Immunosuppressive treatment for myasthenia gravis crises improve the taste disorder in patients with thymoma: two case reports.

Background: Taste disorders in patients with thymoma accompanied by myasthenia gravis (MG) is rare. Case Description: The first case was a male in his 50s who underwent surgery for Masaoka stage III type B3 thymoma. He experienced a loss of taste before surgery, which showed no improvement after surgery. Due to a MG crisis 44 days after surgery, the patient underwent intensive treatment with mechanical ventilation, steroid pulse therapy, and intravenous immunoglobulin (IVIG) therapy. The patient recovered taste when he started oral food intake after the treatment for the MG crisis (about 3 months after surgery). Despite the recovery of taste after steroid pulse therapy and IVIG therapy, taste disorder gradually worsened about 1 year and 9 months after surgery, resulting in an almost complete loss of sweet taste 2 years after surgery. The second case was a male in his 60s who underwent surgery for Masaoka stage II type B1 thymoma. He experienced loss of taste before surgery, which showed no improvement after surgery. Five years and two months after surgery, the patient was diagnosed with a MG crisis and underwent steroid pulse therapy. Along with improvements in MG symptoms, taste disorders gradually improved. After 6 years and 10 months of surgery, the patient is still alive without MG symptoms (only pyridostigmine, 180 mg/body/day), taste disorder, and thymoma recurrence. Conclusions: The autoimmune mechanism may contribute to taste disorders in patients with thymoma, which can be recovered by immunosuppressive treatment in our cases.

[Postoperative Complications of Open Window Thoracostomy:Report of a Case].

While open window thoracostomy is used to treat empyema with a high rate of infection control, it is an invasive procedure that leads to a decline in the quality of life. An 80-year-old man who had undergone wedge resection for pulmonary nodules subsequently developed postoperative empyema and underwent open window thoracostomy. After thoracostomy, the patient developed several complications, including bleeding from the lung surface and air leakage. Window closure was planned at this time;however, the plan was scuttled due to his low nutritional status and pulmonary air leakage. After the patient's condition improved with persistent conservative treatment, window closure was performed, and he overcame his complications. Patients with postoperative empyema requiring thoracostomy are at a high risk of developing postoperative complications. Therefore, it is important to manage the patients' condition persistently so that they can receive window closure at an appropriate time.

New method for delineation of the intersegmental line in a deflated lung.

Background: Preoperative three-dimensional (3D) computed tomography (CT) images have been widely used as surgical guides in lung surgery; however, the lungs tend to be deflated during surgery. Discrepancies between the preoperatively constructed 3D image and the intraoperative view of the deflated lungs often require preoperative and/or intraoperative marking methods for sublobar pulmonary resection. We have developed a lung deflation simulation algorithm in which 3D CT images of the deflated lungs can be predicted only based on the preoperative CT taken in an inflated phase of respiration. Using this system, we conducted a preliminary study to retrospectively compare the intersegmental line predicted by our lung deflation simulation algorithm with the intersegmental line delineated by the intravenous administration of indocyanine green. Methods: Sixteen patients who underwent unilateral segmentectomy between January 1, 2020, and June 30, 2022, were included in the study. The identified intersegmental lines were confirmed intraoperatively using indocyanine green. These actual intersegmental lines were compared with those delineated on 3D images using the lung deflation simulation algorithm. Results: Of the 16 patients who underwent pulmonary segmentectomy, the consistency of these intersegmental lines was in complete agreement in twelve patients, partial agreement in three patients, and disagreement in one patient. The concordance rate of the intersegmental lines was 75%. Conclusions: The lung deflation simulation algorithm provides a new surgical guide in addition to the currently utilized ones. Continuous innovation might lead to a less invasive surgical technique for delineating the intersegmental line.

Pathologically confirmed spontaneous regression of small cell lung cancer after computed tomography-guided percutaneous transthoracic needle biopsy followed by surgery.

