Volumetric response analysis during chemoradiation as predictive tool for optimizing treatment strategy in locally advanced unresectable NSCLC

Accelerated Hypofractionated Chemoradiation Followed by Stereotactic Ablative Radiotherapy Boost for Locally Advanced, Unresectable Non-Small Cell Lung Cancer: A Nonrandomized Controlled Trial

Importance

Intrathoracic progression remains the predominant pattern of failure in patients treated with concurrent chemoradiation followed by a consolidation immune checkpoint inhibitor for locally advanced, unresectable non-small cell lung cancer (NSCLC).

Objective

To determine the maximum tolerated dose (MTD) and use of hypofractionated concurrent chemoradiation with an adaptive stereotactic ablative radiotherapy (SABR) boost.

Design, Setting, and Participants

This was an early-phase, single-institution, radiation dose-escalation nonrandomized controlled trial with concurrent chemotherapy among patients with clinical stage II (inoperable/patient refusal of surgery) or III NSCLC (American Joint Committee on Cancer Staging Manual, seventh edition). Patients were enrolled and treated from May 2011 to May 2018, with a median patient follow-up of 18.2 months. Patients advanced to a higher SABR boost dose if dose-limiting toxic effects (any grade 3 or higher pulmonary, gastrointestinal, or cardiac toxic effects, or any nonhematologic grade 4 or higher toxic effects) occurred in fewer than 33% of the boost cohort within 90 days of follow-up. The current analyses were conducted from January to September 2023.

Intervention

All patients first received 4 Gy × 10 fractions followed by an adaptive SABR boost to residual metabolically active disease, consisting of an additional 25 Gy (low, 5 Gy × 5 fractions), 30 Gy (intermediate, 6 Gy × 5 fractions), or 35 Gy (high, 7 Gy × 5 fractions) with concurrent weekly carboplatin/paclitaxel.

Main Outcome and Measure

The primary outcome was to determine the MTD.

Results

Data from 28 patients (median [range] age, 70 [51-88] years; 16 [57%] male; 24 [86%] with stage III disease) enrolled across the low- (n = 10), intermediate- (n = 9), and high- (n = 9) dose cohorts were evaluated. The protocol-specified MTD was not exceeded. The incidences of nonhematologic acute and late (>90 days) grade 3 or higher toxic effects were 11% and 7%, respectively. No grade 3 toxic effects were observed in the intermediate-dose boost cohort. Two deaths occurred in the high-dose cohort. Two-year local control was 74.1%, 85.7%, and 100.0% for the low-, intermediate-, and high-dose cohorts, respectively. Two-year overall survival was 30.0%, 76.2%, and 55.6% for the low-, intermediate-, and high-dose cohorts, respectively.

Conclusions and Relevance

This early-phase, dose-escalation nonrandomized controlled trial showed that concurrent chemoradiation with an adaptive SABR boost to 70 Gy in 15 fractions with concurrent chemotherapy is a safe and effective regimen for patients with locally advanced, unresectable NSCLC.

Trial Registration

ClinicalTrials.gov Identifier: NCT01345851.

A Pilot Study Examining the Prognostic Utility of Tumor Shrinkage on Cone-Beam Computed Tomography (CBCT) for Stage III Locally Advanced Non-Small Cell Lung Cancer Patients Treated with Definitive Chemoradiation

