Survey of malignant pleural mesothelioma treatment in Japan: Patterns of practice and clinical outcomes in tomotherapy facilities.

We conducted a nationwide survey of tomotherapy for malignant pleural mesothelioma (MPM) in Japan. Fifty-six facilities were surveyed and data on 31 patients treated curatively between 2008 and 2017 were collected from 14 facilities. Twenty patients received hemithorax irradiation after extrapleural pneumonectomy (EPP) (first group). Five patients received irradiation without EPP (second group), while six received salvage radiotherapy for local recurrence (salvage group). Among the seven patients not undergoing EPP, five (four in the second group and one in the salvage group) were treated with lung sparing pleural irradiation (LSPI) and two with irradiation to visible tumors. Two-year overall survival (OS) rates in the first and second groups were 33% and 60%, respectively (median, 13 vs 30 months, P = 0.82). In the first and second groups, 2-year local control (LC) rates were 53 and 67%, respectively (P = 0.54) and 2-year progression-free survival (PFS) rates were 16% and 60%, respectively (P = 0.07). Distant metastases occurred in 15 patients in the first group and three in the second group. In the salvage group, the median OS was 18 months. Recurrence was observed in the irradiated volume in four patients. The contralateral lung dose was higher in LSPI than in hemithorax irradiation plans (mean, 11.0 ± 2.2 vs 6.1 ± 3.1 Gy, P = 0.002). Grade 3 or 5 lung toxicity was observed in two patients receiving EPP and hemithorax irradiation, but not in those undergoing LSPI. In conclusion, outcomes of EPP and hemithorax irradiation were not satisfactory, whereas LSPI appeared promising and encouraging.

Surgery for malignant pleural mesothelioma after radiotherapy (SMART): final results from a single-centre, phase 2 trial.

BACKGROUND: A novel approach for managing malignant pleural mesothelioma, surgery for mesothelioma after radiotherapy (SMART), consisting of a short accelerated course of high-dose, hemithoracic, intensity modulated radiotherapy (IMRT) followed by extrapleural pneumonectomy was developed. The aim of this study was to evaluate the clinical feasibility of the SMART protocol. METHODS: In this single-centre, phase 2 trial, patients aged 18 years or older with an Eastern Cooperative Oncology Group performance status of 0-2, with histologically proven, resectable, cT1-3N0M0 disease who had previously untreated malignant pleural mesothelioma were eligible for inclusion. Patients received 25 Gy in five daily fractions over 1 week to the entire ipsilateral hemithorax with a concomitant 5 Gy boost to high risk areas followed by extrapleural pneumonectomy within 1 week. Adjuvant chemotherapy was offered to patients with ypN+ disease on final pathology. The primary endpoint was feasibility, which was defined as the number of patients with 30-day perioperative treatment-related death (grade 5 events) or morbidity (grade 3 or 4 events). A key secondary endpoint was cumulative incidence of distant recurrence. The final analysis was done on an intention-to-treat basis (including all eligible patients). This trial is registered with ClinicalTrials.gov, NCT00797719. FINDINGS: Between Nov 1, 2008, and Oct 31, 2019, 102 patients were enrolled onto the trial and 96 eligible patients were treated with SMART on protocol and included in the analysis. Extrapleural pneumonectomy was done at a median of 5 days (range 2-12) after completing IMRT. 47 (49%) patients had 30-day perioperative grade 3-4 events and one (1%) patient died within 30 days perioperatively (grade 5 event; pneumonia). After a median follow-up of 46·8 months (IQR 13·4-61·2), the 5-year cumulative incidence of distant recurrence was 62 (63·3% [95% CI 52·3-74·4]). The most common first sites of recurrence were the contralateral chest (33 [46%] of 72 patients) and the peritoneal cavity (32 [44%]). INTERPRETATION: Results from this study suggest that extrapleural pneumonectomy after radiotherapy can be done with good early and long-term results. However, minimising grade 4 events on the protocol is technically demanding and might affect survival beyond the post-operative period. FUNDING: Princess Margaret Hospital Foundation Mesothelioma Research Fund.

RapidPlan for Knowledge-Based Planning of Malignant Pleural Mesothelioma.

