Current situation of management of spontaneous pneumothorax in Japan: A cross-sectional cohort study.

BACKGROUND: Limited epidemiological information is available on spontaneous pneumothorax. To address this gap, the Japan Society for Pneumothorax and Cystic Lung Disease (JSPCLD) conducted a nationwide retrospective survey to investigate the current epidemiology of spontaneous pneumothorax in Japan. METHODS: In this study, we conducted a retrospective cross-sectional cohort study to demonstrate the clinical features of spontaneous pneumothorax in one year from April 2019 to March 2020, compare patient characteristics and treatment outcomes between primary (PSP) and secondary spontaneous pneumothorax (SSP), and investigate the risk factors associated with in-hospital mortality among patients with SSP. RESULTS: A total of 1784 patients from 28 institutions were enrolled in the study, with PSP observed in 956 cases (53.6%) and SSP in 817 cases (45.8%). The age distribution showed a biphasic peak caused by the different peaks between PSP and SSP. In-hospital mortality occurred in 42 cases (2.4%) among all patients, with 0 cases (0%) in PSP and 42 cases (5.1%) in SSP. Multivariable analyses revealed that interstitial pneumonia as an underlying disease (odds ratio: 2.4700, 95% confidence interval: 1.1100 to 5.4800, p = 0.0269), performance status≧3 (odds ratio: 7.3900, 95% confidence interval: 3.1900 to 17.2000, p < 0.0001), and lower value of serum albumin on admission (odds ratio: 0.4060, 95% confidence interval: 0.2140 to 0.7690, p = 0.0057) were significantly associated with in-hospital mortality among patients with SSP. CONCLUSIONS: SSP patients with poor baseline conditions are at a higher risk for in-hospital mortality. It is crucial to provide close and meticulous management for SSP patients with compromised conditions.

Suitable Patient Selection and Optimal Timing of Treatment for Persistent Air Leak after Lung Resection.

OBJECTIVES: The choice of therapeutic intervention for postoperative air leak varies between institutions. We aimed to identify the optimal timing and patient criteria for therapeutic intervention in cases of postoperative air leaks after lung resection. METHODS: This study utilized data from a prospective multicenter observational study conducted in 2019. Among the 2187 cases in the database, 420 cases with air leaks on postoperative day 1 were identified. The intervention group underwent therapeutic interventions, such as pleurodesis or surgery, while the observation group was monitored without intervention. A comparison between the intervention group and the observation group were analyzed using the cumulative distribution and hazard functions. RESULTS: Forty-six patients (11.0%) were included in the intervention group. The multivariate analysis revealed that low body mass index (p = 0.019), partial resection (p = 0.010), intraoperative use of fibrin glue (p = 0.008), severe air leak on postoperative day 1 (p < 0.001), and high forced expiratory volume in 1 s (p = 0.021) were significant predictors of the requirement for intervention. The proportion of patients with persistent air leak in the observation group was 20% on postoperative day 5 and 94% on postoperative day 7. The hazard of air leak cessation peaked from postoperative day 3 to postoperative day 7. CONCLUSIONS: This research contributes valuable insights into predicting therapeutic interventions for postoperative air leaks and identifies scenarios where spontaneous cessation is probable. A validation through prospective studies is warranted to affirm these findings.

A Novel Filtration Membrane for Clustered Circulating Tumor Cell Extraction: A Prospective Feasibility Study.

BACKGROUND/AIM: Circulating tumor cells (CTCs) have garnered attention as biomarkers for therapeutic response and prognosis in malignant neoplasms. Nonetheless, existing literature predominantly relies on surrogate markers of tumor cells or focuses on single-cell CTC, failing to adequately address the challenge of detecting cluster-forming CTCs, which bear considerable prognostic implications. This prospective study aims to validate the efficacy of a novel filtration membrane, namely Soft Micro Pore Filter (S-MPF®), for rare cell recovery in detecting CTCs through the analysis of clinical samples. PATIENTS AND METHODS: Patients with confirmed lung cancer or highly suspected lung cancer based on specific criteria (solid tumor size >2.0 cm, serum carcinoembryonic level >7.5 ng/ml, maximum standard uptake value derived from fluorodeoxyglucose-position emission tomography >2.9) were included in the study. CTCs were extracted from preoperative peripheral arterial blood samples using S-MPF®, and the validity of the filtration system was positively verified. RESULTS: Out of the 25 enrolled patients, 23 had lung cancer. CTC positivity was observed in 17 cases (73.9%), whereas cluster CTC positivity was observed in 16 cases (69.6%), with a median count of two clusters. Single CTC positivity was observed in 11 cases (52.1%), with a median count of one cell. CONCLUSION: The utilization of the newly developed S-MPF® filtration membrane exhibited a high rate of CTC identification, demonstrating its suitability for clinical applications.