There has been growing interest in utilizing information from cone-beam computed tomography (CBCT) to help guide both treatment delivery and prognosis. In this assessment of locally advanced unresectable stage III non-small cell lung cancer (NSCLC) treated with definitive chemoradiation, we aimed to determine the survival advantage associated with using CBCT to measure tumor regression. Patient, tumor, and treatment characteristics were collected. The serial tumor shrinkage for each patient was determined from tumor volume contours on weekly CBCTs. Survival analysis was performed using the Kaplan–Meier technique and a Cox proportional hazards model. At least two-thirds of patients had a tumor volume reduction of at least 5% after each week of chemoradiation. A weekly reduction in tumor volume of 5% or greater seen on the CBCT images during radiation therapy was significantly associated with improved overall survival, which remained significant when adjusted for age, histology, grade, and T- and N-stages (p = 0.0036). Additionally, the presence of N3 disease was associated with a five-fold increased risk of recurrence (p = 0.0006) and a nearly three-fold increased risk of death (p = 0.053) compared with N0–N2 disease. Tumor volume shrinkage observed in the CBCT images during definitive chemoradiation holds promise as a prognostic indicator of stage III NSCLC, especially given its affordability, availability, and applicability. Further evaluation in a prospective fashion is warranted to validate the tumor volume shrinkage and its clinical utility.

Incidence and evolution of imaging changes on cone-beam CT during and after radical radiotherapy for non-small cell lung cancer

BACKGROUND AND PURPOSE

Cone beam CT (CBCT) is used to improve accuracy of radical radiotherapy by adjusting treatment to the observed imaging changes. To ensure appropriate adjustment, image interpretation should precede any changes to treatment delivery. This study provides the methodology for image interpretation and the frequency and evolution of the changes in patients undergoing radical radiotherapy for localised and locally advanced non-small cell lung cancer (NSCLC).

PATIENTS AND METHODS

From December 2012 to December 2014, 250 patients with localised and locally advanced NSCLC had 2462 chest CBCT scans during the course of fractionated radical radiotherapy (RT) (3-5 daily CBCTs in the first week followed by at least weekly imaging, mean 9.5 per patient, range 1-21). All CBCT images were reviewed describing changes and their evolution using diagnostic imaging definitions and validated by an independent chest radiologist.

RESULTS

During radical RT for NSCLC 328 imaging changes were identified on CBCT in 180 (72%) patients; 104 (32%) had reduction and 41 (13%) increase in tumour size; 48 (15%) had changes in consolidations contiguous to the primary lesion, 26 (8%) non-contiguous consolidations, 43 (13%) changes in tumour cavitation, 36 (11%) pleural effusion and 30 (9%) changes in atelectasis. In 105 patients imaging changes were noted in continuity with the treated tumour of which only 41 (39%) represented tumour enlargement; others included new or enlarging adjacent consolidation (34%), and new or enlarging atelectasis (19%). The changes evolved during treatment.

CONCLUSION

Imaging changes on CBCT include real and apparent changes in tumour size and parenchymal changes which evolve during treatment. Correct image interpretation, particularly when occurring adjacent to the tumour, is essential prior to adjustment to treatment delivery.

Validating a Predictive Atlas of Tumor Shrinkage for Adaptive Radiotherapy of Locally Advanced Lung Cancer

PURPOSE

To cross-validate and expand a predictive atlas that can estimate geometric patterns of lung tumor shrinkage during radiation therapy using data from 2 independent institutions and to model its integration into adaptive radiation therapy (ART) for enhanced dose escalation.

METHODS AND MATERIALS

Data from 22 patients at a collaborating institution were obtained to cross-validate an atlas, originally created with 12 patients, for predicting patterns of tumor shrinkage during radiation therapy. Subsequently, the atlas was expanded by integrating all 34 patients. Each study patient was selected via a leave-one-out scheme and was matched with a subgroup of the remaining 33 patients based on similarity measures of tumor volume and surroundings. The spatial distribution of residual tumor was estimated by thresholding the superimposed shrinkage patterns in the subgroup. A Bayesian method was also developed to recalibrate the prediction using the tumor observed on the midcourse images. Finally, in a retrospective predictive treatment planning (PTP) study, at the initial planning stage, the predicted residual tumors were escalated to the highest achievable dose while maintaining the original prescription dose to the remainder of the tumor. The PTP approach was compared isotoxically to ART that replans with midcourse imaging and to PTP-ART with the recalibrated prediction.

