Surgically resected sarcomatoid carcinoma of the lung: a nationwide retrospective study in 2010.

BACKGROUND: Sarcomatoid carcinoma of the lung is a rare histological type of non-small cell lung cancer with a poor prognosis. We aimed to investigate the clinicopathological characteristics and prognostic factors of surgically resected sarcomatoid carcinoma of the lung. METHODS: We retrospectively reviewed 14999 patients who underwent surgical resection for non-small cell lung cancer accumulated by the Japanese Joint Committee of Lung Cancer Registry in 2010. Clinicopathological characteristics and survival were compared between the sarcomatoid carcinoma and other non-small cell cancer groups. The prognostic factors in the sarcomatoid carcinoma group were identified using a multivariate Cox proportional hazard model. RESULTS: Patients with sarcomatoid carcinoma comprised 1.4% of all patients. The sarcomatoid carcinoma group demonstrated a more aggressive pathology with presentation at more advanced stages, requiring more frequent extensive surgical resections. The sarcomatoid carcinoma group had remarkably poorer overall and recurrence-free survival than the other non-small cell lung cancer group. Adjuvant chemotherapy was associated with improved survival for pathological stage II-III sarcomatoid carcinoma cases rather than for pathological stage I disease. In the multivariate analysis, larger tumor size, lymphatic permeation, and no adjuvant chemotherapy were associated with the sarcomatoid carcinoma group's overall and recurrence-free survival. CONCLUSIONS: Surgically resected sarcomatoid carcinoma of the lung has a higher aggressive and metastatic potential and a worse prognosis than other non-small cell lung cancers. Adjuvant chemotherapy, which was associated with enhanced survival in patients with pathological stage II-III of the disease, could be considered for treating patients with pathological stage II-III sarcomatoid carcinoma of the lung.

Preoperative risk-factors for secondary spontaneous pneumothorax surgery in Japan: a nationwide database study.

PURPOSE: We aimed to identify preoperative risk factors for secondary spontaneous pneumothorax surgery. METHODS: The National Clinical Database of Japan, with six annual datasets from 2014 to 2019, was used. All patients who underwent surgery for secondary spontaneous pneumothorax were included, excluding those < 15 years old and those with incomplete data. The effects of preoperative risk factors were analyzed for operative mortality (mortality during hospitalization or within 30 days, regardless of hospitalization status), 30-day mortality, and postoperative respiratory morbidities. RESULTS: Of the 18,309 patients enrolled in the study, operative mortality, 30-day mortality, and postoperative respiratory morbidities were observed in 654 (3.6%), 343 (1.9%), and 2258 (12.3%) patients, respectively. Increasing age, male sex, body mass index < 18.5 or > 30, performance status > 2, emergent surgery, interstitial pneumonia, and diabetes in preoperative co-morbidity, tumors, and other diseases in underlying lung disease were significant risk factors for operative mortality. Those for 30-day mortality included autoimmune disease instead of male sex and diabetes, while those for postoperative respiratory morbidities included lymphangiomyomatosis instead of a body mass index > 30. CONCLUSION: We identified many preoperative risk factors for operative mortality, 30-day mortality, and postoperative respiratory morbidities in secondary spontaneous pneumothorax surgery. These findings will assist in selecting appropriate surgical candidates.

Clinicopathological Features and Survival Outcomes of Resected Lung Adenosquamous Carcinoma: Results From a Nationwide Japanese Registry Data.

OBJECTIVES: The objective of this study was to clarify the clinicopathological features and prognostic factors of resected lung adenosquamous carcinoma (ASC) using a nationwide multi-institutional database. METHODS: We retrospectively reviewed the records of 15,542 patients who underwent complete R0 resection for ASC (n = 326), adenocarcinoma (AC, n = 11,820), or squamous cell carcinoma (SC, n = 3396) from a Japanese lung cancer registry in 2010. To reduce the selection bias, an inverse probability of treatment weighting (IPTW) method using a propensity score was implemented. RESULTS: The ASC group showed worse recurrence-free and overall survival (RFS and OS) than both the AC and SC groups (5-year OS: 57.5% in ASC, 83.9% in AC [< 0.001], and 62.3% in SC [P = .086]). In multivariate analyses, prognostic factors that affected OS for ASC included male, p-stage II-III, and postoperative complications within 30 days (grade ≥ 3 in the Clavien-Dindo classification). The sensitizing EGFR mutation was detected in 28 (21.5%) of 130 screened patients with ASC, but it did not affect either RFS, OS, or postrecurrence survival. Although more patients in the ASC group received adjuvant chemotherapy compared to the AC and SC groups, both multivariate and IPTW-adjusted analyses did not show positive impact of adjuvant chemotherapy on RFS and OS in ASC. CONCLUSIONS: In this nationwide registry study, lung ASC was more aggressive than both AC and SC. No apparent survival impact of conventional adjuvant chemotherapy prompted us to investigate novel adjuvant strategies to optimize survival outcomes.

