Predicting surgical outcomes of acute diffuse peritonitis: Updated risk models based on real-world clinical data.

Aim: The existing predictive risk models for the surgical outcome of acute diffused peritonitis (ADP) need renovation by adding relevant variables such as ADP's definition or causative etiology to pursue outstanding data collection reflecting the real world. We aimed to revise the risk models predicting mortality and morbidities of ADP using the latest Japanese Nationwide Clinical Database (NCD) variable set. Methods: Clinical dataset of ADP patients who underwent surgery, and registered in the NCD between 2016 and 2019, were used to develop a risk model for surgical outcomes. The primary outcome was perioperative mortality. Results: After data cleanup, 45 379 surgical cases for ADP were derived for analysis. The perioperative and 30-day mortality were 10.6% and 7.2%, respectively. The prediction models have been created for the mortality and 10 morbidities associated with the mortality. The top five relevant predictors for perioperative mortality were age >80, advanced cancer with multiple metastases, platelet count of <50 000/mL, serum albumin of <2.0 g/dL, and unknown ADP site. The C-indices of perioperative and 30-day mortality were 0.859 and 0.857, respectively. The predicted value calculated with the risk models for mortality was highly fitted with the actual probability from the lower to the higher risk groups. Conclusions: Risk models for postoperative mortality and morbidities with good predictive performance and reliability were revised and validated using the recent real-world clinical dataset. These models help to predict ADP surgical outcomes accurately and are available for clinical settings.

Open left diaphragm method enables safe surgery with a good visual field in a laparoscopic transhiatal approach for esophagogastric junction adenocarcinoma laparoscopic transhiatal reconstruction via an open left diaphragm method.

BACKGROUND: Despite being oncologically acceptable for esophagogastric junction adenocarcinoma with an esophageal invasion length of 3-4 cm, the transhiatal approach has not yet become a standard method given the difficulty of reconstruction in a narrow space and the risk of severe anastomotic leakage. This study aimed to clarify the safety and feasibility of the open left diaphragm method during the transhiatal approach for esophagogastric junction adenocarcinoma. METHODS: This retrospective study compared the clinical outcomes of patients who underwent proximal or total gastrectomy with lower esophagectomy for Siewert type II/III adenocarcinomas with esophageal invasion via the laparoscopic transhiatal approach with or without the open left diaphragm method from April 2013 to December 2021. RESULTS: Overall, 42 and 13 patients did and did not undergo surgery with the open left diaphragm method, respectively. The median operative time was only slightly shorter in the open left diaphragm group than in the non-open left diaphragm group (369 vs. 482 min; P = 0.07). Grade ≥ II postoperative respiratory complications were significantly less common in the open left diaphragm group than in the non-open left diaphragm group (17% vs. 46%, P = 0.03). Neither group had grade ≥ IV anastomotic leakage, and two cases of anastomotic leakage requiring reoperation were drained using the left diaphragmatic release technique. CONCLUSIONS: Transhiatal lower esophagectomy with gastrectomy using the open left diaphragm method is safe, highlighting its advantages for Siewert type II/III esophagogastric junction adenocarcinoma with an esophageal invasion length of ≤ 4 cm.

The number of resected lymph nodes from the upper mediastinal area predicts long-term outcomes of esophageal squamous cell carcinoma after minimally invasive esophagectomy.