RESULTS

Predictive accuracy (true positive plus true negative ratios based on predicted and actual residual tumor) were comparable across institutions, 0.71 versus 0.73, and improved to 0.74 with an expanded atlas including 2 institutions. Recalibration further improved accuracy to 0.76. PTP increased the mean dose to the actual residual tumor by an averaged 6.3Gy compared to ART.

CONCLUSION

A predictive atlas found to perform well across institutions and benefit from more diversified shrinkage patterns and tumor locations. Elevating tumoricidal dose to the predicted residual tumor throughout the entire treatment course could improve the efficacy and efficiency of treatment compared to ART with midcourse replanning.

Predictive and prognostic value of tumor volume and its changes during radical radiotherapy of stage III non-small cell lung cancer : A systematic review

PURPOSE

Lung cancer remains the leading cause of cancer-related mortality worldwide. Stage III non-small cell lung cancer (NSCLC) includes heterogeneous presentation of the disease including lymph node involvement and large tumour volumes with infiltration of the mediastinum, heart or spine. In the treatment of stage III NSCLC an interdisciplinary approach including radiotherapy is considered standard of care with acceptable toxicity and improved clinical outcome concerning local control. Furthermore, gross tumour volume (GTV) changes during definitive radiotherapy would allow for adaptive replanning which offers normal tissue sparing and dose escalation.

METHODS

A literature review was conducted to describe the predictive value of GTV changes during definitive radiotherapy especially focussing on overall survival. The literature search was conducted in a two-step review process using PubMed®/Medline® with the key words "stage III non-small cell lung cancer" and "radiotherapy" and "tumour volume" and "prognostic factors".

RESULTS

After final consideration 17, 14 and 9 studies with a total of 2516, 784 and 639 patients on predictive impact of GTV, GTV changes and its impact on overall survival, respectively, for definitive radiotherapy for stage III NSCLC were included in this review. Initial GTV is an important prognostic factor for overall survival in several studies, but the time of evaluation and the value of histology need to be further investigated. GTV changes during RT differ widely, optimal timing for re-evaluation of GTV and their predictive value for prognosis needs to be clarified. The prognostic value of GTV changes is unclear due to varying study qualities, re-evaluation time and conflicting results.

CONCLUSION

The main findings were that the clinical impact of GTV changes during definitive radiotherapy is still unclear due to heterogeneous study designs with varying quality. Several potential confounding variables were found and need to be considered for future studies to evaluate GTV changes during definitive radiotherapy with respect to treatment outcome.

A geometric atlas to predict lung tumor shrinkage for radiotherapy treatment planning

To develop a geometric atlas that can predict tumor shrinkage and guide treatment planning for non-small-cell lung cancer. To evaluate the impact of the shrinkage atlas on the ability of tumor dose escalation. The creation of a geometric atlas included twelve patients with lung cancer who underwent both planning CT and weekly CBCT for radiotherapy planning and delivery. The shrinkage pattern from the original pretreatment to the residual posttreatment tumor was modeled using a principal component analysis, and used for predicting the spatial distribution of the residual tumor. A predictive map was generated by unifying predictions from each individual patient in the atlas, followed by correction for the tumor's surrounding tissue distribution. Sensitivity, specificity, and accuracy of the predictive model for classifying voxels inside the original gross tumor volume were evaluated. In addition, a retrospective study of predictive treatment planning (PTP) escalated dose to the predicted residual tumor while maintaining the same level of predicted complication rates for a clinical plan delivering uniform dose to the entire tumor. The effect of uncertainty on the predictive model's ability to escalate dose was also evaluated. The sensitivity, specificity and accuracy of the predictive model were 0.73, 0.76, and 0.74, respectively. The area under the receiver operating characteristic curve for voxel classification was 0.87. The Dice coefficient and mean surface distance between the predicted and actual residual tumor averaged 0.75, and 1.6 mm, respectively. The PTP approach allowed elevation of PTV D95 and mean dose to the actual residual tumor by 6.5 Gy and 10.4 Gy, respectively, relative to the clinical uniform dose approach. A geometric atlas can provide useful information on the distribution of resistant tumors and effectively guide dose escalation to the tumor without compromising the organs at risk complications. The atlas can be further refined by using more patient data sets.