ERK5 Activity Prevention Improves the Antitumor Efficacy of Fluvastatin on Thymic Carcinoma.

BACKGROUND/AIM: Thymic carcinoma is a rare cancer type with limited treatment options. Our previous study demonstrated that statins, which inhibit 3-hydroxy-3-methylglutaryl coenzyme A reductase, can prevent thymic carcinoma. However, the mechanisms through which statins affect intracellular events in cancer cells are not well understood. The aim of the study was to determine how thymic carcinoma modulates the intracellular signals in response to statin administration. MATERIALS AND METHODS: We analyzed statin-induced protein phosphorylation in Ty82 human thymic carcinoma cells, which were cultured with fluvastatin, and protein phosphorylation was examined using western blotting. RESULTS: Treating Ty82 with fluvastatin led to ERK5 phosphorylation via protein prenylation attenuation. The antitumor effects of fluvastatin on thymic carcinoma were enhanced when combined with an ERK5 inhibitor. CONCLUSION: Statin therapy in combination with ERK5 inhibition may be a promising therapeutic approach for treating thymic carcinoma.

Clinical outcomes of left upper segmentectomy vs. lobectomy for early non-small-cell lung cancer: a nationwide database study in Japan.

PURPOSE: Given that left upper lobe and right upper and middle lobes share a similar anatomy, segmentectomy, such as upper division and lingulectomy, should yield identical oncological clearance to left upper lobectomy. We compared the prognosis of segmentectomy with that of lobectomy for early stage non-small-cell lung cancer (NSCLC) in the left upper lobe. METHODS: We retrospectively examined 2115 patients who underwent segmentectomy or lobectomy for c-stage I (TNM 8th edition) NSCLC in the left upper lobe in 2010. We compared the oncological outcomes of segmentectomy (n = 483) and lobectomy (n = 483) using a propensity score matching analysis. RESULTS: The 5-year recurrence-free and overall survival rates in the segmentectomy and lobectomy groups were comparable, irrespective of c-stage IA or IB. Subset analyses according to radiological tumor findings showed that segmentectomy yielded oncological outcomes comparable to those of lobectomy for non-pure solid tumors. In cases where the solid tumor exceeded 20 mm, segmentectomy showed a recurrence-free survival inferior to that of lobectomy (p = 0.028), despite an equivalent overall survival (p = 0.38). CONCLUSION: Segmentectomy may be an acceptable alternative to lobectomy with regard to the overall survival of patients with c-stage I NSCLC in the left upper lobe.

Effect of revised organ transplant law in Japan on lung transplantation.

PURPOSE: To investigate how revision of the organ transplant law in Japan affected lung transplantation in this country. METHODS: Lung transplant candidates registered between January, 2000 and December, 2009 were designated as the pre-revision group (n = 396) and those registered between January, 2011 and December, 2020, as the post-revision group (n = 1326). Both groups were analyzed retrospectively using data collected by the Japanese Society of Lung and Heart-Lung Transplantation. RESULTS: The number of patients who underwent brain-dead donor lung transplantation (BDLT) increased significantly after the law amendment (32.2 vs. 13.8%, p < 0.01). The median waiting time for BDLT was significantly reduced (708 days vs. 1163 days, p < 0.01) and the mortality rate while waiting for BDLT improved significantly after the law amendment (33.1 vs. 42.6%, p < 0.01). In the post-revision group, 18 pediatric patients underwent BDLT. The 5-year survival rates after BDLT were comparable between the groups (73.5% in the pre-revision group vs. 73.2% in the post-revision group, p = 0.32). CONCLUSIONS: The organ transplant law revision shortened the waiting time for BDLT significantly and decreased the mortality rate while waiting for BDLT. The posttransplant outcomes in Japan remained favorable throughout the study period.

