Supplementary Data from The Expression of Three Genes in Primary Non–Small Cell Lung Cancer Is Associated with Metastatic Spread to the Brain

Background: Non-small cell lung cancer (NSCLC) is the most common cause of cancer-death due to early metastatic spread, in many cases primarily to the brain. Organ-specific pattern of spread of disease might be driven by the activity of a specific signaling pathway within the primary tumors. We aimed to identify an expression signature of genes and the relevant signaling associated with the development of brain metastasis (BM) after surgical resection of NSCLC. Methods: Rapidly frozen NSCLC surgical specimens were procured from tumor banks. RNA was extracted and analyzed by RNA-sequencing (Illumina HiSeq 2500). Clinical parameters and gene expression were examined for differentiating between patients with BM, patients with metastases to sites other than brain, and patients who did not develop metastatic disease at a clinically significant follow up. Principal component analysis and pathway enrichments studies were done. Results: A total of 91 patients were included in this study, 32 of which developed BM. Stage of disease at diagnosis (P=0.004) and level of differentiation (P=0.007) were significantly different between BM and control group. We identified a set of 22 genes which correlated specifically with BM, and not with metastasis to other sites. This set achieved 93.4% accuracy (95% CI: 86.2-97.5%), 96.6% specificity and 87.5% sensitivity of correctly identifying BM patients in a leave-one-out internal validation analysis. The oxidative phosphorylation pathway was strongly correlated with BM risk. Conclusions: Expression level of a small set of genes from primary tumors was found to predict BM development, distinctly from metastasis to other organs. These genes and the correlated oxidative phosphorylation pathway require further validation as potentially clinically useful predictors of BM and possibly as novel therapeutic targets for BM prevention.

Objective: Intensity-modulated radiotherapy (IMRT) has better normal-tissue sparing compared with 3-dimensional conformal radiation (3DCRT). We sought to assess the impact of radiation technique on pathological and clinical outcomes in locally advanced non-small cell lung cancer (LANSCLC) treated with a trimodality strategy. Methods: Retrospective review of LANSCLC patients treated from August 2012 to August 2018 at Sheba Medical Center, Israel. The trimodality strategy consisted of concomitant chemoradiation to 60 Gray (Gy) followed by completion surgery. The planning target volume (PTV) was defined by co-registered PET/CT. Here we compare the pathological regression, surgical margin status, local control rates (LC), disease free (DFS) and overall survival (OS) between 3DCRT and IMRT. Results: Our cohort consisted of 74 patients with mean age 62.9 years, male in 51/74 (69%), adenocarcinoma in 46/74 (62.1%), stage 3 in 59/74 (79.7%) and chemotherapy in 72/74 (97.3%). Radiation mean dose: 59.2 Gy (SD ± 3.8). Radiation technique : 3DCRT in 51/74 (68.9%), IMRT in 23/74 (31%). Other variables were similar between groups.Major pathological response (including pathological complete response or less than 10% residual tumor cells) was similar: 32/51 (62.7%) in 3DCRT and 15/23 (65.2%) in IMRT, p=0.83. Pathological complete response (pCR) rates were similar: 17/51 (33.3%) in 3DCRT and 8/23 (34.8%) in IMRT, p=0.9. Surgical margins were negative in 46/51 (90.1%) in 3DCRT vs. 17/19 (89.4%) in IMRT (p=1.0).The 2-year LC rates were 81.6% (95% CI 69-89.4%); DFS 58.3% (95% CI 45.5-69%) and 3-year OS 70% (95% CI57-80%). Comparing radiation techniques, there were no significant differences in LC (p=0.94), DFS (p=0.33) and OS (p=0.72). Conclusion: When used to treat LANSCLC in the neoadjuvant setting, both IMRT and 3DCRT produce comparable pathological and clinical outcomes. Advances in knowledge: This study validates the real-world effectiveness of IMRT compared to 3DCRT.

