Clinical Significance of SIRPα Expression on Tumor-Associated Macrophages in Patients with Lung Squamous Cell Carcinoma.

BACKGROUND: Signal-regulatory protein alpha (SIRPα) is an immune checkpoint molecule expressed on macrophages that functions to inhibit phagocytosis by binding to CD47 expressed on tumor cells. SIRPα has attracted increasing attention as a novel target for cancer immunotherapy; however, the expression and immune function of SIRPα in lung squamous cell carcinoma (LUSC) remain unclear. Therefore, this study aimed to identify the clinical importance of SIRPα expression in LUSC and to explore the factors that elevate SIRPα expression. PATIENTS AND METHODS: Primary LUSC specimens surgically resected from 172 patients underwent immunohistochemical evaluation of the association of SIRPα expression on tumor-associated macrophages with clinicopathological features and clinical outcomes. Furthermore, we analyzed the association of SIRPα expression with tumor-infiltrating lymphocytes and the expression of programmed cell death ligand 1 (PD-L1). In vitro, monocytes were treated with cytokines, and SIRPα protein expression was assessed by flow cytometry. RESULTS: There were no differences in SIRPα expression and clinicopathological factors. High SIRPα expression was significantly associated with PD-L1-positive expression, and high CD8, PD-1, and CD163 expression. The high SIRPα expression group showed significantly shorter recurrence-free survival (RFS) and overall survival (OS). On multivariate analysis, high SIRPα expression was an independent poor prognostic factor for RFS and OS. The expression of SIRPα protein in monocytes was upregulated by treatment with IFNγ. CONCLUSION: Our analysis revealed that high SIRPα expression significantly predicts poor prognosis in patients with surgically resected LUSC.

CD155 Expression in Early-stage Lung Adenocarcinoma.

BACKGROUND: CD155 is a transmembrane protein that belongs to the nectin-like molecule family that is widely overexpressed in several types of cancer. However, the clinical significance of CD155 in pathological stage I lung adenocarcinoma remains poorly understood. METHODS: We analyzed 320 patients diagnosed with pathological stage I lung adenocarcinoma who underwent surgical treatment at Kyushu University Hospital between 2006 and 2015. The number of tumor cells expressing CD155 was assessed by immunohistochemistry, and patients were categorized into high and low CD155 expression groups. We compared the clinicopathological characteristics and clinical outcomes between these groups. RESULTS: EGFR mutation status was determined in 237 patients. A total of 106 patients (33.1%) had EGFR wild-type, while 131 patients (40.9%) were EGFR mutant-type. Regarding CD155 expression, 77 patients (24.1%) were classified as high and 243 (75.9%) as low. The multivariate analysis identified pleural invasion and EGFR wild-type as independent predictors of high CD155 expression. The Kaplan-Meier plot demonstrated significantly poorer recurrence-free survival and overall survival in the high CD155 group compared with the low CD155 group. In multivariate analysis, high CD155 expression was an independent poor prognostic factor for both recurrence-free and overall survival. Subgroup analyses revealed that a prognostic difference related to CD155 expression was observed only in patients with EGFR wild-type but not in those with EGFR mutant-type. CONCLUSIONS: Our findings suggest that high expression of CD155 is associated with EGFR wild-type and could serve as a valuable prognostic marker in pathological stage I lung adenocarcinoma, particularly in cases without EGFR mutation.

Oncological feasibility of segmentectomy for inner-located lung cancer.

Objective: Oncological feasibility of segmentectomy for internal non-small cell lung cancer (NSCLC) has not been assessed adequately. We assessed the oncological feasibility of segmentectomy for inner-located NSCLC by investigating surgical margins and patient prognosis after undergoing the procedure. Methods: Of the 3555 patients who underwent resection for lung cancer between 2013 and 2019 at our institution, 659 patients who underwent segmentectomy for clinical stage 0 to stage1A NSCLC were included in this study. Patients were separated into 2 groups according to whether the tumor was in the inner or outer third of the lung area. Clinical characteristics and prognoses were retrospectively compared between the groups. Results: Of the included 659 cases, 183 (27.8%) were inner-located, and 476 (72.2%) had outer-located NSCLC. The surgical margin was significantly shorter in the inner-located group than in the outer group (median, 16 vs 25 mm; P < .001). The 5-year recurrence-free survival and overall survival probabilities were 91.1%/91.8% (P = .530) and 94.1%/95.6% (P = .345) for inner/outer-located groups, respectively. Multivariate analysis showed that clinical stage IA2 or 3 (P = .043), lymphovascular invasion (P < .001), and surgical margins <20 mm (P = .017) were independent prognostic factors for recurrence-free survival. The location of the inner or outer tumors was not related to the prognosis. Conclusions: For clinical stage 0 to stage1A NSCLC, tumor location in the inner two-thirds of the lung was not associated with prognosis after segmentectomy. Because one of the independent prognostic factors is margin distance, segmentectomy for inner-located NSCLC would be oncologically acceptable when an adequate surgical margin is secured.

