Intensity-modulated radiotherapy for resected mesothelioma: the Duke experience

Malignant Pleural Mesothelioma: Preliminary Toxicity Results of Adjuvant Radiotherapy Hypofractionation in a Prospective Trial (MESO-RT)

Malignant Pleural Mesothelioma (MPM) is a rare malignancy with an overall poor prognosis. The standard therapeutic strategy in early-stage disease is trimodality therapy. In this publication, we report the preliminary toxicity results of the first 20 patients treated with accelerated hypofractionated radiotherapy. Between July 2017 to June 2019, 20 MPM patients were enrolled and treated with accelerated hypofractionated radiotherapy using helical tomotherapy and intensity-modulated arc therapy. The prescription dose was 30 Gy in five daily fractions, while an inhomogeneous dose escalation to 40 Gy was prescribed based solely upon the presence of gross residual tumor. Only one case of G3 toxicity was reported, which was a bilateral pneumonitis that occurred two years after treatment probably due to superinfection. Median Time to Progression reached 18.2 months while one- and three-year Overall Survival rates were 85% (95% CI:60.4-94.9) and 49.5% (95% CI:26.5-68.9), respectively. Treatment of the intact lung with pleural intensity-modulated arc irradiation is a novel treatment strategy that appears to be safe, feasible, and without a high grade of lung toxicity. Survival rates and Time to Progression are encouraging.

Use of Continuous Positive Airway Pressure (CPAP) to Limit Diaphragm Motion-A Novel Approach for Definitive Radiation Therapy for Inoperable Pleural Mesothelioma: A Pilot Study

Simple Summary

Radiotherapy is an important part of the multimodality approach to treating malignant pleural mesothelioma. In recent studies there is a new trend to treat patients with intact lungs instead of following surgery. This treatment creates significant concerns regarding lung toxicity. We describe two methods to reduce that toxicity. One is the use of constant pulmonary airway pressure (CPAP) to inflate the lungs during treatment. The second is utilizing a novel method of planning and delivering radiotherapy called volumetric modulated arc therapy (VMAT).

Abstract

Malignant pleural mesothelioma (MPM) is a deadly disease and radiotherapy (RT) plays an important role in its management. Recent developments in technique have made it is possible to deliver RT to MPM in the intact lung. However, it is imperative to reduce normal lung doses. We present a pilot study examining the use of CPAP and VMAT radiotherapy to reduce toxicity when treating MPM, involving three consecutive patients with MPM, not amenable to surgery, who were treated according to Helsinki committee approval. Patients were simulated using four-dimentional CT simulation with the assistance of CPAP lung inflation, then were treated using both IMRT and VMAT techniques. Radiation lung dose was optimized based on accepted lung dose constraints. Patients were followed for toxicity as well as local control and survival. Results: Three patients were treated with CPAP-based IMRT treatment. These patients tolerated the treatment and DVH constraints were able to be met. The comparison plans among the four VMAT arcs and the IMRT static field treatment were able to accomplish the treatment planning objectives without significant advantages with either technique. The treatment combined with CPAP reduced the normal lung dose in MPM patients with intact lungs. This technique is worthy of further investigation.

Radiation Therapy for Malignant Pleural Mesothelioma

The treatment of malignant pleural mesothelioma with radiation therapy has always been a technical challenge. For many years, radiation therapy was delivered after extrapleural pneumonectomy with acceptable results. As the utilization of pleurectomy/decortication increased, techniques, such as pleural intensity-modulated radiation therapy (IMRT) have been introduced. The experience with these techniques have grown and multiple trials using IMRT, both in the setting of extrapleural pneumonectomy or pleurectomy, are being conducted to assess its effectiveness.

Fatal Radiation Pneumonitis: Literature Review and Case Series

Purpose

Fatal radiation pneumonitis is a rare event. In recent years, higher incidences of grade 5 pneumonitis have been reported. Based on 3 cases in our clinic, a literature review was performed to assess specific clinical features and risk factors for fatal pneumonitis.

Methods and Materials

Three patients with nonsmall cell lung cancer were treated with conventionally fractionated radiation therapy, 2 with volumetric modulated arc therapy and one with intensity modulated radiation therapy. All 3 patients had high volumes of 5 Gy in the total lung and contralateral lungs. Patients died of pneumonitis between 2 and 5 months after the end of radiation therapy. A literature review focused on grade 5 pneumonitis was performed for conventionally fractioned and stereotactic radiation therapy for lung cancer.

Results

Patients with grade 5 pneumonitis develop symptoms sooner than lower grade pneumonitis. Symptoms often do not respond to steroid treatment or return after steroid taper. Imaging features extend beyond the high dose area and involve the contralateral lung. Dosimetric risk factors include both low dose and high dose lung volumes. For patients undergoing stereotactic radiation therapy interstitial lung disease has been described as a risk factor.

Conclusions

Despite decades of investigating radiation pneumonitis, the question of the optimum dose distribution in the lung, a large dose to a small volume versus a small dose to a large volume, is still unresolved. When both low and high dose lung volume constraints are followed, the risk for grade 5 pneumonitis has been shown to be low even with intensity modulated radiation therapy and concurrent chemotherapy. In addition to dose factors, underlying clinical and radiographic parameters play an important role for the development of grade 5 pneumonitis.

Return to intended oncologic treatment after surgery for malignant pleural mesothelioma

OBJECTIVE

Trimodality therapy may prolong survival for patients with resectable malignant pleural mesothelioma. However, many patients are unable to complete therapy. We sought to identify risk factors for failing to complete adjuvant intensity-modulated radiation therapy after cytoreduction for malignant pleural mesothelioma.

METHODS

We performed a single-institution review of those who received an extrapleural pneumonectomy or pleurectomy/decortication for malignant pleural mesothelioma from 2004 to 2017. Multivariable logistic regression was used to assess preoperative or intraoperative risk factors associated with failing to complete adjuvant intensity-modulated radiation therapy.

RESULTS

A total of 160 patients were identified, among whom 94 (59%) received an extrapleural pneumonectomy and 66 (41%) received a pleurectomy/decortication. Adjuvant intensity-modulated radiation therapy was completed among 105 patients (66%). Reasons for failing to complete adjuvant intensity-modulated radiation therapy included mortality (19), dose constraints (21), postoperative morbidity or delayed recovery (11), and refused or unknown status (4). On multivariable analysis, American Society of Anesthesiologists 3+ classification (P = .002) and smoking history (P = .022) were associated with failure to complete adjuvant intensity-modulated radiation therapy, whereas forced expiratory volume in 1 second 70% or less of predicted and pStage 4 (T4) were significant on univariable analysis only. Other factors, including extrapleural pneumonectomy or pleurectomy/decortication, margin status, age, and histology, were not associated with receiving adjuvant intensity-modulated radiation therapy.

CONCLUSIONS

Many patients are unable to complete adjuvant intensity-modulated radiation therapy after cytoreduction. Failure to complete adjuvant intensity-modulated radiation therapy was associated with worse preoperative comorbidity, but not the type of surgery or margin status.

Intensity-modulated radiotherapy is a safe and effective treatment for localized malignant pleural mesothelioma

Background

Malignant pleural mesothelioma (MPM) is a rare disease and management of localized disease is controversial. Radiotherapy has been shown to be useful after extrapleural pneumonectomy (EPP), as well as with less aggressive surgery. As no reports of the treatment of this disease have ever been published from Israel, we report our experience with MPM and intensity‐modulated radiotherapy (IMRT).