BACKGROUND: The total number of resected lymph nodes (LNs) is an important determinant of longer survival after esophagectomy for esophageal squamous cell carcinoma (ESCC). However, the resected LN counts from areas that affect long-term outcomes remain unclear. METHODS: This study included 406 patients who underwent minimally invasive esophagectomies (MIEs) at Kobe University Hospital. Resected LN counts were evaluated in the following areas: upper mediastinal (UM), middle mediastinal (MM), lower mediastinal (LM), and abdominal (Abd). Cut-off values for LN counts from each area were determined using receiver operating characteristics analysis of the survival status. Cox proportional hazards regression analyses were performed to identify prognostic factors. RESULTS: The cut-off values for large or small numbers of resected LN counts in the UM, MM, LM, and Abd areas were 4, 8, 5, and 18, respectively, in patients with upper and middle thoracic (Ut/Mt) ESCC and 7, 6, 5, and 24, respectively, in patients with lower thoracic (Lt) ESCC. Multivariate analysis in patients with Ut/Mt ESCC revealed that tumor invasion depth, LN metastasis, and the resected LN count from the UM area were independent risk factors for overall survival [hazard ratio (HR), 7.04; 95% confidence interval (CI) 4.47-11.1; HR, 4.01; 95% CI 1.96-8.21; HR, 2.18; 95% CI 1.24-3.82, respectively]. In patients with Lt ESCC, tumor invasion depth, LN metastasis, and pulmonary complications were independent risk factors for overall survival (HR, 4.23; 95% CI 2.14-8.35; HR, 3.83; 95% CI 1.75-8.38; HR, 2.80; 95% CI 1.38-5.65, respectively). Resected LN counts from no areas were prognostic factors. CONCLUSION: The number of resected LNs from the UM area influenced the survival outcomes of patients with Ut/Mt ESCC after MIE.

C16, a PKR inhibitor, suppresses cell proliferation by regulating the cell cycle via p21 in colorectal cancer.

Double-stranded RNA-activated protein kinase R (PKR) is highly expressed in colorectal cancer (CRC). However, the role of PKR in CRC remains unclear. The aim of this study was to clarify whether C16 (a PKR inhibitor) exhibits antitumor effects and to identify its target pathway in CRC. We evaluated the effects of C16 on CRC cell lines using the MTS assay. Enrichment analysis was performed to identify the target pathway of C16. The cell cycle was analyzed using flow cytometry. Finally, we used immunohistochemistry to examine human CRC specimens. C16 suppressed the proliferation of CRC cells. Gene Ontology (GO) analysis revealed that the cell cycle-related GO category was substantially enriched in CRC cells treated with C16. C16 treatment resulted in G1 arrest and increased p21 protein and mRNA expression. Moreover, p21 expression was associated with CRC development as observed using immunohistochemical analysis of human CRC tissues. C16 upregulates p21 expression in CRC cells to regulate cell cycle and suppress tumor growth. Thus, PKR inhibitors may serve as a new treatment option for patients with CRC.

A case of robot-assisted resection for cecum cancer with anomalous venous confluence.

There are many reports on the positional relationship between the ileocolic artery and superior mesenteric vein (SMV). However, there have been no reports of anomalous venous confluence in the ileocecal vessel area. A 69-year-old man was diagnosed with cecal cancer on a preoperative examination of a lung tumor. We planned to perform surgery for the cecal cancer. Computed tomography angiography revealed an anomalous vein confluence in the ileocolic region. We performed robot-assisted ileocecal resection. Although the small intestinal vein was misidentified as the SMV at first, we confirmed the misidentification, identified the SMV on the dorsal side of the ileocolic artery, and ligated the ileocolic vessels with precise forceps manipulation during robotic surgery. Especially for cases with vascular anomalies revealed by preoperative computed tomography angiography, robotic surgery may be useful, as flexible forceps manipulation prevents vascular injury.

Protocol for a phase II study to evaluate the efficacy and safety of nivolumab as a postoperative adjuvant therapy for patients with esophageal cancer treated with preoperative docetaxel, cisplatin plus 5-fluorouracil treatment (PENTAGON trial).