Angiopoietin-like 4 Is a Critical Regulator of Fibroblasts during Pulmonary Fibrosis Development.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and irreversible interstitial pneumonia caused by the excessive production and deposition of extracellular matrix components, including type I collagen. Activated fibroblasts, called α-SMA (α-smooth muscle actin)-expressing myofibroblasts, are the major source of type I collagen in pulmonary fibrosis (PF), but the mechanisms underlying disease progression have not been fully elucidated. Here, we obtained lung fibroblasts from patients with IPF from both nonfibrotic and fibrotic areas as determined by a lung computed tomography scan and compared gene expression between these areas by DNA microarray. We found that ANGPTL4 (angiopoietin-like 4) was highly expressed only in fibroblasts from the fibrotic area. ANGPTL4 was selectively expressed in the fibroblastic area of IPF lungs, where the myofibroblast marker α-SMA was also expressed. ANGPTL4 also regulates the gene expression of fibrosis-related markers, cell migration, and proliferation. In addition, ANGPTL4 expression in a murine model of PF induced by treatment with bleomycin was significantly induced in the lungs from the acute to the chronic phase. Single-cell transcriptome analysis during the course of bleomycin-induced PF revealed that Angptl4 was predominantly expressed in the activated fibroblasts and myofibroblasts. Moreover, the administration of recombinant ANGPTL4 to the bleomycin-induced fibrosis model significantly increased collagen deposition and exacerbated the PF. In contrast, the pathogenesis of PF in Angptl4-deficient mice was improved. These results indicate that ANGPTL4 is critical for the progression of PF and might be an early diagnostic marker and therapeutic target for IPF.

Primary pulmonary diffuse large B-cell lymphoma presenting multiple nodules mimicking metastasis: A case report.

Primary pulmonary diffuse large B-cell lymphoma is a rare entity. We describe a case of pulmonary lymphoma with multiple nodules mimicking metastases in a treated patient with rheumatoid arthritis. A 73-year-old man was diagnosed with rheumatoid arthritis at the age of 30. He was treated with leflunomide. He was followed up for a nontuberculous mycobacterial infection. He underwent percutaneous coronary intervention for acute myocardial infarction at the age of 70. In April 2022, routine follow-up revealed new-onset multiple nodules on chest computed tomography (CT). A position emission tomography/CT scan with 18F-fluorodeoxyglucose showed a low-high maximum standardized uptake value by multiple nodules. Pathologic examination of a video-assisted thoracic surgical biopsy revealed pulmonary diffuse large B-cell lymphoma. Systemic chemotherapy with rituximab, cyclophosphamide, vincristine, and prednisolone reduced and eliminated multiple nodules. Pulmonary lymphoma should be considered as a differential diagnosis in the case of multiple nodules on a chest CT.

Outcome of Resected Lung Cancers with Subcentimeter Solid Component on Computed Tomography.

BACKGROUND: Although the opportunity to treat subcentimeter lung cancers has increased, the optimal surgical methods remain unclear. We performed a retrospective study to examine the clinical outcome of subcentimeter lung cancers. PATIENTS AND METHODS: In total, 118 patients who underwent curative resection for subcentimeter lung cancer from January 2005 to December 2013 were analyzed. Multivariate Cox proportional hazards models were used to calculate the hazard ratio to identify independent predictors of recurrence-free survival (RFS) and overall survival (OS). RESULTS: Anatomical resections were performed for 64 patients (59 lobectomies and 5 segmentectomies) and wedge resections for 54 patients. Recurrence developed in six patients who had consolidation-predominant tumors (consolidation/tumor [C/T] ratio of >0.5) and underwent wedge resections. The first recurrence patterns were regional recurrences in three patients, both regional and distant in one, and distant in two. Seventeen patients died of other causes. The multivariate analysis revealed that the C/T ratio was the independent predictor of RFS (p = 0.008) and OS (p = 0.011). CONCLUSION: Patients with subcentimeter lung cancer rarely developed recurrence. The C/T ratio was the independent prognostic factor, and all relapsed patients received wedge resections. Even for subcentimeter lung cancers, we should select the extent of pulmonary resection after thoroughly considering whether wedge resection (less invasiveness) is a reasonable alternative to anatomical resection (superior oncologic efficacy) considering the C/T ratio of the lesion.