Methods

The complete medical records of patients treated for MPM at the Rabin Medical Center from 1 August 2007 to 31 March 2016 were reviewed. Twenty‐seven patients were treated with IMRT, either post‐EPP or without EPP. Patients received 54 Gy in 2 Gy fractions using the restricted field IMRT technique. Chemotherapy was administered sequentially in 26% of patients. Patients were followed up from the date of diagnosis to death or treatment failure.

Results

Seventy‐eight percent of patients had the epithelioid subtype. Nearly all patients were male (85%) and 90% of non‐surgical patients were administered chemotherapy compared to 56% of post‐EPP patients. All patients completed therapy and only 16% had grade 1–2 radiation pneumonitis, with no incidence of grade 3 or higher. The median follow‐up was 22 months and the mean overall survival was 34.9 months. The mean time to progression following radiation therapy was 26.7 months. The mean time to local and distant failure was 19 and 16 months, respectively.

Conclusions

IMRT for localized pleural mesothelioma is a tolerable and effective therapy both post‐EPP or without surgery. These results suggest that future investigation in this area is required.

Preoperative contralateral lung radiation dose is associated with postoperative pulmonary toxicity in patients with locally advanced non-small cell lung cancer treated with trimodality therapy

PURPOSE

In patients with non-small cell lung cancer (NSCLC) who undergo trimodality therapy (chemoradiation followed by surgical resection), it is unknown whether limiting preoperative radiation dose to the uninvolved lung reduces postsurgical morbidity. This study evaluated whether radiation fall-off dose parameters to the contralateral lung that is unaffected by NSCLC are associated with postoperative complications in NSCLC patients treated with trimodality therapy.

METHODS AND MATERIALS

We retrospectively reviewed NSCLC patients who underwent trimodality therapy between March 2008 and October 2016, with available restored digital radiation plans. Fischer's exact test was used to assess associations between patient and treatment characteristics and the development of treatment-related toxicity. Spearman rank correlation was used to measure the strength of association between dosimetric parameters.

RESULTS

Forty-six patients were identified who received trimodality therapy with intensity modulated radiation (median, 59.4 Gy; range, 45-70) and concurrent platinum doublet chemotherapy, followed by surgical resection. The median age was 64.9 years (range, 45.6-81.6). The median follow-up time was 1.9 years (range, 0.3-8.4). Twenty-four (52.2%) patients developed any-grade pulmonary toxicity and 14 (30.4%) patients developed grade 2+ pulmonary toxicity. There was an increased incidence of any-grade pulmonary toxicity in patients with contralateral lung volume receiving at least 20 Gy (V20) ≥7% compared with <7% (90%, n = 9 vs 41.7%, n = 15; P = .01). Similarly, contralateral lung V10 ≥20% was associated with an increased rate of any-grade pulmonary toxicity compared with V10 <20% (80%, n = 12 vs 38.7%, n = 12; P = .01). Pneumonectomy/bilobectomy was associated with grade 2+ pulmonary toxicity (P = .04).

CONCLUSIONS

Patients who received a higher radiation fall-off dose volume parameter (V20 ≥7% and V10 ≥20%) to the contralateral uninvolved lung had a higher incidence of any-grade postoperative pulmonary toxicity. Limiting radiation fall-off dose to the uninvolved lung may be an important modifiable radiation parameter in limiting postoperative toxicity in trimodality patients.

Proton beam therapy for malignant pleural mesothelioma

Malignant pleural mesothelioma (MPM) is a rare disease with a poor prognosis. Surgical techniques have made incremental improvements over the last few decades while new systemic therapies, including immunotherapies, show promise as potentially effective novel therapies. Radiation therapy has historically been used only in the palliative setting or as adjuvant therapy after extrapleural pneumonectomy, but recent advances in treatment planning and delivery techniques utilizing intensity-modulated radiation therapy and more recently pencil-beam scanning (PBS) proton therapy, have enabled the delivery of radiation therapy as neoadjuvant or adjuvant therapy after an extended pleurectomy and decortication or as definitive therapy for patients with recurrent or unresectable disease. In particular, PBS proton therapy has the potential to deliver high doses of irradiation to the entire effected pleura while significantly reducing doses to nearby organs at risk. This article describes the evolution of radiation therapy for MPM and details how whole-pleural PBS proton therapy is delivered to patients at the Maryland Proton Treatment Center.

Trimodality Treatment of Malignant Pleural Mesothelioma: An Institutional Review

OBJECTIVE

Malignant pleural mesothelioma (MPM) is a deadly disease with varying treatment options. This study retrospectively describes treatment practices at the University of Washington Medical System from 1980 to 2011, and evaluates the impact of trimodality therapy and radiation (photon and neutron) on survival.

METHODS

A retrospective study was conducted on patients treated for MPM. Univariate and multivariate methods were utilized to evaluate potential factors associated with survival. Treatments received and baseline characteristics were included. Survival analysis of trimodality therapy was performed using a propensity score method to control for baseline characteristics.

RESULTS

Among 78 eligible patients, the median age at diagnosis was 59 years and the median survival was 13.7 months. On multivariate analysis, the significant predictors of improved survival were age, smoking history, location, and receipt of radiation therapy or chemotherapy. In the 48 patients receiving radiation therapy, the difference in survival between neutron therapy and non-neutron therapy patients was not statistically significant: hazard ratio, 1.20 (95% confidence interval, 0.68-2.13), P=0.52. Patients receiving trimodality therapy were more likely to have early-stage disease (60% vs. 30%) and epithelioid histology (86% vs. 58%). In a propensity score-weighted Cox proportional hazards model, trimodality therapy patients had improved overall survival, hazard ratio 0.45, P=0.004, median 14.6 versus 8.6 months.

CONCLUSIONS

Trimodality therapy was significantly associated with prolonged survival in patients with MPM, even when adjusting for baseline patient factors. Radiation therapy was associated with improved survival, but the modality of radiation therapy used was not associated with outcome.

High dose irradiation after pleurectomy/decortication or biopsy for pleural mesothelioma treatment

PURPOSE

The role played by radiation therapy after pleurectomy/decortication or surgical biopsy in malignant pleural mesothelioma is uncertain. We treated patients with accelerated hypofractionated radiotherapy using helical tomotherapy and intensity-modulated arc therapy in an attempt to keep lung toxicity to a minimum. The present study reports the feasibility and toxicity of this approach.

MATERIAL AND METHODS

Between 2008 and 2012, 36 patients with malignant pleural mesothelioma underwent accelerated hypofractionated radiotherapy to the hemithorax after pleurectomy/decortication (19 patients) or biopsy (17 patients). The prescription dose was 25Gy in five fractions over 5 consecutive days.

RESULTS

We observed three patients with G3 pneumonitis, five cases of grade 2 dyspnea and six cases of grade 2 cough. The median follow-up was 37 months (range: 3-54 months). The median overall survival for patients who underwent pleurectomy/decortication followed by radiotherapy was 21.6 months [95% confidence interval (95% CI): 15.5-24.1] compared to 19.4 months for patients not submitted to surgery.