Modelling and Bayesian adaptive prediction of individual patients' tumour volume change during radiotherapy

The aim of this study is to develop a mathematical modelling method that can predict individual patients’ response to radiotherapy, in terms of tumour volume change during the treatment. The main concept is to start from a population-average model, which is subsequently updated from an individual’s tumour volume measurement. The model becomes increasingly personalized and so too does the prediction it produces. This idea of adaptive prediction was realised by using a Bayesian approach for updating the model parameters. The feasibility of the developed method was demonstrated on the data from 25 non-small cell lung cancer patients treated with helical tomotherapy, during which tumour volume was measured from daily imaging as part of the image-guided radiotherapy. The method could provide useful information for adaptive treatment planning and dose scheduling based on the patient’s personalised response.

Image guided volumetric response during chemoradiotherapy for head and neck squamous cell carcinoma as a predictor of disease outcomes

PURPOSE

The goal of this study was to correlate volumetric image guided disease response to clinical outcomes in patients receiving chemoradiation therapy (CRT) for locally advanced head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

Thirty four patients completing definitive CRT for locally advanced HNSCC with megavoltage computed tomography (MVCT) guided tomotherapy IMRT were retrospectively reviewed for volumetric response. Grossly identifiable primary tumor (PT) and nodal disease (ND) response was evaluated by weekly MVCT regression. Percent end-of-treatment (EOT) residual volumes and regression rates were correlated with risk of local failure (LF), progression free survival (PFS), and overall survival (OS).

RESULTS

A total of 7 LFs were identified in 6 patients at a median follow-up of 8months. The mean percent EOT residual volumes for PT and ND in patients with and without LF were 20% vs. 5% (p=0.005) and 47% vs. 6% (p=0.0001), respectively. The PT and ND volume regression rates for patients with and without LF were 12.7% per week vs. 15.9% per week (p=0.04) and 3.4% per week vs. 10.5% per week (p<0.001), respectively. Utilizing an EOT cut-off value of 25% residual volume, the relative risks of LF for PT and ND were 14.7 (p=0.03) and 25 (p=0.001), respectively. Patients found with PT and/or ND residual volumes <25% at EOT had longer 2year OS of 100% vs. 67% (p=0.0023) and PFS of 87% vs. 17% (p<0.001) compared with patients with residual volumes >/= 25% at EOT.

CONCLUSION

Patients with locally advanced HNSCC who have significant MVCT volume reduction over the course of definitive CRT tend to have favorable clinical outcomes.

Quantification of metabolic tumor activity and burden in patients with non-small-cell lung cancer: Is manual adjustment of semiautomatic gradient-based measurements necessary?

PURPOSE

Metabolic tumor burden (MTB) measurements including metabolic tumor volume and total lesion glycolysis have been shown to have prognostic value in non-small-cell lung cancer (NSCLC). The calculation of MTB typically utilizes software to semiautomatically draw volumes of interest around the tumor, which are subsequently manually adjusted by the radiologist to include the entire tumor. The manual adjustment step can be time-consuming and observer-dependent. We compared the agreement of MTB values obtained using the semiautomatic method with and without manual adjustment in NSCLC patients.

METHODS

This IRB-approved prospective study included 134 patients with histologically proven NSCLC who underwent fluorine-18 fluorodeoxyglucose PET/computed tomography. The MTB of the primary tumor was measured with a semiautomatic gradient-based method without manual adjustment (the semiautomatic gradient method) and with manual adjustment (the manually adjusted semiautomatic gradient method) by two radiologists using the MIM PETedge tool. The paired t-test, Wilcoxon signed-rank test, and concordance correlation coefficient (CCC) were calculated to evaluate the agreement between MTB measures obtained with these two methods, as well as agreement between the two radiologists for each method.