8534 Background: Resected NSCLC clinical stage I or II harbor a 5 year survival of only 30-50%. Immunotherapy might be more effective in low-burden disease. We hypothesized that neo-adjuvant immunotherapy is a feasible, safe and effective treatment (Tx) for early stage NSCLC. Methods: MK3475-223 is an ongoing phase I study of neoadjuvant pembrolizumab in stage I-II NSCLC. All Pembro Txs are 200mg q 3 weeks (wks). Objectives: determine safety; recommended phase 2 dose/schedule; pathological & radiological response. Doses-schedule limiting toxicities (DLT) were defined as significant surgical complications (bleeding, delayed wound healing, ARDS, prolonged air-leak) or a significant delay of surgery. The doses-schedule escalation cohorts were (i) single pembro dose 3 wk prior to surgery; (ii) 2 pembro doses, 2 wks later surgery; (iii) 2 pembro doses, 1 wk later surgery. Expansion cohort received the doses-schedule of cohort (iii). Percentages of remaining viable tumor in the post-Tx were assessed, 10% or less was considered amajor pathological response (MPR). IHC for pre-Tx PDL1 was done. Efficacy was evaluated for the patients who had received 2 doses of pembrolizumab. Results: No DLT occurred in the dose-schedule escalation cohorts. 10 patients received 2 cycles of neo-adjuvant pembrolizumab. 4 patients achieved a MPR (4/10 who received 2 cycles of pembro; 40%; 95% C.I. 16.7-68.8%). No correlation is seen between the levels of PDL1 pre-Tx and the pathologic response. Size of the tumor and N status was also not in any apparent correlation with MPR (data not shown). Interestingly, all of the MPR cases had a relatively long interval from 1st Tx till surgery. Clinical trial information: NCT02938624. Conclusions: Neo-adjuvant pembro is safe and feasible. A promising sign of efficacy is seen. Achieving MPR might require a longer 1st-Tx-surgery interval. Predictive biomarkers for response might be different from those in advanced disease. Recruitment and correlative studies are ongoing.[Table: see text]

BACKGROUNDStereotactic ablative radiation therapy (SABR) is the application of a very high radiation dose to a small treatment volume. It is the new standard of care in medically inoperable early-stage lung cancer.OBJECTIVESTo report the outcomes of SABR in stage I lung cancer at Sheba Medical Center since its introduction in 2009.METHODSWe conducted a retrospective chart review of patients with stage I lung cancer treated during the period 2009-2015. Survival status was retrieved from the electronic medical records and confirmed with the national registry. Local failure was defined as increased FDG uptake on PETCT scan within a 2 cm radius of the treated region. Toxicity was estimated from medical records and graded according to common toxicity criteria for adverse events (CTCAE) version 4.03. Overall survival and local control were estimated by the Kaplan-Meier method.RESULTSDuring the study period 114 patients were treated for 122 stage I lung cancer lesions. Median follow-up time was 27 months (range 8.2-69.5 months), median age was 76 years. Eighty-two percent of the tumors were stage IA (size ≤ 3 cm). Median survival was 46 months; estimated 3 year overall survival was 59% (95%CI 47-69%) and local control was 88% (95%CI 78-94%). Toxicity included chest wall pain in 8.4% of patients, rib fracture in 0.9%, grade 1-2 pneumonitis in 12%, grade 3 in 12% and grade 5 (death) in 0.9%.CONCLUSIONSSABR has been successfully implemented at Sheba Medical Center for the treatment of stage I lung cancer in inoperable patients. It is associated with excellent local control, minor toxicity and an acceptable overall survival.

Laparoscopic sleeve gastrectomy is a common surgical management of morbid obesity. Major complication rate is 3–8%. Staple line leak is one of the most serious complications. In a small group of patients, a gastro-pulmonary fistula is formed. Endoscopic and minimally invasive measures are the first line of treatment with considerable success rate. There are very poor data in the literature what should be done in cases of failure. In this paper, we report our positive experience with definitive surgical repair.

BACKGROUND Neoadjuvant chemo-radiation therapy (CRT) dosages in locally advanced non-small cell lung cancer (NSCLC) were traditionally limited to 45 Gray (Gy). OBJECTIVES To retrospectively analyze outcomes of patients treated with 60 Gy CRT followed by surgery. METHODS A retrospective chart review identified patients selected for CRT to 60 Gy followed by surgery between August 2012 and April 2016. Selection for surgery was based on the extent of disease, cardiopulmonary function, and response to treatment. Pathological response after neoadjuvant CRT was scored using the modified tumor regression grading. Local control (LC), disease free survival (DFS), and overall survival (OS) were estimated by the Kaplan-Meier method. RESULTS Our cohort included 52 patients: 75% (39/52) were stage IIIA. A radiation dose of 60 Gy (range 50-62Gy) was delivered in 82.7%. Surgeries performed included: lobectomy, chest-wall resection, and pneumonectomy in 67.3%, 13.4%, and 19.2%, respectively. At median follow-up of 22.4 months, the 3 year OS was 74% (95% confidence interval [CI] 52-87%), LC was 84% (95%CI 65-93), and DFS 35% (95%CI 14-59). Grade 4-5 postoperative complications were observed in 17.3% of cases and included chest wall necrosis (5.7%), bronco-pleural fistula (7.7%), and death (3.8%). A major pathologic regression with < 10% residual tumor occurred in 68.7% of patients (36/52) and showed a trend to improved OS (P = 0.1). Pneumonectomy cases had statistically worse OS (P = 0.01). CONCLUSIONS Major pathologic regression was observed 68.7% with 60 Gy neoadjuvant CRT with a trend to improved survival. Pneumonectomy correlated with worse survival.

