Standardized Classification of Lung Adenocarcinoma Subtypes and Improvement of Grading Assessment Through Deep Learning.

The histopathologic distinction of lung adenocarcinoma (LADC) subtypes is subject to high interobserver variability, which can compromise the optimal assessment of patient prognosis. Therefore, this study developed convolutional neural networks capable of distinguishing LADC subtypes and predicting disease-specific survival, according to the recently established LADC tumor grades. Consensus LADC histopathologic images were obtained from 17 expert pulmonary pathologists and one pathologist in training. Two deep learning models (AI-1 and AI-2) were trained to predict eight different LADC classes. Furthermore, the trained models were tested on an independent cohort of 133 patients. The models achieved high precision, recall, and F1 scores exceeding 0.90 for most of the LADC classes. Clear stratification of the three LADC grades was reached in predicting the disease-specific survival by the two models, with both Kaplan-Meier curves showing significance (P = 0.0017 and 0.0003). Moreover, both trained models showed high stability in the segmentation of each pair of predicted grades with low variation in the hazard ratio across 200 bootstrapped samples. These findings indicate that the trained convolutional neural networks improve the diagnostic accuracy of the pathologist and refine LADC grade assessment. Thus, the trained models are promising tools that may assist in the routine evaluation of LADC subtypes and grades in clinical practice.

Efficacy and safety of add-on mirogabalin to conventional therapy for the treatment of peripheral neuropathic pain after thoracic surgery: the multicenter, randomized, open-label ADMIT-NeP study.

BACKGROUND: For chronic pain after thoracic surgery, optimal timing of its diagnosis and effective treatment remains unresolved, although several treatment options are currently available. We examined the efficacy and safety of mirogabalin, in combination with conventional pain therapy (nonsteroidal anti-inflammatory drugs and/or acetaminophen), for treating peripheral neuropathic pain (NeP) after thoracic surgery. METHODS: In this multicenter, randomized, open-label, parallel-group study, patients with peripheral NeP were randomly assigned 1:1 to mirogabalin as add-on to conventional therapy or conventional treatment alone. RESULTS: Of 131 patients of consent obtained, 128 were randomized (mirogabalin add-on group, 63 patients; conventional treatment group, 65 patients). The least squares mean changes (95% confidence interval [CI]) in Visual Analogue Scale (VAS) score for pain intensity at rest from baseline to Week 8 (primary endpoint) were - 51.3 (- 54.9, - 47.7) mm in the mirogabalin add-on group and - 47.7 (- 51.2, - 44.2) mm in the conventional group (between-group difference: - 3.6 [95% CI: - 8.7, 1.5], P = 0.161). However, in patients with Self-administered Leeds Assessment of Neuropathic Symptoms and Signs (S-LANSS) score (used for the screening of NeP) ≥ 12 at baseline, the greater the S-LANSS score at baseline, the greater the decrease in VAS score in the mirogabalin add-on group, while no such trend was observed in the conventional treatment group (post hoc analysis). This between-group difference in trends was statistically significant (interaction P value = 0.014). Chronic pain was recorded in 7.9% vs. 16.9% of patients (P = 0.171) at Week 12 in the mirogabalin add-on vs. conventional treatment groups, respectively. Regarding activities of daily living (ADL) and quality of life (QOL), changes in Pain Disability Assessment Scale score and the EQ-5D-5L index value from baseline to Week 8 showed significant improvement in the mirogabalin add-on group vs. conventional treatment group (P < 0.001). The most common adverse events (AEs) in the mirogabalin add-on group were dizziness (12.7%), somnolence (7.9%), and urticaria (3.2%). Most AEs were mild or moderate in severity. CONCLUSIONS: Addition of mirogabalin to conventional therapy did not result in significant improvement in pain intensity based on VAS scores, but did result in significant improvement in ADL and QOL in patients with peripheral NeP after thoracic surgery. TRIAL REGISTRATION: Japan Registry of Clinical Trials jRCTs071200053 (registered 17/11/2020).

Risk factors for pulmonary complications after colorectal cancer surgery: a Japanese multicenter study.

