A gut microbiota rheostat forecasts responsiveness to PD-L1 and VEGF blockade in mesothelioma.

Malignant mesothelioma is a rare tumour caused by asbestos exposure that originates mainly from the pleural lining or the peritoneum. Treatment options are limited, and the prognosis is dismal. Although immune checkpoint blockade (ICB) can improve survival outcomes, the determinants of responsiveness remain elusive. Here, we report the outcomes of a multi-centre phase II clinical trial (MiST4, NCT03654833) evaluating atezolizumab and bevacizumab (AtzBev) in patients with relapsed mesothelioma. We also use tumour tissue and gut microbiome sequencing, as well as tumour spatial immunophenotyping to identify factors associated with treatment response. MIST4 met its primary endpoint with 50% 12-week disease control, and the treatment was tolerable. Aneuploidy, notably uniparental disomy (UPD), homologous recombination deficiency (HRD), epithelial-mesenchymal transition and inflammation with CD68+ monocytes were identified as tumour-intrinsic resistance factors. The log-ratio of gut-resident microbial genera positively correlated with radiological response to AtzBev and CD8+ T cell infiltration, but was inversely correlated with UPD, HRD and tumour infiltration by CD68+ monocytes. In summary, a model is proposed in which both intrinsic and extrinsic determinants in mesothelioma cooperate to modify the tumour microenvironment and confer clinical sensitivity to AtzBev. Gut microbiota represent a potentially modifiable factor with potential to improve immunotherapy outcomes for individuals with this cancer of unmet need.

[Malignant mesothelioma of the vaginal testis: diagnostic and therapeutic considerations]. / Le mésothéliome malin de la vaginale testiculaire : aspects diagnostiques et thérapeutiques.

Mesothelioma of the testicular vagina is a rare malignant tumour, most often discovered by chance. The rarity of this type of tumour has not led to the development of specific guidelines. Median survival is estimated at 30 months. The lack of data and official recommendations makes surgical and medical management and follow-up difficult. Men who have not undergone radical orchiectomy die very rapidly after diagnosis. The remission rate at 1 year post-orchidectomy is 47 %, the recurrence rate at 1 year is 53 % and 92 % of relapses occur within 5 years post-operatively. The treatment option of hemiscrotectomy in the first instance has rarely been used; a second-look resection with negative margins may be proposed. The usefulness of adjuvant chemotherapy and/or radiotherapy has not been clearly demonstrated. Local recurrence is accompanied by metastasis in 85 % of cases. In the case of metastatic cancer (15 %), the retro-peritoneal, inguinal and iliac lymph nodes may be invaded. Follow-up by injected thoraco-abdomino-pelvic CT scan is recommended every 3 months for 2 years, then once a year for 3 years, for a total of 5 years of close follow-up. The long-term recurrence rate is 3 %.

Le mésothéliome de la vaginale testiculaire est une tumeur maligne rare et souvent de découverte fortuite. Sa rareté d'apparition n'a pas permis de développer des recommandations spécifiques. La survie médiane est estimée à 30 mois. Le manque de recommandations officielles rend sa prise en charge chirurgicale, médicale et son suivi difficiles. Les hommes n'ayant pas bénéficié d'orchidectomie radicale décèdent très rapidement après le diagnostic. Le taux de rémission à 1 an post-orchidectomie est de 47 %, le taux de récurrence à 1 an est de 53 % et 92 % des rechutes se font endéans les 5 ans post-opératoires. L'option thérapeutique par hémi-scrotectomie en première intention a rarement été pratiquée, une résection de «second look¼ en marges saines peut être proposée. L'utilité d'une chimiothérapie et/ou d'une radiothérapie adjuvante n'a pas été clairement démontrée. Une rechute locale est accompagnée de métastases dans 85 % des cas. En cas de cancer d'emblée métastatique (15 %), les relais ganglionnaires rétro-péritonéaux, inguinaux et iliaques peuvent être envahis. Un suivi par scanner thoraco-abdomino-pelvien injecté est recommandé tous les 3 mois pendant 2 ans, puis 1 fois par an pendant 3 ans pour un total de 5 ans. Le taux de récidive au long cours est de 3 %.

Mesothelioma: molecular pathology and biomarkers.