Nationwide prospective registry database of patients with newly diagnosed untreated pleural mesothelioma in Japan.

Due to the scarcity of large-sized prospective databases, the Japanese Joint Committee for Lung Cancer Registry conducted a nationwide prospective registry for newly diagnosed and untreated pleural mesothelioma. All new cases diagnosed pathologically as any subtype of pleural mesothelioma in Japan during the period between April 1, 2017, to March 31, 2019, were included before treatment. Data on survival were collected in April 2021. The eligible 346 patients (285 men [82.3%]; 61 women [17.7%]; median age, 71.0 years [range, 44-88]) were included for analysis. Among these patients, 138 (39.9%) underwent surgery, 164 (47.4%) underwent non-surgical therapy, and the remaining 44 (12.7%) underwent best supportive care. The median overall survival for all 346 patients was 19.0 months. Survival rates at 1, 2, and 3 years for all patients were, 62.8%, 42.3%, and 26.5%, respectively. Median overall survival was significantly different among patients undergoing surgery, non-surgical treatment, and best supportive care (32.2 months vs. 14.0 months vs. 3.8 months, p < 0.001). The median overall survival of patients undergoing pleurectomy/decortication and extrapleural pneumonectomy was 41.8 months and 25.0 months, respectively. Macroscopic complete resection resulted in longer overall survival than R2 resection and partial pleurectomy/exploratory thoracotomy (41.8 months vs. 32.2 months vs. 16.8 months, p < 0.001). Tumor shape, maximum tumor thickness, and sum of three level thickness were significant prognostic factors. The data in the prospective database would serve as a valuable reference for clinical practice and further studies for pleural mesothelioma.

Benefit of Adjuvant Chemotherapy for Patients Older Than 75 Years With Completely Resected p-Stage II-IIIA Non-Small-Cell Lung Cancer: A Retrospective Cohort Study Using Japanese Nationwide Real-World Data.

BACKGROUND: The efficacy of adjuvant chemotherapy (ACT) in elderly patients with completely resected p-stage II-IIIA non-small-cell lung cancer (NSCLC) remains unclear because all previous randomized controlled trials on ACT have been conducted among patients aged <75 years. Thus, this study aimed to evaluate the effectiveness of ACT in elderly patients with completely resected NSCLC. PATIENTS: We extracted the nationwide data of 812 patients aged ≥75 years who underwent lobectomy with mediastinal nodal dissection in 2010 and were diagnosed with p-stage II-IIIA NSCLC, from nationwide registry data accumulated in 2016. METHODS: We classified the 812 patients into 2 groups based on the ACT administration status and analyzed the differences in their postoperative overall survival (OS). RESULTS: Overall, 295 patients received ACT (36.3%; group A), whereas 517 patients did not (63.70%; group N). Group A showed significantly better OS as a whole (hazard ratio [HR]: 0.650 [95% confidence interval {CI}: 0.526-0.804]), in the p-stage II subset (HR: 0.688 [95% CI: 0.513-0.925]), and p-stage IIIA subset (HR: 0.547 [95% CI: 0.402-0.743]) than group N. Even after propensity score matching, group A showed significantly better OS as a whole (HR: 0.626 [95% CI: 0.495-0.792]), in the p-stage II subset (HR: 0.690 [95% CI: 0.493-0.964]), and p-stage IIIA subset (HR: 0.554 [95% CI: 0.398-0.772]) than group N. CONCLUSION: ACT is recommended even in elderly patients with completely resected p-stage II-IIIA NSCLC. Hence, physicians should not avoid ACT in patients with completely resected NSCLC based solely on age.

[Considerations for Perioperative Management of Patients with Complicated Respiratory Dysfunction].

This article describes the perioperative complications, perioperative risk assessment, and perioperative management of patients with chronic obstructive pulmonary disease (COPD) and interstitial lung disease, especially idiopathic pulmonary fibrosis( IPF), which are the leading diseases in respiratory dysfunction. In COPD, testing for forced expiratory volume during the first second and pulmonary diffusing capacity is important and an algorithm for testing has been presented by the Japanese Association for Chest Surgery. Acute exacerbation of IPF is the leading cause of postoperative mortality in Japan, and risk factors are being analyzed. To reduce the occurrence of postoperative complications, it is important to carry out a risk assessment, select appropriate surgical strategy, and implement a well-planned perioperative management.