Clinical and Prognostic Significance of Glutathione Peroxidase 2 in Lung Adenocarcinoma.

BACKGROUND: Glutathione peroxidase 2 (GPX2) is an antioxidant enzyme with an important role in tumor progression in various cancers. However, the clinical significance of GPX2 in lung adenocarcinoma has not been clarified. METHODS: Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to analyze GPX2 mRNA expression. Then, we conducted immunohistochemistry (IHC) to assess GPX2 expression in specimens acquired from 351 patients with lung adenocarcinoma who underwent surgery at Kyushu University from 2003 to 2012. We investigated the association between GPX2 expression and clinicopathological characteristics and further analyzed the prognostic relevance. RESULTS: qRT-PCR revealed that GPX2 mRNA expression was notably higher in tumor cells than in normal tissues. IHC revealed that high GPX2 expression (n = 175, 49.9%) was significantly correlated with male sex, smoking, advanced pathological stage, and the presence of pleural, lymphatic, and vascular invasion. Patients with high GPX2 expression exhibited significantly shorter recurrence-free survival (RFS) and overall survival. Multivariate analysis identified high GPX2 expression as an independent prognostic factor of RFS. CONCLUSIONS: GPX2 expression was significantly associated with pathological malignancy. It is conceivable that high GPX2 expression reflects tumor malignancy. Therefore, high GPX2 expression is a significant prognostic factor of poor prognosis for completely resected lung adenocarcinoma.

Impact of 18F-FDG PET on TNM Staging and Prognosis in Thymic Epithelial Tumors.

BACKGROUND: Preoperative fluorine-18-fluorodeoxyglucose positron emission tomography (18F-FDG PET) of thymic epithelial tumors (TETs) is well known for identifying malignant-grade TETs; however, its predictive power for determining locally advanced tumors, lymph node (LN) metastasis, and prognosis remains unknown. PATIENTS AND METHODS: We retrospectively evaluated patients with resectable TETs who were preoperatively assessed using 18F-FDG PET from January 2012 to January 2023. The receiver operating characteristic curve was used to evaluate the cutoff value of the maximum standardized uptake value (SUVmax) to predict advanced-stage disease. Recurrence/progression-free survival (RFS/PFS) was analyzed using the Kaplan-Meier method. The staging was classified according to the tumor-node-metastasis system. RESULTS: Our study included 177 patients; 145 (81.9%) had pathological early-stage TET (stage I or II), and 32 (19.1%) had advanced stage (stage III or IV). The area under the curve value for predicting the advanced stage was 0.903, and the cutoff value was 5.6 (sensitivity 81.3%, specificity 84.8%). SUVmax > 5.6 was associated with worse prognosis for RFS/PFS. LN metastasis was preoperatively detected by FDG uptake in 30.8% of patients with pathological LN positivity, whereas LN metastasis was not pathologically detected in patients with SUVmax < 5.9. In patients with advanced-stage TETs, LN recurrence was more frequent in patients who were preoperatively detected by 18F-FDG PET than those who were not (75.0% versus 7.1%). CONCLUSIONS: 18F-FDG PET is a potentially valuable tool for predicting advanced stage and poor prognosis of recurrence in patients with TETs. SUVmax can help thoracic surgeons to guide them in selecting appropriate therapeutic strategies for TETs.

Impact of Chronic Obstructive Pulmonary Disease on the Long-term Prognosis of Patients Undergoing Lobectomy for Non-small-cell Lung Cancer: A Propensity Score-matched Analysis.