RESULTS

Maximum standardized uptake value was identical between the two methods. No statistically significant difference was present for peak standardized uptake value, metabolic tumor volume, and total lesion glycolysis values between the two methods (P=0.23, 0.45, and 0.37, respectively). Excellent agreement between the two methods was found in terms of CCC (CCC>0.98 for all measures). Interobserver reliability was excellent for all measures (CCC>0.90).

CONCLUSION

The semiautomatic gradient-based tumor-segmentation method can be used without the additional manual adjustment step for MTB quantification of primary NSCLC tumors.

Cone-beam CT-guided radiotherapy in the management of lung cancer: Diagnostic and therapeutic value

BACKGROUND

Recent studies have demonstrated an increase in the necessity of adaptive planning over the course of lung cancer radiation therapy (RT) treatment. In this study, we evaluated intrathoracic changes detected by cone-beam CT (CBCT) in lung cancer patients during RT.

METHODS AND MATERIALS

A total of 71 lung cancer patients treated with fractionated CBCT-guided RT were evaluated. Intrathoracic changes and plan adaptation priority (AP) scores were compared between small cell lung cancer (SCLC, n = 13) and non-small cell lung cancer (NSCLC, n = 58) patients.

RESULTS

The median cumulative radiation dose administered was 54 Gy (range 30-72 Gy) and the median fraction dose was 1.8 Gy (range 1.8-3.0 Gy). All patients were subjected to a CBCT scan at least weekly (range 1-5/week). We observed intrathoracic changes in 83 % of the patients over the course of RT [58 % (41/71) regression, 17 % (12/71) progression, 20 % (14/71) atelectasis, 25 % (18/71) pleural effusion, 13 % (9/71) infiltrative changes, and 10 % (7/71) anatomical shift]. Nearly half, 45 % (32/71), of the patients had one intrathoracic soft tissue change, 22.5 % (16/71) had two, and three or more changes were observed in 15.5 % (11/71) of the patients. Plan modifications were performed in 60 % (43/71) of the patients. Visual volume reduction did correlate with the number of CBCT scans acquired (r = 0.313, p = 0.046) and with the timing of chemotherapy administration (r = 0.385, p = 0.013).

CONCLUSION

Weekly CBCT monitoring provides an adaptation advantage in patients with lung cancer. In this study, the monitoring allowed for plan adaptations due to tumor volume changes and to other anatomical changes.

Predictive treatment management: incorporating a predictive tumor response model into robust prospective treatment planning for non-small cell lung cancer

PURPOSE

We hypothesized that a treatment planning technique that incorporates predicted lung tumor regression into optimization, predictive treatment planning (PTP), could allow dose escalation to the residual tumor while maintaining coverage of the initial target without increasing dose to surrounding organs at risk (OARs).

METHODS AND MATERIALS

We created a model to estimate the geometric presence of residual tumors after radiation therapy using planning computed tomography (CT) and weekly cone beam CT scans of 5 lung cancer patients. For planning purposes, we modeled the dynamic process of tumor shrinkage by morphing the original planning target volume (PTVorig) in 3 equispaced steps to the predicted residue (PTVpred). Patients were treated with a uniform prescription dose to PTVorig. By contrast, PTP optimization started with the same prescription dose to PTVorig but linearly increased the dose at each step, until reaching the highest dose achievable to PTVpred consistent with OAR limits. This method is compared with midcourse adaptive replanning.

RESULTS

Initial parenchymal gross tumor volume (GTV) ranged from 3.6 to 186.5 cm(3). On average, the primary GTV and PTV decreased by 39% and 27%, respectively, at the end of treatment. The PTP approach gave PTVorig at least the prescription dose, and it increased the mean dose of the true residual tumor by an average of 6.0 Gy above the adaptive approach.

CONCLUSIONS

PTP, incorporating a tumor regression model from the start, represents a new approach to increase tumor dose without increasing toxicities, and reduce clinical workload compared with the adaptive approach, although model verification using per-patient midcourse imaging would be prudent.