CONCLUSION

Treatment of intact lung with pleural intensity-modulated arc irradiation in malignant pleural mesothelioma patients with malignant pleural mesothelioma proved safe and feasible, with an acceptable rate of pneumonitis. Survival rates were encouraging for both biopsy-only and pleurectomy/decortication groups. We are currently conducting a phase II dose escalation trial in a similar patient setting to prospectively evaluate the impact of radiotherapy on toxicity, disease-free survival and overall survival.

Radiotherapy for the treatment of malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive disease that continues to be associated with poor outcomes. Although, traditionally this disease is considered to be resistant to radiotherapy, more recent evidence suggests that radiotherapy can produce positive outcomes. Over the past 15 years, the development of new, highly conformal radiotherapy techniques, such as intensity-modulated radiation therapy (IMRT), has enabled investigators to optimise the delivery of high-dose radiotherapy to the whole of the hemithorax. Prospective single-arm trials have shown that the median survival of patients who have completed high-dose hemithoracic radiotherapy after extrapleural pneumonectomy could reach 23·9-39·4 months independent of the chemotherapeutic response, suggesting that IMRT could potentially have an intrinsic benefit to this subset of patients. These observations have led to a change in practice, with the introduction of adjuvant pleural IMRT after pleurectomy-decortication and the development of induction-accelerated hemithoracic IMRT followed by extrapleural pneumonectomy. This Review focuses on recent observations on the role of radiotherapy in the treatment of malignant pleural mesothelioma, with particular emphasis on the results of clinical trials that evaluate the role of high-dose hemithoracic radiotherapy.

Proton Therapy for Malignant Pleural Mesothelioma: A Three Case Series Describing the Clinical and Dosimetric Advantages of Proton-Based Therapy

Malignant pleural mesothelioma (MPM) is a malignancy of the pleural cavity that typically presents at an advanced stage. Due to its large, circumferential clinical target volume (CTV) and proximity to major structures, including the heart and contralateral lung, delivering hemithoracic intensity-modulated radiotherapy (IMRT) with photon therapy to achieve loco-regional control following macroscopic complete resection is challenging. Intensity-modulated proton therapy (IMPT) has been shown to be a method for achieving higher therapeutic doses while limiting exposure to organs at risk (OARs), but patient outcomes after treatment have yet to be reported. We present three patients who received IMPT to 54 Gy after extrapleural pneumonectomy (EPP), with two patients receiving boosts to 66 and 60 Gy. All three tolerated treatment well and received doses to OARs markedly lower than those seen in comparison volumetric-modulated arc therapy (VMAT) IMRT photon plans. Radiation pneumonitis, a highly morbid and potentially fatal toxicity in patients receiving thoracic radiotherapy, was not observed even with boost treatments. In practice, IMPT appears to match dosimetric predictions as a feasible and safer alternative to photon IMRT-based radiotherapy. 

The role of radical radiotherapy in the management of malignant pleural mesothelioma: A systematic review

Malignant pleural mesothelioma (MPM) is a devastating disease with limited treatment options and a dismal prognosis. Attempts to employ radical radiotherapy in this disease have been limited by the complex shape of the pleura and the dose restrictions necessitated by the close proximity of radiosensitive structures. Recent shifts towards a 'lung sparing' surgical approach in MPM have further heightened these challenges. The aim of this systematic review is to assess recent advances in radiotherapy planning and delivery, to ascertain how these developments have impacted on the feasibility of delivering photon-based, high-dose radiotherapy with radical intent in MPM. Three electronic databases were searched and a total of 249 articles reviewed. The challenge of generating high quality, practice-defining data for diseases such as MPM was highlighted by the identification of just two randomised studies. Much of the literature consisted of low quality, retrospective data with small cohorts and inconsistent reporting on radiotherapy techniques and dosimetry. Nevertheless, a number of prospective phase II studies were identified to suggest that radical doses of radiotherapy can be delivered safely after a lung sparing procedure in MPM, reporting encouraging survival data and acceptable levels of toxicity.

Malignant pleural mesothelioma - Pleural cavity irradiation after decortication with helical tomotherapy

BACKGROUND

Malignant pleural mesothelioma (MPM) is a rare and aggressive disease that poses a treatment challenge in spite of recent technical developments. The aim of this retrospective analysis is to assess the feasibility of administering intensity-modulated radiotherapy (IMRT) to the pleural cavity using helical tomotherapy in patients who had undergone pleurectomy/decortication (P/D) and also the resulting toxicity levels.

PATIENTS AND METHODS

Ten patients who had MPM and had undergone P/D were treated with pleural cavity irradiation that included a median dose of 52.2 Gy using helical tomotherapy. The median age of the patients was 53 years (31-74). In addition to clinical and diagnostic findings from regular follow-up examinations, we evaluated the dose distribution for other organs at risk to assess treatment in relation to toxicity, with special regard for the underlying intact lung.

RESULTS

The mean lung dose on the treatment site was 32.8 Gy (±6.8). The V_20 Gy was 71.7% (±17.2). No treatment-related toxicity that exceeded grade III according to common toxicity criteria (CTC) was observed. Median progression-free survival (PFS) was 13 months with a median overall survival (OAS) of 19 months.

CONCLUSION

The findings of this analysis provide data indicating that sparing the underlying lung in patients with MPM after P/D is not only feasible with helical tomotherapy, but that this treatment also causes reasonably few side effects.

Induction chemotherapy vs post-operative adjuvant therapy for malignant pleural mesothelioma

INTRODUCTION

Malignant pleural mesothelioma (MPM) is an aggressive neoplasia. Multidisciplinary treatments, including the association of induction and/or adjuvant therapeutic regimens with surgery, have been reported to give encouraging results. Current therapeutic options are not well standardized yet, especially regarding the best association between surgery and medical treatments. The present review aims to assess safety, efficacy and outcomes of different therapies for MPM. Areas covered: This article focuses on the multimodality treatment of mesothelioma. A systematic review was performed by using electronic databases to identify studies that considered induction and adjuvant approaches in MPM therapy in a multidisciplinary setting, including surgery. Endpoints included overall survival, disease free survival, disease recurrence, and complications. Expert commentary: This systematic review offers a comprehensive view of current multidisciplinary therapeutic strategies for MPM, suggesting that multimodality therapy offers acceptable outcomes with better results reported for trimodality approaches. Individualization of care for each patient is fundamental in choosing the most appropriate treatment. The growing complexity of treatment protocols mandates that MPM patients be referred to specialized Centers, in which every component of the interdisciplinary team can provide the necessary expertise and quality of care.

Malignant pleural mesothelioma: adjuvant therapy with radiation therapy

It is a challenge to treat malignant pleural mesothelioma with radiation therapy (RT). For many years, conventional RT was delivered after extrapleural pneumonectomy (EPP) with acceptable results. However, the benefit of RT has never been definitively proven. Intensity modulated radiation therapy (IMRT) has been used, but some of the early experiences revealed fatal toxicity. As experience has increased, it now appears that RT, particularly with IMRT, is both feasible and effective.

Intensity modulated radiation therapy after extra-pleural pneumonectomy for malignant pleural mesothelioma is feasible without fatal pulmonary toxicity and provides good survival

AIM

To analyze patterns of failure, toxicity, relapse-free survival (RFS), and overall survival (OS) in malignant pleural mesothelioma (MPM) patients treated with intensity-modulated radiation therapy following extrapleural pneumonectomy (EPP).