BACKGROUND: Spontaneous regression of malignant tumors is a rare phenomenon, especially in primary lung cancer. The underlying mechanisms remain unclear, but they may often involve immunological mechanisms. CASE PRESENTATION: In January 2020, a 78-year-old female underwent examination during follow-up of interstitial pneumonia. Chest X-ray and computed tomography (CT) scan revealed a 1.2 × 1.2 cm nodule in the left lower lobe. Based on CT-guided percutaneous transthoracic needle biopsy (PTNB), it was diagnosed as small cell lung cancer (SCLC). Immunohistochemical staining showed that tumor cells were positive for CD56, synaptophysin, and chromogranin A. Twenty-three days after the CT-guided PTNB, repeat CT scan showed that the tumor size regressed to 0.6 × 0.6 cm. The tumor showed positive uptake in fluorodeoxyglucose (FDG) positron emission tomography (PET)-CT. The maximum standardized uptake value of the nodule was 2.24. PET-CT and enhanced magnetic resonance imaging of the brain showed no distant or lymph node metastasis. The patient's preoperative disease was diagnosed as cT1aN0M0, stageIA1, SCLC. In March 2020, she underwent left lower lobectomy and mediastinal lymph node dissection. Pathological examination of the resected specimen showed that the small tumor cells were dense with a high nucleus to cytoplasm ratio, and the morphological diagnosis was small cell carcinoma. The resected tumor size regressed to 0.05 × 0.02 cm, and no lymph node metastasis was observed. Because it was extremely small, immunohistochemical staining could not be conducted. Active fibrosis and inflammation were present around the tumor. Finally, the patient was pathologically diagnosed as SCLC pT1miN0M0, stage IA1. The patient is alive without recurrence 23 months after surgery with no adjuvant therapy. CONCLUSIONS: We present a rare surgical case of pathologically confirmed spontaneous regression of SCLC after CT-guided PTNB. Although spontaneous regression is extremely rare, we should recognize this phenomenon.

Prognostic impact of highly solid component in early-stage solid lung adenocarcinoma.

Background: Based on computed tomography (CT) findings of lung cancer, solid nodules have a much worse prognosis than subsolid nodules, even if the nodules are subcentimeter in size. There is, however, no systematic method for determining the prognosis of solid tumors on CT. This study aimed to discover the prognostic factor of early-stage solid lung adenocarcinoma using three-dimensional CT volumetry. Methods: Patients with pathological stage I solid lung adenocarcinoma who underwent complete resection between 2007 and 2012 were selected in this retrospective study. Clinicopathological data and preoperative multidetector CT findings, such as tumor size on the two-dimensional axial image, three-dimensional tumor volume between -600 and 199 HU, and three-dimensional solid volume between 0 and 199 HU, which corresponded to highly solid components, were compared between recurrence and non-recurrence. Furthermore, these radiological values were compared to pathological invasive volume (PIV). Results: During this time, 709 patients had their lung cancer completely removed. From this cohort, 90 patients with pathological stage I solid lung adenocarcinoma were selected. In addition, recurrence was found in 26 patients (28.9%). Although two-dimensional axial image, serum carcinoembryonic antigen (CEA) level, and SUVmax on 18F fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) did not differ statistically between recurrent and non-recurrent patients, three-dimensional tumor and solid tumor volume did. Multivariate analysis indicated that three-dimensional solid tumor volume [hazard ratio: 2.440; 95% confidence interval (CI): 1.110-5.361, P=0.026] and epidermal growth factor receptor (EGFR) mutation (hazard ratio: 4.307; 95% CI: 1.328-13.977, P=0.015) were significantly associated with disease-free survival (DFS). When three-dimensional tumor and solid tumor volume were compared to PIV, three-dimensional solid tumor volume (3,091 mm3 on average) showed a highly similar value with PIV (2,930 mm3 on average), whereas three-dimensional tumor volume (6,175 mm3 on average) was significantly larger than PIV (P<0.001). Conclusions: In patients with early-stage solid lung adenocarcinoma, the measurement of three-dimensional solid tumor volume, which is correlated with PIV, accurately predicted the postoperative outcome.

Clinical application of resection process map as a novel surgical guide in thoracic surgery.

Resection Process Map (RPM) is a surgical simulation system that uses preoperative three-dimensional computed tomography. Unlike the usual static simulation, this system provides surgeons an individualized dynamic deformation of the lung parenchyma and vessels. RPM was first introduced in 2020. Although the intraoperative usefulness of this system has been evaluated experimentally, there have been no reports on its clinical use. Herein, we presented in detail the first experience on RPM during robot-assisted anatomical lung resection in the real clinical setting.

Lingular-segment torsion after extended left-upper division segmentectomy by video-assisted thoracic surgery with indocyanine green fluorescence imaging.

