume of half the prescription dose to the volume of the PTV).

RESULTS

Sixty plans in total were assessed. Mean PTV coverage with the prescription isodose was similar between coplanar (95.14%) and non-coplanar (95.26%) techniques (P = 0.47). There was significant difference between all coplanar and all non-coplanar fields for the R50% (P < 0.0001) but none for the D2cm (P = 0.19). The seven and nine field beam arrangements with two non-coplanar fields had less unacceptable protocol deviations (10 and 7) than the seven and nine field plans with only coplanar fields (13 and 8). The 13 field coplanar fields did not improve protocol compliance with eight unacceptable deviations. The 10 field non-coplanar beam arrangement achieved best compliance with the RTOG 1021 dose criteria with only one unacceptable deviation (maximum rib dose).

CONCLUSION

A 3DCRT planning technique using 10 fields with ≥6 non-coplanar beams best satisfied high and intermediate dose constraints stipulated in the RTOG 1021 trial. Further investigations are required to determine if minor protocol deviations should be balanced against efficiency with the extended treatment times required to deliver non-coplanar fields and if treatment times can be improved using novel intensity modulated techniques.

Delineation of clinical target volume for postoperative radiotherapy in stage IIIA-pN2 non-small-cell lung cancer

With the high locoregional relapse rate and the improvement of radiation technology, postoperative radiotherapy (PORT) has been widely used in the treatment of completely resected stage IIIA-pN2 non-small-cell lung cancer (NSCLC). However, there is still no definitive consensus on clinical target volume for the pN2 subgroup. This review will discuss how to delineate the clinical target volume (CTV) for pN2 subgroups of IIIA-N2 NSCLC based on the published literature and to investigate the optimal PORT CTV in this cohort of patients. Besides overall survival (OS), locoregional recurrence (LR), and radiotherapy-related toxicity of this subset of the population in the modern PORT era, selection of proper patients will also be considered in this review. In summary, it is appropriate to include involved lymph node stations and uninvolved stations at high risk in PORT CTV for patients with pN2 disease when PORT is administered. PORT can reduce LR and has the potential to improve OS. In the current era of modern radiation technology, PORT can be administered safely with well-tolerated toxicity. Clinicopathological characteristics may be helpful in selecting proper candidates for PORT.

The Response, Outcome and Toxicity of Aggressive Palliative Thoracic Radiotherapy for Metastatic Non-Small Cell Lung Cancer Patients with Controlled Extrathoracic Diseases

Background and Purpose

For metastatic non-small cell lung cancer (NSCLC) patients with controlled extrathoracic disease after systemic treatment, stable or progressive primary lung lesions may cause respiratory symptoms and increase comorbidities. In the present study, we sought to investigate whether aggressive palliative thoracic radiotherapy (RT) can enhance local control and improve the survival for this subgroup of patients.

Materials and Methods

Between March 2006 and December 2014, 56 patients with metastatic NSCLC who had responsive or stable extrathoracic diseases after chemotherapy and/or molecular targets, and received thoracic RT for stable and progressive primary lung lesions were included. RT with a median dose of 55 Gy (range, 40–62 Gy) was administered in 1.8–2.5 Gy fractions to primary lung tumor and regional mediastinal lymph nodes using modern RT technique. Overall survival (OS) from diagnosis, and locoregional progression-free survival (LRPFS), and survival calculated from radiotherapy (OS-RT) were estimated using the Kaplan-Meier method.

Results

There were 37 men and 19 women with a median age of 60 years at diagnosis. The median interval from the diagnosis of metastatic disease to thoracic RT was 8 months. Following thoracic RT, 26 patients (46%) achieved complete or partial response (overall response rate, ORR). Patients with squamous cell carcinoma or poorly-differentiated carcinoma had a higher ORR than those with adenocarcinoma (63% vs. 34%, P = 0.034). EGFR mutations was closely associated with a better ORR (45% vs. 29%, P = 0.284). At a median follow-up time of 44 months, the median OS, LRPFS after RT, and OS-RT were 50 months, 15 months, and 18 months.

Conclusion

Radical palliative throractic RT is safe and might be beneficial for primary lung lesions of metastatic NSCLC patients with controlled extrathoracic diseases.

