Predictive biomarkers for response to EGFR-directed monoclonal antibodies for advanced squamous cell lung cancer.

Background: Upregulated expression and aberrant activation of the epidermal growth-factor receptor (EGFR) are found in lung cancer, making EGFR a relevant target for non-small-cell lung cancer (NSCLC). Treatment with anti-EGFR monoclonal antibodies (mAbs) is associated with modest improvement in overall survival in patients with squamous cell lung cancer (SqCLC) who have a significant unmet need for effective treatment options. While there is evidence that using EGFR gene copy number, EGFR mutation, and EGFR protein expression as biomarkers can help select patients who respond to treatment, it is important to consider biomarkers for response in patients treated with combination therapies that include EGFR mAbs. Design: Randomized trials of EGFR-directed mAbs cetuximab and necitumumab in combination with chemotherapy, immunotherapy, or antiangiogenic therapy in patients with advanced NSCLC, including SqCLC, were searched in the literature. Results of associations of potential biomarkers and outcomes were summarized. Results: Data from phase III clinical trials indicate that patients with NSCLC, including SqCLC, whose tumors express high levels of EGFR protein (H-score of ≥200) and/or gene copy numbers of EGFR (e.g. ≥40% cells with ≥4 EGFR copies as detected by fluorescence in situ hybridization; gene amplification in ≥10% of analyzed cells) derive greater therapeutic benefits from EGFR-directed mAbs. Biomarker data are limited for EGFR mAbs used in combination with immunotherapy and are absent when used in combination with antiangiogenic agents. Conclusions: Therapy with EGFR-directed mAbs in combination with chemotherapy is associated with greater clinical benefits in patients with NSCLC, including SqCLC, whose tumors express high levels of EGFR protein and/or have increased EGFR gene copy number. These data support validating the role of these as biomarkers to identify those patients who derive the greatest clinical benefit from EGFR mAb therapy. However, data on biomarkers for EGFR-directed mAbs combined with immunotherapy or antiangiogenic agents remain limited.

A phase II trial of imatinib (ST1571) in patients with c-kit expressing relapsed small-cell lung cancer: a CALGB and NCCTG study.

BACKGROUND: The aim of the present study was to evaluate the clinical activity of imatinib mesylate in patients with recurrent and refractory c-kit-expressing small-cell lung cancer. PATIENTS AND METHODS: Patients with c-kit-expressing SCLC (> or =1+ by immunohistochemistry) were enrolled in two groups. Arm A included patients with disease progression <3 months and arm B included patients with disease progression > or =3 months after previous treatment. Imatinib was administered at a dose of 400 mg b.i.d. continuously, with a cycle length of 28 days. A single stage Simon design with a planned interim analysis was used to evaluate the 16-week progression free rate in each arm. RESULTS: A total of 29 evaluable patients were entered into the study (seven in arm A, median age 68; 22 in arm B, median age 64.5). Median number of treatment cycles was one in both arms. Grade 3+ non-hematologic adverse events were seen in 15 (52%) patients, with nausea, vomiting, dyspnea, fatigue, anorexia and dehydration each occurring in at least 10% of patients. Median survival was 3.9 and 5.3 months and median time to progression was 1 and 1.1 months for arms A and B, respectively. Enrollment to arm A was temporarily suspended prior to reaching interim analysis due to striking early disease progression (29%), early deaths (29%) and patient refusal (42%). No objective responses and no confirmed stable disease > or =6 weeks were seen in either arm. Accrual was permanently terminated to both arms as only one patient was progression-free at 16 weeks. CONCLUSION: Imatinib failed to demonstrate any clinical activity in spite of patient selection for c-kit-expressing SCLC. Our results strengthen the collective evidence that prediction of efficacy of novel therapeutic agents based on target expression, rather than pathway activation (for example, through activating mutations), may not be a valid paradigm for drug development.

Phase II study of topotecan and paclitaxel for patients with previously untreated extensive stage small-cell lung cancer.