The consecutive impact of COVID-19 on thoracic surgical procedures in Japan: an analysis of data from the National Clinical Database.

PURPOSE: The current study was designed to analyze the impact of the COVID-19 pandemic on general thoracic surgeries in Japan. METHODS: Changes in surgeries for lung cancer and metastatic lung tumors were evaluated based on National Clinical Database data regarding cancer screening. RESULTS: In 2021, surgeries for primary lung cancer increased by 3.4% compared to 2020, which, given the increase from 2014 to 2019, indicates an overall 11.1% decrease. In contrast, surgeries for metastatic lung tumors in 2021 decreased by 5.8% compared to 2020, which, given the increase from 2014 to 2020, indicates an overall 9.2% decrease. Half of the primary diseases for metastatic lung tumor were cases of colorectal cancer. Low anterior resection procedures in 2020 decreased by 5.5% compared to 2019. Lung and colon cancer screening examinees in 2021 were increased compared to 2020; however, they still showed respective decreases of 11% and 9.0% compared to 2019. CONCLUSIONS: Surgeries for primary lung cancer still decreased substantially during the COVID-19 pandemic. The continued stagnation of screening was responsible for this decrease. Surgeries for metastatic lung tumors decreased profoundly, and the decrease in screening for primary tumors was responsible for this reduction. Our findings emphasize the significance of maintaining cancer screening efforts, even during a pandemic.

Is adjuvant chemotherapy for completely resected p-stage IA (>2 cm) and stage IB non-small-cell lung cancer beneficial for elderly patients? A large, retrospective cohort study based on real-world data from Japan.

OBJECTIVE: The efficacy of tegafur-uracil as adjuvant chemotherapy for patients with completely resected stage I non-small-cell lung cancer is proven; however, its efficacy for elderly patients remains unclear. Herein, we evaluated the effectiveness of adjuvant chemotherapy for elderly patients with completely resected stage I non-small-cell lung cancer based on real-world Japanese data using propensity score matching. METHODS: This retrospective study extracted data from a nationwide registry study, performed in 2016, on patients ≥75 years who underwent lobectomy with mediastinal nodal dissection for non-small-cell lung cancer in 2010 and were diagnosed with p-stage IA (>2 cm) or stage IB non-small-cell lung cancer. We classified the 1294 patients into two groups-Group A, postoperative adjuvant chemotherapy (n = 295, 22.8%) and Group N, no adjuvant chemotherapy (n = 999, 77.2%)-and analyzed differences in postoperative overall survival between groups. RESULTS: Group A showed no advantage in overall survival over Group N as a whole (hazard ratio: 0.824 [95% confidence interval: 0.631-1.076]), in p-stage IA (hazard ratio: 0.617 [95% confidence interval: 0.330-1.156]) and in p-stage IB (hazard ratio: 0.806 [95% confidence interval: 0.597-1.088]) subsets. Even after propensity score matching, Group A showed no significant advantage in overall survival over Group N as a whole (hazard ratio: 0.975 [95% confidence interval: 0.688-1.381]), in p-stage IA (hazard ratio: 1.390 [95% confidence interval: 0.539-3.586]) and in p-stage IB (hazard ratio: 0.922 [95% confidence interval: 0.633-1.343]). CONCLUSIONS: adjuvant chemotherapy for completely resected p-stage IA (>2 cm) and stage IB non-small-cell lung cancer showed no benefit for recommendation for elderly patients; considering the risk of adverse events, we do not recommend adjuvant chemotherapy for elderly patients.

[Robot-assisted Minimally Invasive Surgery for Mediastinal Tumors].

The subxiphoid approach in thymectomy provides better visibility around the left brachiocephalic vein than the lateral thoracic approach. Robot-assisted thoracoscopic surgery is easier to parform than video- assisted thoracoscopic surgery for surgery of the upper mediastinum, because the forceps can be moved with many joints. Robot-assisted thymectomy using the subxiphoid approach may be less traumatic and less invasive than median sternotomy. We must continue to devise surgical procedures to make oncologically curative surgery more minimally invasive.

Features of anaplastic lymphoma kinase rearrangement in early-stage lung cancer: Analysis of a nationwide Japanese database.