PURPOSE: Pulmonary complications (PC) are a serious condition with a 20% mortality rate. However, few reports have examined risk factors for PC after colorectal surgery. This study investigated the frequency, characteristics, and risk factors for PC after colorectal cancer surgery. METHODS: Between January 2016 and December 2022, we retrospectively reviewed 3979 consecutive patients who underwent colorectal cancer surgery in seven participating hospitals. Patients were divided into patients who experienced PC (PC group, n = 54) and patients who did not (non-PC group, n = 3925). Clinical and pathological features were compared between groups. RESULTS: Fifty-four patients (1.5%) developed PC, of whom 2 patients (3.7%) died due to PC. Age was greater (80 years vs 71 years; p < 0.001), frequency of chronic obstructive pulmonary distress was greater (9.3% vs 3.2%; p = 0.029), performance status was poorer (p < 0.001), the proportion of underweight was higher (42.6% vs 13.4%, p < 0.001), frequency of open surgery was greater (24.1% vs 9.3%; p < 0.001), and blood loss was greater (40 mL vs 22 mL; p < 0.001) in the PC group. Multivariate analysis revealed male sex (odds ratio (OR) 2.165, 95% confidence interval (CI) 1.176-3.986; p = 0.013), greater age (OR 3.180, 95%CI 1.798-5.624; p < 0.001), underweight (OR 3.961, 95%CI 2.210-7.100; p < 0.001), and poorer ASA-PS (OR 3.828, 95%CI 2.144-6.834; p < 0.001) as independent predictors of PC. CONCLUSION: Our study revealed male sex, greater age, underweight, and poorer ASA-PS as factors associated with development of PC, and suggested that pre- and postoperative rehabilitation and pneumonia control measures should be implemented for patients at high risk of PC.

A surgical training system designed to help trainees acquire laparoscopic surgical skills at a rural Japanese institute.

PURPOSE: The Endoscopic Surgical Skill Qualification System was established in Japan to evaluate safe endoscopic surgical techniques and teaching skills. Trainee surgeons obtaining this certification in rural hospitals are disadvantaged by the limited number of surgical opportunities. To address this problem, we established a surgical training system to educate trainee surgeons. METHODS: Eighteen certified expert surgeons affiliated with our department were classified into an experienced training system group (E group, n = 9) and a non-experienced group (NE group, n = 9). Results of the training system were then compared between the groups. RESULTS: The number of years required to become board certified was shorter in the E group (14 years) than that in the NE group (18 years). Likewise, the number of surgical procedures performed before certification was lower in the E group (n = 30) than that in the NE group (n = 50). An expert surgeon was involved in the creation of the certification video of all the E group participants. A questionnaire to board-certified surgeons revealed that guidance by a board-certified surgeon and trainee education (surgical training system) was useful for obtaining certification. CONCLUSIONS: Continuous surgical training, starting with trainee surgeons, appears useful for expediting their acquisition of technical certification in rural areas.

Effect of the lymphocyte-to-monocyte ratio on the prognosis of patients with obstructive colorectal cancer with a colonic stent: a retrospective multicenter study in Japan.

PURPOSE: The prognostic value of the lymphocyte-to-monocyte (LMR) ratio has been reported for various cancers, including colorectal cancer (CRC). The insertion of colonic stents is considered effective for patients with surgically indicated obstructive CRC, but their LMR can vary depending on factors such as inflammation associated with stent dilation and improvement of obstructive colitis. However, the usefulness of the LMR in patients with obstructive CRC and colonic stents and the optimal timing for its measurement remain unclear. We conducted this study to investigate the relationship between the pre-stent LMR and the mid-term prognosis of patients with obstructive CRC and stents as a bridge to surgery (BTS). METHODS: The subjects of this retrospective multicenter study were 175 patients with pathological stage 2 or 3 CRC. Patients were divided into a low pre-stent LMR group (n = 87) and a high pre-stent LMR group (n = 83). RESULTS: Only 3-year relapse-free survival differed significantly between the low and high pre-stent LMR groups (39.9% vs. 63.6%, respectively; p = 0.015). The pre-stent LMR represented a prognostic factor for relapse-free survival in multivariate analyses (hazard ratio 2.052, 95% confidence interval 1.242-3.389; p = 0.005), but not for overall survival. CONCLUSIONS: A low pre-stent LMR is a prognostic factor for postoperative recurrence in patients with obstructive CRC and a colonic stent as a BTS.