BACKGROUND: This phase II study was conducted to evaluate the safety and efficacy of the combination of paclitaxel and topotecan for patients with extensive stage small-cell lung cancer (ED-SCLC). PATIENTS AND METHODS: Previously untreated ED-SCLC patients with Eastern Coperative Oncology Group performance status <2 were eligible. Treatment consisted of topotecan 1 mg/m2 (first three patients received 1.25 mg/m2), on days 1-5, and paclitaxel 135 mg/m2 over 24 h on day 5, every 4 weeks. Prophylactic granulocyte colony-stimulating factor was administered to all patients. RESULTS: Thirty-two patients received a median of four cycles of chemotherapy. Grade 4 anemia, neutropenia and thrombocytopenia occurred in 13, 31 and 18 patients, respectively. Thirty episodes of febrile neutropenia occurred in 22 patients. Grade 3 fatigue, esophagitis, stomatitis and hypotension occurred in one patient each. Of 26 patients eligible for response evaluation, there were six complete and 12 partial responses (overall response rate 69%). The median survival was 54 weeks. The 1-, 2- and 3-year survival rates were 50%, 10% and 3%, respectively. CONCLUSIONS: The combination of topotecan and paclitaxel is active as initial therapy in SCLC, but the efficacy is similar to 'standard therapy'. This combination was associated with a high incidence of myelosuppression and febrile neutropenia, at the doses evaluated.

The correlation of emphysema or airway obstruction with the risk of lung cancer: a matched case-controlled study.

A matched case-controlled study was conducted to determine if airway obstruction or emphysema were associated with an increased risk of lung cancer. Lung cancer cases (n=24) were identified through a low-dose spiral computed tomography (CT) screening trial from 1,520 participants. Four controls without lung cancer were selected for each case from the participants and matched by sex, age and smoking history. Emphysema was assessed by quantitative CT analysis. Conditional logistic regression was employed to assess results of spirometry and CT quantitative analysis as potential risk factors for lung cancer. The likelihood of lung cancer was found to be significantly increased for those with forced expiratory volume in one second (FEV1) < or = 40% of predicted. The results suggested that a lower percentage of predicted FEV1 was indicative of lung cancer. No compelling evidence was found to suggest that the percentage of emphysema was associated with lung cancer. These results suggest an increased risk of lung cancer associated with airway obstruction. However, percentage of emphysema as determined by computed tomography was not associated with an increased risk of lung cancer.

Alterations of p14ARF, p53, and p73 genes involved in the E2F-1-mediated apoptotic pathways in non-small cell lung carcinoma.

Overexpression of E2F-1 induces apoptosis by both a p14ARF-p53- and a p73-mediated pathway. p14ARF is the alternate tumor suppressor product of the INK4a/ARF locus that is inactivated frequently in lung carcinogenesis. Because p14ARF stabilizes p53, it has been proposed that the loss of p14ARF is functionally equivalent to a p53 mutation. We have tested this hypothesis by examining the genomic status of the unique exon 1beta of p14ARF in 53 human cell lines and 86 primary non-small cell lung carcinomas and correlated this with previously characterized alterations of p53. Homozygous deletions of p14ARF were detected in 12 of 53 (23%) cell lines and 16 of 86 (19%) primary tumors. A single cell line, but no primary tumors, harbored an intragenic mutation. The deletion of p14ARF was inversely correlated with the loss of p53 in the majority of cell lines (P = 0.02), but this relationship was not maintained among primary tumors (P = 0.5). E2F-1 can also induce p73 via a p53-independent apoptotic pathway. Although we did not observe inactivation of p73 by either mutation or DNA methylation, haploinsufficiency of p73 correlated positively with either p14ARF or p53 mutation or both (P = 0.01) in primary non-small cell lung carcinomas. These data are consistent with the current model of p14ARF and p53 interaction as a complex network rather than a simple linear pathway and indicate a possible role for an E2F-1-mediated failsafe, p53-independent, apoptotic pathway involving p73 in human lung carcinogenesis.

Typical and atypical pulmonary carcinoids : outcome in patients presenting with regional lymph node involvement.