Tumor volume as a potential imaging-based risk-stratification factor in trimodality therapy for locally advanced non-small cell lung cancer

INTRODUCTION

The role of trimodality therapy for locally advanced non-small cell lung cancer (NSCLC) continues to be defined. We hypothesized that imaging parameters on pre- and postradiation positron emission tomography (PET)-computed tomography (CT) imaging are prognostic for outcome after preoperative chemoradiotherapy (CRT)/resection/consolidation chemotherapy and could help risk-stratify patients in clinical trials.

METHODS

We enrolled 13 patients on a prospective clinical trial of trimodality therapy for resectable locally advanced NSCLC. PET-CT was acquired for radiation planning and after 45 Gy. Gross tumor volume (GTV) and standardized uptake value were measured at pre- and post-CRT time points and correlated with nodal pathologic complete response, loco-regional and/or distant progression, and overall survival. In addition, we evaluated the performance of automatic deformable image registration (ADIR) software for volumetric response assessment.

RESULTS

All patients responded with average total GTV reductions after 45 Gy of 43% (range: 27-64%). Pre- and post-CRT GTVs were highly correlated (R² = 0.9), and their respective median values divided the patients into the same two groups. ADIR measurements agreed closely with manually segmented post-CRT GTVs. Patients with GTV ≥ median (137 ml pre-CRT and 67 ml post-CRT) had 3-year progression-free survival (PFS) of 14% versus 75% for GTV less than median, a significant difference (p = 0.049). Pre- and post-CRT PET-standardized uptake value did not correlate significantly with pathologic complete response, PFS, or overall survival.

CONCLUSIONS

Preoperative CRT with carboplatin/docetaxel/45 Gy resulted in excellent response rates. In this exploratory analysis, pre- and post-CRT GTV predicted PFS in trimodality therapy, consistent with our earlier studies in a broader cohort of NSCLC. ADIR seems robust enough for volumetric response assessment in clinical trials.

Metabolism of tumors under treatment: mapping of metabolites with quantitative bioluminescence

BACKGROUND AND PURPOSE

The metabolic switch to aerobic glycolysis (Warburg effect) and enhanced lactate production is characteristic for aggressive tumor cells and is a co-determining factor for tumor response and treatment outcome. Thus analysis of the metabolic status under treatment is important to understand and improve treatment modalities.

MATERIALS AND METHODS

Metabolite concentrations were determined by the immersion of tumor sections in an ATP, lactate or glucose-depending luciferase-containing buffer system. Integrated light output is detected in a bioluminescent detection system.

RESULTS

Mice carrying tumor xenografts derived from A549 lung cancer cells were treated with the microtubule stabilizing agent patupilone, ionizing radiation or in combination. Lactate levels were significantly reduced and glucose levels drastically increased in comparison to untreated tumors. Interestingly, these changes were only minimal in tumors derived from patupilone-resistant but otherwise isogenic A549EpoB40 cells. ATP levels of all tumors tested did not change under any treatment. When compared with histological endpoints, basal and treatment-dependent changes of lactate levels in the different tumors mainly correlated with the proliferative activity and the tumor growth response to treatment.

CONCLUSIONS

This study shows that the tumor metabolism is responsive to different treatment modalities and could eventually be used as an early surrogate marker for treatment response.

Localization accuracy of the clinical target volume during image-guided radiotherapy of lung cancer

PURPOSE

To evaluate the position and shape of the originally defined clinical target volume (CTV) over the treatment course, and to assess the impact of gross tumor volume (GTV)-based online computed tomography (CT) guidance on CTV localization accuracy.

METHODS AND MATERIALS

Weekly breath-hold CT scans were acquired in 17 patients undergoing radiotherapy. Deformable registration was used to propagate the GTV and CTV from the first weekly CT image to all other weekly CT images. The on-treatment CT scans were registered rigidly to the planning CT scan based on the GTV location to simulate online guidance, and residual error in the CTV centroids and borders was calculated.