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.

Long-term outcomes and early recurrence after resection for metachronous pulmonary metastases from colorectal cancer.

PURPOSE: Properly selecting patients for aggressive curative resection for pulmonary metastases (PMs) from colorectal cancer (CRC) is desirable. We purposed to clarify prognostic factors and risk factors for early recurrence after metachronous PM resection. METHODS: Clinical data of 151 patients who underwent R0 resection for metachronous PMs from CRC at two institutions between 2008 and 2021 were reviewed. RESULTS: Seventy-six patients (50.3%) were male, and the median age was 71 (42-91) years. The numbers of colon/rectal cancers were 76/75, with pStage I/II/III/IV/unknown in 15/34/86/13/3. The duration from primary surgery to PM was 19.7 (1.0-106.4) months. The follow-up period was 41.9 (0.3-156.2) months. The 1-, 3-, and 5-year recurrence-free survival (RFS) rates were 75.1%, 53.7%, and 51.1%, and the 1-, 3-, and 5-year overall survival (OS) rates were 97.7%, 87.5%, and 68.2%. On multivariate analysis, lymph node metastasis of the primary lesion (HR 1.683, 95%CI 1.003-2.824, p = 0.049) was an independent predictor of poor RFS, and history of resection for extrapulmonary metastasis (e-PM) (HR 2.328, 95%CI 1.139-4.761, p = 0.021) was an independent predictor of poor OS. Patients who experienced early recurrence (< 6 months) after PM resection showed poorer OS than others (3-year OS 50.8% vs. 90.2%, p = 0.002). On multivariate analysis, e-PM was an independent predictor of early recurrence after PM resection (OR 3.989, 95%CI 1.002-15.885, p = 0.049). CONCLUSION: Since a history of e-PM was a predictor of early recurrence and poor OS after R0 resection for PM, surgical treatment of patients with a history of e-PM should be considered carefully.

Development and evaluation of an original phantom model of ultrasonography-guided thyroid gland biopsy for the training of surgical residents and students.

PURPOSES: Fine-needle aspiration cytology (FNAC) is a specific and important test used for the diagnosis of thyroid gland cancer. We developed a thyroid gland phantom using original manufacturing techniques and direct three-dimensional (3D) printing. The aim of this study was to confirm the effectiveness of this phantom by collecting data to evaluate puncture training. METHODS: Data from 45 ultrasonography-guided thyroid nodule FNAC procedures performed on our thyroid phantom were evaluated in our department. The first group comprised qualified physicians who specialized in thyroid gland treatment (group A; n = 10). The second and third groups comprised senior and junior residents (group B; n = 8 and group C; n = 12; respectively). The fourth group comprised students (group D; n = 15). We measured the times taken by these groups to complete each task. RESULTS: The skills of all participants in groups B, C, and D improved after using this phantom involving the major (parallel)- (0.47 ± 0.07) and short (orthogonal)-axes (0.52 ± 0.07) methods (P < 0.001). The number of erroneous punctures decreased from 53 to 3. CONCLUSIONS: Our original phantom improved the puncture skills of students and junior doctors and was suitable as a tailored training model for practicing thyroid gland transfixion.

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.

Balance of the prooxidant and antioxidant system is associated with mortality in critically ill patients.