STUDY OBJECTIVE: Typical pulmonary carcinoid tumors are well-differentiated neuroendocrine tumors that are associated with good patient survival rates, while atypical carcinoid tumors are more aggressive and have worse patient survival rates. Because these tumors rarely involve the thoracic lymph nodes at presentation, it is currently unknown to what extent the presence of thoracic lymph node metastases at the time of diagnosis influences patient survival. METHODS: A computerized search of the medical records for pulmonary carcinoid tumor at the Mayo Clinic from 1976 to 1997 revealed 517 patients, from which we identified 36 patients with pulmonary carcinoid tumors involving regional thoracic lymph nodes but without distant disease. For each patient, we reviewed the tumor histology, stage, and outcome. In addition, because the histologic criteria for the diagnosis of carcinoid tumors had changed significantly during the time of the study, we reexamined all of the histologic specimens using the current World Health Organization (WHO) criteria for classifying pulmonary neuroendocrine tumors. RESULTS: After reclassification with the WHO criteria for neuroendocrine tumors, 23 patients had typical carcinoid tumors with thoracic lymph node involvement. At the last follow-up, 19 patients had no evidence of disease (NED), 2 patients had developed systemic metastases (SM) and are still alive, and 2 patients had died. Eleven patients had atypical carcinoid tumors with thoracic lymph node involvement. At the last follow-up, four patients had NED, seven patients had developed SM within a median time of 17 months, and six patients with SM died shortly thereafter (median survival time, 25.5 months), while one is still alive. Two patients had been reclassified with large cell neuroendocrine carcinoma at the time of this review; both of these patients had developed SM (at 4 months and 21 months after diagnosis) and had died (at 15 months and 21 months after diagnosis, respectively). CONCLUSIONS: These data suggest that patients with atypical pulmonary carcinoid tumors with regional lymph node metastases have a high likelihood of developing recurrent disease if treated with surgical resection alone and have significantly worse outcome (p < 0.001) compared to those patients with typical carcinoid tumors with thoracic lymph node involvement.

Stage II (T3) lung cancer.

The tumors classified under T3 are diverse and usually present a difficult problem; however, with the improvements in surgery, radiation, and systemic therapies described above, a significant improvement in survival and quality of life can be anticipated for the future.

A randomized phase II trial of two schedules of topotecan for the treatment of advanced stage non-small cell lung cancer.

We conducted a randomized phase II trial of two different schedules of topotecan in patients with advanced-stage non small lung cancer (NSCLC) without prior cytotoxic chemotherapy. All patients had histologic or cytologic confirmation of stage IV (M1) or III-B NSCLC. Patients were stratified by performance status, stage and weight loss. Patients were randomized to receive topotecan at intravenous doses of 1.5 mg/m(2)/day over 30 min for 5 days every 3 weeks (Arm A) or 1.3 mg/m(2)grade 3 in both arms included leukopenia, thrombocytopenia, malaise, constipation, diarrhea, lethargy, pulmonary, vomiting, infection and myalgia. Severe (> or = grade 3) thrombocytopenia occurred in 15.8% of Arm A patients and 37.8% of Arm B patients and this difference was statistically significant (P=0.03). The median times to progression are 101 and 63 days (P=0. 75) and the median survival times are 257 and 179 days (P=0.83) for Arms A and B, respectively. These differences in time to progression and overall survival are not statistically significant. Topotecan has limited, single agent activity in advanced NSCLC when given as 1. 5 mg/m(2)/day over 30 min for 5 days every 3 weeks. We do not intend to pursue further investigations with topotecan in patients with NSCLC.

Screening for lung cancer in high-risk groups: current status of low-dose spiral CT scanning and sputum markers.

Lung cancer is the number one cause of death from cancer in the United States. Currently, there is no official recommendation to screen for lung cancer even in high-risk populations. Accordingly, we wait for patients to present with symptoms. Only 15-20% of patients are stage I lung cancer at diagnosis. Past screening trials with chest roentgenogram and sputum cytology did not show a reduction of lung cancer mortality in the screened population. Since the completion of those trials in the early 1980s we have learned that the chest X ray is not sensitive at detecting lesions <2 cm in size, and patients with chronic obstructive pulmonary disease (COPD) have a 4- to 6-fold increased risk of lung cancer independent of their smoking history. Recent trials with spiral computed tomography (CT) scan screening have detected 80-85% of lung cancers while they are stage I. The problems related to spiral CT screening are the cost and the frequent detection of benign lesions. Algorithms are being developed to try and prevent unnecessary biopsies and/or surgery. Sputum cytology is currently the only clinically approved sputum test for detecting lung cancer. However, in patients with moderate dysplasia of cytology, the LIFE autofluorescence bronchoscopy system may yield an increased sensitivity of detecting precancerous or cancerous lesions. More studies are needed before the LIFE system can be adopted as a standard clinical tool. Currently, investigators are evaluating the sputum for early lung cancer detection markers. The marker that is the most developed is the monoclonal antibody to the heterogeneous nuclear ribonucleoprotein A2/B1 on the sputum epithelial cell surface. Encouraging preliminary results have been reported and trials are ongoing. The future looks bright for the field of lung cancer screening.