A retrospective multi-institutional survey of characteristics of surgically treated spontaneous hemopneumothorax patients.

OBJECTIVE: The Japan Society for Pneumothorax and Cystic Lung Disease conducted a nationwide retrospective survey to identify correlations between the timing of surgical intervention and the incidence of transfusion, and to examine the factors contributing to the need for transfusion among clinical features in surgically treated spontaneous hemopneumothorax (SHP) patients. METHODS: We analyzed the characteristics and perioperative results of patients with SHP who underwent thoracoscopy or thoracotomy between April 2009 and March 2019. RESULTS: From 17 institutions, 171 cases were enrolled in this study. Receiver-operating characteristic curve analyses for the incidence of transfusion and waiting time before the operation revealed an area under the curve of 0.54 (95% confidence interval [CI] 0.44-0.64). Therefore, we did not compare the clinical features using a cutoff value of waiting time before the operation. More than 80% of the patients underwent surgical treatment within 24 h from admission. Multivariate analysis revealed that the total volume of hemorrhage was the only significant factor contributing to the incidence of transfusion (p = 0.00011, odds ratio: 0.03, 95% CI 0.0051-0.18). Moreover, multivariate analyses revealed that the waiting time before the operation was a contributing factor for prolonged total hospitalization (p < 0.0001, estimated regression coefficient: 0.036, 95% CI 0.027-0.045). CONCLUSION: In SHP patients, a reduction in the waiting time before the operation significantly contributed to not the avoidance of transfusion but a reduction in total hospitalization time. In addition, transfusion was performed depending on the volume of blood loss.

Optimal Chest Drainage Method After Anatomic Lung Resection: A Prospective Observational Study.

BACKGROUND: Several methods for chest drainage after pulmonary resection of malignant lung tumors exist, but consensus on the ideal method has not been reached. METHODS: We conducted a multicenter prospective observational study. We enrolled 2200 patients who underwent lung resection for lung tumors. Of the 1470 patients who underwent anatomic resection, 347 showed air leak on the morning of postoperative day 1. They were assigned to 3 groups according to the chest drainage method on postoperative day 1. RESULTS: Of 347 patients with postoperative air leaks, 107 (30.8%), 179 (51.6%), and 61 (17.6%) were assigned to water seal, continuous suction, and digital drainage, respectively. The median postoperative air leak duration was significantly longer with digital drainage (4.0 days) than with either water seal (2.5 days) or continuous suction (3.0 days; P = .009). Chest tubes were required for significantly more days on average with digital drainage (6.0 days) than with water seal (4.0 days) or continuous suction (4.0 days; P = .003). Prolongation of air leak duration was significantly more likely to occur in patients with body mass index <18.5 kg/m2 (hazard ratio [HR], 1.6; 95% CI, 1.1-2.3), moderate or severe air leak on postoperative day 1 (HR, 2.0; 95% CI, 1.5-2.6), or digital drainage (HR, 1.4; 95% CI, 1.01-1.9). CONCLUSIONS: Water seal was associated with significantly shorter duration of postoperative air leak and chest drainage compared with continuous suction and digital drainage.

Preference of grade and lymphovascular invasion over invasive size measurement in stage I lung adenocarcinoma.

AIMS: Although it is necessary to measure the invasive size of lung adenocarcinoma with a lepidic component, it is not uncommon to have trouble in measuring the invasive size of lung adenocarcinoma. This study examined whether there were other stronger prognostic factors than invasive size. METHODS: We characterised the clinicopathological features associated with recurrence-free survival (RFS) of 686 patients with the pathological stage (p-Stage) I lung adenocarcinoma. Moreover, we compared the area under the curve (AUC) values for recurrence between various combinations of pathological-baseline (age & sex & p-Stage based on invasive size) (B(i)) and several prognostic factors, and various combinations of p-baseline based on total tumour size (B(t)) and several prognostic factors. RESULTS: AUC showed no significant differences between B(i) & new International Association for the Study of Lung Cancer grade (G) or vascular invasion (V), and B(t) & G or V. AUC was the highest in B & G & lymphatic invasion (L) & V. RFS was significantly shorter in patients with G3 OR L(+) OR V(+) than in those with G≤2 AND L(-) AND V(-) in each p-Stage based on invasive size (p-Stage(i)) and p-Stage based on total tumour size (p-Stage(t)) (p<0.05), and there were no significant differences in RFS between each p-Stage(i) and p-Stage(t). CONCLUSIONS: In any invasive size or total tumour size of p-Stage I lung adenocarcinoma, G, L and V are more powerful prognostic factors than the size criteria of p-Stage. Therefore, pathologists should focus on these pathological findings.