BACKGROUND: In Japan, preoperative adjuvant chemotherapy followed by surgical resection is the standard treatment for patients with locally advanced esophageal squamous cell carcinoma. However, the risk of recurrence after surgical resection remains high. Although a randomized controlled trial evaluating the efficacy of nivolumab, a fully human monoclonal anti-programmed death 1 antibody, as postoperative adjuvant therapy after neoadjuvant chemoradiotherapy and surgery established its superior efficacy as adjuvant therapy, the efficacy for patients who received preoperative adjuvant chemotherapy has not been demonstrated. This study aims to elucidate the efficacy and safety of nivolumab as postoperative adjuvant therapy for patients with esophageal squamous cell carcinoma after preoperative adjuvant chemotherapy with docetaxel and cisplatin plus 5-fluorouracil followed by surgical resection. METHODS: This study is a multi-institutional, single-arm, Phase II trial. We plan to recruit 130 esophageal squamous cell carcinoma patients, who have undergone preoperative adjuvant chemotherapy with docetaxel and cisplatin plus 5-fluorouracil followed by surgical resection. If the patient did not have a pathological complete response, nivolumab is started as a postoperative adjuvant therapy within 4-16 weeks after surgery. The nivolumab dose is 480 mg/day every four weeks. Nivolumab is administered for up to 12 months. The primary endpoint is disease-free survival; the secondary endpoints are overall survival, distant metastasis-free survival, and incidence of adverse events. DISCUSSION: To our knowledge this study is the first trial establishing the efficacy of nivolumab as postoperative adjuvant therapy for patients with esophageal squamous cell carcinoma after preoperative adjuvant chemotherapy with docetaxel and cisplatin plus 5-fluorouracil followed by surgical resection. In Japan, preoperative adjuvant chemotherapy followed by surgery is a well-established standard treatment for resectable, locally advanced esophageal squamous cell carcinoma. Therefore, developing an effective postoperative adjuvant therapy has been essential for improving oncological outcomes.

A case of MCA arising from ICA: a case report.

BACKGROUND: Complete mesocolic excision (CME) and central vascular detachment are very important procedures in surgery for colorectal cancer. Preoperative and intraoperative assessments of the anatomy of major colorectal vessels are necessary to avoid massive bleeding, especially in endoscopic surgery. A case with a rare anomaly in which the middle colic artery (MCA) and ileocolic artery (ICA) had a common trunk is reported. CASE PRESENTATION: The patient was a 73-year-old woman diagnosed with ascending colon cancer on colonoscopy. Preoperative abdominal contrast-enhanced computed tomography confirmed that the MCA and ICA had a common trunk. She underwent laparoscopic ileocecal resection for the ascending colon cancer with D3 lymph node dissection. Intraoperative indocyanine green fluorescence imaging was conducted. After confirming vessel bifurcation, the ICA was dissected at the distal end of the MCA bifurcation. The patient has been followed as an outpatient, with no signs of recurrence as of 2 years postoperatively. CONCLUSION: A case of an ascending colon cancer with a unique vascular bifurcation pattern was presented. Preoperative and intraoperative evaluations of the major colorectal vessels are very important for preventing perioperative and postoperative complications.

Significance of Preoperative Tooth Loss in Patients Who Underwent Gastrectomy for Gastric Cancer.

Background/Aim: The relationship between gastric cancer and oral health has been reported in several studies. This study aimed to determine the relationship between the postoperative prognosis of gastric cancer and oral health using preoperative tooth loss as a simple index. Patients and Methods: We conducted a single-center retrospective cohort study. Patients were divided into two groups according to the number of tooth losses. The survival curve was constructed using the Kaplan-Meier method. We also performed univariate and multivariate analyses of overall survival based on Cox proportional hazard regression to determine prognostic factors. Results: A total of 191 patients were divided into two groups: those with seven or more tooth losses and those with less than seven tooth losses. The three-year overall survival rate was 71.5% in the group with seven or more tooth losses and 87.0% in the group with less than seven tooth losses. The group with seven or more tooth losses had a significantly lower overall survival rate compared to the group with less than seven tooth losses (p=0.0014). However, in multivariate analysis, tooth loss was not identified as an independent prognostic factor whereas age, clinical T stage, CEA level, and serum albumin level were independent poor prognostic factors. Conclusion: Preoperative tooth loss was not a prognostic factor for gastric cancer after gastrectomy, but tooth loss may be a simple and useful method for evaluating frailty in patients.