BACKGROUND/AIM: Recent advances in surgery, such as thoracoscopic surgery, have made it possible to treat patients with chronic obstructive pulmonary disease (COPD) more safely than before. This study evaluated the short- and long-term prognosis of lobectomy in non-small cell lung cancer (NSCLC) patients with COPD. PATIENTS AND METHODS: This retrospective, propensity-matched, cohort analysis was conducted from January 2014 to December 2018. Among 441 patients who underwent lobectomy for NSCLC, 158 (35.8%) had a preoperative diagnosis of COPD. Propensity-matched analysis, incorporating preoperative variables, was used to compare postoperative hospital stay and complications, and long-term prognosis between the groups. RESULTS: Propensity matching estimated 145 patients in each group. There was no difference between the two groups for length of postoperative hospital stay (12 vs. 11 days, p=0.306). Postoperative complications were more frequent in the COPD group (24.1%) than in the non-COPD group (16.6%), but the difference was not significant (p=0.108). The 5-year overall survival rate was 86.2% in the COPD group and 82.1% in the non-COPD group after matching (p=0.580). The corresponding 5-year recurrence-free survival rate was 72.8% in the COPD group and 67.2% in the non-COPD group after matching (p=0.601). CONCLUSION: In case of Global Initiative for Chronic Obstructive Lung Disease (GOLD) I/II classification, COPD did not significantly worsen the prognosis of patients with NSCLC after lobectomy.

Granzyme B (GZMB)-Positive Tumor-Infiltrating Lymphocytes in Lung Adenocarcinoma: Significance as a Prognostic Factor and Association with Immunosuppressive Proteins.

BACKGROUND: Granzyme B (GZMB) is a serine protease produced by cytotoxic lymphocytes that reflects the activity of anti-tumor immune responses in tumor-infiltrating lymphocytes (TILs); however, the prognostic significance of GZMB+ TILs in lung adenocarcinoma is poorly understood. METHODS: We analyzed 273 patients with pathological stage (pStage) I-IIIA lung adenocarcinoma who underwent surgery at Kyushu University from 2003 to 2012. We evaluated GZMB+ TIL counts by immunohistochemistry. We set the cut-off values at 12 cells/0.04 mm2 for GZMB+ TILs and divided the patients into GZMB-High (n = 171) and GZMB-Low (n = 102) groups. Then, we compared the clinicopathological characteristics of the two groups and clinical outcomes. Programmed cell death ligand-1 (PD-L1) and indoleamine 2,3-dioxygenase 1 (IDO1) expression in tumor cells was also evaluated, and combined prognostic analyses of GZMB+ TILs with PD-L1 or IDO1 were performed. RESULTS: GZMB-Low was significantly associated with pStage II-III, PD-L1 positivity, and IDO1 positivity. Disease-free survival (DFS) and overall survival (OS) in the GZMB-Low group were significantly worse than in the GZMB-High group. In multivariable analysis, GZMB-Low was an independent prognostic factor for both DFS and OS. Furthermore, combined prognostic analyses of GZMB+ TILs with PD-L1 or IDO1 showed that GZMB-Low with high expression of these immunosuppressive proteins had the worst prognosis. CONCLUSIONS: We analyzed GZMB+ TIL counts in lung adenocarcinoma and elucidated its prognostic significance and association with PD-L1 and IDO1. GZMB+ TIL counts might reflect the patient's immunity against cancer cells and could be a useful prognostic marker of lung adenocarcinoma.

Role of fluorine-18-fluorodeoxyglucose positron emission tomography in selecting candidates for a minimally invasive approach for thymic epithelial tumour resection.

OBJECTIVES: We evaluated the potential of preoperative fluorine-18-fluorodeoxyglucose positron emission tomography to predict invasive thymic epithelial tumours in patients with computed tomography-defined clinical stage I thymic epithelial tumours ≤5 cm in size who are generally considered to be candidates for minimally invasive approaches. METHODS: From January 2012 to July 2022, we retrospectively analysed patients who exhibited tumour-node-metastasis (TNM) clinical stage I thymic epithelial tumours with lesion sizes ≤5 cm as determined by computed tomography. All patients underwent fluorine-18-fluorodeoxyglucose positron emission tomography preoperatively. We analysed the association of maximum standardized uptake values with both the World Health Organization histological classification and the TNM staging classification. RESULTS: A total of 107 patients with thymic epithelial tumours (thymomas, 91; thymic carcinomas, 14; carcinoids, 2) were evaluated. Nine patients (8.4%) were pathologically upstaged: TNM pathological stage II in 3 (2.8%), III in 4 (3.7%) and IV in 2 (1.9%). Among these 9 upstaged patients, 5 had thymic carcinoma with stage III/IV, 3 had type B2/B3 thymoma with stage II/III and 1 had type B1 thymoma with stage II. Maximum standardized uptake values were a predictive factor that distinguished pathological stage >I thymic epithelial tumours from pathological stage I [best cut-off value, 4.2; area under the curve = 0.820] and thymic carcinomas from other thymic tumours (best cut-off value, 4.5; area under the curve = 0.882). CONCLUSIONS: Thoracic surgeons should carefully determine the surgical approach for high fluorodeoxyglucose-uptake thymic epithelial tumours and keep in mind the issues associated with thymic carcinoma and potential combined resections of neighbouring structures.