PURPOSE: Treatment planning for malignant pleural mesothelioma is a challenging task due to the relatively large size of the target and the need to spare critical organs that overlap with or are within the target volume. We aimed to develop a knowledge-based model using RapidPlan (RP) for patients with 2 intact lungs. METHODS AND MATERIALS: Data from 57 patients treated with volumetric modulated arc therapy were chosen for training the dose estimation model at a single dose level. The prescription dose was 50.4 Gy in 1.8 Gy fractions. The model was validated on 23 new patients by comparing the clinical plan to the RP. Time taken to plan the RP was compared with that for the clinical plan. RESULTS: For similar target coverage and plan inhomogeneity, RP significantly improved the sparing of the contralateral lung, heart, stomach, esophagus, and ipsilateral kidney. On average, the contralateral lung V5 Gy and V10 Gy were reduced by 13.9% (P < .001) and 7.9% (P < .001), respectively. The mean heart dose was reduced by 5 Gy (P < .001) and V30 Gy by 9.1% (P < .001). Mean dose to the stomach and esophagus were both reduced by 5 Gy (P < .001), and the ipsilateral kidney V18 Gy by 4.1% (P < .001). Mean total lung dose was reduced by 0.8 Gy with RP, which enabled an increase in prescription dose by 1 fraction Absolute volume of ipsilateral lung was adequately spared by both techniques, while sparing of all other organs, namely the cord, liver, and bowel, was not compromised with RP. Time taken with RP was 20 minutes, 45 seconds versus at least 4 hours for an experienced treatment planner. CONCLUSIONS: The RP model for malignant pleural mesothelioma showed improved sparing of critical organs with a reduced treatment planning time and increased prescription dose.

Radical Hemithoracic Radiotherapy Versus Palliative Radiotherapy in Non-metastatic Malignant Pleural Mesothelioma: Results from a Phase 3 Randomized Clinical Trial.

PURPOSE: We conducted a phase 3 randomized clinical trial to assess whether radical hemithoracic radiation therapy (RHR) compared with palliative radiation therapy (PR) can achieve overall survival (OS) advantages in patients with malignant pleural mesothelioma (MPM). METHODS AND MATERIALS: From August 2014 to May 2018, patients with histologically diagnosed nonmetastatic MPM, who underwent nonradical lung-sparing surgery and chemotherapy (CHT), were randomly assigned (1:1) to receive RHR or PR. RHR total dose to the involved pleural cavity was 50 Gy in 25 fractions, and the gross residual disease received a simultaneous integrated boost of 60 Gy. The primary endpoint was OS. Secondary endpoints were local control, distant metastasis-free survival, progression-free survival, and acute and late toxicity rates. A sample size of 108 patients considering a type I error (α) of 0.05 and a statistical power of 80% was calculated to prove that RHR could improve the 2-year OS. OS was estimated with the Kaplan-Meier method and the log-rank test (2-sided) tested differences between arms. The univariate and multivariate analyses were performed using Cox proportional hazard model. Possible prognostic factors investigated: age, sex, performance status, lung surgery, gross residual disease, and histology. RESULTS: One hundred eight patients were randomized: 53 to the PR arm and 55 to the RHR arm. Median follow-up was 14.6 months. The 2-year OS rate was 58% in the RHR arm versus 28% in the PR arm (hazard ratio, 0.54; 95% confidence interval, 0.31-0.95; P = .031). In the RHR arm: 11 patients experienced acute toxicity grade ≥3, 17 patients had grade 3 to 4 late toxicity. Nine patients experience a grade ≥2 pneumonitis, including 1 patient with grade 5. CONCLUSIONS: RHR significantly improves survival in patients with MPM treated with nonradical lung-sparing surgery and CHT compared with palliative treatments, although it is associated with a nonnegligible toxicity profile.

The Role of Extrapleural Pneumonectomy in Malignant Pleural Mesothelioma.