METHODS

We reviewed 18 charts of patients with MPM from 2005 to 2014 who underwent EPP followed by hemithoracic intensity-modulated radiation therapy. Intensity-modulated radiation therapy dose delivery adhered to published lung dose constraints. Kaplan-Meier curves were used to assess the RFS and OS. Median survival times are reported for both RFS and OS.

RESULTS

Median age was 65 years (range: 40-76 years). Chemotherapy was administered in four neo-adjuvant and seven adjuvant patients. Pathological American Joint Committee on Cancer stages II, III, IV, surgical margin, lympho-vascular space, pericardium, and chest wall involvement were seen in 3, 12, 3, 9, 7, 12 and 3 patients, respectively. The majority of the patients received 45 Gy in 25 fractions. The mean lung dose was 7.14 Gy (range: 5 Gy-9.3 Gy). The mean V20 was 2.23%. At a median follow-up of 3 years, eight patients were alive (44%); 10 experienced relapse (56%). Median RFS and OS were 24.4 months (95% CI: >16.3 months) and 38.2 months (95% CI: 17.4-78.1 months), respectively. Acute toxicities were fatigue, dermatitis, nausea, esophagitis/dysphagia, cough, and dyspnea on exertion. No grade III, IV, or fatal pulmonary toxicities were observed.

CONCLUSION

Intensity-modulated radiation therapy following EPP for MPM resulted in RFS and OS comparable to the published literature without significant toxicity.

Improved Outcomes with Modern Lung-Sparing Trimodality Therapy in Patients with Malignant Pleural Mesothelioma

INTRODUCTION

Higher target conformity and better sparing of organs at risk with modern radiotherapy (RT) may result in higher tumor control and less toxicity. In this study, we compare our institutional multimodality therapy experience of adjuvant chemotherapy and hemithoracic intensity-modulated pleural RT (IMPRINT) with previously used adjuvant conventional RT (CONV) in patients with malignant pleural mesothelioma (MPM) treated with lung-sparing pleurectomy/decortication (P/D).

METHODS

We analyzed 209 patients who underwent P/D and adjuvant RT (131 who received CONV and 78 who received IMPRINT) for MPM between 1974 and 2015. The primary end point was overall survival (OS). The Kaplan-Meier method and Cox proportional hazards model were used to calculate OS; competing risks analysis was performed for local failure-free survival and progression-free survival. Univariate analysis and multivariate analysis were performed with relevant clinical and treatment factors.

RESULTS

The median age was 64 years, and 80% of the patients were male. Patients receiving IMPRINT had significantly higher rates of the epithelial histological type, advanced pathological stage, and chemotherapy treatment. OS was significantly higher after IMPRINT (median 20.2 versus 12.3 months, p = 0.001). Higher Karnofsky performance score, epithelioid histological type, macroscopically complete resection, and use of chemotherapy/IMPRINT were found to be significant factors for longer OS in multivariate analysis. No significant predictive factors were identified for local failure or progression. Grade 2 or higher esophagitis developed in fewer patients after IMPRINT than after CONV (23% versus 47%).

CONCLUSIONS

Trimodality therapy including adjuvant hemithoracic IMPRINT, chemotherapy, and P/D is associated with promising OS rates and decreased toxicity in patients with MPM. Dose constraints should be applied vigilantly to minimize serious adverse events.

Validation and Modification of a Prediction Model for Acute Cardiac Events in Patients With Breast Cancer Treated With Radiotherapy Based on Three-Dimensional Dose Distributions to Cardiac Substructures

Purpose

A relationship between mean heart dose (MHD) and acute coronary event (ACE) rate was reported in a study of patients with breast cancer (BC). The main objective of our cohort study was to validate this relationship and investigate if other dose-distribution parameters are better predictors for ACEs than MHD.

Patients and Methods

The cohort consisted of 910 consecutive female patients with BC treated with radiotherapy (RT) after breast-conserving surgery. The primary end point was cumulative incidence of ACEs within 9 years of follow-up. Both MHD and various dose-distribution parameters of the cardiac substructures were collected from three-dimensional computed tomography planning data.

Results

The median MHD was 2.37 Gy (range, 0.51 to 15.25 Gy). The median follow-up time was 7.6 years (range, 0.1 to 10.1 years), during which 30 patients experienced an ACE. The cumulative incidence of ACE increased by 16.5% per Gy (95% CI, 0.6 to 35.0; P = .042). Analysis showed that the volume of the left ventricle receiving 5 Gy (LV-V5) was the most important prognostic dose-volume parameter. The most optimal multivariable normal tissue complication probability model for ACEs consisted of LV-V5, age, and weighted ACE risk score per patient (c-statistic, 0.83; 95% CI, 0.75 to 0.91).

Conclusion

A significant dose-effect relationship was found for ACEs within 9 years after RT. Using MHD, the relative increase per Gy was similar to that reported in the previous study. In addition, LV-V5 seemed to be a better predictor for ACEs than MHD. This study confirms the importance of reducing exposure of the heart to radiation to avoid excess risk of ACEs after radiotherapy for BC.

Tomotherapy PET-guided dose escalation: A dosimetric feasibility study for patients with malignant pleural mesothelioma

AIM

The aim of this study was to investigate whether a safe escalation of the dose to the pleural cavity and PET/CT-positive areas in patients with unresectable malignant pleural mesothelioma (MPM) is possible using helical tomotherapy (HT).

MATERIAL AND METHODS

We selected 12 patients with MPM. Three planning strategies were investigated. In the first strategy (standard treatment), treated comprised a prescribed median dose to the planning target volume (PTV) boost (PTV1) of 64.5 Gy (range: 56 Gy/28 fractions to 66 Gy/30 fractions) and 51 Gy (range: 50.4 Gy/28 fractions to 54 Gy/30 fractions) to the pleura PTV (PTV2). Thereafter, for each patient, two dose escalation plans were generated prescribing 62.5 and 70 Gy (2.5 and 2.8 Gy/fraction, respectively) to the PTV1 and 56 Gy (2.24 Gy/fraction) to the PTV2, in 25 fractions. Dose-volume histogram (DVH) constraints and normal tissue complication probability (NTCP) calculations were used to evaluate the differences between the plans.

RESULTS

For all plans, the 95 % PTVs received at least 95 % of the prescribed dose. For all patients, it was possible to perform the dose escalation in accordance with the Quantitative Analysis of Normal Tissue Effects in the Clinic (QUANTEC) constraints for organs at risk (OARs). The average contralateral lung dose was < 8 Gy. NTCP values for OARs did not increase significantly compared with the standard treatment (p > 0.05), except for the ipsilateral lung. For all plans, the lung volume ratio was strongly correlated with the V20, V30, and V40 DVHs of the lung (p < 0.0003) and with the lung mean dose (p < 0.0001).

CONCLUSION

The results of this study suggest that by using HT it is possible to safely escalate the dose delivery to at least 62.5 Gy in PET-positive areas while treating the pleural cavity to 56 Gy in 25 fractions without significantly increasing the dose to the surrounding normal organs.