BACKGROUND AND OBJECTIVES: Anaplastic lymphoma kinase (ALK) rearrangement is a representative driver mutation in lung cancer. However, the biology of early-stage ALK-rearranged lung cancer remains unclear. We aimed to assess the clinicopathological features, prognostic implications, and influence of ALK rearrangement on the postoperative course in surgically resected lung cancer. METHODS: We retrospectively analyzed data from the Japanese Joint Committee of Lung Cancer Registry database. Of the 12 730 patients with lung adenocarcinoma, 794 (6.2%) were tested for ALK rearrangement and were included. RESULTS: ALK rearrangements were detected in 76 patients (10%). The 5-year overall survival (OS) rate was significantly higher in the ALK rearrangement-positive group than in the ALK rearrangement-negative group (p = 0.030). Multivariable analysis revealed that ALK rearrangement was an independent prognostic factor for improved OS (hazard ratio, 0.521; 95% confidence interval, 0.298-0.911; p = 0.022). Regarding the postrecurrence state, there was no difference in the initial recurrence sites between both groups. Administration of ALK-tyrosine kinase inhibitors (TKIs) improved postrecurrence survival in any treatment lines. CONCLUSION: In one of the largest national surveys, ALK rearrangement was associated with improved long-term outcomes in surgically resected patients. ALK-TKIs may be an important treatment strategy for ALK rearrangement-positive lung adenocarcinoma in the postrecurrence state.

Postoperative cerebral infarction and arrhythmia after pulmonary lobectomy in Japan: a retrospective analysis of 77,060 cases in a national clinical database.

PURPOSE: To investigate the incidence of postoperative cerebral infarction after curative lobectomy, its association with the type of lobectomy, and how postoperative new-onset arrhythmia contributes to postoperative cerebral infarction. METHODS: The subjects of this analysis were 77,060 patients who underwent curative lobectomy for lung cancer between 2016 and 2018 according to the National Clinical Database. Incidences of postoperative cerebral infarction and postoperative new-onset arrhythmia were analyzed. Moreover, mediation analysis was performed to evaluate the causal pathway between postoperative new-onset arrhythmia and postoperative cerebral infarction. RESULTS: Postoperative cerebral infarction occurred in 110 (0.7%) patients after left upper lobectomy and in 85 (0.7%) patients after left lower lobectomy. Left upper lobectomy and left lower lobectomy were associated with a higher likelihood of postoperative cerebral infarction than right lower lobectomy. Left upper lobectomy was the strongest independent predictor of postoperative new-onset arrhythmia. However, in the mediation analysis, the odds ratio for cerebral infarction did not change after the addition of the factor of postoperative new-onset arrhythmia. CONCLUSION: Cerebral infarction occurred significantly more often not only after left upper lobectomy, but also after left lower lobectomy. Postoperative new-onset arrhythmia was less likely to be related to cerebral infarction after left upper lobectomy.

Risk-adjusted hazard analysis of survival after pulmonary metastasectomy for uterine malignancies in 319 cases.

Objective: There is little evidence of the outcome of pulmonary metastasectomy for uterine tumors when comparing different histologies. This study aimed to delineate the primary histology that leads to more favorable outcomes after pulmonary metastasectomy. Methods: The database of the Metastatic Lung Tumor Study Group of Japan for 1984 to 2016 was used to analyze the outcomes of patients with gynecologic malignancies who underwent pulmonary metastasectomy. Prognostic factors and long-term outcomes were compared according to the histology of the primary uterine tumors, specifically adenocarcinoma, squamous cell carcinoma, and sarcoma. The adjusted hazard risks according to disease-free intervals (DFIs) and the number and maximum size of resected tumors were also analyzed to delineate the pattern of risk trends. Results: A total of 319 patients were included in the analysis (122 with adenocarcinomas, 113 with squamous cell carcinomas, 46 with sarcomas, and 38 with other types). The 5-year survival rate was 66.5% for the entire cohort, 71.6% for the patients with adenocarcinoma, 61.3% for those with squamous cell carcinoma, and 55.4% for those with sarcoma. Multivariate analyses identified the positive prognostic factors as DFI ≥12 months in adenocarcinoma and sarcoma and the primary site (corpus) of uterine tumors in adenocarcinoma. The nonlinear adjusted hazard risks indicated that a shorter DFI was associated with an elevated risk of death in patients with adenocarcinoma and sarcoma. Conclusions: The survival outcome after pulmonary metastasectomy varies according to primary tumor histology, and the prognostic factors differ among histologic subtypes. Surgical indications should be determined based on the prognostic factors for each histology.