Feasibility and effectiveness of segmentectomy versus wedge resection for clinical stage I non-small-cell lung cancer.

OBJECTIVES: With recent improvements in surgical techniques for segmentectomy, we hypothesized that segmentectomy is feasible and more effective than wedge resection for non-small-cell lung cancer (NSCLC). We compared perioperative and oncological outcomes for segmentectomy and wedge resection. METHODS: We performed a retrospective analysis of 720 patients who underwent sublobar resection (segmentectomy, 479; wedge resection, 241) for clinical stage 0 or I NSCLC from January 2017 to June 2020. An adequate surgical margin was defined as a surgical margin distance of ≥2 cm or ≥ the total tumour size. Recurrence-free survival (RFS) was estimated using the Kaplan-Meier method for clinical stage IA. RESULTS: There was no significant difference in the rate of major (grade ≥III) complications between segmentectomy (1.7%) and wedge resection (1.2%) (P = 0.76). The probability of obtaining adequate surgical margins was significantly higher with segmentectomy (71.4%) versus wedge resection (59.5%) (P = 0.002), and the difference was especially prominent for clinical stage IA2 (75.3% vs 56.9%; P = 0.012). Among patients with clinical stage IA, segmentectomy significantly improved the RFS compared with wedge resection (hazard ratio 2.7; 95% confidence interval 1.60-4.61; log-rank P < 0.001). Subgroup analysis based on the tumour status revealed that segmentectomy had a better RFS in clinical stage IA2 (P < 0.001) and in pure-solid tumours (P = 0.022) than wedge resection. CONCLUSIONS: We demonstrate that segmentectomy is a feasible procedure with comparable safety outcomes and better surgical margins and cancer control than wedge resection, particularly for clinical stage IA2 NSCLC.

An Adult Case of Multiple Extralobar Pulmonary Sequestrations in the Thoracic and Abdominal Cavities.

Extralobar pulmonary sequestration is generally located in the left thoracic cavity and is often identified prenatally or in infants. We identified a rare case of multiple extralobar pulmonary sequestrations in the thoracic and abdominal cavities, incidentally detected in a 60-year-old woman by cancer screening. The patient underwent surgery by thoracoscopic and laparoscopic approaches simultaneously, and extralobar sequestration was histologically confirmed in each lesion. Preoperative diagnosis was difficult because of unusual multiple localization and an undetectable aberrant artery on imaging examinations.

Unexpected Histopathological Diagnosis of Placental Transmogrification of the Lung after Bullectomy for Recurrent Spontaneous Pneumothorax: A Case Report and Literature Review.

We report a 33-year-old man who presented with recurrent right pneumothorax. Computed tomography (CT) showed the presence of a large bulla with a maximum diameter of 8 cm in the right middle lobe; he subsequently underwent bullectomy. Histopathology revealed that pulmonary parenchyma adjacent to the bulla represented nodular proliferation of clear cells characterized by a papillary structure resembling placental chorionic villi. Immunohistochemically, clear cells were positive for CD10, suggesting placental transmogrification of the lung (PTL). We reviewed 36 surgical cases of PTL, and only 2 cases (5.6%), including our case, were operated for spontaneous pneumothorax. Bullous lesions secondary to PTL tend to appear as unilateral large cystic masses in non-upper lobes, which is atypical for primary spontaneous pneumothorax (PSP). Although PTL is considered a very rare cause of secondary pneumothorax, we must carefully differentiate this condition.

Mutual checking system for assessing trainee skills of thoracic surgery.