Radiation therapy for malignant pleural mesothelioma

Malignant pleural mesothelioma is an aggressive tumor where the ability to control the primary tumor (local control) presents a significant challenge. External beam radiation has the potential to improve local control when following established safe and effective protocols. Radiation is primarily used as adjuvant treatment after extrapleural pneumonectomy or pleurectomy/decortication and as palliative treatment in some cases. The target volume for radiotherapy of malignant pleural mesothelioma can be quite extensive and thus toxicity is its chief limitation.

Stereotactic body radiation therapy for a new lung cancer arising after pneumonectomy: dosimetric evaluation and pulmonary toxicity

OBJECTIVE

To evaluate the tolerance of stereotactic body radiation therapy (SBRT) for the treatment of secondary lung tumours in patients who underwent previous pneumonectomy.

METHODS

12 patients were retrospectively analysed. The median maximum tumour diameter was 2.1 cm (1-4.5 cm). The median planning target volume was 20.7 cm(3) (2.4-101.2 cm(3)). Five patients were treated with a single fraction of 26 Gy and seven patients with fractionated schemes (3 × 10 Gy, 4 × 10 Gy, 4 × 12 Gy). Lung toxicity, correlated with volume (V) of lung receiving >5, >10 and >20 Gy, local control and survival rate were assessed. Median follow-up was 28 months.

RESULTS

None of the patients experienced pulmonary toxicity > grade 2 at the median dosimetric lung parameters of V5, V10 and V20 of 23.1% (range 10.7-56.7%), 7.3% (2.2-27.2%) and 2.7% (0.7-10.9%), respectively. No patients required oxygen or had deterioration of the performance status during follow-up if not as a result of clinical progression of disease. The local control probability at 2 years was 64.5%, and the overall survival at 2 years was 80%.

CONCLUSION

SBRT appears to be a safe and effective modality for treating patients with a second lung tumour after pneumonectomy.

ADVANCES IN KNOWLEDGE

Our results and similar literature results show that when keeping V5, V10 V20 <50%, <20% and <7%, respectively, the risk of significant lung toxicity is acceptable. Our experience also shows that biologically effective dose 10 >100 Gy, necessary for high local control rate, can be reached while complying with the dose constraints for most patients.

Optimizing hemithoracic pleural intensity-modulated radiation therapy for malignant pleural mesothelioma

The treatment of malignant pleural mesothelioma (MPM) remains challenging. Optimal management for resectable patients involves an aggressive approach, frequently using trimodality therapy. Historically, poor tumor control and profound pulmonary toxicity prevented conventional radiation therapy from being widely used. The advent of intensity-modulated radiation therapy was a major development in the delivery of radiation for MPM in the adjuvant setting, improving target coverage and dose homogeneity while maintaining acceptable toxicity profiles. Nevertheless, there remains a significant risk of severe pulmonary toxicity, ameliorated by careful target delineation, treatment planning and proactive toxicity management. Innovative technology, including arc therapy, simultaneous integrated boosts and proton therapy as well as neodjuvant delivery of radiation followed by pneumonectomy are being actively investigated to improve outcomes in the treatment of MPM.

Multimodality therapy for malignant pleural mesothelioma: surgery plus chemoradiotherapy?

Malignant pleural mesothelioma, well known for its association with asbestos exposure, is an aggressive cancer of the pleura with poor prognosis if left untreated. There is no defined standard of care, but with curative surgery-based multimodality therapy, long-term survival has been documented. In addition to radiation and/or chemotherapy, multimodality therapy includes one of two operations (extrapleural pneumonectomy or radical pleurectomy/decortication) performed with the goal of resecting all gross disease. Ongoing trials are evaluating various treatment strategies involving radical resection, chemotherapy, radiation, intracavitary chemotherapy, photodynamic therapy and immunologic/biologic agents. Improvement in early diagnosis, targeted treatment and adjuvant therapy to control micrometastatic disease are needed to improve outcomes for patients with this challenging disease.

Local and systemic therapies for malignant pleural mesothelioma

OPINION STATEMENT

Malignant pleural mesothelioma (MPM) is a challenging disease to treat with median overall survival times ranging between 9-17 months for all stages of disease. Recent clinical trials have improved our understanding of the biology of MPM. However, survival results are still not ideal. For early-stage MPM, patients should be evaluated for trimodality therapy in an experienced cancer center. If treating off-protocol, MPM patients should receive a surgical staging evaluation. The decision to proceed with surgical resection also should be considered after an extensive and thorough pulmonary and cardiac evaluation. If deemed a good surgical candidate, patients should receive surgical resection (pleurectomy/decortication or extrapleural pneumonectomy), adjuvant radiation therapy (hemithoracic external beam or intensity modulated radiation therapy), and either neoadjuvant or adjuvant chemotherapy (cisplatin-pemetrexed for 4 cycles). The optimal precise sequence of the trimodality is unclear and should be decided upon by a multidisciplinary consensus for each individual patient. In general, clinical trial participation should be encouraged. Several trials are currently underway to examine intraoperative therapies, vaccines, immunotherapy additions, and novel radiation therapy techniques. Advances in the field of MPM are reliant on participation in clinical trials and identifying biomarkers that are predictive for response to systemic therapies and prognostic for survival benefit.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Hemithoracic radiation therapy after extrapleural pneumonectomy for malignant pleural mesothelioma: Toxicity and outcomes at an Australian institution

INTRODUCTION

We aim to report the outcome of patients with malignant pleural mesothelioma who underwent extrapleural pneumonectomy (EPP) and adjuvant hemithoracic radiotherapy with or without chemotherapy at a single Australian institution.

METHOD

Between July 2004 and March 2013, 53 patients were referred for radiation treatment following EPP, of whom 49 were suitable for adjuvant treatment. Radiation treatment initially involved a 3D conformal, mixed electron/photon technique, delivering 45-50.4 Gy in 25-28 fractions (31 patients) and subsequently a nine-field intensity-modulated radiotherapy technique, delivering 50.4-54 Gy in 28-30 fractions (18 patients). Fifty-five per cent of patients also received pre-operative chemotherapy. We assessed toxicity, disease-specific and overall survival in patients who commenced radiation treatment.

RESULTS

Forty-one patients (84%) completed treatment as prescribed. Six patients stopped prematurely due to toxicity, and two with disease progression. Most patients discontinuing due to toxicity received over 90% of the prescribed dose. Common acute toxicities included nausea, fatigue, anorexia and dermatitis. Severe early toxicities were rare. Late toxicities were uncommon, with the exception of a persistent elevation in liver enzymes in those with right-sided disease. Neither clinical hepatitis nor radiation pneumonitis was documented. With a median follow up of 18.7 months, median disease-free and overall survival were 21.6 and 30.5 months, respectively, and 2-year overall survival was 57.3%.

CONCLUSION

Hemithoracic radiotherapy following EPP, although associated with significant early toxicity, is well tolerated. Most patients complete the prescribed treatment, and clinically significant late toxicities are rare.

Updated patterns of failure after multimodality therapy for malignant pleural mesothelioma

OBJECTIVE

We have previously described patterns of failure after extrapleural pneumonectomy and multimodality therapy for malignant pleural mesothelioma and sought to update our results with a larger cohort of recent patients.

METHODS

A total of 169 patients underwent extrapleural pneumonectomy without preoperative chemotherapy between 2001 and 2010. Data for treatment, recurrence, and survival were determined from medical records. A thoracic radiologist reviewed postoperative computed tomography or positron emission tomography computed tomography scans to determine sites of recurrence. Time to recurrence was estimated by the Kaplan-Meier method. Rates were compared using the Fisher exact test.