Intensity-modulated radiotherapy for lung cancer: current status and future developments

Radiotherapy plays an important role in the management of lung cancer, with over 50% of patients receiving this modality at some point during their treatment. Intensity-modulated radiotherapy (IMRT) is a technique that adds fluence modulation to beam shaping, which improves radiotherapy dose conformity around the tumor and spares surrounding normal structures. Treatment with IMRT is becoming more widely available for the treatment of lung cancer, despite the paucity of high level evidence supporting the routine use of this more resource intense and complex technique. In this review article, we have summarized data from planning and clinical studies, discussed challenges in implementing IMRT, and made recommendations on the minimum requirements for safe delivery of IMRT.

Emerging Role of MRI for Radiation Treatment Planning in Lung Cancer

Magnetic resonance imaging (MRI) provides excellent soft-tissue contrast and allows for specific scanning sequences to optimize differentiation between various tissue types and properties. Moreover, it offers the potential for real-time motion imaging. This makes magnetic resonance imaging an ideal candidate imaging modality for radiation treatment planning in lung cancer. Although the number of clinical research protocols for the application of magnetic resonance imaging for lung cancer treatment is increasing (www.clinicaltrials.gov) and the magnetic resonance imaging sequences are becoming faster, there are still some technical challenges. This review describes the opportunities and challenges of magnetic resonance imaging for radiation treatment planning in lung cancer.

A comparison between radiation therapists and medical specialists in the use of kilovoltage cone-beam computed tomography scans for potential lung cancer radiotherapy target verification and adaptation

Target volume matching using cone-beam computed tomography (CBCT) is the preferred treatment verification method for lung cancer in many centers. However, radiation therapists (RTs) are trained in bony matching and not soft tissue matching. The purpose of this study was to determine whether RTs were equivalent to radiation oncologists (ROs) and radiologists (RDs) in alignment of the treatment CBCT with the gross tumor volume (GTV) defined at planning and in delineating the GTV on the treatment CBCT, as may be necessary for adaptive radiotherapy. In this study, 10 RTs, 1 RO, and 1 RD performed a manual tumor alignment and correction of the planning GTV to a treatment CBCT to generate an isocenter correction distance for 15 patient data sets. Participants also contoured the GTV on the same data sets. The isocenter correction distance and the contoured GTVs from the RTs were compared with the RD and RO. The mean difference in isocenter correction distances was 0.40cm between the RO and RD, 0.51cm between the RTs, and RO and 0.42cm between the RTs and RD. The 95% CIs were smaller than the equivalence limit of 0.5cm, indicating that the RTs were equivalent to the RO and RD. For GTV delineation comparisons, the RTs were not found to be equivalent to the RD or RO. The alignment of the planning defined GTV and treatment CBCT using soft tissue matching by the RTs has been shown to be equivalent to those by the RO and RD. However, tumor delineation by the RTs on the treatment CBCT was not equivalent to that of the RO and RD. Thus, it may be appropriate for RTs to undertake soft tissue alignment based on CBCT; however, further investigation may be necessary before RTs undertake delineation for adaptive radiotherapy purposes.

[Positron emission tomography and stereotactic body radiation therapy for lung cancer: From treatment planning to response evaluation]

Stereotactic body radiation therapy is the standard treatment for inoperable patients with early-stage lung cancer. Local control rates range from 80 to 90 % 2 years after treatment. The role of positron emission tomography in patient selection is well known, but its use for target definition or therapeutic response evaluation is less clear. We reviewed the literature in order to assess the current state of knowledge in this area.

IMRT and 3D conformal radiotherapy with or without elective nodal irradiation in locally advanced NSCLC: A direct comparison of PET-based treatment planning

AIM

The potential of intensity-modulated radiation therapy (IMRT) as opposed to three-dimensional conformal radiotherapy (3D-CRT) is analyzed for two different concepts of fluorodeoxyglucose positron emission tomography (FDG PET)-based target volume delineation in locally advanced non-small cell lung cancer (LA-NSCLC): involved-field radiotherapy (IF-RT) vs. elective nodal irradiation (ENI).

METHODS

Treatment planning was performed for 41 patients with LA-NSCLC, using four different planning approaches (3D-CRT-IF, 3D-CRT-ENI, IMRT-IF, IMRT-ENI). ENI included a boost irradiation after 50 Gy. For each plan, maximum dose escalation was calculated based on prespecified normal tissue constraints. The maximum prescription dose (PD), tumor control probability (TCP), conformal indices (CI), and normal tissue complication probabilities (NTCP) were analyzed.