Alb-dNLR Score as a Novel Prognostic Marker for Patients With Locally Advanced Rectal Cancer Undergoing Neoadjuvant Chemoradiotherapy.

BACKGROUND/AIM: The albumin and derived neutrophil-to-lymphocyte ratio (Alb-dNLR) score, which combines an inflammation index with a nutritional index, has recently been reported as a useful prognostic marker in various cancers. However, evaluation of the usefulness of Alb-dNLR score in patients with locally advanced rectal cancer (LARC) undergoing neoadjuvant chemoradiotherapy (NACRT) has not been reported yet. PATIENTS AND METHODS: This retrospective study included 69 patients with LARC undergoing NACRT followed by surgery between November 2005 and July 2020. The cutoff value of the Alb-dNLR score for relapse-free survival (RFS) was determined using a receiver operating characteristic curve. Patients were divided into high and low Alb-dNLR-score groups and analyzed for RFS and overall survival (OS). RESULTS: A total of 10 patients had high Alb-dNLR scores, and 59 had low Alb-dNLR scores. The high Alb-dNLR-score group had significantly higher rates of open surgery (70.0% vs. 28.8%; p<0.026), greater intraoperative blood loss (2,009 g vs. 421 g; p<0.001), and longer postoperative hospital stays (70 days vs. 42 days, p=0.012) than those of the low-Alb-dNLR-score group. The high Alb-dNLR-score group further demonstrated significantly worse RFS and OS than the low Alb-dNLR-score group (both p<0.001). Multivariate analysis identified the Alb-dNLR score as the most independent prognostic factor for RFS (hazard ratio=5.27; 95% confidence interval=2.09-13.27; p<0.001). CONCLUSION: The Alb-dNLR score is a valuable prognostic marker for predicting the oncological outcomes in patients with LARC undergoing NACRT.

Effectiveness of long-term tube feeding intervention in preventing skeletal muscle loss after minimally invasive esophagectomy.

PURPOSE: Esophageal cancer is a lethal tumor typically treated by neoadjuvant chemotherapy and surgery. For patients undergoing esophagectomy, postoperative enteral nutrition is important in preventing complications. Sarcopenia is associated with poor postoperative outcomes in esophageal cancer. In this study, we evaluated the benefits of tube feeding intervention and compared its short- and long-term outcomes in patients who underwent esophagectomy. METHODS: Propensity score matching was performed in 303 patients who underwent esophagectomy at Kobe University Hospital between 2010 and 2020. Patients were divided into feeding and nonfeeding jejunostomy tube groups (n = 70 each). The feeding jejunostomy tube group was further divided into long-term (≥ 60 days) and short-term (< 60 days) subgroups. The groups were then retrospectively compared regarding postoperative albumin levels, body weight, and psoas muscle area and volume. RESULTS: In the long-term feeding jejunostomy tube group, anastomotic leakage (p = 0.013) and left laryngeal nerve palsy (p = 0.004) occurred frequently. There were no significant between-group differences in postoperative albumin levels, body weight, or psoas muscle area. However, significant psoas muscle volume recovery was confirmed in the long-term jejunostomy tube group at 6 months postoperatively (p = 0.041). CONCLUSIONS: Tube feeding intervention after minimally invasive esophagectomy may attenuate skeletal muscle mass loss and help prevent sarcopenia.

Impact of Tumor Size on Survival Outcome in Esophageal Squamous Cell Carcinoma After Esophagectomy Following Neoadjuvant Chemotherapy.