Diffuse mesotheliomas are characterized by recurrent genomic alterations involving tumor suppressors and epigenetic regulators such as BAP1, CDKN2A, MTAP, and NF2. Depending on the differential diagnosis as informed by histologic assessment, one can apply the appropriate immunohistochemical and/or molecular panels to reach the correct pathologic diagnosis, sometimes even in cases with limited tissues. Biomarkers aid in the diagnosis of mesothelioma in the following scenarios: 1) For a tumor that is overtly malignant, how can one distinguish mesothelioma from other tumors? 2) For a mesothelial proliferation, how can one distinguish mesothelioma from a reactive process? To distinguish mesotheliomas from carcinomas, at least two positive and two negative markers are currently recommended. To distinguish sarcomatoid mesothelioma from pleomorphic carcinoma, even more markers-and sometimes molecular testing-are needed. To distinguish mesothelioma from reactive mesothelial conditions, useful immunohistochemical biomarkers include BAP1, MTAP, and merlin, which serve as surrogates for the corresponding gene mutation status. In patients with unusual clinical history, for tumors with a peculiar microscopic appearance, and/or in cases with an equivocal immunophenotypic profile, molecular testing can help to exclude mimics and to confirm the pathologic diagnosis.

Chemotherapy increases CDA expression and sensitizes malignant pleural mesothelioma cells to capecitabine treatment.

The combination of cisplatin and pemetrexed remains the gold standard chemotherapy for malignant pleural mesothelioma (MPM), although resistance and poor response pose a significant challenge. Cytidine deaminase (CDA) is a key enzyme in the nucleotide salvage pathway and is involved in the adaptive stress response to chemotherapy. The cytidine analog capecitabine and its metabolite 5'-deoxy-5-fluorocytidine (5'-DFCR) are converted via CDA to 5-fluorouracil, which affects DNA and RNA metabolism. This study investigated a schedule-dependent treatment strategy, proposing that initial chemotherapy induces CDA expression, sensitizing cells to subsequent capecitabine treatment. Basal CDA protein expression was low in different mesothelioma cell lines but increased in the corresponding xenografts. Standard chemotherapy increased CDA protein levels in MPM cells in vitro and in vivo in a schedule-dependent manner. This was associated with epithelial-to-mesenchymal transition and with HIF-1alpha expression at the transcriptional level. In addition, pretreatment with cisplatin and pemetrexed in combination sensitized MPM xenografts to capecitabine. Analysis of a tissue microarray (TMA) consisting of samples from 98 human MPM patients revealed that most human MPM samples had negative CDA expression. While survival curves based on CDA expression in matched samples clearly separated, significance was not reached due to the limited sample size. In non-matched samples, CDA expression before but not after neoadjuvant therapy was significantly associated with worse overall survival. In conclusion, chemotherapy increases CDA expression in xenografts, which is consistent with our in vitro results in MPM and lung cancer. A subset of matched patient samples showed increased CDA expression after therapy, suggesting that a schedule-dependent treatment strategy based on chemotherapy and capecitabine may benefit a selected MPM patient population.

Spatial Landscape of Malignant Pleural and Peritoneal Mesothelioma Tumor Immune Microenvironments.

Immunotherapies have demonstrated limited clinical efficacy in malignant mesothelioma treatment. We conducted multiplex immunofluorescence analyses on tissue microarrays (n = 3) from patients with malignant pleural mesothelioma (MPM, n = 88) and malignant peritoneal mesothelioma (MPeM, n = 25). Our study aimed to elucidate spatial distributions of key immune cell populations and their association with lymphocyte activation gene 3 (LAG3), BRCA1-associated protein 1 (BAP1), neurofibromatosis type 2 (NF2), and methylthioadenosine phosphorylase (MTAP), with MTAP serving as a cyclin-dependent kinase inhibitor 2A/2B (CDKN2A/B) surrogate marker. Additionally, we examined the relationship between the spatial distribution of major immune cell types and prognosis and clinical characteristics of patients with malignant mesothelioma. We observed a higher degree of interaction between immune cells and tumor cells in MPM compared with MPeM. Notably, within MPM tumors, we detected a significantly increased interaction between tumor cells and CD8+ T cells in tumors with low BAP1 expression compared with those with high BAP1 expression. To support the broader research community, we have developed The Human Spatial Atlas of Malignant Mesothelioma, containing hematoxylin and eosin and multiplex immunofluorescence images with corresponding metadata. SIGNIFICANCE: Considering the limited therapeutic options available to patients with malignant mesothelioma, there is substantial translational potential in understanding the correlation between the spatial architecture of the malignant mesothelioma tumor immune microenvironment and tumor biology. Our investigation reveals critical cell-cell interactions that may influence the immune response against malignant mesothelioma tumors, potentially contributing to the differential behaviors observed in MPM and MPeM. These findings represent a valuable resource for the malignant mesothelioma cancer research community.