Adoptive cell therapy with tumor infiltrating lymphocytes (TIL) yields 50% response rates in metastatic melanoma and shows promising clinical results in other solid tumors. Autologous TIL cultures are isolated from resected tumor tissue, expanded ex vivo to large numbers and reinfused to the preconditioned patient. In this prospective study, we validate the origin of the tumor biopsy and its effect on T-cell function and clinical response. One hundred forty-four patients underwent surgery and 79 patients were treated with TIL adoptive cell therapy. Cultures from lung tissue were compared with other origins. The success rate of establishing TIL culture from lung tissue was significantly higher compared with nonlung tissue (94% vs. 72%, respectively, P ≤0.003). Lung-derived TIL cultures gave rise to higher cell numbers ( P ≤0.011) and exhibited increased in vitro antitumor reactivity. The average fold expansion for lung-derived TIL during a rapid expansion procedure was 1349±557 compared with 1061±473 for nonlung TIL ( P ≤0.038). Patients treated with TIL cultures of lung origin (compared with nonlung) had prolonged median overall survival (29 vs. 9.5 mo; P ≤0.065). Given the remarkable advancement in minimally invasive thoracic surgery and the results of this study, we suggest efforts should be taken to resect lung metastasis rather than other sites to generate TIL cultures for clinical use.

Abstract PD1-PDL1 interaction is one mechanism of tumor evasion of the immune system, and inhibitors of this interaction can allow cancer cell killing by cytotoxic T cells. In NSCLC as well as in most other cancers, the clinical benefit from such inhibitors is far from universal; around 20% of tumors respond to this treatment. Response of tumors to anti-cancer agents depends on interactions of epithelial tumor cells and the microenvironment, including stromal cells such as fibroblasts, immune cells and extracellular matrix. Studying cell signaling and drug-sensitivity of cancer should take into consideration the different compartments of an individual tumor. Regarding immunotherapy, manipulating regulators of PDL1 expression might augment the activity of these drugs, or possibly be active as an immunotherapy on its own. Specifically, little is known about the impact of chemotherapy, radiotherapy or targeted agents on the expression and activity of the PD1-PDL1 signaling in human cancer. Combining such treatments with immunotherapy is a potentially promising approach that is currently investigated clinically. However, the number of potential combinations is vast, and no valid and convenient experimental model exists to test candidate treatments and combinations. Experimental procedures: Ex vivo organ cultures (EVOC) were directly established from fresh NSCLC tissues, as a model that recapitulates real tumor and its microenvironment, including immune cells. Tissue elements were mechanistically dispersed to cell clumps (30-100 cells per clump), or cut to one cubic mm pieces and placed in culture. LDH release was used as a surrogate of cell death. Samples were analyzed by formalin fixation and paraffin embedment, sectioning and hematoxilin and eosin visualization of cells. PDL1 mRNA and protein levels were measured by RT-PCR and western blots. Results: Cell viability of NSCLC EVOC is maintained over a time window of at least 4-7 days. Cytotoxic drugs evoke cell death. PDL1 mRNA and protein levels are elevated in NSCLC EVOC in response to inflammation signals as Interferon gamma. Glucocorticoid steroidal drugs causes reduction in PDL1 mRNA and protein in NSCLC EVOC. Cisplatin treatment causes elevation in PDL1 protein. Variability in basal and induced PDL1 protein levels was detected in response to inflammation signals in EVOCs generated from different patients. Conclusions: Our results indicate the feasibility of EVOC for NSCLC and the potential to use it as a model to study the impact of immunotherapy agents, alone or in combination with other therapeutic tools such as chemotherapy or radiotherapy. Citation Format: Jair Bar, Inbal Daniel-Meshulam, Amir Onn, Alon Ben-Nun, David Simansky, Nona Zeitlin, Nir Golan, Meirav Rokah, Ronni Ben-Avi, Iris Kamer. Modeling immunotherapy in ex vivo organ culture of non-small cell lung cancer (NSCLC). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4910.