It is well known that oxidative stress causes certain diseases and organ damage. However, roles of oxidative stress in the acute phase of critical patients remain to be elucidated. This study aimed to investigate the balance of oxidative and antioxidative system and to clarify the association between oxidative stress and mortality in critically ill patients. This cohort study enrolled 247 patients transported to our emergency department by ambulance. Blood was drawn on hospital arrival, and serum derivatives of reactive oxidant metabolites (dROMs, oxidative index) and biological antioxidant potential (BAP, antioxidative index) were measured. Modified ratio (MR) is also calculated as BAP/dROMs/7.51. There were 197 survivors and 50 non-survivors. In the non-survivors, dROMs were significantly lower (274 vs 311, p<0.01), BAP was significantly higher (2,853 vs 2,138, p<0.01), and MR was significantly higher (1.51 vs 0.92, p<0.01) compared to those in the survivors. The AUC of MR was similar to that for the APACHE II score. Contrary to our expectations, higher BAP and lower dROMs were observed on admission in non-survivors. This may suggest that the antioxidative system is more dominant in the acute phase of severe insults and that the balance toward a higher antioxidative system is associated with mortality.

Preoperative respiratory intervention eliminated the operation cancelations of lobectomy surgery.

In Nagasaki University Hospital, the patients undergoing surgery with abnormal respiratory function have been automatically referred to specialized clinic by Medical Support Center (MSC) since July 2016 to reduce surgery cancellations due to insufficient preoperative evaluation. Whether the MSC system decreased post-hospital surgery cancellation, variance rate, or length of hospital stays in patients received "lobectomy" were retrospectively compared between Period A (n = 264, before MSC introduction) and Period B (n = 264, after MSC introduction). Four patients' operations were cancelled after hospitalization in Period A, while 0 patients in Period B (p < 0.05). The length of hospital stay, operation time, anesthesia time, and postoperative extubation oxygen administration time were all shorten in Period B significantly. "Period B", "operation time", and "postoperation oxygenation time" were independent factors for "hospital days", but chronic obstructive pulmonary disease or age were not. The preoperative intervention eliminated the operation cancellation. Preoperative MSC interventions may have contributed to the reduction in hospital days even for the patients with pulmonary dysfunction.

[Airway Complications after Lung Transplantation].

Lung transplantation is the only option for patients with end-stage pulmonary diseases. During recent years, satisfactory results in terms of long-term survival and quality of life have been achieved with improvements in perioperative management, surgical technique, and immunosuppression. Airway complications after lung transplantation are associated with significant morbidity and mortality. Common airway complications after lung transplantation include anastomotic granulation, airway stenosis, bronchomalacia, fistulas, and anastomotic infection. These airway complications often result in repeated hospitalisations and interventions. If bronchoscopic interventions are not effective, other alternatives like surgical intervention or re-transplantation become necessary. While numerous strategies for airway complications have been proven effective, there are still some issues that to be solved. Further research is necessary to reduce mortality and improve quality of life of these patients.

A randomized phase II study of S-1 monotherapy versus cisplatin with vinorelbine for completely resected stage II/IIIA non-small cell lung cancer: rationale and study protocol design for the LOGIK1702 study.

BACKGROUND: The current standard postoperative treatment for stage II-IIIA non-small cell lung cancer (NSCLC) is a regimen of platinum doublet adjuvant chemotherapy. These regimens, which are the same as for solid NSCLC tumors, often cause severe adverse reactions in the treated patients. Therefore, an effective treatment regimen with fewer side effects is needed. METHODS/DESIGN: The purpose of this study is to evaluate the effectiveness and safety of S-1 monotherapy (80 mg/m2 orally administrated twice daily, at day 1-14, 16 cycles) and cisplatin with vinorelbine combination therapy (cisplatin 80 mg/m2 at day 1,vinorelbine 25 mg/m2 at day 1, 8, 4 cycles) in patients with II/IIIA stage non-small-cell lung cancer who underwent a total resection. In addition, we will also evaluate the level of treatment side effects by assessing quality of life (QOL), work productivity and activity performance. The primary endpoint is a 2-year relapse free survival (RFS) and the second primary endpoints are 2-year overall survival (OS), rate of treatment completion, safety, work productivity and activity, and quality of adjusted life years (QALY). At the same time, we aim to obtain precise information required to perform future phase 3 randomized controlled trials. The study is designed to estimate the primary endpoint with accuracy determined as the width of its 95% confidence interval to be less than 20%. Recruitment started in May 2017 and is ongoing. DISCUSSION: This study has been conceived to establish a superior regimen for completely resected NSCLC based on efficacy, safety and QOL. TRIAL REGISTRATION: Registry number: UMIN000027435 . Registered May 22, 2017.