Real-World efficacy and safety of combination nivolumab plus ipilimumab for Untreated, Unresectable, pleural Mesothelioma: The Meso-Immune (GFPC 04-2021) trial.

BACKGROUND: First-line standard-of-care for unresectable, pleural mesothelioma (PM) changed with the phase 3 CheckMate 743 study results, showing that nivolumab plus ipilimumab (Nivo + Ipi) significantly extended overall survival (OS) versus platinum + pemetrexed chemotherapy for PM (median OS 18.1 versus 14.1 months; hazard ratio: 0.74; p = 0.002). Efficacy and safety data in real-world (rw) settings are needed to confirm these results. METHODS: This French multicenter, retrospective cohort study was undertaken to assess the outcomes of treatment-naïve PM patients given Nivo + Ipi via an early-access program (EAP). The primary objective was investigator-assessed real world -progression-free survival (PFS). The secondary objectives were the combination's -overall survival (OS) and safety. RESULTS: From 1 April 2021 to 15 Feb 2022, the analysis included 201 of the 305 EAP-enrolled patients treated in 63 centers (79.6 % men; median age: 75 years; 91.8 % Eastern Cooperative Oncology Group performance status (ECOG-PS) 0/1; 74.5 % epithelioid histology). With median (95 % CI) follow-up for all patients of 18.4 (17.7-19.2) months, -PFS and OS were 6.3 (5.3-7.5) and 18.9 (17.6-not reached (NR)) months, with 1-year OS at 66.4 % (60.1-73.3 %). Median OS and 1-year survival rates were 21.0 (18.7-NR) and 70.8 % (63.9 %-780.6 %), and 14.1 (10.9-21.0) months and 54.9 % (42.8 %-70.4 %) for epithelioid and non-epithelioid PM subgroups, respectively. PFS was equal between the two subgroups. Grade 3-4 adverse events occurred in 23.3 % of patients and three deaths were treatment-related. CONCLUSIONS: For this unselected PM population, efficacy and safety outcomes compared favorably with CheckMate 743 trial results.

Female Adnexal Tumor of Probable Wolffian Origin (Wolffian Tumor): A Potential Mimic of Peritoneal Mesothelioma.

Wolffian tumor and its nosologic relative, the recently defined STK11 adnexal tumor are rare neoplasms thought to arise from mesonephric remnants. These tumors typically arise in the broad ligament, fallopian tube, and ovarian hilum and although most are associated with a good prognosis, up to 50% of STK11 adnexal tumors demonstrate aggressive clinical behavior. The chief differential diagnoses include endometrioid adenocarcinoma and sex cord stromal tumors. However, the morphologic and immunohistochemical features of these tumors exhibit considerable overlap with peritoneal mesothelioma. To fully characterize their immunophenotypic signature, we examined a total of 21 cases (18 Wolffian and 3 STK11 adnexal tumors) with standard markers used in the diagnosis of mesothelioma. Morphologic and immunohistochemical (IHC) features were reviewed and additional IHC performed for cases with available material. Patient age ranged from 25 to 73 (mean: 51) years. Sites included adnexa/broad ligament (6, 28%), paratubal (5, 24%), ovary/paraovarian (5, 24%), tubal (intraluminal) (2, 9.5%), pelvis (2, 9.5%), and liver (1, 5%). The mean tumor size was 9.3 cm (range: 0.2 to 22 cm). The histomorphology in most cases (14/21, 66%) consisted of tubular to solid sheets of neoplastic cells lined by columnar to cuboidal cells containing uniform round to oval nuclei. Compressed tubules with slit-like lumens and sieve-like pattern were also seen in at least 7 (33%) cases. Three cases demonstrated interanastomosing cords and trabeculae of epithelioid cells with cribriform and microacinar patterns growing within prominent myxoid stroma as described in STK11 adnexal tumors. In the cases with available IHC for 3 mesothelial markers (calretinin, WT1, D2-40), 55.5% (5 of 9) showed reactivity with all 3 markers. In cases with at least 2 available mesothelial markers, 69% (11/16) were positive for 2 markers (mostly calretinin and WT1). Claudin-4, MOC31, and BER-EP4 were negative in most cases tested (78% [7/9], 71.4% [5/7], and 100% [6/6], respectively). Given the resemblance to mesothelioma, there was initial strong consideration and/or actual misdiagnosis of mesothelioma in 3 cases (14%). In summary, the morphologic and immunohistochemical features of Wolffian tumor and its recently defined relative, STK11 adnexal tumor, can lead to misdiagnosis of mesothelioma, particularly when encountered in the disseminated or metastatic setting. Wolffian tumor and STK11 adnexal tumor should be considered in the differential diagnosis of all pelvic and peritoneal mesotheliomas.