BACKGROUND: Video-assisted surgery helps surgeons learn surgical skills efficiently. The aim of this study was to evaluate the effect of mutual evaluation of trainees' surgical techniques using tabulated common evaluation criteria. METHODS: We created a check sheet in which a standard pulmonary lobectomy procedure was divided into six parts and the checkpoints to note listed. Both the trainees and trainers used tabulated common evaluation criteria to evaluate lobectomies performed by the trainees. RESULTS: From September 2019 to March 2020, 30 lobectomies were performed by three trainees. The trainee's evaluations of their own procedures were relatively high at first, then decreased, then gradually increased; however, the trainers' evaluations showed no such tendency. CONCLUSIONS: Mutual evaluation of surgery using tabulated common evaluation criteria enables trainees to review their own surgery objectively and receive evaluations by trainers, thus helping them to avoid the Dunning-Kruger effect and efficiently acquire basic surgical skills.

VATS right apical segmentectomy for lung cancer in a patient with tracheal bronchus.

INTRODUCTION: A tracheal bronchus is rarely observed, occurring in only 1% of all patients who undergo thoracic surgeries. We rarely encounter lung cancer in a patient with a tracheal bronchus; however, it is essential to know the distinctive perioperative management strategy for patients with a tracheal bronchus. CASE PRESENTATION: We report a 72-year-old man with lung cancer located in the right apical segment supplied by a tracheal bronchus. Annual chest computed tomography performed as follow-up after colon cancer resection showed an enlarging pulmonary nodule with pure ground-glass opacity, which was suspected to be lung adenocarcinoma. The nodule was located in the right apical segment. The apical segment was independently supplied by a single pulmonary artery superior trunk and a tracheal bronchus that branched directly from the trachea at 1.2 cm above the carina. The pulmonary vein branching pattern was uncommon in that the central vein that usually runs through B2 (posterior bronchus) and B3 (anterior bronchus) was missing. The patient underwent video-assisted thoracoscopic apical segmentectomy under one-lung ventilation using a left-sided double-lumen tube. DISCUSSION: Anomalous venous return accompanied with tracheal bronchus has been described in some reports. Since pulmonary vein is important during segmentectomy, the surgeon should pay particular attention to the venous return. CONCLUSION: Preoperative three-dimensional graphic imagery helped us accurately identify the anatomical anomaly to enable the successful segmentectomy in a patient with a tracheal bronchus. We review the relevant literature regarding the perioperative management of patients with a tracheal bronchus.

Assessment of Intraoperative Microbiological Culture in Patients with Empyema: Comparison with Preoperative Microbiological Culture.

PURPOSE: Assessing microbiological culture results is essential in the diagnosis of empyema and appropriate antibiotic selection; however, the guidelines for the management of empyema do not mention assessing microbiological culture intraoperatively. Therefore, we tested the hypothesis that intraoperative microbiological culture may improve the management of empyema. METHODS: We performed a retrospective analysis of 47 patients who underwent surgery for stage II/III empyema from January 2011 to May 2019. We compared the positivity of microbiological culture assessed preoperatively at empyema diagnosis versus intraoperatively. We further investigated the clinical characteristics and postoperative outcomes of patients whose intraoperative microbiological culture results were positive. RESULTS: The positive rates of preoperative and intraoperative microbiological cultures were 27.7% (13/47) and 36.2% (17/47), respectively. Among 34 patients who were culture-negative preoperatively, eight patients (23.5%) were culture-positive intraoperatively. Intraoperative positive culture was significantly associated with a shorter duration of preoperative antibiotic treatment (p = 0.002). There was no significant difference between intraoperative culture-positive and -negative results regarding postoperative complications. CONCLUSIONS: Intraoperative microbiological culture may help detect bacteria in patients whose microbiological culture results were negative at empyema diagnosis. Assessing microbiological culture should be recommended intraoperatively as well as preoperatively, for the appropriate management of empyema.

Preoperative prognostic nutritional index level is associated with tumour-infiltrating lymphocyte status in patients with surgically resected lung squamous cell carcinoma.