A new method using a vessel-sealing system provides coagulation effects to various types of bleeding with less thermal damage.

BACKGROUND: Hemostasis is very important for a safe surgery, particularly in endoscopic surgery. Accordingly, in the last decade, vessel-sealing systems became popular as hemostatic devices. However, their use is limited due to thermal damage to organs, such as intestines and nerves. We developed a new method for safe coagulation using a vessel-sealing system, termed flat coagulation (FC). This study aimed to evaluate the efficacy of this new FC method compared to conventional coagulation methods. METHODS: We evaluated the thermal damage caused by various energy devices, such as the vessel-sealing system (FC method using LigaSure™), ultrasonic scissors (Sonicision™), and monopolar electrosurgery (cut/coagulation/spray/soft coagulation (SC) mode), on porcine organs, including the small intestine and liver. Furthermore, we compared the hemostasis time between the FC method and conventional methods in the superficial bleeding model using porcine mesentery. RESULTS: FC caused less thermal damage than monopolar electrosurgery's SC mode in the porcine liver and small intestine (liver: mean depth of thermal damage, 1.91 ± 0.35 vs 3.37 ± 0.28 mm; p = 0.0015). In the superficial bleeding model, the hemostasis time of FC was significantly shorter than that of electrosurgery's SC mode (mean, 19.54 ± 22.51 s vs 44.99 ± 21.18 s; p = 0.0046). CONCLUSION: This study showed that the FC method caused less thermal damage to porcine small intestine and liver than conventional methods. This FC method could provide easier and faster coagulation of superficial bleeds compared to that achieved by electrosurgery's SC mode. Therefore, this study motivates for the use of this new method to achieve hemostasis with various types of bleeds involving internal organs during endoscopic surgeries.

Presence of heat shock protein 47-positive fibroblasts in cancer stroma is associated with increased risk of postoperative recurrence in patients with lung cancer.

BACKGROUND: Heat shock protein 47 (HSP47), a collagen-binding protein, has a specific role in the intracellular processing of procollagen production. HSP47 expression is associated with cancer growth and metastasis in several types of cancers. However, none of the studies have assessed whether HSP47 expression is associated with the risk of postoperative recurrence of lung cancer until now. Therefore, we aimed to assess this association. METHODS: The study population consisted of a cohort of consecutive patients who underwent surgery for lung cancer at Nagasaki University Hospital, Nagasaki, Japan, from January 2009 to December 2010. Patient characteristics, survival and disease-free survival (DFS), and laboratory findings were compared between patients who tested positive and negative for HSP47 expression in lung cancer cells and between those who showed high and low numbers of HSP47-positive fibroblasts in cancer stroma. RESULTS: A total of 133 patients underwent surgery for lung cancer. Sixty-seven patients (50.4%) had HSP47-positive cancer cells, and 91 patients (68.4%) had a higher number of HSP47-positive fibroblasts. The patients with a high number of HSP47-positive fibroblasts had a shorter DFS than those with a low number of HSP47-positive fibroblasts. Multivariate analysis identified only the presence of a high number of HSP47-positive fibroblasts as an independent risk factor for recurrence of lung cancer after surgery (odds ratio, 4.371; 95% confidence interval, 1.054-29.83; P = 0.042). CONCLUSION: The present study demonstrated that the presence of a high number of HSP47-positive fibroblasts in the cancer stroma was a risk factor for recurrence of lung cancer after surgery.

Left upper lobectomy is a risk factor for cerebral infarction after pulmonary resection: a multicentre, retrospective, case-control study in Japan.