Comparative efficacy of immune checkpoint inhibitors versus chemotherapy alone in diffuse pleural mesothelioma.

BACKGROUND: This study aimed to investigate the effects of immune checkpoint inhibitors (ICIs) versus chemotherapy on the prognosis of real-world diffuse pleural mesothelioma patients in China. METHODS: Clinical data of 90 patients with diffuse pleural mesothelioma from 2019 to 2022 were collected from Harbin Medical University Cancer Hospital. Patients were divided into two groups: the ICIs-treated group (n = 46) and the chemotherapy-only group (n = 44). The efficacy and safety of immunotherapy relative to chemotherapy at different treatment stages were explored. RESULTS: The median progression-free survival (PFS) was 10.0 and 7.0 months, and the median overall survival (OS) was 24.7 and 15.8 months in the ICIs-treated group and the chemotherapy group, respectively. The ICIs-treated group showed an 11% increase in objective response rate (ORR) (52.2% vs. 41.0%) and an 8.0% increase in disease control rate (DCR) (78.3% vs. 70.0%) compared to the chemotherapy group. The Kaplan-Meier curves demonstrated significant PFS (HR: 0.61; 95% CI: 0.38-0.98; p = 0.038) and OS (HR: 0.47; 95% CI: 0.26-0.86; p = 0.011) benefits of receiving immunotherapy over chemotherapy alone. Subgroup analysis according to treatment timing showed the same trend. CONCLUSION: In patients with nonsurgical diffuse pleural mesothelioma, immunotherapy achieved better survival benefits compared to chemotherapy in both first- and second-/third-line treatments. The early addition of immunotherapy improved survival in patients with nonsurgical diffuse pleural mesothelioma.

Imaging in pleural Mesothelioma: A review of the 16th International Conference of the International Mesothelioma Interest Group.

Imaging continues to gain a greater role in the assessment and clinical management of patients with mesothelioma. This communication summarizes the oral presentations from the imaging session at the 2023 International Conference of the International Mesothelioma Interest Group (iMig), which was held in Lille, France from June 26 to 28, 2023. Topics at this session included an overview of best practices for clinical imaging of mesothelioma as reported by an iMig consensus panel, emerging imaging techniques for surgical planning, radiologic assessment of malignant pleural effusion, a radiomics-based transfer learning model to predict patient response to treatment, automated assessment of early contrast enhancement, and tumor thickness for response assessment in peritoneal mesothelioma.

Comparison of FDG-PET/CT and CT for evaluation of tumor response to nivolumab plus ipilimumab combination therapy and prognosis prediction in patients with unresectable malignant pleural mesothelioma.

OBJECTIVES: Results for malignant pleural mesothelioma (MPM) patients following first-line treatment with nivolumab plus ipilimumab obtained with immunotherapy-modified PERCIST (imPERCIST), shown by [18F]fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT), and modified RECIST (mRECIST), shown by CT, were compared for response evaluation and prognosis prediction. RESULTS: imPERCIST indicated nine progressive metabolic disease (PMD), eight stable metabolic disease (SMD), four partial metabolic response (PMR), and five complete metabolic response (CMR) cases. mRECIST showed nine with progressive disease (PD), nine stable disease (SD), seven partial response (PR), and one complete response (CR). Although high concordance was noted (κ = 0.827), imPERCIST correctly judged a greater percentage with CMR (15.4%). Following a median 10.0 months, 15 patients showed progression and eight died from MPM. With both, progression-free survival (PFS) and overall survival (OS) were significantly longer in patients without progression (CMR/PMR/SMD, CR/PR/SD, respectively) as compared to PMD/PD patients (imPERCIST p < 0.0001 and p = 0.015, respectively; mRECIST p < 0.0001 and p = 0.015, respectively). METHODS: Twenty-six patients (23 males, 3 females; median 73.5 years) with histologically proven MPM and no curative surgery received nivolumab plus ipilimumab combination therapy. FDG-PET/CT and diagnostic CT scanning at the baseline, and after 2-4 cycles (2 in three, 3 in 17, 4 in six patients) were performed. Therapeutic response findings evaluated using imPERCIST and mRECIST were compared. PFS and OS analyses were done using log-rank and Cox methods. CONCLUSION: For unresectable MPM patient examinations, FDG-PET and CT provide accurate findings for evaluating tumor response and also prognosis prediction following first-line nivolumab plus ipilimumab immunotherapy (approximately three cycles).