RESULTS

The mean GTV after 5 weeks relative to volume at the beginning of treatment was 77% ± 20%, whereas for the prescribed CTV, it was 92% ± 10%. The mean absolute residual error magnitude in the CTV centroid position after a GTV-based localization was 2.9 ± 3.0 mm, and it varied from 0.3 to 20.0 mm over all patients. Residual error of the CTV centroid was associated with GTV regression and anisotropy of regression during treatment (p = 0.02 and p = 0.03, respectively; Spearman rank correlation). A residual error in CTV border position greater than 2 mm was present in 77% of patients and 50% of fractions. Among these fractions, residual error of the CTV borders was 3.5 ± 1.6 mm (left-right), 3.1 ± 0.9 mm (anterior-posterior), and 6.4 ± 7.5 mm (superior-inferior).

CONCLUSIONS

Online guidance based on the visible GTV produces substantial error in CTV localization, particularly for highly regressing tumors. The results of this study will be useful in designing margins for CTV localization or for developing new online CTV localization strategies.

Large volume unresectable locally advanced non-small cell lung cancer: acute toxicity and initial outcome results with rapid arc

BACKGROUND

To report acute toxicity, initial outcome results and planning therapeutic parameters in radiation treatment of advanced lung cancer (stage III) with volumetric modulated arcs using RapidArc (RA).

METHODS

Twenty-four consecutive patients were treated with RA. All showed locally advanced non-small cell lung cancer with stage IIIA-IIIB and with large volumes (GTV:299 ± 175 cm3, PTV:818 ± 206 cm3). Dose prescription was 66Gy in 33 fractions to mean PTV. Delivery was performed with two partial arcs with a 6 MV photon beam.

RESULTS

From a dosimetric point of view, RA allowed us to respect most planning objectives on target volumes and organs at risk. In particular: for GTV D1% = 105.6 ± 1.7%, D99% = 96.7 ± 1.8%, D5%-D95% = 6.3 ± 1.4%; contra-lateral lung mean dose resulted in 13.7 ± 3.9Gy, for spinal cord D1% = 39.5 ± 4.0Gy, for heart V45Gy = 9.0 ± 7.0Gy, for esophagus D1% = 67.4 ± 2.2Gy. Delivery time was 133 ± 7s. At three months partial remission > 50% was observed in 56% of patients. Acute toxicities at 3 months showed 91% with grade 1 and 9% with grade 2 esophageal toxicity; 18% presented grade 1 and 9% with grade 2 pneumonia; no grade 3 acute toxicity was observed. The short follow-up does not allow assessment of local control and progression free survival.

CONCLUSIONS

RA proved to be a safe and advantageous treatment modality for NSCLC with large volumes. Long term observation of patients is needed to assess outcome and late toxicity.

Daily cone-beam computed tomography used to determine tumour shrinkage and localisation in lung cancer patients

PURPOSE/OBJECTIVE

Daily Cone-beam computed tomography (CBCT) in room imaging is used to determine tumour shrinkage during a full radiotherapy (RT) course. In addition, relative interfractional tumour and lymph node motion is determined for each RT fraction.

MATERIAL AND METHODS

From November 2009 to March 2010, 20 consecutive lung cancer patients (14 NSCLC, 6 SCLC) were followed with daily CBCT during RT. The gross tumour volume for lung tumour (GTV-t) was visible in all daily CBCT scans and was delineated at the beginning, at the tenth and the 20th fraction, and at the end of treatment. Whenever visible, the gross tumour volume for lymph nodes (GTV-n) was also delineated. The GTV-t and GTV-n volumes were determined. All patients were setup according to an online bony anatomy match. Retrospectively, matching based on the internal target volume (ITV), the GTV-t or the GTV-n was performed.