RESULTS

The median age of patients was 62 years. Histology on final pathology was epithelial for 104 patients (62%) and nonepithelial for 65 patients (38%). A total of 132 patients (78%) received heated intraoperative chemotherapy; 77 patients (45%) received adjuvant chemotherapy, and 71 patients (42%) received adjuvant radiation therapy. Most chemotherapy regimens included platinum or pemetrexed. Median radiation therapy dose was 54 Gy. Among 158 evaluable patients, a recurrence developed in 118 (75%). Median follow-up was 83 months, median time to recurrence was 13.1 months, and median survival was 15 months. Sites of first recurrence were in the ipsilateral hemithorax or mediastinum for 54% of patients, in the abdomen for 39% of patients, in the contralateral hemithorax for 28% of patients, and in other distant sites for 5% of patients. Some patients had simultaneous recurrences in multiple sites.

CONCLUSIONS

The most common site of recurrence after extrapleural pneumonectomy and planned multimodality therapy remains the ipsilateral hemithorax (including mediastinum), and true distant failure (other than the abdomen or contralateral hemithorax) remains unusual. The distribution of recurrences is strikingly similar to our prior report.

Hemithoracic intensity modulated radiation therapy after pleurectomy/decortication for malignant pleural mesothelioma: toxicity, patterns of failure, and a matched survival analysis

PURPOSE

To investigate safety, efficacy, and recurrence after hemithoracic intensity modulated radiation therapy after pleurectomy/decortication (PD-IMRT) and after extrapleural pneumonectomy (EPP-IMRT).

METHODS AND MATERIALS

In 2009-2013, 24 patients with mesothelioma underwent PD-IMRT to the involved hemithorax to a dose of 45 Gy, with an optional integrated boost; 22 also received chemotherapy. Toxicity was scored with the Common Terminology Criteria for Adverse Events v4.0. Pulmonary function was compared at baseline, after surgery, and after IMRT. Kaplan-Meier analysis was used to calculate overall survival (OS), progression-free survival (PFS), time to locoregional failure, and time to distant metastasis. Failures were in-field, marginal, or out of field. Outcomes were compared with those of 24 patients, matched for age, nodal status, performance status, and chemotherapy, who had received EPP-IMRT.

RESULTS

Median follow-up time was 12.2 months. Grade 3 toxicity rates were 8% skin and 8% pulmonary. Pulmonary function declined from baseline to after surgery (by 21% for forced vital capacity, 16% for forced expiratory volume in 1 second, and 19% for lung diffusion of carbon monoxide [P for all = .01]) and declined still further after IMRT (by 31% for forced vital capacity [P=.02], 25% for forced expiratory volume in 1 second [P=.01], and 30% for lung diffusion of carbon monoxide [P=.01]). The OS and PFS rates were 76% and 67%, respectively, at 1 year and 56% and 34% at 2 years. Median OS (28.4 vs 14.2 months, P=.04) and median PFS (16.4 vs 8.2 months, P=.01) favored PD-IMRT versus EPP-IMRT. No differences were found in grade 4-5 toxicity (0 of 24 vs 3 of 24, P=.23), median time to locoregional failure (18.7 months vs not reached, P not calculable), or median time to distant metastasis (18.8 vs 11.8 months, P=.12).

CONCLUSIONS

Hemithoracic intensity modulated radiation therapy after pleurectomy/decortication produced little high-grade toxicity but led to progressive declines in pulmonary function; OS and PFS were better in PD-IMRT compared with EPP-IMRT.

IMRT sparing of normal tissues in locoregional treatment of breast cancer

Purpose

This clinical study was designed to prospectively evaluate the acute and moderately-late cardiac and lung toxicities of intensity modulated radiation therapy delivered by helical tomotherapy (IMRT-HT) for locoregional breast radiation treatment including the internal mammary nodes (IMN).

Material/methods

30 patients with stage III breast cancers have been accrued in this study. All patients received adjuvant chemotherapy. Target volumes were defined as follows: the PTV included breast/chest wall, axillary level II, III, infra/supraclavicular, IM nodes CTVs plus 3 mm margins. The heart with subunits and the lungs were defined as critical organs. Dose to PTV was 50 Gy in 25 fractions. Acute toxicities were assessed every week and 2 weeks post treatment using the CTCAE v3.0.scale. The moderately-late toxicities were assessed clinically plus by cardiac myoview perfusion tests scheduled at baseline, 3 and 12-month follow-up, as well a CT chest at the 6 month follow-up. The data analysis is descriptive.

Results

All participants completed the 5-week course of radiation without interruption. Skin erythema was modest and mainly grade 1–2 between the 3rd and the 5th week of radiation treatment. Only 4/30 patients experienced grade 3 skin reactions, mostly seen 2 weeks post radiation. Only 5 patients demonstrated grade 1 or 2 dyspnea, but 3 of them already had symptoms pre-radiation treatment. With a median follow-up of 58 (24–76) months, there have been infrequent moderately-late side effects. Most were grade 1 and were sometimes present at the baseline assessment. Cardiac myoview tests done at baseline and 1-year follow-up for 15 out of 18 left sided breast cancers did not show any abnormalities related to radiation. The 6-month follow-up chest CT-scans done for 25 out of 30 patients showed minimal anterior lung fibrosis for 7 patients and were completely normal for the other 18. No locoregional recurrence has been recorded and the 5-year survival is 78% (95% CI: 70-97%).

Conclusion

IMRT-HT for locoregional breast radiation is very well tolerated with minimal acute or moderately-late side effects. Cardiac and respiratory tests did not show any strong evidence of significant treatment related abnormalities.

Trial registration

clinicaltrials.gov: http://NCT00508352.

[Helical tomotherapy in the treatment of malignant pleural mesothelioma: The impact of low doses on pulmonary and oesophageal toxicity]

PURPOSE

To evaluate the adjuvant treatment of malignant pleural mesothelioma by helical tomotherapy and the impact of low doses on esophageal and pulmonary toxicity.

PATIENTS AND METHODS

Between June 2007 and May 2011, 29 patients diagnosed with malignant pleural mesothelioma received adjuvant radiotherapy by helical tomotherapy. The median age was 63 years (34-72). Histologically, 83 % of patients had epithelioid malignant pleural mesothelioma. Clinically, 45 % of patients were T3 and 55 % N0. Eighty six percent of the patients were treated by extrapleural pneumonectomy and 35 % received neoadjuvant chemotherapy with platinum and pemetrexed. The median dose in the pneumonectomy cavity was 50Gy at 2Gy/fraction.

RESULTS

The mean follow-up was 2.3 years after diagnosis. Overall survival at 1 and 2 years was 65 and 36 % respectively. The median survival from diagnosis was 18 months. Median lung volumes receiving 2, 5, 10, 13, 15 and 20Gy (V2, V5, V10, V13, V15 and V20) were 100, 98, 52, 36, 19 and 5 %. The median of the mean remaining lung dose was 11Gy. Two patients died of pulmonary complications, three patients had grade 3 lung toxicity, while esophageal grade 3-4 toxicity was observed in three other patients. No significant impact of clinical characteristics and dosimetric parameters were found on pulmonary toxicity, however a V10≥50 %, a V15≥15 % and mean lung dose of 10Gy or more had a tendency to be predictive of pulmonary toxicity (P<0.1). Moreover, in our analysis, the mean lung dose seems to have a significant impact on esophageal toxicity (P=0.03) as well as low doses to the controlateral lung: V5, V10 and V13 (P<0.05).