Clinicopathological and genetic analyses of pulmonary enteric adenocarcinoma.

AIMS: Pulmonary enteric adenocarcinoma (PEAC) is a rare variant of pulmonary adenocarcinoma. Due to its rarity, few pathological and molecular studies have been performed on PEAC. We herein conducted clinicopathological, immunohistochemical and molecular analyses of PEAC with a focus on its differentiation from invasive mucinous adenocarcinoma (IMA). METHODS: We examined the clinicopathological features of 16 cases of PEAC and performed a genetic analysis using next-generation sequencing (NGS). The results obtained were compared with those for IMA. RESULTS: The average age of patients with PEAC (seven men and nine women) was 72.9 years. A comparison of clinical data on PEAC and IMA revealed no significant differences in age, sex or smoking history. Fifteen PEAC cases had dirty necrosis. Immunohistochemically, the positive rates for each antibody in PEAC were as follows: CK7, 88% (14/16); CK20, 81% (13/16); CDX2, 88% (14/16); p53, 69% (11/16); MUC1, 100% (16/16); MUC2, 19% (3/16); MUC5AC, 69% (11/16); MUC6, 19% (3/16). The positive rates for these antibodies in IMA were 100%, 87%, 0%, 7%, 93%, 0%, 100% and 80%, respectively. EGFR mutations, the MET exon 14 skipping mutation, BRAF mutations, the ALK fusion gene and ROS-1 fusion gene were not detected in any cases of PEAC or IMA. Among PEAC cases, NGS identified KRAS mutations in seven (44%, 7/16) and TP53 mutations in nine (56%, 9/16). Among IMA cases, the most commonly mutated gene was KRAS (90%). CONCLUSIONS: The rates of dirty necrosis, immunopositivity for CDX2 and TP53 mutations were significantly higher, while that of KRAS mutations was significantly lower in PEAC cases than in IMA cases.

Pulmonary sarcoidosis with a cavitary lesion in the lung caused by a TNF-α inhibitor: A case report.

A 28-year-old man with ankylosing spondylitis (AS) who was treated with a tumour necrosis factor-alpha (TNF-α) inhibitor, adalimumab, presented with newly detected multiple bilateral pulmonary nodules on chest computed tomography (CT). We suspected bacterial infection, including those caused by acid-fast bacilli, or adalimumab-related condition, such as sarcoidosis. After adalimumab cessation, no resolution of the pulmonary shadows was observed. Moreover, pulmonary cavitation appeared on chest CT at 7 weeks, prompting surgical lung biopsy. Acid-fast bacteria culture of the lung tissue showed negative results. Pathological examination suggested that confluent granulomas associated with sarcoidosis might have obstructed the blood vessels, causing necrosis and lung cavitation. Consequently, prednisolone was initiated, and these shadows were reduced. After administering anti-interleukin (IL)-17A antibody for treatment of AS and prednisolone withdrawal, these shadows were not exacerbated. TNF-α inhibitor-induced sarcoidosis could cause cavitary lesions due to vascular invasion of granulomas.

Pure Solid Pattern of Non-Small Cell Lung Cancer and Clustered Circulating Tumor Cells.

There are two solid patterns of non-small cell lung cancer (NSCLC) on computed tomography (CT): pure or mixed with ground-glass opacities (GGOs). They predict the degree of invasiveness, which may suggest the presence of clustered circulating tumor cells (CTCs), a predictor of poor prognosis. In this study, we assessed the implications of the solid patterns on CT and the preoperative clustered CTCs in surgically resected NSCLC. CTCs were detected using a size selection method. The correlation between the presence of preoperative clustered CTCs and the solid pattern and the prognostic implications were evaluated using co-variables from the clinical-pathological findings. Of the 142 cases, pure solid lesions (Group PS) and mixed GGOs (Group G) were observed in 92 (64.8%) and 50 (35.2%) patients, respectively. In Groups PS and G, clustered CTCs were detected in 29 (31.5%) and 1 (2.0%) patient (p < 0.01), respectively. The PS appearance was an independent predictor of preoperative clustered CTCs in the multivariable analysis, and preoperative clustered CTCs were an independent predictor of poor recurrence-free survival; the solid pattern was not an independent variable. Thus, the PS pattern of NSCLC on CT is an indicator of preoperative clustered CTCs, which is an independent poor prognosis predictor.