Extrapleural pneumonectomy (EPP) is the most extensive form of surgery for mesothelioma, involving en bloc resection of visceral and parietal pleura, lung, diaphragm and pericardium, with reconstruction of the pericardium and diaphragm. It can be performed safely in carefully selected patients. It should be performed in experienced centers as part of a multimodality treatment plan. The SMART approach, with a short course of induction hemithoracic radiation followed by EPP has demonstrated safety and value of hypofractionated hemithoracic radiation combined with complete macroscopic resection. We are conducting a clinical trial with oligofractionated hemithoracic radiation in early-stage mesothelioma.

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.

Locoregional control and toxicity after pleurectomy/decortication and intensity-modulated pleural radiation therapy in patients with malignant pleural mesothelioma.

BACKGROUND: Treatment of malignant pleural mesothelioma (MPM) represents a major challenge for oncologists. Multimodality treatment, which generally involves induction chemotherapy, surgery and radiotherapy have recently shown promising results. The aim of this study was to evaluate the locoregional control and toxicity of intensity modulated radiotherapy (IMRT) after pleurectomy and decortication (P/D) as part of trimodality therapy for patients with locally advanced MPM. METHODS: We prospectively analyzed data from 20 patients with MPM treated at a single tertiary-care institution. Initially every patient received induction chemotherapy with platinum-based chemotherapy. After chemotherapy, patients without progression underwent P/D, and if feasible, hemi-thoracic IMRT was administered at a planned dose of 50.4-54 Gy in 28-30 fractions and treated with 9-11 noncoplanar fields. RESULTS: A total of 15 of the 20 enrolled patients underwent P/D followed by IMRT to the hemi-thoracic cavity. The median total radiotherapy dose was 48.7 Gy (23.4-54 Gy). Radiation pneumonitis (RP) developed in nine patients (60%), and of these, two patients (13.3%) experienced G3 or G4 RP. The estimated locoregional-relapse-free survival at two years was 75.9%, and the main pattern of recurrence was distant (72.7%). For the entire cohort median follow-up was 22.7 months, median progression-free survival was 18.9 months and median overall survival 23.6 months. CONCLUSIONS: Platinum-based chemotherapy followed by lung-sparing surgery (P/D) and IMRT is a feasible and safe treatment modality that yields acceptable locoregional control in patients with locally advanced MPM; however, these results should be corroborated in larger studies.

Volumetric Modulated Arc Therapy After Lung Sparing Surgery for Malignant Pleural Mesothelioma: A Single Institution Experience.

INTRODUCTION: We investigated the possible role of volumetric modulated arc therapy (VMAT) in the setting of adjuvant treatment of malignant pleural mesothelioma (MPM) after lung-sparing surgery with pleurectomy and decortication. MATERIALS AND METHODS: Patients affected by MPM who had undergone pleurectomy and decortication and adjuvant radiotherapy with VMAT were included. The endpoints of the present analysis were local control, progression-free survival, and overall survival. Assessment of the variables affecting survival was performed using univariate and multivariate Cox proportional hazard models. RESULTS: A total of 49 patients were included in the present study. Of the 49 patients, 96% had been treated with a trimodality approach. Radiotherapy was delivered to a median dose of 44 Gy in 22 fractions (range, 22-59.4 Gy). The treatment was well tolerated, with just 2 grade 3 acute toxicities, 1 grade 5, and 2 grade 4 toxicities recorded during the follow-up period. The median follow-up period was 27.4 months. The local control rate at 12, 24, and 36 months was 75.2%, 67.4%, and 56.5%, respectively. The median progression-free survival was 14.9 months (95% confidence interval [CI], 7.5-25.2). The median overall survival was 21.5 months (95% CI, 15.3-37.1). On multivariate analysis, the administration of carboplatin- instead of cisplatin-based chemotherapy (hazard ratio, 2.97; 95% CI, 1.22-7.26; P = .017) and R2 resection (hazard ratio, 1.95; 95% CI, 1.27-2.99; P = .002) showed a negative correlation with overall survival. On univariate analysis, the percentage of the heart receiving >20 Gy and >30 was associated with the occurrence of late pneumonitis (P = .018 and P = .077). CONCLUSION: VMAT is feasible in the setting of MPM after lung-sparing surgery. The toxicity rates were reduced with this technique compared with historical data of older techniques. Local and distant failure remain a major issue to be addressed in future trials.