CONCLUSION

Helical tomotherapy is a promising technique in the multimodality treatment of malignant pleural mesothelioma. Low doses received by the contralateral lung appear to be the limiting factor. A dosimetric comparison with volumetric modulated arctherapy techniques would be interesting in this setting.

Role of new radiation techniques in the treatment of pleural mesothelioma

Malignant pleural mesothelioma (MPM) is an aggressive neoplasm arising from the surface serosal cells of the pleural cavity. Surgery remains the main therapeutic standard in the treatment of MPM with the goal of complete gross cytoreduction of the tumor. Because MPM is a diffuse disease affecting the entire mesothelial lining of the hemithorax, surgery alone can rarely achieve adequate tumor-free resection margins. The surgical choices are pleurectomy/decortication (P/D) or extrapleural pneumonectomy (EPP). Radiotherapy (RT) is usually applied postoperatively with the aim to improve local control. However, the efficacy of RT is limited by the large volume of the target to be irradiated (tumor and pleural cavity) and the radiosensitivity of the nearby organs (heart, liver, lung, spinal cord, and esophagus). These factors have historically limited the effective radiation doses that can be given to the patient. There is no role for radical RT alone, but the role of RT as part of multimodality therapy is discussed. After EPP adjuvant RT to the entire hemithorax can reduce the recurrence rate and is well tolerated if strict limits to the dose to contralateral lung are applied: the V20 and V5 (the percent volume of the lung receiving more than 20Gy and 5Gy of radiation) correlate with increased lung toxicity. The use of modern sophisticated techniques allows good target coverage, more conformal high dose delivery, and clinically relevant normal tissue sparing.

Patterns of failure, toxicity, and survival after extrapleural pneumonectomy and hemithoracic intensity-modulated radiation therapy for malignant pleural mesothelioma

INTRODUCTION

We investigated safety, efficacy, and recurrence after postoperative hemithoracic intensity-modulated radiation therapy (IMRT) in patients with malignant pleural mesothelioma treated with extrapleural pneumonectomy (EPP), during the past decade at a single institution.

METHODS

In 2001-2011, 136 consecutive patients with malignant pleural mesothelioma underwent EPP with planned adjuvant IMRT. Eighty-six patients (64%) underwent hemithoracic IMRT; the rest were not eligible because of postoperative complications, disease progression, or poor performance status. We assessed toxicity, survival, and patterns of failure in these 86 patients. Toxicity was scored with the Common Terminology Criteria for Adverse Events version 4.0; survival outcomes were estimated with the Kaplan-Meier method; and locoregional patterns of failure were classified as in-field, marginal, or out-of-field. Risk factors related to survival were identified by univariate and multivariate Cox regression analysis.

RESULTS

Median overall survival time for all 86 patients receiving IMRT was 14.7 months. Toxicity rates of grade of 3 or more were: skin 17%, lung 12%, heart 2.3%, and gastrointestinal toxicity 16%. Five patients experienced grade 5 pulmonary toxicity. Rates of locoregional recurrence-free survival, distant metastasis-free survival, and overall survival (OS) were 88%, 55%, and 55% at 1 year and 71%, 40%, and 32% at 2 years. On multivariate analysis, pretreatment forced expiratory volume in 1 second, nonepithelioid histology, and nodal status were associated with distant metastasis-free survival and OS.

CONCLUSION

IMRT after EPP is associated with low rates of locoregional recurrence, though some patients experience life-threatening lung toxicity. Tumor histology and nodal status can be helpful in identifying patients for this aggressive treatment.

Tomotherapy after pleurectomy/decortication or biopsy for malignant pleural mesothelioma allows the delivery of high dose of radiation in patients with intact lung

INTRODUCTION

This study aimed to assess the safety of high doses of radiation delivered with tomotherapy to the intact lung after radical pleurectomy/decortication or biopsy for malignant pleural mesothelioma (MPM).

METHODS

Twenty-eight patients were enrolled in this prospective study and underwent adjuvant or definitive tomotherapy after radical pleurectomy/decortication (n = 20) or pleural biopsy (n = 8) for MPM. The dose prescribed to the planning target volume, defined as the entire hemithorax, including chest-wall incisions and drain sites and excluding the intact lung, was 50 Gy delivered in 25 fractions. All patients underwent fluorodeoxyglucose-positron emission tomography for staging after surgery. Any fluorodeoxyglucose-avid areas or regions of particular concern for residual disease were given a simultaneous boost of radiotherapy to 60 Gy. Specific lung dosimetric parameters were reported. Toxicity was graded using the modified Common Toxicity Criteria version 3.0.

RESULTS

The median follow-up was of 19 months (range, 6-29 months). Five patients (17.8%) experienced severe respiratory symptoms corresponding to grade 2 pneumonitis in three cases, and grade 3 pneumonitis in two cases. No fatal respiratory toxicity was reported. Controlateral lung V5 was strongly correlated with the risk of pneumonitis. Patients who developed grade 2 and 3 pneumonitis had a higher controlateral lung V5 (mean V5=32%) than those without pneumonitis (mean V5=17%) (p=0.002). Other two grade 3 toxicities were registered: one severe pain to the chest wall, and one severe thrombocytopenia.

CONCLUSIONS

Tomotherapy allows the safe delivery of high dose of radiation to the hemithorax of MPM patients with intact lung.

Effect of increasing experience on dosimetric and clinical outcomes in the management of malignant pleural mesothelioma with intensity-modulated radiation therapy

PURPOSE

To assess the impact of increasing experience with intensity-modulated radiation therapy (IMRT) after extrapleural pneumonectomy (EPP) for malignant pleural mesothelioma (MPM).

METHODS AND MATERIALS

The records of all patients who received IMRT following EPP at Duke University Medical Center between 2005 and 2010 were reviewed. Target volumes included the preoperative extent of the pleural space, chest wall incisions, involved nodal stations, and a boost to close/positive surgical margins if applicable. Patients were typically treated with 9-11 beams with gantry angles, collimator rotations, and beam apertures manually fixed to avoid the contalateral lung and to optimize target coverage. Toxicity was graded retrospectively using National Cancer Institute common toxicity criteria version 4.0. Target coverage and contralateral lung irradiation were evaluated over time by using linear regression. Local control, disease-free survival, and overall survival rates were estimated using the Kaplan-Meier method.

RESULTS

Thirty patients received IMRT following EPP; 21 patients also received systemic chemotherapy. Median follow-up was 15 months. The median dose prescribed to the entire ipsilateral hemithorax was 45 Gy (range, 40-50.4 Gy) with a boost of 8-25 Gy in 9 patients. Median survival was 23.2 months. Two-year local control, disease-free survival, and overall survival rates were 47%, 34%, and 50%, respectively. Increasing experience planning MPM cases was associated with improved coverage of planning target volumes (P=.04). Similarly, mean lung dose (P<.01) and lung V5 (volume receiving 5 Gy or more; P<.01) values decreased with increasing experience. Lung toxicity developed after IMRT in 4 (13%) patients at a median of 2.2 months after RT (three grade 3-4 and one grade 5). Lung toxicity developed in 4 of the initial 15 patients vs none of the last 15 patients treated.