Phase III comparison of twice-daily split-course irradiation versus once-daily irradiation for patients with limited stage small-cell lung carcinoma.

PURPOSE: Because small-cell lung cancer is a rapidly proliferating tumor, it was hypothesized that it may be more responsive to thoracic irradiation (TI) given twice-daily than once-daily. This hypothesis was tested in a phase III trial. PATIENTS AND METHODS: Patients with limited-stage small-cell lung cancer were entered onto a phase III trial, and all patients initially received three cycles of etoposide (130 mg/m(2) x 3) and cisplatin (30 mg/m(2) x 3). Subsequently, patients who did not have progression to a distant site (other than brain) were randomized to twice-daily thoracic irradiation (TDTI) versus once-daily thoracic irradiation (ODTI) given concomitantly with two additional cycles of etoposide (100 mg/m(2) x 3) and cisplatin (30 mg/m(2) x 3). The irradiation doses were TDTI, 48 Gy in 32 fractions, with a 2.5-week break after the initial 24 Gy, and ODTI, 50.4 Gy in 28 fractions. After thoracic irradiation, the patients received a sixth cycle of etoposide/cisplatin, followed by prophylactic cranial irradiation (30 Gy/15 fractions) if they had a complete response. RESULTS: Of 311 assessable patients enrolled in the trial, 262 underwent randomization to TDTI or ODTI. There were no differences between the two treatments with respect to local-only progression rates, overall progression rates, or overall survival. The patients who received TDTI had greater esophagitis (> or = grade 3) than those who received ODTI (12.3% v 5.3%; P =.05). Although patients received thoracic irradiation encompassing the postchemotherapy volumes, only seven of 90 local failures were out of the portal of irradiation. CONCLUSION: When TI is delayed until the fourth cycle of chemotherapy, TDTI does not result in improvement in local control or survival compared with ODTI.

Paclitaxel and G-CSF in previously untreated patients with extensive stage small-cell lung cancer: a phase II study of the North Central Cancer Treatment Group.

Paclitaxel is an antimicrotubule agent that interferes with cell division. It has demonstrated promising single-agent activity against non-small-cell lung cancer. The purpose of this study was to evaluate the therapeutic effectiveness of paclitaxel in previously untreated patients with extensive stage small-cell lung cancer (SCLC). The study was designed as a two-stage phase II trial. All patients who entered received paclitaxel by intravenous infusion at a dose of 250 mg/m2 during 24 hours. Granulocyte colony stimulating factor was also provided to ameliorate neutropenia. Cycles were repeated at 21-day intervals. Patients who achieved a complete response received a maximum of 10 cycles of treatment, whereas those who achieved a partial response/regression continued treatment until progression or undue toxicity developed. Patients who progressed or maintained stable disease for six cycles were crossed over to cisplatin and etoposide. Forty-three patients entered the study and all were evaluable for analysis. Responses were observed in 23 (53%) of the patients. There was no significant difference in the response rates in patients with measurable or evaluable disease (13/23 versus 10/20, p = 0.76). At the time of analysis, 39 patients had progressed with a median time to progression of 95 days, and 39 patients had died with a median survival of 278 days. The 1-year achieved survival rate was 24%. Significant neutropenia (absolute neutrophil count <1,000/microl) occurred in 24 (56%) of the patients, but only 2 patients experienced severe infection (grade > or = 3), and there were no septic deaths. The results indicate that paclitaxel is active against SCLC. Myelosuppression was the main side effect in this patient population. Response duration was short (median = 3.4 months), which suggests that paclitaxel is not sufficient as a single agent. Further studies of paclitaxel in combination with other agents against SCLC are currently in progress within the North Central Cancer Treatment Group and other cancer treatment groups. Key Words: Paclitaxel-G-CSF-Small-cell lung cancer-North Central Cancer Treatment Group.

Phase II study of high-dose somatostatin analogue in patients either previously treated or untreated who have extensive-stage small cell lung cancer.