Lingular-segment torsion after left-upper division segmentectomy (LUDS) is a rare complication, and the cause remains unclear. Here we report the case of a patient who developed lingular-segment torsion after LUDS for multiple lung metastases of breast cancer. One lung nodule was located in the S1 + 2 segment and another between the upper lobe and S6 on an incomplete interlobar fissure. The lung metastases were resected by extended LUDS using video-assisted thoracic surgery with indocyanine green fluorescence imaging. The staple line on the lingular segment was vertically tilted against the interlobar line because of the atypical defect of the fluorescence plane and nodule position. Chest X-ray and contrast-enhanced computed tomography indicated ischemia and torsion of the lingular segment on the second postoperative day, and completion of lingular segmentectomy was performed. This case showed the vertical intersegment staple line during LUDS was one of the important causes of postoperative torsion of the lingular segment.

Real-world evidence of safety and influence for lung cancer surgery under COVID-19 pandemic in Japan.

Background: The COVID-19 pandemic has affected the clinical practice of lung cancer surgery in Japan, but few studies have revealed the real situation of surgical practice for lung cancer in this country. This latest information will help us to decide the future direction of lung cancer surgery under pandemic circumstances. Methods: We collected data from patients with primary lung cancer who underwent thoracic surgery between 2018 and 2021. To investigate the impact of the COVID-19 pandemic on lung cancer surgery, we compared between 2018-2019 (prepandemic group) and 2020-2021 (pandemic group) in the respect of patient characteristics, pathological findings, and short-term outcome after lung cancer resection by Mann-Whitney and Fisher's exact tests. Moreover, the monthly number of surgeries for lung cancer in our institution during 2020-2021 was compared with the number of newly diagnosed COVID-19 patients in Japan by Spearman correlation analysis. Results: From 2018 through 2021, 936 patients with primary lung cancer underwent surgical intervention in our institute and were included in this study. The number of surgeries did not decrease in the pandemic group (n=443) compared with that in the prepandemic group (n=493). Tumor and invasive size in stage I which was measured by pathologist were significantly larger in the pandemic group than in the prepandemic group (tumor size: P=0.031, invasive size: P<0.001). In terms of postoperative short-term outcome, the median hospital stay was 6 days, 30-day mortality was 2, and morbidity was around 20% in both groups. Only one patient suffered from COVID-19 infection 5 months after right upper lobectomy. An increased ratio of newly diagnosed COVID-19 cases in Japan was negatively correlated with the number of surgeries for lung cancer in our institution in the next month (r=-0.393, P=0.007), although there was no correlation in the present or the month after next. Conclusions: Even during the COVID-19 pandemic period, lung cancer surgery could be performed safely and in a sustainable manner. However, pathological findings of lung cancer tended to be progressive in early-stage lung cancer.

Video-assisted thoracoscopic surgery for pleuroperitoneal communication.

Here we report the cases of five patients on continuous ambulatory peritoneal dialysis (CAPD) who developed hydrothorax because of pleuroperitoneal communication. Preoperative computed tomography (CT) peritoneography revealed penetrated sites on the diaphragm in all patients. All patients underwent video-assisted thoracoscopic surgery (VATS), and a dialysate containing indigo carmine was injected intraperitoneally through a CAPD catheter to confirm the fistula. In all patients, a thinned bleb was found at the center of the diaphragmatic tendon consistent with that noted on preoperative CT peritoneography. The bleb was resected using a surgical stapler in four patients, and the pleuroperitoneal communication did not recur. However, in one patient, the bleb was only covered with reinforcement agents and the hydrothorax recurred after CAPD. This study demonstrates that VATS treatment for pleuroperitoneal communication is safe and effective but that lesion resection would be more useful for preventing hydrothorax recurrence in patients undergoing CAPD.

Setting a quality indicator for actual surgery time relative to scheduled surgery time in the context of increasing robotic-assisted thoracic surgery cases.

OBJECTIVE: This study aimed to demonstrate to the involved departments the goal of increasing the number of robotic-assisted thoracic surgery (RATS) cases/surgeons and acceptable surgery times. METHODS: This retrospective study included 1572 patients who underwent thoracic surgery from fiscal year (FY) 2018 to FY 2021. The factors evaluated included the number of surgery cases and actual and scheduled surgery times. RESULTS: The total number of RATS and total surgery cases increased after the quality indicator (QI) setting (n = 363, 360, 417, and 432 in FY 2018, 2019, 2020, and 2021, respectively). In FY 2020, 93.3% of the QI target was achieved, while in FY 2021, 88% was achieved. The number of RATS lobectomy/segmentectomy increased as the FY progressed (n = 31, 47, 58, and 116 in FY 2018, 2019, 2020, and 2021, respectively). The mean surgical time by RATS starters decreased in FY 2020 and 2021 (171.4 min.; 74 cases; seven RATS starters) compared with those in FY 2018 and 2019 (198.0 min.; 57 cases; six RATS starters) (P = 0.002). CONCLUSIONS: The goal of increasing the number of surgery cases and RATS cases/surgeons within the given framework was achieved by setting the QI.