CONCLUSIONS

With increasing experience, target volume coverage improved and dose to the contralateral lung decreased. Rates of pulmonary toxicity were relatively low. However, both local and distant control rates remained suboptimal.

Pleural intensity-modulated radiotherapy for malignant pleural mesothelioma

PURPOSE

In patients with malignant pleural mesothelioma who are unable to undergo pneumonectomy, it is difficult to deliver tumoricidal radiation doses to the pleura without significant toxicity. We have implemented a technique of using intensity-modulated radiotherapy (IMRT) to treat these patients, and we report the feasibility and toxicity of this approach.

METHODS AND MATERIALS

Between 2005 and 2010, 36 patients with malignant pleural mesothelioma and two intact lungs (i.e., no previous pneumonectomy) were treated with pleural IMRT to the hemithorax (median dose, 46.8 Gy; range, 41.4-50.4) at Memorial Sloan-Kettering Cancer Center.

RESULTS

Of the 36 patients, 56% had right-sided tumors. The histologic type was epithelial in 78%, sarcomatoid in 6%, and mixed in 17%, and 6% had Stage I, 28% had Stage II, 33% had Stage III, and 33% had Stage IV. Thirty-two patients (89%) received induction chemotherapy (mostly cisplatin and pemetrexed); 56% underwent pleurectomy/decortication before IMRT and 44% did not undergo resection. Of the 36 patients evaluable for acute toxicity, 7 (20%) had Grade 3 or worse pneumonitis (including 1 death) and 2 had Grade 3 fatigue. In 30 patients assessable for late toxicity, 5 had continuing Grade 3 pneumonitis. For patients treated with surgery, the 1- and 2-year survival rate was 75% and 53%, and the median survival was 26 months. For patients who did not undergo surgical resection, the 1- and 2-year survival rate was 69% and 28%, and the median survival was 17 months.

CONCLUSIONS

Treating the intact lung with pleural IMRT in patients with malignant pleural mesothelioma is a safe and feasible treatment option with an acceptable rate of pneumonitis. Additionally, the survival rates were encouraging in our retrospective series, particularly for the patients who underwent pleurectomy/decortication. We have initiated a Phase II trial of induction chemotherapy with pemetrexed and cisplatin with or without pleurectomy/decortication, followed by pleural IMRT to prospectively evaluate the toxicity and survival.

Adjuvant intensity-modulated proton therapy in malignant pleural mesothelioma. A comparison with intensity-modulated radiotherapy and a spot size variation assessment

PURPOSE

Intensity-modulated radiation therapy (IMRT) is the state-of-the-art treatment for patients with malignant pleural mesothelioma (MPM). The goal of this work was to assess whether intensity-modulated proton therapy (IMPT) could further improve the dosimetric results allowed by IMRT.

PATIENTS AND METHODS

We re-planned 7 MPM cases using both photons and protons, by carrying out IMRT and IMPT plans. For both techniques, conventional dose comparisons and normal tissue complication probability (NTCP) analysis were performed. In 3 cases, additional IMPT plans were generated with different beam dimensions.

RESULTS

IMPT allowed a slight improvement in target coverage and clear advantages in dose conformity (p < 0.001) and dose homogeneity (p = 0.01). Better organ at risk (OAR) sparing was obtained with IMPT, in particular for the liver (D(mean) reduction of 9.5 Gy, p = 0.001) and ipsilateral kidney (V(20) reduction of 58%, p = 0.001), together with a very large reduction of mean dose for the contralateral lung (0.2 Gy vs 6.1 Gy, p = 0.0001). NTCP values for the liver showed a systematic superiority of IMPT with respect to IMRT for both the esophagus (average NTCP 14% vs. 30.5%) and the ipsilateral kidney (p = 0.001). Concerning plans obtained with different spot dimensions, a slight loss of target coverage was observed along with sigma increase, while maintaining OAR irradiation always under planning constraints.

CONCLUSION

Results suggest that IMPT allows better OAR sparing with respect to IMRT, mainly for the liver, ipsilateral kidney, and contralateral lung. The use of a spot dimension larger than 3 × 3 mm (up to 9 × 9 mm) does not compromise dosimetric results and allows a shorter delivery time.

A novel correction factor based on extended volume to complement the conformity index

OBJECTIVE

We propose a modified conformity index (MCI), based on extended volume, that improves on existing indices by correcting for the insensitivity of previous conformity indices to reference dose shape to assess the quality of high-precision radiation therapy and present an evaluation of its application.

METHODS

In this paper, the MCI is similar to the conformity index suggested by Paddick (CI(Paddick)), but with a different correction factor. It is shown for three cases: with an extended target volume, with an extended reference dose volume and without an extended volume. Extended volume is generated by expanding the original volume by 0.1-1.1 cm isotropically. Focusing on the simulation model, measurements of MCI employ a sphere target and three types of reference doses: a sphere, an ellipsoid and a cube. We can constrain the potential advantage of the new index by comparing MCI with CI(Paddick). The measurements of MCI in head-neck cancers treated with intensity-modulated radiation therapy and volumetric-modulated arc therapy provide a window on its clinical practice.

RESULTS

The results of MCI for a simulation model and clinical practice are presented and the measurements are corrected for limited spatial resolution. The three types of MCI agree with each other, and comparisons between the MCI and CI(Paddick) are also provided.

CONCLUSION

The results from our analysis show that the proposed MCI can provide more objective and accurate conformity measurement for high-precision radiation therapy. In combination with a dose-volume histogram, it will be a more useful conformity index.

Intensity-modulated radiotherapy after extrapleural pneumonectomy in the combined-modality treatment of malignant pleural mesothelioma

INTRODUCTION

Local therapy is becoming increasingly important as a part of the definitive treatment for malignant pleural mesothelioma after extrapleural pneumonectomy (EPP) because of the emergence of trimodality therapy consisted of chemotherapy, EPP, and adjuvant radiotherapy. Herein, we explore the current evidence and indications for adjuvant intensity-modulated radiotherapy (IMRT), as well as how to further improve this technique and adapt new technology in the delivering adjuvant radiotherapy in the setting of trimodality therapy.

METHODS

A systematic review of relevant studies identified through PubMed, ISI Web of Knowledge (Web of Science), the Cochrane Library, and the National Guideline Clearinghouse search engines was performed.

RESULTS

Local control remains poor despite the inclusion of conventional adjuvant radiation therapy in trimodality therapy. This can be improved by the delivery of adjuvant IMRT. However, IMRT can be associated with severe pulmonary toxicity if the radiation dose to the remaining lung is not kept to a very low level. This is especially true when patients are receiving chemotherapy. New advances in technology can allow for lower doses to the contralateral lung, decreased treatment delivery time, and improved target dose coverage.

CONCLUSION

Excellent local control can be achieved through adjuvant IMRT after EPP for malignant pleural mesothelioma. Severe pulmonary toxicity may be avoided by setting stringent dose constraints for the contralateral lung. This can be aided by the advances in technology. Post-treatment surveillance may be reliably conducted by periodical [18F]-fluorodeoxyglucose-positron emission tomography imaging.