BACKGROUND: Large tumor size is a prognostic factor in esophageal squamous cell carcinoma (ESCC). However, the effect of tumor size on outcomes following neoadjuvant chemotherapy (NAC) has not been evaluated. This study aimed to assess the influence of tumor size on prognosis of patients undergoing esophagectomy after NAC. PATIENTS AND METHODS: This study was made up of 272 patients who underwent esophagectomy after NAC at Kobe University Hospital. We evaluated the pathological tumor size and determined the cutoff level for tumor size using receiver operating characteristics analysis to the survival status. Cox proportional hazards regression analyses were performed to identify prognostic factors. RESULTS: The patients were categorized into two groups: patients with tumor sizes ≥ 36 mm and < 36 mm. Deep pathological tumor invasion and worse histological response to NAC were associated with tumor size ≥ 36 mm. In patients with pT0-1, pT2, and pT4 ESCC, no significant differences in overall survival (OS) rates were observed between the two groups. In patients with pT3, OS of the tumor size ≥ 36 mm group was significantly worse than that of the tumor size < 36 mm group (p < 0.0001). Multivariate analysis in pT3 patients revealed tumor size ≥ 36 mm was an independent risk factor for OS. The 5-year OS rate was 10% in patients with tumor size ≥ 36 mm pT3 ESCC with pathological lymph node metastasis (p < 0.0001). CONCLUSIONS: Tumor size ≥ 36 mm is an independent risk factor for poorer survival in pT3 patients. Furthermore, tumor size ≥ 36 mm with pathological lymph node metastasis in pT3 patients was associated with very poor survival.

Safety and Efficacy of Neoadjuvant Chemotherapy for Advanced Gastric Cancer in Elderly Patients.

BACKGROUND/AIM: Elderly patients with pathological stage II/III gastric cancer struggle to complete adjuvant chemotherapy. Neoadjuvant chemotherapy (NAC) for treating locally advanced gastric cancer (LAGC) has drawn attention; however, its indication for elderly patients who are vulnerable to chemotherapy is unclear. This study aimed to investigate the feasibility and efficacy of NAC for elderly patients with gastric cancer. PATIENTS AND METHODS: In this study, patients aged ≥75 years who underwent curative gastrectomy for LAGC or adenocarcinoma of the esophagogastric junction between April 2013 and November 2021 were included. Vulnerable patients, with poor Eastern Cooperative Oncology Group Performance Status (ECOG-PS) of 2-3 were also included. The patients were classified into NAC+ (n=20) and NAC - (n=45) groups. The clinicopathological data of the patients were retrospectively investigated. RESULTS: The NAC+ group showed a higher R0 resection rate than the NAC- group (100% vs. 89.1%, p=0.3) and pathological downstaging was achieved in 12 (60%) cases, including five (25%) pathological complete responses. The incidence of adverse events during postoperative chemotherapy was 35%, and the rate of postoperative complications greater than Clavien-Dindo Grade II was comparable between the two groups (35% vs. 46.7%, p=0.43). The NAC+ group showed a higher three-year overall survival rate (75% vs. 36%, p=0.015). CONCLUSION: NAC was feasible and effective for elderly patients including vulnerable patients with LAGC or adenocarcinoma of the esophagogastric junction. It can be considered as treatment option, with a high down staging rate and better survival.

The modified Glasgow prognostic score is a reliable predictor of oncological outcomes in patients with rectal cancer undergoing neoadjuvant chemoradiotherapy.

There has been no reliable marker for predicting oncological outcomes in patients with locally advanced rectal cancer (LARC) undergoing neoadjuvant chemoradiotherapy (NACRT). We retrospectively analyzed 73 patients with LARC who underwent curative surgery after NACRT. The modified Glasgow prognostic score (mGPS) was assessed after NACRT, and clinical outcomes were compared between the high (mGPS = 1 or 2; n = 23) and low (mGPS = 0; n = 50) groups. Body mass index was significantly higher in the low mGPS group. The 5-year disease-free survival (DFS) rate was significantly worse in the high mGPS group than that in the low mGPS group (36.7% vs. 76.6%, p = 0.002). Univariate and multivariate analyses of DFS revealed that mGPS was the most significant predictor (p < 0.001). mGPS appears to be a reliable predictor of oncological outcomes in patients with LARC undergoing NACRT.