Verification of A New Filter for Isolation of Circulating Tumor Cells by Only Blood Filtration.

BACKGROUND/AIM: Since circulating tumor cells (CTCs) are precursors of metastatic lesions, extracting CTCs from whole blood is useful in obtaining information for cancer treatment. One of the CTC isolation methods is the size selection method; however, since the conventional methods are expensive and cumbersome, we developed an affordable and simple filter, whose usefulness is verified in this study. MATERIALS AND METHODS: The new filter [hereafter, soft micropore filter (S-MPF)] is made up of a polyethylene film with a thickness of 15 µm and conical pores having a diameter of 8-10 µm, which are opened uniformly (opening rate, 20%). This filter can filter whole blood by free-falling under gravity. The possibilities of the filter's usage for model CTC isolation, immunostaining, short-term cell culture, and gene mutation detection in extracted model CTCs were verified. RESULTS: S-MPF was able to extract model CTCs with an isolation rate of up to 15%. These model CTCs were detected by cytology, immunostaining, and culture by short-term incubation of filtered cells. Furthermore, genetic mutations were identified in the cultured cells. In addition, CTC isolation from the peripheral blood of patients with lung cancer was demonstrated by setting the volume of collected blood to 15 ml to prevent a low recovery rate. CONCLUSION: The S-MPF can be used to extract model CTCs quickly and easily. Moreover, cytological diagnosis, immunostaining, short-term culture, and gene mutation search are possible with this filter. Given its proven applicability in clinical samples, this filter can be used in clinical settings.

Identification of fusion transcripts in sarcoma from archival formalin-fixed paraffin-embedded tissues: A next-generation sequencing approach.

Most sarcomas are highly aggressive, and cause necrosis and hemorrhage. The diagnosis of sarcoma is challenging because of the lack of specificity of immunohistochemical staining; however, molecular biological approaches, such as genetic mutation, chromosomal translocation, and gene amplification, are promising. In this study, we extracted RNA from formalin-fixed paraffin-embedded (FFPE) tissue derived from surgically resected specimens of sarcoma stored for various periods and performed next-generation sequencing (NGS) analysis by MiniSeq using the Archer Fusion-Plex Sarcoma Panel. RNA was extracted from 63 FFPE tissue samples, and the degree of RNA degradation was assessed. The number of reads and fragment lengths were evaluated by NGS analysis. RNA extraction and cDNA synthesis were successful in 56 cases and library preparation was possible. Fusion genes were detected in 16 of 63 archived FFPE tissue samples in this study. However, in 18 cases, fragmentation was strong, and high-quality libraries could not be obtained. Nevertheless, comprehensive analysis of fusion genes with high sequence specificity by NGS can be a powerful alternative to reverse transcription-polymerase chain reaction and fluorescence in situ hybridization methods.

TAS-Seq is a robust and sensitive amplification method for bead-based scRNA-seq.

Single-cell RNA-sequencing (scRNA-seq) is valuable for analyzing cellular heterogeneity. Cell composition accuracy is critical for analyzing cell-cell interaction networks from scRNA-seq data. However, droplet- and plate-based scRNA-seq techniques have cell sampling bias that could affect the cell composition of scRNA-seq datasets. Here we developed terminator-assisted solid-phase cDNA amplification and sequencing (TAS-Seq) for scRNA-seq based on a terminator, terminal transferase, and nanowell/bead-based scRNA-seq platform. TAS-Seq showed high tolerance to variations in the terminal transferase reaction, which complicate the handling of existing terminal transferase-based scRNA-seq methods. In murine and human lung samples, TAS-Seq yielded scRNA-seq data that were highly correlated with flow-cytometric data, showing higher gene-detection sensitivity and more robust detection of important cell-cell interactions and expression of growth factors/interleukins in cell subsets than 10X Chromium v2 and Smart-seq2. Expanding TAS-Seq application will improve understanding and atlas construction of lung biology at the single-cell level.