PURPOSE: The anatomical site of resected lobes may influence postoperative cerebral infarction. The objective of the current study was to determine if left upper pulmonary lobectomy is a risk factor for postoperative cerebral infarction. METHODS: This was a retrospective case-control study in patients undergoing pulmonary lobectomy from 2004 to 2013 in Japan. We retrospectively identified 610 patients from 153 institutions who had developed postoperative cerebral infarction following pulmonary lobectomy. The control group consisted of 773 patients who underwent lobectomy without cerebral infarction during a randomly selected single month in 2009 at the same institutions. RESULTS: Factors associated with cerebral infarction were age [10-year intervals, odds ratio (OR): 1.46; 95% confidence interval (CI): 1.23-1.73; p < 0.001], male sex (OR 1.92; 95% CI 1.29-2.86; p = 0.001), presence of comorbidities (OR 1.82; 95% CI 1.35-2.44; p < 0.001), perioperative anti-platelet or anti-coagulant drug use (OR 1.71; 95% CI 1.20-2.45; p = 0.003), and lobectomy. Subgroup analyses revealed that cerebral infarction was strongly associated with left upper lobectomy. CONCLUSIONS: Our findings suggest that left upper lobectomy is associated with a higher risk of cerebral infarction than other types of lobectomy, particularly in the early postoperative period.

Correction to: Left upper lobectomy is a risk factor for cerebral infarction after pulmonary resection: a multicentre, retrospective, case-control study in Japan.

The original article can be found online.

New Concept for a Thoracic Drainage System Using Magnetic Actuation.

Objectives. Thoracic drainage is a common procedure to drain fluid, blood, or air from the pleural cavity. Some attempts to develop approaches to new thoracic drainage systems have been made; however, a simple tube is often currently used. The existing drain presupposes that it is placed correctly and that the tip does not require moving after insertion into the thoracic cavity. However, in some cases, the drain is not correctly placed and reinsertion of an additional drain is required, resulting in significant invasiveness to the patient. Therefore, a more effective drainage system is needed. This study aimed to develop and assess a new thoracic drain via a collaboration between medical and engineering personnel. Methods. We developed the concept of a controllable drain system using magnetic actuation. A dry laboratory trial and accompanying questionnaire assessment were performed by a group of thoracic and general surgeons. Objective mechanical measurements were obtained. Porcine experiments were also carried out. Results. In a dry laboratory trial, use of the controllable drain required significantly less time than that required by replacing the drain. The average satisfaction score of the new drainage system was 4.07 out of 5, indicating that most of the research participants were satisfied with the quality of the drain with a magnetic actuation. During the porcine experiment, the transfer of the tip of the drain was possible inside the thoracic cavity and abdominal cavity. Conclusion. This controllable thoracic drain could reduce the invasiveness for patients requiring thoracic or abdominal cavity drainage.

Balloon-Based Organ Retractor With Increased Safety and Reduced Invasiveness During Video-Assisted Thoracoscopic Surgery.

OBJECTIVES: In recent years, video-assisted thoracoscopic surgery (VATS) has increasingly become the preferred technique for thoracic surgery. However, the inherent characteristics of the lungs as large, soft, slippery, and delicate creates difficulties for pulmonary surgery. In this article, we outline the development and assessment of a balloon-based organ retractor for VATS via collaboration between medical and engineering personnel. METHODS: A dry lab trial and accompanying questionnaire assessment were performed by a group of thoracic surgeons. Objective pressure measurements were obtained, and animal experiment on pigs was performed. RESULTS: In the dry lab trial, use of the developed organ retractor required significantly less time and resulted in fewer difficulties than using a Cherry Dissector. The measured pressure per mm2 of the developed retractor was clearly lower than that for the Cherry Dissector. The questionnaire completed by the surgeons following the dry lab and animal experiments showed that most of the surgeons (7 surgeons out of 9) were satisfied with the quality of the balloon-based retractor based on a score of 3.13 ± 0.28 (mean ± standard deviation) out of 4.0. During the animal experiment, the balloon-based retractor provided stable and clear viewing with minimal need for adjustment. CONCLUSION: This balloon-based retractor could contribute to increased safety and less-invasive VATS.