To compare the postoperative recovery of patients with superior sulcus tumors (Pancoast tumors) following conventional open surgery vs. a hybrid video-assisted and limited open approach (VALO).

Identification of non-small cell lung carcinoma (NSCLC) patients at high-risk for recurrence after complete resection would potentially direct surveillance frequency and administration of adjuvant treatments. Genetic profiling of tumors could provide clinicians with information regarding recurrence risk. Conflicting evidence exists regarding EGFR, KRAS, and TP53 mutations as prognostic for recurrence. We aimed to test such mutations for prognostic significance in a cohort of early-resected NSCLC specimens.

OBJECTIVESThe optimal timing for tracheostomy after cardiac surgery in patients undergoing prolonged ventilation is controversial. The aim of this study was to assess the effect of tracheostomy timing on short- and long-term mortality of these patients.DESIGNRetrospective study of prospectively collected data.SETTINGCardiac surgical intensive care unit (ICU) in a tertiary-care, university-affiliated hospital.PARTICIPANTSAll patients undergoing tracheostomy after cardiac surgery between September 2004 and March 2013 were included.INTERVENTIONSThe authors compared the outcome in 2 groups of patients according to the timing of tracheostomy: Group I, early-intermediate tracheostomy (0-14 days) and Group II, late tracheostomy (≥15 days).MEASUREMENTS AND MAIN RESULTSDuring the study period, 6,069 patients underwent cardiac surgery; among them, 199 patients (3.26%) received a tracheostomy. There were 90 patients in Group I and 109 patients in Group II. There was no significant difference in the severity of the patients' illness between the groups. The mortality rate at 3 months, 6 months, 1 year, and 2 years was 37%, 48%, 56%, and 58% in Group I, respectively, and 58%, 70%, 74%, and 77% in Group II, respectively (p< 0.01).CONCLUSIONSEarly-intermediate (0-14 days) tracheostomy after cardiac surgery in patients requiring prolonged mechanical ventilation was associated with reduced mortality compared with late tracheostomy (≥15 days).

OBJECTIVES:Patients with breast cancer following mastectomy and silicone implant reconstruction may have enlarged internal mammary lymph nodes with pathological uptake on positron emission tomography with (18)F-fluorodeoxyglucose. This lymphadenopathy is usually considered as metastatic in nature, but has also been reported to be related to other conditions, including silicon migration. The purpose of this study was to determine the rate of metastatic disease in this unique group of patients.METHODS:A retrospective comparative study of 12 female patients with breast cancer with silicone implants referred for biopsy due to isolated internal mammary lymph node fluorodeoxyglucose uptake on positron emission tomography.RESULTS:Five patients (41.6%) had histological findings related to silicone (n = 4) or non-specific inflammation (n = 1). The remaining 7 (58.3%) had histological evidence of cancer recurrence. There was no significant difference in the fluorodeoxyglucose-standardized uptake value between the two groups.CONCLUSIONS:Fluorodeoxyglucose-positive mammary lymph nodes in patients with breast cancer following silicone implant reconstruction may be due to metastatic deposits, non-specific inflammation or silicone migration. Clinical and imaging characteristics are insufficient in differentiating between these conditions. Biopsy is recommended prior to initiation of further treatment.

Background: Concomitant lesions of the heart and lung are uncommon, but when present they pose a challenge for cardiac and thoracic surgeons. Patients with lung cancer and heart disease are at a high risk for postoperative death or severe cardiovascular complications.Aim of the study: To report our results of concomitant cardiac surgery and lung resection.Material and methods: From 1994 to 2012, 18 patients with cardiac disorders and lung cancer or another lung disease were operated on. Twelve patients underwent coronary artery bypass grafting, 3 patients underwent aortic valve replacement and 3 patients underwent another cardiac surgery procedure. The pulmonary resections consisted of pneumonectomy in 1 patient, lobectomy in 6 patients and wedge excision in 10 patients. Follow-up was obtained for all 18 patients (mean follow-up 70.6 months; range 224 to 0.7 months).Results: The pathologic examination confirmed lung malignancy in 12 patients. Five patients were operated on due to a non-oncologic pathology and 1 patient underwent lung volume resection. Overall late survival was 88% and 67% at 1 and 5 years, respectively.Conclusions: Lung resection carried out concomitantly with cardiac surgery is safe and effective. A combined procedure avoids the need for a second major thoracic procedure and may improve clinical outcome.