Thymic Mucoepidermoid Carcinoma: A Clinicopathologic and Molecular Study.

Thymic mucoepidermoid carcinoma (MEC) is a rare tumor, and its characteristics remain to be clarified. Here we investigated 20 cases of thymic MEC to systematically characterize its clinical, histopathologic, and molecular features. The median age of the patients was 56 years (range, 19 to 80 y), there was a slight male predilection (3:2), and 44% of the patients were asymptomatic at diagnosis. The median tumor size was 6.8 cm in diameter, 55% were pT1 tumors, and 50% were TNM stage I tumors. When 4 tumor grading systems for salivary MEC (Armed Forces Institutes of Pathology, Brandwein, modified Healey, and the Memorial Sloan-Kettering) were employed, low-grade, intermediate-grade, and high-grade tumors accounted for 35% to 70%, 5% to 25%, and 25% to 50%, respectively. Many histologic variants were noted, and 70% of the cases were classified as nonclassic variants. MAML2 rearrangement was detected in 56% of cases, and the fusion partner was CRTC1 in all cases. CRTC1-MAML2 fusion was associated with lower pT classification and lower TNM stage. The overall survival rate of all patients was 69% and 43% at 5 and 10 years, respectively. Worse overall survival was associated with higher pT stage, higher TNM stage, residual tumors, greater tumor size, high-grade tumor histology (Armed Forces Institutes of Pathology and Memorial Sloan-Kettering, but not the other 2), and with the absence of CRTC1-MAML2 fusion. Of note, none of the patients with CRTC1-MAML2 fusion-positive tumors died during the follow-up. In conclusion, the clinicopathologic and molecular findings of thymic MEC presented here are expected to contribute to the management of this rare tumor.

Circulating Tumor Cells and the Non-Touch Isolation Technique in Surgery for Non-Small-Cell Lung Cancer.

Circulating tumor cells (CTCs) are dislodged from the primary tumor into the bloodstream, travel within the bloodstream to distant organs, and finally extravasate and proliferate as epithelial metastatic deposits. The relationship between the existence of CTCs and tumor prognosis has been demonstrated by many researchers. In surgery for malignancies, the surgical manipulation of tumors and tissues around the tumor may lead to the release of CTCs into the bloodstream. The non-touch isolation technique (NTIT) has been advocated to prevent the release of CTCs during surgery. The concept of NTIT is the prevention of intraoperative increment of CTCs from the primary tumor by the early blockade of outflow vessels, and 'pulmonary vein (PV)-first lobectomy' during surgery for non-small-cell lung cancer (NSCLC) corresponds to this technique. The concept of PV-first lobectomy is well known among thoracic surgeons, but evidence of its efficacy for preventing the increase of intra- and postoperative CTCs and for improving postoperative prognosis is still uncertain. Our study summarizes evidence regarding the relationship between NTIT and CTCs in NSCLC and suggests the need for further research on CTCs and CTC-detecting modalities.

Surgical treatment for secondary spontaneous pneumothorax: a risk factor analysis.

PURPOSE: While surgery is an effective treatment for secondary spontaneous pneumothorax (SSP), it can be difficult, because affected patients are usually in a poor general condition. The present study investigated the risk factors of postoperative complications after surgery for SSP. METHODS: Eighty-eight patients with SSP who underwent surgery from January 2006 to March 2018 were investigated. Clinical data were reviewed, and a multivariate analysis was performed. RESULTS: Eighty-four patients (95%) were males, and the median patient age was 72 years. Underlying lung diseases were chronic obstructive pulmonary disease in 58 patients (65.9%), interstitial pneumonia in 26 (29.5%), and others in 4 (4.5%). Postoperative complications developed in 21 patients (24%). Hospital mortality/prolonged length of stay occurred in 6 patients (7%). A multivariate analysis showed that the preoperative performance status (performance status 0-2 vs. 3, hazard ratio: 6.570, 95% confidence interval: 1.980-21.800) was an independent predictor of postoperative complications. CONCLUSION: Surgery for SSP contributed to early chest tube removal and favorable outcomes. However, rare fatal events occurred, and the patient performance status was a risk factor for postoperative complications. A careful evaluation of each patient's performance status is needed to determine the need for surgical intervention for SSP.