RESULTS

IMRT resulted in statistically significant higher prescription doses for both target volume concepts as compared with 3D-CRT (ENI: 68.4 vs. 60.9 Gy, p < 0.001; IF: 74.3 vs. 70.1 Gy, p < 0.03). With IMRT-IF, a PD of at least 66 Gy was achieved for 95 % of all plans. For IF as compared with ENI, there was a considerable theoretical increase in TCP (IMRT: 27.3 vs. 17.7 %, p < 0.00001; 3D-CRT: 20.2 vs. 9.9 %, p < 0.00001). The esophageal NTCP showed a particularly good sparing with IMRT vs. 3D-CRT (ENI: 12.3 vs. 30.9 % p < 0.0001; IF: 15.9 vs. 24.1 %; p < 0.001).

CONCLUSION

The IMRT technique and IF target volume delineation allow a significant dose escalation and an increase in TCP. IMRT results in an improved sparing of OARs as compared with 3D-CRT at equivalent dose levels.

Adaptive radiotherapy for locally advanced non-small cell lung cancer, can we predict when and for whom?

BACKGROUND

Adaptive radiotherapy (ART) could be a tool to reduce toxicity and to facilitate dose escalation in stage III NSCLC. Our aim was to identify the most appropriate time and potential benefit of ART.

MATERIAL AND METHODS

We analyzed volume reduction and dosimetric consequences of 41 patients who were treated with concurrent (cCRT) (n = 21) or sequential (sCRT) chemoradiotherapy to a median dose of 70 Gy, 2 Gy/F. At every treatment fraction a cone-beam CT (CBCT) was performed. The gross tumor volume (GTV-T) was adapted (exclusion of lymph nodes) to create the GTV-T-F1. Every fifth fraction (F5-F30), the GTV-T-F1 was adapted on the CBCT to create a GTV-T-Fx. Dose volume histograms were recalculated for every GTV-T-Fx, enabling to create lookup tables to predict the theoretical dosimetric advantage on common lung dose constraints.

RESULTS

The average GTV reduction was 42.1% (range 4.0-69.3%); 50.1% and 33.7% for the cCRT and sCRT patients, respectively. A linear relationship between GTV-T-F1 volume and absolute volume decrease was found for both groups. The mean V5, V20, V30 and mean lung dose increased by 0.8, 3.1, 5.2 and 3.4%, respectively. A larger increase (p < 0.05) was observed for peripheral tumors and cCRT. Lookup tables were generated.

CONCLUSION

ART offers the most beneficial dosimetric effects when performed around fraction 15, especially for patients with a large initial GTV-T treated by cCRT.

Quantification of CT-assessed radiation-induced lung damage in lung cancer patients treated with or without chemotherapy and cetuximab

BACKGROUND AND PURPOSE

Prediction models for radiation-induced lung damage (RILD) are still unsatisfactory, with clinical toxicity endpoints that are difficult to quantify objectively. We therefore evaluated RILD more objectively, quantitatively and on a continuous scale measuring the lung tissue density changes per voxel.

MATERIAL AND METHODS

Patients treated with radiotherapy (RT) alone, sequential and concurrent chemo-RT with and without the addition of cetuximab were studied. Follow-up computed tomography (CT) scans were co-registered using deformable registration to baseline CT scans. CT density changes were correlated to the RT dose delivered in every part of the lungs.

RESULTS

One hundred and seventeen lung cancer patients were included. Mean dose to tumor was 60 Gy (range 45-79.2 Gy). Dose response curves showed a linear increase in the dose region between 0 and 65 Gy having a slope (based on coefficients of the multilevel model) expressed as a lung density increase per dose of 0.86 (95% CI 0.73-0.99), 1.31 (95% CI 1.19-1.43), 1.39 (95% CI 1.28-1.50) and 2.07 (95% CI 1.93-2.21) for patients treated only with RT (N=19), sequential chemo-RT (N=30), concurrent chemo-RT (N=49), and concurrent chemo-RT with cetuximab (N=19), respectively.

CONCLUSIONS

CT density changes allow quantitative assessment of lung damage after fractionated RT, giving complementary information to standard used clinical endpoints. Patients receiving cetuximab showed a significantly larger dose response compared with other treatments.