Objective: Our objective was to evaluate whether resection and heated pleural chemoperfusion (HPCP) is an effective treatment for de novo stage IVa thymoma (DNT) and thymic carcinoma (TC) and for thymoma with pleural relapse (TPR).Methods: A retrospective study was conducted of patients undergoing resection and HPCP in 1 center. HPCP with cisplatinum +/- doxorubicin (adriamycin) was performed for 60 minutes using a standard roller pump and a modified heat exchanger to a maximal intrapleural temperature of 43 degrees C. Follow-up included at least 1 annual computed tomographic scan until death or March 2012.Results: Thirty-five patients, 17 DNT, 14 TPR, and 4 TC, completed 42 intended treatments and were followed up for 4 to 202 months (median, 62 months). Seven patients had repeated HPCP at an interval of 2 to 12 years. There was no systemic toxicity. Ninety-day mortality was 2.5%. Major and minor morbidity occurred in 12% each. Five-, 10-, and 15-year overall survivals for DNT, TPR, and TC were 81%, 73%, 58% (DNT), 67%, 56%, 28% (TPR), and 0%, 0%, 0% (TC). Five- and 10- year progression-free survival was 61%, 43% for DNT and 48%, 18% for TPR. Presently, 11 of 17 DNT patients are alive (6, no evidence of disease), and 8 of 14 TPR are alive (6, no evidence of disease). Median survival for thymoma was 157 months. Overall survival was unrelated to any preoperative or intraoperative variable. Progression-free survival was improved in R0 compared with R1-2 resection (P < .001). Local control achieved in 21 (57%) of 37 procedures in thymoma patients was related only to completeness of resection (P = .015).Conclusions: (1) Lung-sparing resection and HPCP is feasible and safe. (2) In thymoma with pleural spread it offers excellent survival despite moderate pleural control. (3) Preliminary results with stage IVa TC are disappointing. (J Thorac Cardiovasc Surg 2013;145:83-9)

BACKGROUND:Malignant pleural effusion (MPE) has a profound impact on quality of life and survival in patients with lung cancer. Identification of the factors within the tumor and its environment that mediate MPE is still lacking. PATIENTS AND METHODS:Intratumoral microvessel density (MVD), endothelial cell and pericyte (PC) capillary coverage, endothelial cell (EC)-PC relationship, lymphatic endothelium integrity, and the expression of receptor tyrosine kinases were all assessed immunohistochemically in pleural tumor biopsy specimens from 24 patients with lung adenocarcinoma (ADC) with and without pleural disease, with the aim to evaluate the involvement with MPE. RESULTS:In the effusion-positive⁺ specimens, MVD values were found to be significantly higher, and a number of vessels were noted to lack immunoreactivity for ECs (CD31). Likewise, PC α-smooth muscle actin (αSMA) expression was also less extensive in the MPE⁺ cases. The observation of only sporadic staining of PCs can also explain the findings regarding platelet-derived growth factor receptors (PDGFRs), the expression of which, although more prominent in MPE⁺ samples, were almost exclusively detected on tumor stromal cells and not on vascular PCs. Conversely, vascular endothelial growth factor receptors (VEGFRs) appeared on both kinds of cells. With respect to lymphatic vessels, lymphatic intraluminal tumor cells were occasionally found in MPE⁺ specimens. CONCLUSION:Our study suggests that disturbed vessel wall integrity, as well as abnormalities of fluid clearance by the lymphatic system, together with overexpression of growth factors, may take part in the pleural fluid accumulation in lung ADCs. Results of the decreased PC capillary coverage and PDGFR expression in MPE are discussed.