RESULTS

In eight patients, we observed a significant GTV-t shrinkage (15-40%) from the planning CT until the last CBCT. Only five patients presented a significant shrinkage (21-37%) in the GTV-n. Using the daily CBCT imaging, it was found that the mean value of the difference between a setup using the skin tattoo and an online matching using the ITV was 7.3±2.9 mm (3D vector in the direction of ITV). The mean difference between the ITV and bony anatomy matching was 3.0±1.3 mm. Finally, the mean distance between the GTV-t and the GTV-N was 2.9±1.6 mm.

CONCLUSION

One third of all patients with lung cancer undergoing chemo-RT achieved significant tumour shrinkage from planning CT until the end of the radiotherapy. Differences in GTV-t and GTV-n motion was observed and matching using the ITV including both GTV-t and GTV-n is therefore preferable.

Prospective, risk-adapted strategy of stereotactic body radiotherapy for early-stage non-small-cell lung cancer: results of a Phase II trial

PURPOSE

Validation of a prospective, risk-adapted strategy for early-stage non-small-cell lung cancer (NSCLC) patients treated with stereotactic body radiotherapy (SBRT).

METHODS AND MATERIALS

Patients with a T1-3N0M0 (American Joint Committee on Cancer 6th edition) NSCLC were accrued. Using the Radiation Therapy Oncology Group definition, patients were treated to a total dose of 60,Gy in three fractions for peripherally located lesions and four fractions for centrally located lesions. The primary endpoint was toxicity, graded according to the Radiation Therapy Oncology Group acute and late morbidity scoring system, and the National Cancer Institute Common Terminology Criteria for Adverse Events Version 3.0. Secondary endpoints were local control and survival.

RESULTS

A total of 40 patients were included, 17 with a centrally located lesion. The lung toxicity-free survival estimate at 2 years was 74% and was related to the location (central vs. peripheral) and the size of the target volume. No dose volumetric parameters could predict the occurrence of lung toxicity. One patient died because of treatment-related toxicity. The 1-year and 2-year local progression-free survival estimates were 97% and 84%, respectively, and were related to stage (T1 vs. T2) related (p = 0.006). Local failure was not more frequent for patients treated in four fractions. The 1-year local progression-free survival estimate dropped below 80% for lesions with a diameter of more than 4 cm.

CONCLUSION

The proposed risk-adapted strategy for both centrally and peripherally located lesions showed an acceptable toxicity profile while maintaining excellent local control rates. The correlation between local control and tumor diameter calls for the inclusion of tumor stage as a variable in future study design.

Daily megavoltage computed tomography in lung cancer radiotherapy: correlation between volumetric changes and local outcome

PURPOSE

To assess the predictive or comparative value of volumetric changes, measured on daily megavoltage computed tomography during radiotherapy for lung cancer.

PATIENTS AND METHODS

We included 80 patients with locally advanced non-small-cell lung cancer treated with image-guided intensity-modulated radiotherapy. The radiotherapy was combined with concurrent chemotherapy, combined with induction chemotherapy, or given as primary treatment. Patients entered two parallel studies with moderately hypofractionated radiotherapy. Tumor volume contouring was done on the daily acquired images. A regression coefficient was derived from the volumetric changes on megavoltage computed tomography, and its predictive value was validated. Logarithmic or polynomial fits were applied to the intratreatment changes to compare the different treatment schedules radiobiologically.

RESULTS

Regardless of the treatment type, a high regression coefficient during radiotherapy predicted for a significantly prolonged cause-specific local progression free-survival (p = 0.05). Significant differences were found in the response during radiotherapy. The significant difference in volumetric treatment response between radiotherapy with concurrent chemotherapy and radiotherapy plus induction chemotherapy translated to a superior long-term local progression-free survival for concurrent chemotherapy (p = 0.03). An enhancement ratio of 1.3 was measured for the used platinum/taxane doublet in comparison with radiotherapy alone.

CONCLUSION

Contouring on daily megavoltage computed tomography images during radiotherapy enabled us to predict the efficacy of a given treatment. The significant differences in volumetric response between treatment strategies makes it a possible tool for future schedule comparison.