OBJECTIVES: The prognostic nutritional index (PNI) is an indicator of systemic immune-nutritional condition and is a well-known prognostic biomarker in lung cancer patients. Tumour-infiltrating lymphocytes (TILs) is a specific histological feature of cancers, influencing an individual's immunological tumour responses. However, whether PNI can reflect lung cancer patients' prognosis through local immunity such as TIL is unclear. METHODS: We selected 64 lung squamous cell carcinoma patients who underwent curative operations. We investigated the significance of preoperative PNI level and evaluated the relationship between PNI and immune cells surrounding the lung cancer tissue using immunohistochemical analysis of a cluster of differentiation (CD)3, CD4, CD8 and CD68. RESULTS: A low-PNI level was significantly associated with a worse postoperative prognosis (P = 0.042). The PNI (hazard ratio 2.768, 95% confidence interval 1.320-5.957; P = 0.007) was an independent prognostic factor. The low-PNI group had a significantly shorter recurrence-free survival and overall survival (P = 0.013 and P = 0.002, log-rank test) compared with the high-PNI group. A significant positive correlation between PNI components including preoperative peripheral blood lymphocyte count and serum albumin concentration, and TILs, was observed. Absolute numbers of TILs in the preoperative high-PNI group were significantly increased compared with those in the preoperative low-PNI group (CD3+ cells; P = 0.002, CD4+ cells; P = 0.049 and CD8+ cells; P = 0.024). CONCLUSIONS: The preoperative PNI level was strongly associated with the postoperative outcome in lung cancer patients. Considering the positive relationship between preoperative PNI level and TIL status, preoperative immune-nutritional condition may influence lung cancer patients' postoperative prognosis through local immunity as well as systemic immune response.

Interleukin-38 promotes tumor growth through regulation of CD8+ tumor-infiltrating lymphocytes in lung cancer tumor microenvironment.

BACKGROUND: Interleukin (IL)-38 was discovered in 2001 and is a member of the IL-1 family of cytokines. IL-38 shows anti-inflammatory activity in several inflammatory diseases. In lung adenocarcinoma, we previously demonstrated that high IL-38 expression in tumor cells was associated with poor prognosis. However, the role of IL-38 in the tumor microenvironment has not been clarified. METHODS: IL-38-plasmid-transfected Lewis lung carcinoma cells (LLC-IL38) and empty vector-transfected LLC cells (LLC-vector) were established. Cell proliferation in vitro and tumor growth in vivo were examined, and immunohistochemical staining was used to assess tumor-infiltrating lymphocytes (TILs). A CD8+ lymphocyte depletion model was established to show the association between IL-38 and CD8+ lymphocytes. Moreover, we examined the association between IL-38 expression and CD8+ TILs in human samples, analyzing immunohistochemical staining in 226 patients with radically resected lung adenocarcinoma. RESULTS: Tumor growth of LLC-IL38 in vivo was significantly increased compared with that of LLC-vector, although cell proliferation of LLC-IL38 in vitro was lower than that of LLC-vector. CD8+ TILs were significantly decreased in LLC-IL38 tumor compared with LLC-vector tumor. The difference in tumor growth between LLC-IL38 and LLC-vector became insignificant after depletion of CD8+ lymphocytes. In immunohistochemical staining in tissues from patients with lung adenocarcinoma, multivariate analysis showed high IL-38 expression was an independent negative predicter of high density of CD8+ TILs. CONCLUSION: We demonstrated that high IL-38 expression in tumor cells was significantly associated with reduction of CD8+ TILs and tumor progression. These results suggest that IL-38 could be a therapeutic target for lung cancer.

Spontaneous pneumothorax associated with cavitating pulmonary metastasis from breast cancer: a case report and literature review.

We report a 69-year-old woman with spontaneous pneumothorax associated with cavitating pulmonary metastasis from breast cancer. She was treated for right breast cancer (invasive ductal carcinoma, ypT4bN1M0, stage IIIB) 2 years earlier, and was admitted for right pneumothorax and chest computed tomography, which showed multiple small cavitating lesions in bilateral lungs. The pneumothorax was treated conservatively with chest drainage, but subsequently recurred ipsilaterally. During video-assisted thoracic surgery, we detected small white nodules with visceral pleural rupture; therefore, we performed partial lung resection. The pathological findings revealed metastatic breast cancer with pleural invasion. Forty days later, ipsilateral pneumothorax recurred, and chemical pleurodesis was performed, which resolved the pneumothorax and prevented subsequent recurrence. Early diagnosis and definitive treatment, including pleurodesis, should be considered to prevent recurrence of spontaneous pneumothorax and improve patients' quality of life, even in patients with advanced malignancy.