Mutations in early non-small-cell lung cancer (NSCLC) could determine prognosis. We tested for mutations in 22 genes in 96 early NSCLC specimens. A trend for worse outcome was found with a greater number of mutations and for smokers. KRAS and PIK3CA were the most common co-mutations. Our findings demonstrate the feasibility of large-scale genetic tests in early NSCLC. They might also suggest the importance of smoking cessation.Background: Testing for genetic abnormalities in epithelial growth factor receptor (EGFR), anaplastic lymphoma receptor tyrosine kinase (ALK), and potentially additional genes is a critical tool in the care of advanced NSCLC. There is conflicting evidence for the role of such tests in early NSCLC. We report a single-institute Sequenom testing for a wide range of mutations and their clinical correlations in early-resected NSCLC specimens. Materials and Methods: Early NSCLC paraffin-embedded, formalin-fixed (FFPE) specimens were collected, DNA extracted, and using Sequenom-based matrix-assisted laser desorption/ionization-time of flight analysis, mutations in 22 oncogenes and tumor suppressor genes were evaluated. Clinical data was collected retrospectively. Results: The technique was found to be feasible. Thirty-six of 96 patients (37.5%) had any genetic abnormality identified, and 8 (8.3%) had 2 or more mutations. Kirsten rat sarcoma viral oncogene homolog (KRAS) and EGFR were the most common genes to appear mutated (15.6%); phosphatidylinositol-4,5-bisphosphate 3-kinase, catalytic subunit alpha (PIK3CA) was the gene to be found most commonly in tumors with co-mutations. Transversions were found mostly in KRAS gene mutations and to be nonprognostic. No difference in the spectrum of mutations was found between squamous-cell and nonesquamous-cell lung cancers. Ever-smokers showed a trend for worse prognosis, with a similar spectrum of mutations. Conclusion: Sequenom-based mutation screen is feasible using FFPE samples. More than a third of the patients were found to harbor some genetic abnormality, and 8% were found to have more than a single mutated gene. Wide-range gene screens using large sample depositories are required for further insight into the important genes at play in early NSCLC. (C) 2014 Elsevier Inc. All rights reserved.

Abstract Background. Malignant pleural effusion (MPE) is a common and debilitating condition in patients with lung cancer. For unknown reasons, some tumors are more strongly associated with the condition than others. The pathophysiology of this condition has not been fully determined and to date no specific medical treatment is available. Our goal was to study the structure and assess the permeability related factors in MPE associated blood vessels to better understand the mechanisms of this condition. Methods. Immunohistochemical analysis of human NSCLC formalin-fixed paraffin-embedded specimens from patients who underwent lobectomy (MPE- cases) or pleural biopsy (MPE+ cases) was employed. Nine adenocarcinomas (AC) and eight squamous cell carcinomas (SCC) with and without MPE were studied. For endothelial cell (EC) staining and microvessel density (MVD) determination, the anti-CD31 Abs was employed. Pericytes were stained by aSMA Abs. Coexpression of some of receptor tyrosine kinases (PDGFR, VEGF/VEGFR, Tie-2) was also evaluated. Results. In SCC complicated with MPE a narrow, clogged and fibrotic vessels were seen in tumors located near the pleura (pleura involved). In MPE positive AC specimens there were regions of tumor vessels where ECs were irregularly laminated and hardly noticed. This observation was also confirmed by CD31 staining where lower number of positive vessels related to the total number of vessels was observed (88.4% in MPE+ vs. 94.8% in MPE- cases, p<0.05). Regarding the vessel coverage by pericytes, the pericyte expression (aSMA staining) was shown to be less extensive in cases with than without effusion (59.1% vs 96.2%, p<0.001) probably because of their thinning or even detachment. This clarification could also explain the finding that the PDGFR was more expressed on ECs on MPE - tumors than on MPE + ones. For VEGF and VEGFR staining, the staining index was more prominent in tumors with than without effusion, for both staining area and staining intensity (1.7 and 1.9, respectively). However, in distinction to the staining of tumor cells almost no vessel EC staining by VEGFR Abs was seen, while staining by anti-VEGF Abs was substantial. Similarly, the staining of Ang-2 receptor (Tie-2) was found in the cytoplasm of the tumor cells, but not in the vascular endothelium, regardless the pleura effusion positive or negative features. Conclusions. To our knowledge this is one of the first studies on structural abnormalities of blood vessels in human lung cancer malignant pleural effusion. For now, because of the relatively small number of cases analyzed no single mechanism was found able to explain the occurrence of a pleural effusion, and it is likely that multiple factors contribute to effusion formation. This formulation may also better explain why some patients with pleural metastases have malignant effusions while others do not. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5301. doi:1538-7445.AM2012-5301