Dendritic cells loaded with allogeneic tumour cell lysate plus best supportive care versus best supportive care alone in patients with pleural mesothelioma as maintenance therapy after chemotherapy (DENIM): a multicentre, open-label, randomised, phase 2/3 study.

BACKGROUND: Dendritic cell immunotherapy has proven to be safe and induces an immune response in humans. We aimed to establish the efficacy of dendritic cells loaded with allogeneic tumour cell lysate (MesoPher, Amphera BV, 's-Hertogenbosch, Netherlands) as maintenance therapy in patients with pleural mesothelioma. METHODS: In this open-label, randomised, phase 2/3 study, patients with histologically confirmed unresectable pleural mesothelioma, aged 18 years or older, with an Eastern Cooperative Oncology Group performance status score of 0-1, and non-progressing disease after four to six cycles of standard chemotherapy (with pemetrexed 500 mg/m2 plus platinum [cisplatin 75 mg/m2 or carboplatin area under the curve of 5]) were recruited from four centres in Belgium, France, and The Netherlands. Participants were randomly assigned (1:1), using block randomisation (block size of 4), stratified by centre and histology (epithelioid vs other), to MesoPher treatment plus best supportive care or best supportive care alone. Patients received up to a maximum of five MesoPher infusions, with treatment administered on days 1, 15, and 29, and weeks 18 and 30. At each timepoint, participants received an injection of 25 × 106 dendritic cells (two-thirds of the dendritic cells were administered intravenously and a third were injected intradermally). Best supportive care was per local institutional standards. The primary endpoint was overall survival, assessed in all participants randomly assigned to treatment (full analysis set) and safety assessed in all randomly assigned participants, and who underwent leukapheresis if they were in the MesoPher group. This study is registered with ClinicalTrials.gov, NCT03610360, and is closed for accrual. FINDINGS: Between June 21, 2018, and June 10, 2021, 176 patients were screened and randomly assigned to the MesoPher group (n=88) or best supportive care alone group (n=88). One participant in the MesoPher group did not undergo leukapheresis. Mean age was 68 years (SD 8), 149 (85%) of 176 were male, 27 (15%) were female, 173 (98%) were White, two were Asian (1%), and one (1%) was other race. As of data cutoff (June 24, 2023), after a median follow up of 15·1 months (IQR 9·5-22·4), median overall survival was 16·8 months (95% CI 12·4-20·3; 61 [69%] of 88 died) in the MesoPher group and 18·3 months (14·3-21·9; 59 [67%] of 88 died) in the best supportive care group (hazard ratio 1·10 [95% CI 0·77-1·57]; log-rank p=0·62). The most common grade 3-4 treatment-emergent adverse events were chest pain (three [3%] of 87 in the MesoPher group vs two [2%] of 88 in the best supportive care group), dyspnoea (none vs two [2%]), anaemia (two [2%] vs none), nausea (none vs two [2%]), and pneumonia (none vs two [2%]). No deaths due to treatment-emergent adverse events were recorded. Treatment-related adverse events consisted of infusion-related reactions (fever, chills, and fatigue), which occurred in 64 (74%) of 87 patients in the MesoPher group, and injection-site reactions (itch, erythema, and induration), which occurred in 73 (84%) patients, and all were grade 1-2 in severity. No deaths were determined to be treatment related. INTERPRETATION: MesoPher did not show improvement in overall survival in patients with pleural mesothelioma. Immune checkpoint therapy is now standard of care in pleural mesothelioma. Further randomised studies are needed of combinations of MesoPher and immune checkpoint therapy, which might increase efficacy without adding major toxicities. FUNDING: Amphera BV and EU HORIZON.

Malignant pleural mesothelioma: Description of pleural decortication and hyperthermic chemotherapy technique in multimodal therapy.

