Intra-thoracic failure pattern and survival status following 3D conformal radiotherapy for non-small cell lung cancer: a preliminary report

An improved method for analyzing and reporting patterns of in-field recurrence after stereotactic ablative radiotherapy in early-stage non-small cell lung cancer

INTRODUCTION

Patterns of local, regional, and distant failure after stereotactic ablative radiotherapy (SABR) for early-stage non-small cell lung cancer (NSCLC) have been widely reported. However, reliable methods for analyzing causes of local failure are lacking. We describe a method for analyzing and reporting patterns of in-field recurrence after SABR, incorporating dosimetric parameters from initial treatment plan as well as geometric information from diagnostic images at recurrence.

MATERIAL AND METHODS

Diagnostic CT images at recurrence were registered with initial treatment planning images and radiation dose by deformable image registration. Recurrent gross tumor volume (rGTV) and centroid (geometric center of rGTV) were delineated. In-field failure was classified as centroids originating within the original planning target volume. Dose-volume histograms for each rGTV were used to further classify in-field recurrences as central high-dose (dose to 95% of rGTV [rGTVD95%] ≥95% of dose prescribed to PTV) or peripheral high-dose (rGTVD95% <95% of dose prescribed to PTV).

RESULTS

634 patients received SABR from 2004 to 2014 with 48 local recurrences. 35 of these had evaluable images with 16 in-field recurrences: 9 central high-dose, 6 peripheral high-dose, and 1 had both. Time to and volume of recurrence were not statistically different between central versus peripheral high-dose recurrences. However mean rGTV dose, mean centroid dose, and rGTVD95% were higher for central versus peripheral high-dose recurrences.

CONCLUSION

We report a standardized method for analysis and classification of in-field recurrence after SABR. There were more central as opposed to peripheral high-dose recurrences, suggesting biological rather than technical issues underlying majority of in-field failures.

Effect of Midtreatment PET/CT-Adapted Radiation Therapy With Concurrent Chemotherapy in Patients With Locally Advanced Non-Small-Cell Lung Cancer: A Phase 2 Clinical Trial

Importance

Our previous studies demonstrated that tumors significantly decrease in size and metabolic activity after delivery of 45 Gy of fractionated radiatiotherapy (RT), and that metabolic shrinkage is greater than anatomic shrinkage. This study aimed to determine whether 18F-fludeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) acquired during the course of treatment provides an opportunity to deliver higher-dose radiation to the more aggressive areas of the tumor to improve local tumor control without increasing RT-induced lung toxicity (RILT), and possibly improve survival.

Objective

To determine whether adaptive RT can target high-dose radiation to the FDG-avid tumor on midtreatment FDG-PET to improve local tumor control of locally advanced non-small-cell lung cancer (NSCLC).

Design, Setting, and Participants

A phase 2 clinical trial conducted at 2 academic medical centers with 42 patients who had inoperable or unresectable stage II to stage III NSCLC enrolled from November 2008, to May 2012. Patients with poor performance, more than 10% weight loss, poor lung function, and/or oxygen dependence were included, providing that the patients could tolerate the procedures of PET scanning and RT.

Intervention

Conformal RT was individualized to a fixed risk of RILT (grade >2) and adaptively escalated to the residual tumor defined on midtreatment FDG-PET up to a total dose of 86 Gy in 30 daily fractions. Medically fit patients received concurrent weekly carboplatin plus paclitaxel followed by 3 cycles of consolidation.

Main Outcomes and Measures

The primary end point was local tumor control. The trial was designed to achieve a 20% improvement in 2-year control from 34% of our prior clinical trial experience with 63 to 69 Gy in a similar patient population.

Results

The trial reached its accrual goal of 42 patients: median age, 63 years (range, 45-83 years); male, 28 (67%); smoker or former smoker, 39 (93%); stage III, 38 (90%). Median tumor dose delivered was 83 Gy (range, 63-86 Gy) in 30 daily fractions. Median follow-up for surviving patients was 47 months. The 2-year rates of infield and overall local regional tumor controls (ie, including isolated nodal failure) were 82% (95% CI, 62%-92%) and 62% (95% CI, 43%-77%), respectively. Median overall survival was 25 months (95% CI, 12-32 months). The 2-year and 5-year overall survival rates were 52% (95% CI, 36%-66%) and 30% (95% CI, 16%-45%), respectively.

Conclusions and Relevance

Adapting RT-escalated radiation dose to the FDG-avid tumor detected by midtreatment PET provided a favorable local-regional tumor control. The RTOG 1106 trial is an ongoing clinical trial to validate this finding in a randomized fashion.

Trial Registration

clinicaltrials.gov Identifier: NCT01190527.

Spontaneous pneumothorax due to bronchopleural fistula following reirradiation for locoregionally recurrent squamous cell lung cancer

Spontaneous pneumothorax following radiotherapy for pulmonary malignancy is an unusual clinical condition. Here, we report a case of a 78‐year‐old male suffering from dyspnea during radiotherapy for squamous cell lung cancer of the right main bronchus. Imaging studies and fiberoptic bronchoscopy revealed that pneumothorax was due to a bronchopleural fistula.