Impact of Pleural Thickness on Occurrence of Postoperative Complications in Patients with Malignant Pleural Mesothelioma.

OBJECTIVES: The rates of postoperative mortality and morbidity are high in patients with malignant pleural mesothelioma (MPM). Therefore, it is important to identify variables that increase the risk of postoperative complications. Pleural thickness has recently been identified as a prognostic indicator in patients with MPM. The aim of this study was to investigate clinical variables, including pleural thickness, that contribute to postoperative complications in patients with MPM. PATIENTS AND METHODS: A total of 47 patients who underwent surgical excision of MPM between 2005 and 2021 were enrolled in this study. Correlations between postoperative complications within 90 days of surgery and preoperative clinical factors were investigated. RESULTS: A total of 27 patients underwent extrapleural pneumonectomy (EPP), and the remaining 20 underwent pleurectomy/decortication (P/D). Macroscopic complete resections were obtained in all but three patients. Of the 47 patients, 23 (49%) experienced postoperative complications of grade 3 or worse. The major complication in patients with EPP was respiratory failure (n = 6), whereas the major complication in patients with P/D was prolonged air leakage (n = 7). Univariate logistic regression analysis found a correlation between postoperative complications and age, surgical side, and pleural thickness, while multivariate logistic regression analysis found surgical side (p = 0.04, 95% Cl 1.10-21.71, OR 4.90) and pleural thickness (p = 0.03, 95% Cl 1.21-23.00, OR 5.26) to significantly influence the occurrence of postoperative complications. CONCLUSIONS: Pleural thickness has a significant effect on the occurrence of postoperative complications. Patients with thick pleura on the right side are at greater risk of postoperative complications.

Skeletal muscle and related protein expression as prognostic factors in thymic squamous cell carcinoma.

Background: Sarcopenia and its marker, the psoas muscle index (PMI), have attracted attention as prognostic factors for various types of cancers. The fragile X-related 1 (FXR1) gene is highly expressed in myocytes, and FXR1 overexpression is a candidate biomarker for poor survival in several types of cancers. Thymic squamous cell carcinoma (TSQCC) is rare, and no studies assessing its prognostic factors, particularly in terms of skeletal muscle mass and FXR1 expression, are available. Methods: We retrospectively investigated the prognostic significance of PMI in 34 patients who underwent TSQCC resection, considering the status of FXR1 and tumor programmed death-ligand 1 (PD-L1). PMI was calculated from the bilateral psoas muscle using preoperative computed tomography (CT). Patients were divided into two groups: low PMI (<58.2%, n=17) and normal PMI (≥58.2%, n=17). Immunohistochemical analysis was performed to determine the FXR1 and PD-L1 expression levels. Results: Low PMI was significantly associated with worse overall survival (OS) (5-year survival rate; 86% vs. 100%; P=0.026) and marginally associated with worse disease-free survival (DFS) (5-year survival rate; 39% vs. 66%; P=0.090) compared with normal PMI. The immunohistochemical analysis revealed that the FXR1 intensity score (0-1+: 6% vs. 0%; 2+-3+: 94% vs. 100%; P=0.31), median FXR1 distribution (95% vs. 90%; P=0.63), and PD-L1 status (high: 47% vs. 59%; P=0.49) were not significantly different between the two groups. Conclusions: Our findings suggest that PMI might be considered as a potential prognostic factor in TSQCC and that FXR1 is widely expressed regardless of the PMI status. Skeletal muscle mass may play a role in the prognosis of TSQCC.

Neoadjuvant Therapy for Patients With Non-small Cell Lung Cancer Complicated With Chest Wall Invasion.