The current treatment for mesothelioma, in selected cases, consists of extended pleurodecortication and intrathoracic hyperthermic chemotherapy. This technique is laborious and detailed and must be followed step by step to achieve good results. We present the case of a patient with epithelioid mesothelioma meeting surgical criteria who underwent the mentioned technique, experiencing an adequate postoperative period and an early discharge. This experience demonstrates that the technique is safe when performed in centres with experience and the means to address this complex pathology.

[Benign mesothelial tumors]. / Benigne Tumoren des Mesothels.

Benign mesothelial tumors are rarer than malignant mesotheliomas and are often found in the peritoneum as incidental findings in women. They include the adenomatoid tumor (AT), the well-differentiated mesothelial tumor (WDPMT), the mesothelioma in situ (MIS), and the solid papillary mesothelial tumor (SPMT). ATs are always benign and predominantly manifest in the genital tract. WDPMTs can develop multifocally and are prone to recurrence, particularly in the case of incomplete resection. Only MISs are considered a confirmed precursor lesion of malignant mesothelioma according to the currently valid World Health Organization (WHO) classifications. As with malignant mesothelioma, alterations of BAP1, MTAP, and p16 are detectable for MIS in contrast to the other three tumors. SPMTs cannot be clearly assigned to the other mesothelial tumors and have so far only been described in the peritoneum in women with a benign course.

Combination of calretinin, MALAT1, and GAS5 as a potential prognostic biomarker to predict disease progression in surgically treated mesothelioma patients.

BACKGROUND: The role of cytoreductive surgery for epithelioid pleural mesothelioma within a multimodal treatment approach remains controversial. Carefully selected patients benefit from cytoreductive surgery and adjuvant chemotherapy, but there is no established biomarker to predict tumor recurrence or progression during the course of the disease. The aim of this study was to identify potential biomarkers to predict therapeutic response in terms of progression-free survival. METHODS: Between 03/2014 and 08/2022, preoperative blood samples were collected from 76 patients with epithelioid pleural mesothelioma who underwent cytoreductive surgery as part of a multimodal treatment approach. Identification of potential biomarkers was performed by determination of mesothelin and calretinin, as well as specific long non-coding RNAs and microRNAs. Receiver operating characteristic analysis, Kaplan-Meier survival analysis, and Cox regression were used to assess the association between biomarker concentrations and patient recurrence status and survival. RESULTS: MALAT1, GAS5, and calretinin showed statistically significant increased biomarker levels in patients with recurrence in contrast to recurrence-free patients after surgical treatment (p < 0.0001, p = 0.0190, and p = 0.0068, respectively). The combination of the three biomarkers resulted in a sensitivity of 68 % and a specificity of 89 %. CONCLUSION: MALAT1, GAS5, and calretinin could be potential biomarkers for the prediction of tumor recurrence, improving the benefit from multimodal treatment including cytoreductive surgery.

Predictive potential of MRI in differentiating the predominant component in biphasic pleural mesothelioma.

PURPOSE: To assess the potential of apparent diffusion coefficient (ADC) values derived from diffusion weighted (DW) MRI preoperatively to predict the predominant histologic component among biphasic pleural mesothelioma (PM) tumors. METHODS: ADC maps were generated from DW MRI scans. Histology and predominant component of biphasic PM were confirmed following surgical resection. Statistical analyses were done with R (R Foundation for Statistical Computing, Vienna, Austria). Average ADC values corresponding to epithelioid- and sarcomatoid-predominant tumors were compared. ADC thresholding was accomplished by recursive partitioning and confirmed with ROC analysis. RESULTS: Eighty-four patients with biphasic PM's, 69 (82 %) epithelioid-predominant (BE) and 15(18 %) sarcomatoid-predominant (BS) tumors were evaluated. Thirty-eight (45 %) patients underwent extrapleural pneumonectomy (EPP), 39 (46 %) had extended pleural decortication (ePDC) and 7 (8 %) had pleural decortication (PDC). ADC values ranged between 0.696 x 10-3 to 1.921 x 10-3 mm2/s. BE tumors demonstrated significantly higher ADC values than BS tumors (p = 0.026). ADC values above 0.94 x 10-3 mm2/s were associated with a significant increase of relative risk of being in group BE over group BS (relative risk: 1.47, 95 %CI: 1.05-2.06, p = 0.027) CONCLUSION: Average ADC values of BE tumors were higher than BS tumors and the two groups can be separated by a cut off value of 0.94 X 10-3 mm2/s.