Deep Learning-based Image Cytometry Using a Bit-pattern Kernel-filtering Algorithm to Avoid Multi-counted Cell Determination.

BACKGROUND/AIM: In pathology, the digitization of tissue slide images and the development of image analysis by deep learning have dramatically increased the amount of information obtainable from tissue slides. This advancement is anticipated to not only aid in pathological diagnosis, but also to enhance patient management. Deep learning-based image cytometry (DL-IC) is a technique that plays a pivotal role in this process, enabling cell identification and counting with precision. Accurate cell determination is essential when using this technique. Herein, we aimed to evaluate the performance of our DL-IC in cell identification. MATERIALS AND METHODS: Cu-Cyto, a DL-IC with a bit-pattern kernel-filtering algorithm designed to help avoid multi-counted cell determination, was developed and evaluated for performance using tumor tissue slide images with immunohistochemical staining (IHC). RESULTS: The performances of three versions of Cu-Cyto were evaluated according to their learning stages. In the early stage of learning, the F1 score for immunostained CD8+ T cells (0.343) was higher than the scores for non-immunostained cells [adenocarcinoma cells (0.040) and lymphocytes (0.002)]. As training and validation progressed, the F1 scores for all cells improved. In the latest stage of learning, the F1 scores for adenocarcinoma cells, lymphocytes, and CD8+ T cells were 0.589, 0.889, and 0.911, respectively. CONCLUSION: Cu-Cyto demonstrated good performance in cell determination. IHC can boost learning efficiencies in the early stages of learning. Its performance is expected to improve even further with continuous learning, and the DL-IC can contribute to the implementation of precision oncology.

Patients younger than 40 years with colorectal cancer have a similar prognosis to older patients.

PURPOSE: Colorectal cancer (CRC) is a leading cause of cancer-related deaths worldwide. In recent years, the proportion of patients diagnosed with CRC at younger ages has increased. The clinicopathological features and oncological outcomes in younger patients with CRC remain controversial. We aimed to analyze the clinicopathological features and oncological outcomes in younger patients with CRC. METHODS: We examined 980 patients who underwent surgery for primary colorectal adenocarcinoma between 2006 and 2020. Patients were divided into two cohorts: younger (< 40 years old) and older (≥ 40 years old). RESULTS: Of the 980 patients, 26 (2.7%) were under the age of 40 years. The younger group had more advanced disease (57.7% vs. 36.6%, p = 0.031) and more cases beyond the transverse colon (84.6% vs. 65.3%, p = 0.029) than the older group. Adjuvant chemotherapy was administered more frequently in the younger group (50% vs. 25.8%, p < 0.01). Relapse-free survival and overall survival were similar between the groups at all stages. Moreover, in stages II and III they were also comparable, regardless of the administration of adjuvant chemotherapy. CONCLUSIONS: Younger patients with CRC have a prognosis equivalent to that of older patients. Further studies are needed to establish the optimal treatment strategies for these patients.

Updating the Predictive Models for Mortality and Morbidity after Low Anterior Resection Based on the National Clinical Database.

INTRODUCTION: We previously developed risk models for mortality and morbidity after low anterior resection using a nationwide Japanese database. However, the milieu of low anterior resection in Japan has undergone drastic changes since then. This study aimed to construct risk models for 6 short-term postoperative outcomes after low anterior resection, i.e., in-hospital mortality, 30-day mortality, anastomotic leakage, surgical site infection except for anastomotic leakage, overall postoperative complication rate, and 30-day reoperation rate. METHODS: This study enrolled 120,912 patients registered with the National Clinical Database, who underwent low anterior resection between 2014 and 2019. Multiple logistic regression analyses were performed to generate predictive models of mortality and morbidity using preoperative information, including the TNM stage. RESULTS: We developed new risk prediction models for the overall postoperative complication and 30-day reoperation rates for low anterior resection, which were absent from the previous version. The concordance indices for each endpoint were 0.82 for in-hospital mortality, 0.79 for 30-day mortality, 0.64 for anastomotic leakage, 0.62 for surgical site infection besides anastomotic leakage, 0.63 for complications, and 0.62 for reoperation. The concordance indices of all four models included in the previous version showed improvement. CONCLUSION: This study successfully updated the risk calculators for predicting mortality and morbidity after low anterior resection using a model based on vast nationwide Japanese data.