The authors conducted a phase II study of somatostatin analogue in 18 patients with extensive stage small cell lung cancer (four with previous treatment, 14 without previous treatment). Patients received 2,000 mg subcutaneously thrice daily. They were required to have an Eastern Cooperative Oncology Group performance score of 0-2 and acceptable pretreatment biochemical parameters. No patient responded to treatment. The median time to progression was 44 days. The median survival was 106 days. Toxicity related to treatment consisted of mild diarrhea and anorexia. Somatostatin analogue is not active as a single agent in the treatment of extensive-stage small cell lung cancer.

Erdheim-Chester disease: clinical, radiologic, and histopathologic findings in five patients with interstitial lung disease.

Erdheim-Chester disease is a clinicopathologic entity defined by a characteristic pattern of symmetric osteosclerosis caused by an infiltrate of mononuclear cells that include prominent numbers of foamy histiocytes. About half of patients have extraskeletal manifestations, including involvement of the hypothalamus/posterior pituitary, orbit, retroperitoneum, skin, lung, and heart. Pulmonary involvement is an uncommon but important manifestation of Erdheim-Chester disease because it causes significant morbidity and mortality. A review of the Mayo Clinic files produced four patients with confirmed Erdheim-Chester disease in whom lung biopsy had been performed. One additional patient was included from the University of Pittsburgh. Four patients were women. The mean age was 53.6 years (range 25-70 years). All patients had bilateral and symmetric sclerotic bone lesions characteristic of Erdheim-Chester disease, although in three the skeletal abnormalities were discovered only after lung biopsy. Four patients had dyspnea, and one also had a dry cough. One patient died 17 months after diagnosis. Chest radiographs showed diffuse interstitial infiltrates in all patients, with an upper zone predominance in three. Thoracic computed tomography (CT) scans showed thickening of the visceral pleura and interlobular septa with patchy associated fine reticular and centrilobular opacities and ground glass attenuation. Lung biopsy specimens showed an infiltrate of foamy histiocytes, lymphocytes, and scattered Touton giant cells with associated fibrosis in a striking lymphatic distribution. The infiltrate involved visceral pleura, interlobular septa, and bronchovascular bundles. Immunohistochemical stains were positive for CD68 in all cases and S-100 protein in four cases. Stains for CD1a were consistently negative. Ultrastructural studies in one case showed no Birbeck granules. Although in bone the histologic features of Erdheim-Chester disease may overlap with Langerhans' cell histiocytosis, its expression in the lung is distinct. Lung involvement in Erdheim-Chester disease has emerged as a unique radiographic and histologic entity.

Phase II trial of topotecan for the treatment of mesothelioma.

The North Central Cancer Treatment Group designed a phase II trial to assess the efficacy and toxicity of topotecan in patients with unresectable malignant pleural mesothelioma. Twenty-two previously untreated patients with unresectable pleural mesothelioma and good performance status (Eastern Cooperative Oncology Group performance status 0, 1, or 2) were enrolled on this trial from October 1993 through July 1994. Nineteen men and three women, median age 66 years (range, 44-78 years), were treated with topotecan 1.5 mg/m2 intravenously over 30 minutes daily for 5 days at 3-week intervals until toxicity, progression of disease, or a patient decided to discontinue treatment. There were seven patients with measurable disease and 15 with evaluable disease; all were assessable for response and toxicity. A total of 113 cycles of treatment were given, for a median of three cycles (range, 1-26 cycles). Myelosuppression was the most frequent toxicity. Eighteen of 21 patients (86%) experienced grade 3 or 4 neutropenia during the initial treatment cycle. The median neutrophil nadir was 0.5 x 10(3)/microl (range, 0.1-1.6 x 10(3)/microl), and the median platelet nadir was 127 x 10(3)/microl (range, 18-460 x 10(3)/microl). Other toxicities more than grade 2 included malaise (two patients), and anorexia, infection, fever, pulmonary, and cardiac in one patient each. There were no objective responses, and 18 patients had stable disease for a median of 74 days. The median survival for all patients was 230 days, with 23% alive at 1 year. Topotecan as administered in this trial is reasonably well tolerated; however, the response rate was insufficient to warrant additional study in pleural mesothelioma.

p21waf1/cip1 and transforming growth factor beta 1 protein expression correlate with survival in non-small cell lung cancer.