BACKGROUND/AIM: Multidisciplinary treatment including anatomical pulmonary and chest wall resection is recommended for lung cancer complicated by chest wall invasion. The present study aimed to investigate the survival benefit and safety of preoperative therapy followed by surgery for non-small cell lung cancer with chest wall invasion. PATIENTS AND METHODS: Sixty-five patients who underwent surgical excision of lung cancer complicated with chest wall invasion between 2009 and 2020 were enrolled in this study. RESULTS: The median age was 65 (37-81) years old, with 59 males and 6 females. Histological types included squamous cell carcinoma (n=32) and adenocarcinoma (n=21). The median tumor diameter was 5.5 cm (2.3-12.5 cm). The clinical nodal status was N0 in 49 cases and N positive in 16 cases. Of the 65 eligible patients, 5- and 10-year overall survival (OS) rates were 58.4% and 46.0%, respectively, and 5- and 10-year progression-free survival (PFS) rates were 54.2% and 41.7%, respectively. For patients receiving preoperative therapy followed by surgery (Pre-Tx), 5- and 10-year OS survival rates were 69.2% and 62.9%, and among patients receiving up-front surgery (UFS) were 48.5% and 29.1%, respectively (p=0.03). The 5- and 10-year PFS rates for pre-Tx were 65.8% and 59.2%, respectively, and 44.7% and 26.8% for UFS, respectively (p=0.02). Cox regression analysis preoperative therapy was significantly associated with OS and PFS. CONCLUSION: We demonstrate the survival benefit of preoperative therapy followed by surgery for patients with lung cancer and chest wall invasion.

Relationship of smoking cessation period with the incidence of complications in lung cancer surgery.

OBJECTIVES: The incidence of postoperative complications is relatively high in smokers. Although 4-week smoking cessation before surgery is generally recommended, it has not been sufficiently studied in lung cancer surgery. This study investigated whether smoking cessation for a short period of time significantly reduced complications after lung cancer surgery. METHODS: This was a retrospective, observational study that investigated the relationship between the smoking cessation period and the incidence of complications in lung cancer surgery. Patients who underwent curative-intent surgery for lung cancer at our institution between January 2014 and December 2017 were included. The smokers were classified into the following 4 categories of smoking cessation period before surgery: current (<4 weeks), recent (4 weeks to 12 months), distant (12 months to 5 years) and ex-smokers (>5 years). RESULTS: A total of 911 patients were included in this study. The incidence of pulmonary complications was 5 times higher in the smoker group than in the never smoker group (12.9% vs 2.5%, P < 0.001). On multivariable analysis in both models, the odds ratio for complications was significantly higher in distant smokers than in recent smokers and never smokers. Across all models, low lung function significantly predicted the development of postoperative complications. CONCLUSIONS: The evidence-based smoking cessation duration that reduces the incidence of complications after thoracic surgery remains unclear. The incidence of postoperative complications was more strongly affected by low pulmonary function than by the duration of preoperative smoking cessation. For patients with marginal indications for surgery, postponing surgery to accommodate a smoking cessation period seemed unnecessary.

Risk Assessment for Loss-of-Exercise Capacity After Lung Cancer Surgery: Current Advances in Surgery and Systemic Treatment.

BACKGROUND: Considering advances in current post-recurrence treatment, we examined the prognostic significance of the number of risk factors for loss-of-exercise capacity (LEC) after lung cancer surgery, which were identified by our previous prospective observational study. METHODS: Risk factors for LEC were defined as a short baseline 6-min walk distance (<400 m), older age (≥75 years), and low predicted postoperative diffusing capacity for carbon monoxide (<60%). Patients were classified as Risk 0/I/II/III according to the number of risk factors. The survival data were retrospectively analyzed. RESULTS: Between 2014 and 2017, 564 patients (n = 307, 193, 57, 7; Risk 0/I/II/III) who underwent lung cancer surgery were included in the study. The number of risk factors was associated with smoking status, predicted postoperative forced expiratory volume in 1 s, histology, pathological stage, and adjuvant therapy. In a multivariate Cox regression analysis, compared to Risk 0, Risk I/II/III showed significant associations with overall survival (hazard ratios: 1.92, 3.35, 9.21; 95% confidence interval: 1.27-2.92, 2.01-5.58, 3.64-23.35; Risk I/II/III, respectively). In 141 patients with recurrence, molecular targeted therapies (MTTs) or immune checkpoint inhibitors (ICIs) were included in 58%, 47%, 32%, and 0% (Risk 0/I/II/III) during the course of treatment. In patients with MTT/ICI treatment, the estimated 1-year and 3-year post-recurrence survival rates were 88% and 58%, respectively. CONCLUSIONS: Risk classification for LEC was associated with survival after lung cancer surgery, as well as post-recurrence treatment. The concept of physical performance-preserving surgery may contribute to improving the outcomes of current lung cancer treatment.