Prognostic factors for lung transplant recipients focusing on age and gender: the Japanese lung transplantation report 2022.

PURPOSE: To clarify the impact of donor and recipient characteristics on the survival of recipients before and after lung transplantation in the Japanese population. METHODS: Patients' data were collected for retrospective analysis from all authorized lung transplant centers in Japan. We included 1963 patients listed for lung transplantation by the end of December 2021, comprised of 658 deceased-donor and 270 living-donor lung transplants. RESULTS: Primary disease had a significant impact on the mortality of patients waiting for transplantation. The indications for transplant significantly affected the post-transplant survival rate of deceased-donor lung transplant recipients. The recipient's age also significantly affected the post-transplant survival rate of the deceased-donor and living-donor lung transplant recipients. The recipients of grafts transplanted from donors aged 61 years or older showed a worse post-transplant survival rate (≧60 years old). The survival rate for the combination of a female donor to a male recipient among the deceased-donor lung transplant recipients was the worst among the four combinations. CONCLUSION: The donor and recipient characteristics significantly impacted the survival of recipients after lung transplantation. The underlying mechanism of the negative impact of the gender mismatch of female donor to male recipient on post-transplant survival needs to be investigated further.

The efficacy of thoracoscopic surgery for descending necrotizing mediastinitis.

OBJECTIVES: Thoracotomy is a reliable approach for descending necrotizing mediastinitis (DNM), and the use of video-assisted thoracic surgery (VATS), a minimally invasive procedure, has been increasing. However, which approach is more effective for DNM treatment is controversial. METHODS: We analysed patients who underwent mediastinal drainage via VATS or thoracotomy, using a database with DNM from 2012 to 2016 in Japan, which was constructed by the Japanese Association for Chest Surgery and the Japan Broncho-esophagological Society. The primary outcome was 90-day mortality, and the adjusted risk difference between the VATS and thoracotomy groups using a regression model, which incorporated the propensity score, was estimated. RESULTS: VATS was performed on 83 patients and thoracotomy on 58 patients. Patients with a poor performance status commonly underwent VATS. Meanwhile, patients with infection extending to both the anterior and posterior lower mediastinum frequently underwent thoracotomy. Although the postoperative 90-day mortality was different between the VATS and thoracotomy groups (4.8% vs 8.6%), the adjusted risk difference was almost the same, -0.0077 with 95% confidence interval of -0.0959 to 0.0805 (P = 0.8649). Moreover, we could not find any clinical and statistical differences between the 2 groups in terms of postoperative 30-day and 1-year mortality. Although patients who underwent VATS had higher postoperative complication (53.0% vs 24.1%) and reoperation (37.9% vs 15.5%) rates than those who underwent thoracotomy, the complications were not serious and most could be treated with reoperation and intensive care. CONCLUSIONS: The outcome of DNM treatment does not depend on thoracotomy or VATS.

Perioperative outcomes of minimally invasive surgery for large malignant thymic epithelial tumors and for total thymectomy.

PURPOSE: Minimally invasive surgery (MIS) for thymic tumors is now accepted widely, in line with improved surgical techniques; however, we occasionally encounter complicated cases of large tumors or of total thymectomy requiring prolonged operative duration or conversion to an open procedure (OP). We reviewed patients registered in a nationwide database to identify the technical feasibility of MIS for thymic epithelial tumors. METHODS: Data on patients treated surgically between 2017 and 2019 were extracted from the National Clinical Database of Japan. Clinical factors and operative outcomes were calculated by tumor diameter using trend analyses. Perioperative outcomes of MIS for non-invasive thymoma were investigated using propensity score-matched analyses. RESULTS: MIS was performed in 46.2% of the patients. The operative duration and conversion rate increased with the tumor diameter (p < .001). After propensity score-matching, operative duration and postoperative hospital stay were shorter (p < .001), and the transfusion rate was lower (p = .007) in patients who underwent MIS than in those who underwent OP for thymomas ≥ 5 cm. Among patients who underwent total thymectomy, blood loss was less (p < .001) and the postoperative hospital stay was shorter (p < .001) in those who underwent MIS than in those who underwent OP. There were no significant differences in postoperative complications and mortality. CONCLUSIONS: MIS is technically feasible even for large non-invasive thymomas or for total thymectomy, although the operative duration and open conversion rate increase with the tumor diameter.