Systematic Endobronchial Ultrasound-guided Mediastinal Staging Versus Positron Emission Tomography for Comprehensive Mediastinal Staging in NSCLC Before Radical Radiotherapy of Non-small Cell Lung Cancer: A Pilot Study

Despite known limitations of positron emission tomography (PET) for mediastinal staging of non-small cell lung cancer (NSCLC), radiation treatment fields are generally based on PET-identified disease extent. However, no studies have examined the accuracy of FDG-PET/CT on a per-node basis in patients being considered for curative-intent radiotherapy in NSCLC.In a prospective trial, patients with NSCLC being considered for definitive thoracic radiotherapy (± systemic chemotherapy) underwent minimally invasive systematic mediastinal evaluation with endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) following noninvasive staging with integrated PET-CT.Thirty patients underwent EBUS-TBNA, with TBNA performed from a mean 2.5 lymph node (LN) stations per patient (median 3, range 1-5). Discordant findings between PET-CT and EBUS-TBNA were observed in 10 patients (33%, 95% CI 19%-51%). PET-occult LN metastases were demonstrated by EBUS in 4 patients, whereas a lesser extent of mediastinal involvement, compared with FDG-PET, was demonstrated by EBUS in 6 patients, including 2 patients downstaged from cN3 to pN2. LNs upstaged by EBUS were significantly smaller than nodes downstaged by EBUS, 7.5 mm (range 7-9) versus 12 mm (range 6-21), P = 0.005.A significant proportion of patients considered for definitive radiotherapy (+/-chemotherapy) undergoing systematic mediastinal evaluation with EBUS-TBNA in this study have an extent of mediastinal NSCLC involvement discordant with that indicated by PET-CT. Systematic EBUS-TBNA may aid in defining the extent of mediastinal involvement in NSCLC patients undergoing radiotherapy. Systematic EBUS-TBNA has the potential to contribute significantly to radiotherapy planning and delivery, by either identifying occult nodal metastases, or demonstrating FDG-avid LNs to be disease-free.

Pattern of failure after high-dose thoracic radiation for non-small cell lung cancer: the University of Michigan experience

PURPOSE

Our main purpose is to study the pattern of local failure for patients with non-small cell lung cancer treated with conformal therapy.

METHODS

This study included patients who failed locally and a matched group without failures after 3D conformal radiation per a radiation dose-escalation trial. Radiation doses ranged from 65.1 to 102.9 Gy in 2.1 Gy fractions, originally computed using an equivalent path length algorithm. The recurrent gross target volumes (RGTV) were contoured. The original and recurrent planning target volume (PTV and RPTV) were generated by 1 cm uniform expansion from GTV. DVHs and generalized equivalent uniform doses (EUD={Σ _i (d_i ) ^a }^1/a ) were computed. Marginal failures were defined for RGTVs covered by the original 10 to 90 % isodose surfaces.

RESULTS

There were no significant differences between the failed and control groups with regard to average original GTV volumes, GTV and PTV doses, and minimum PTV doses. Of the 18 RGTVs, four had marginal failure, 12 failed mostly within, and two failed outside of the original PTV. The mean EUDs were 57.1 Gy (95 % confidence interval (CI) 43.9-70.6) and 47.5 Gy (95 % CI 33.7-61.2), for the RGTVs and RPTVs, respectively, significantly below the prescribed doses (p=0.03). EUDs were less than 60 Gy for 39 % of the RGTVs and 56 % of the RPTVs.

CONCLUSIONS

Recurrent tumors had significantly lower doses than the prescribed dose suggesting that some of these failures could have been avoided with modern technology such as 4D CT simulation and image-guided radiation therapy.

How can we further improve radiotherapy for stage-III non-small-cell lung cancer?

Combined modality treatment in advanced NSCLC has produced some gain in treatment outcome. Local control as addressed by radiotherapy is still a significant site of failure. Doses higher than achieved by conventional conformal radiotherapy are shown to result in better control rates. Volume restriction seems to be the most important issue in dose escalation. Integration of PET imaging into target definition, omission of clinically uninvolved lymph-node areas and measures to decrease set-up and movement uncertainties are explored. Introduction of risk estimation based on dose-volume analysis for dose prescription may further optimise individual treatment.

Complex and controversial issues in locally advanced non-small cell lung carcinoma

Locally advanced non-small cell lung carcinoma (NSCLC) presents enormous challenges to clinicians and researchers. Because of the absence of metastatic disease, it is a potentially curable condition, greatly differentiating it from stage IV NSCLC. The median and actuarial survival rates are poor, though clearly improved in the past decade, and clearly better than several other types of locally advanced malignancies (e.g., pancreatic cancer, glioblastoma). As demonstrated in Table I, the combination of chemotherapy and radiotherapy has earned the designation of "standard of care" for most good-performance-status patients with locally advanced NSCLC. It is likely that improvements in radiotherapy have also contributed to the enhanced survival and local control rates in this disease. With concurrent chemoradiotherapy, the majority of patients can receive a substantial local response (Fig. 1). Many achieve durable local control, only to succumb to eventual distant metastatic failure. There remains much room for improvement, and there are several avenues for clinical and translational research that offer promise. These include new systemic chemotherapy options (and newer ways of combining these drugs with radiotherapy), improvements in radiotherapy fractionation and dose intensity, methods of protection from chemoradiotherapy toxicity, specific therapies to prevent brain metastatic failure, and the integration of biologically targeted molecules into chemoradiation programs. This article summarizes the advances in the treatment of locally advanced NSCLC over the past several decades and explores some of the many remaining controversies and areas for future investigation.