Prognostic Value of Uncertain Resection for Overall Survival in Non-small Cell Lung Cancer.

BACKGROUND: In this study we evaluated the R(un) category proposed by the International Association for the Study of Lung Cancer (IASLC) for non-small cell lung cancer (NSCLC). METHODS: We retrospectively reviewed the medical records of patients with NSCLC who underwent segmentectomy or lobectomy between 2014 and 2015 at our institution. Residual tumor (R) status was reclassified from the Union for International Cancer Control designation to the IASLC-proposed R classification of R0 and R(un). The underlying reasons for the R(un) reclassification were analyzed according to pathologic stage, lymph node status, and resected lobe. A Cox proportional hazard model was used to evaluate the impacts of R(un) categorization on overall survival. RESULTS: Of 355 patients, 44.5% were reclassified as R(un). The most common reason for the reclassification was insufficient number of harvested lymph nodes or no station 7 lymph nodes. When stratified by tumor location, the absence of station 7 lymph nodes was especially prominent in both the right and left upper lung resections. In the multivariate Cox regression model, the IASLC R classification was associated with poor overall survival in node-positive patients (hazard ratio, 2.657; P = .016). CONCLUSIONS: Various factors resulted in reclassification to R(un) because the R(un) group was highly heterogeneous. Careful consideration is required to determine whether the R(un) classification can be used as an indicator of lymph node dissection quality. For advanced cases, the R(un) definition may be useful in predicting poor prognosis.

Lobectomy with bronchoplasty and pulmonary arterial angioplasty for lung cancer after correction of contralateral partial anomalous pulmonary venous connection.

BACKGROUND: There have been few reports on surgically treated primary lung cancer accompanied by contralateral partial anomalous pulmonary venous connection (PAPVC). In such cases, repair of the PAPVC might be necessary to avoid postoperative right-heart failure due to the increased flow of the left-to-right shunt. CASE PRESENTATION: We herein report a case of lung adenocarcinoma treated by left-upper lobectomy with bronchoplasty and pulmonary arterial angioplasty after induction chemoradiation therapy followed by surgical correction of the PAPVC in the right-upper lobe. The patient is alive without recurrence of lung cancer or any symptoms of heart failure 17 months after pulmonary resection. CONCLUSION: When considering performing major pulmonary resection for lung tumor, thoracic surgeons should pay close attention to the presence of a PAPVC not only on the ipsilateral side of the lung tumor, but also the contralateral side, although it is a rare phenomenon.

Impact of the preoperative body mass index on the postoperative outcomes in patients with completely resected non-small cell lung cancer: A retrospective analysis of 16,503 cases in a Japanese Lung Cancer Registry Study.

OBJECTIVES: The aim of this study was to evaluate the impact of the preoperative body mass index (BMI) on the postoperative outcomes in patients with completely resected non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: The data of patients with NSCLC in whom R0 resection was achieved were extracted from the database of NSCLC samples accumulated by the Japanese Joint Committee of Lung Cancer Registry in the year 2010, and the surgical outcomes including postoperative morbidity, mortality and the prognosis, were evaluated. RESULTS: Among 18,978 registered lung cancer cases, 16,509 patients (9996 men and 6513 women) were extracted. The median of age was 69 years old, and the histologic types included adenocarcinoma (n = 12,029), squamous cell carcinoma (n = 3286), large-cell carcinoma (n = 488) and others. The patients were divided into three groups according to their BMI: normal (BMI 18.5 to <25), underweight (BMI < 18.5) and overweight (BMI ≥ 25). Multivariate logistic regression analyses of factors associated with postoperative morbidity and mortality showed no significant differences among the three groups. In comparison to the normal group, the overall survival (OS) of the underweight group was significantly worse (p < 0.001) while that of the overweight group was marginally better (p = 0.075). A multivariate analysis of factors associated with OS showed that in addition to the age, sex and clinical stage, the preoperative BMI (underweight group vs. normal group: hazard ratio [HR] 1.417 [95% confidence interval {CI}: 1.278-1.572, p < 0.001], overweight group vs. normal group: HR 0.883 [95% CI: 0.806-0.967, p = 0.007]) was an independent prognostic factor. A multivariate analysis for the disease-free survival (DFS) also showed the preoperative BMI to be an independent significant prognostic factor. CONCLUSIONS: The preoperative BMI is an independent prognostic factor in patients with completely resected NSCLC. A low preoperative BMI was associated with significantly poor survival in Japan.