p21waf1/cip1 encodes a cyclin-dependent kinase inhibitor that is transcriptionally activated by the p53 tumor suppressor gene, transforming growth factor beta 1 (TGF-beta 1), AP2, and other pathways. Because p21waf1/cip1, p53, and TGF-beta 1 all regulate apoptosis and the cell cycle, we tested the hypothesis that their relative protein levels would correlate with biological features including the survival of non-small cell lung cancer (NSCLC) patients. We conducted an immunohistochemical analysis of p21waf1/cip1 and TGF-beta 1 and identified four patient groups with distinct survival outcomes. Concordant p21waf1/cip1 and TGF-beta 1 expression (i.e., either high p21waf1/cip1 and high TGF-beta 1 expression or low p21waf1/cip1 and low TGF-beta 1 expression) predicted 70% disease-free survival at 2000 days of follow-up. Discordant p21waf1/cip1 and TGF-beta 1 expression (i.e., either high p21waf1/cip1 and low TGF-beta 1 expression or low p21waf1/cip1 and high TGF-beta 1 expression) predicted 35% disease-free survival (P = 0.0003; log-rank test). These survival relationships were not attributable to differences in grade, stage, or p53 status. Although current models do not fully explain these complex interactions, most of these data fit a paradigm whereby TGF-beta 1 regulation determines NSCLC survival. In addition to the survival correlation, we found that high p21waf1/cip1 protein expression correlated with high tumor grade (P = 0.014). There is little evidence that p21waf1/cip1 protein levels accurately predict p53 mutation status in NSCLC; specifically, 20 of 48 (42%) tumors with p53 mutations contained high levels of p21waf1/cip1 protein. These findings indicate that p21waf1/cip1 immunohistochemical analysis may provide useful information concerning the biological properties of NSCLC.

New agents in the treatment of small cell lung cancer.

The treatment of small cell lung cancer (SCLC) has evolved significantly over the past 3 decades. Single-agent and combination chemotherapies given with radiotherapy have greatly improved response rates and median survival. Combination regimens such as cisplatin/etoposide, carboplatin/etoposide, ifosfamide/carboplatin/etoposide, cyclophosphamide/doxorubicin/vincristine, and etoposide/ifosfamide/cisplatin have all achieved good response rates. Improving long-term survival, however, has remained problematic. Treatment with biological response modifiers (interferons alpha and gamma) has not shown promise in this setting. New agents showing good preliminary single-agent activity in untreated SCLC include paclitaxel, vinorelbine, gemcitabine, topotecan, and teniposide. Results obtained with single-agent docetaxel and CPT-11 are thus far inconclusive. Studies evaluating response and survival rates of these new agents in combination with agents of known activity are underway.

p53 mutation spectrum in relation to GSTM1, CYP1A1 and CYP2E1 in surgically treated patients with non-small cell lung cancer.

p53 mutation status was analysed in relation to DNA polymorphisms of GSTM1, CYP1A1 and CYP2E1 from 105 surgically resected non-small cell lung cancer cases. Demographic factors, smoking, occupation, family history, tumour histology, grade and stage were taken into account. p53 mutations, detected either directly by DNA sequencing (P = 0.04, adjusted for smoking) or indirectly by immunostaining (P = 0.06), were overrepresented among CYP1A1 variants. Mutations in exon 8 and transitions at CpG sites in the p53 gene were favoured in this subset. There was no relation between the individual gene polymorphisms or p53 mutations and disease-free survival by Kaplan-Meier analysis. The finding of excess CYP1A1 heterozygotes in individuals with p53 mutations after adjustment for smoking suggests that CYP1A1 activation contributes to lung cancer via p53 inactivation.

Primary mediastinal tumors: part II. Tumors of the middle and posterior mediastinum.

Lymphoma, mediastinal cysts, and neurogenic neoplasms are the most common primary middle and posterior mediastinal tumors. Lymphoma may involve the anterior, middle and/or posterior mediastinum, frequently as lymphadenopathy or as a discrete mass. Foregut cysts are common congenital mediastinal cysts and frequently arise in the middle mediastinum. Pericardial cysts are rare. Schwannoma and neurofibroma are benign peripheral nerve neoplasms, represent the most common mediastinal neurogenic tumors, and rarely degenerate into malignant tumors of nerve sheath origin. Sympathetic ganglia tumors include benign ganglioneuroma and malignant ganglioneuroblastoma and neuroblastoma. Lateral thoracic meningocele is a rare cause of a posterior mediastinal mass.