Safety of Laparoscopic Gastrectomy for Advanced Gastric Cancer With Greater than Serosal Invasion Depth.

BACKGROUND/AIM: There are several concerns about oncological contamination and technical difficulty in the laparoscopic approach for locally advanced gastric cancer. We aimed to determine the safety and usefulness of laparoscopic gastrectomy for patients with advanced gastric cancer with tumor depth greater than serosal invasion. PATIENTS AND METHODS: Sixty-two laparoscopic and 82 laparotomy gastric cancer cases surgically diagnosed as serosal or other organ invasions intraoperatively between 2011 and 2021 were included. The laparoscopic and open gastrectomy results were compared by propensity score matching using stage, preoperative chemotherapy, curative resection, surgical technique, and age as explanatory variables and laparoscopy and open resection as outcome variables. RESULTS: No difference in median operative time (341 vs. 386 minutes, p=0.24) was observed, but median blood loss (0 vs. 510 ml, p<0.001) and blood transfusion requirement (9.5 vs. 43%, p<0.001) were lower in the laparoscopic group. No difference was observed between the two groups regarding complications. Furthermore, 3-year overall survival was also similar (43 vs. 42%, p=0.74). CONCLUSION: The laparoscopic surgery results are comparable to those of open surgery in treating gastric cancer with T4a or greater depth. In addition, it is minimally invasive with less blood loss, making it a standard approach.

Improvement Effect of Upper Mediastinal Lymphadenectomy During Minimally Invasive Esophagectomy on the Prognosis in Squamous Cell Carcinoma: Efficacy Index and Propensity Score Matching Analyses.

BACKGROUND: The effect of lymphadenectomy around the recurrent laryngeal nerve (RLN) in open esophagectomy has been demonstrated with the efficacy index (EI). However, it remains unclear whether this effect exists for minimally invasive esophagectomy (MIE) in the prone position. The purpose of this study was to clarify whether the upper mediastinal lymphadenectomy contributed to improved prognosis in patients with esophageal squamous cell carcinoma. STUDY DESIGN: This study included 339 patients with esophageal squamous cell carcinoma treated with MIE in the prone position at Kobe University or Hyogo Cancer Center, Japan, from 2010 to 2015. EIs for each station, correlations between metastatic lymph nodes around the left RLN and RLN palsy, and survival of patients with and without upper mediastinal lymphadenectomy were investigated. RESULTS: Among 297 patients treated with upper mediastinal lymphadenectomy, Clavien- Dindo grade ≥ II left RLN palsy occurred in 59 patients (20%). Overall, EIs for the right RLN (7.4) and left RLN (6.6) were higher than EIs for other stations. For patients with upper-third or middle-third tumors, the trend was stronger. Left RLN palsy was more likely in patients with metastatic lymph nodes around the left RLN than in those without (44% vs 15%, p < 0.0001). After propensity score-matching, 42 patients were included in each group with and without upper mediastinal lymphadenectomy. In survival analyses, the 5-year overall survival rates were 55% vs 35% and cause-specific survival rates were 61% vs 43% for the patients with and without upper mediastinal lymphadenectomy respectively. Significant differences were confirmed in survival curves (overall survival: p = 0.03; cause-specific survival: p = 0.04, respectively). CONCLUSIONS: Upper mediastinal lymphadenectomy contributes to improved prognosis with high EIs in MIE in the prone position.