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Background: While a neoadjuvant chemotherapy regimen using docetaxel, cisplatin, and 5-fluorouracil (NAC-DCF) is considered the standard treatment for locally advanced esophageal cancer (EC) in Japan, a reliable marker for early prediction of treatment efficacy remains unclear. We investigated the utility of the tumor response after a first course of NAC-DCF as a post-surgery survival predictor in patients with EC., Methods: We enrolled 150 consecutive patients who underwent NAC-DCF followed by surgery for EC between September 2009 and January 2019. The initial tumor reduction (ITR), defined as the percentage decrease in the shorter diameter of the tumor after the first course of NAC-DCF, was evaluated using computed tomography. We analyzed the relationship between ITR, clinicopathological parameters, and survival., Results: The median ITR was 21.07% (range -11.45 to 50.13%). The optimal cut-off value for ITR for predicting prognosis was 10% (hazard ratio [HR] 3.30, 95% confidence interval [CI] 1.98-5.51), based on univariate logistic regression analyses for recurrence-free survival (RFS). Compared with patients with ITR <10%, patients with ITR ≥10% showed a significantly higher proportion of ypM0 (80.0% vs. 92.5%) and responders in terms of overall clinical response (50.0% vs. 80.8%). Multivariate analysis for RFS revealed that ypN2-3 (HR 2.78, 95% CI 1.67-4.62), non-response in terms of overall clinical response (HR 1.87, 95% CI 1.10-3.18), and ITR <10% (HR 2.48, 95% CI 1.42-4.32) were independent prognostic factors., Conclusions: Tumor response after the first course of NAC-DCF may be a good predictor of survival in patients with EC who underwent NAC-DCF plus surgery., (© 2024. Society of Surgical Oncology.)

Most of esophageal squamous cell carcinoma (ESCC) develop in smoking males in Japan, but the genomic etiology and immunological characteristics of rare non-smoking female ECSS remain unclear. To elucidate the genomic and immunological features of ESCC in non-smoking females, we analyzed whole-genome or transcriptome sequencing data from 94 ESCCs, including 20 rare non-smoking female cases. In addition, 31,611 immune cells were extracted from four ESCC tissues and subject to single-cell RNA-seq. We compared their immuno-genomic and microbiome profiles between non-smoking female and smoking ESCCs. Non-smoking females showed much better prognosis. Whole-genome sequencing analysis showed no significant differences in driver genes or copy number alterations depending on smoking status. The mutational signatures specifically observed in non-smoking females ESCC could be attributed to aging. Immune profiling from RNA-seq revealed that ESCC in non-smoking females had high tumor microenvironment signatures and a high abundance of eosinophils with a favorable prognosis. Single-cell RNA-sequencing of intratumor immune cells revealed gender differences of eosinophils and their activation in female cases. ESCCs in non-smoking females have age-related mutational signatures and gender-specific tumor immune environment with eosinophils, which is likely to contribute to their favorable prognosis., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction: This study aimed to clarify the impact of the average relative dose intensity (RDI) of neoadjuvant chemotherapy with docetaxel, cisplatin, and 5-fluorouracil (DCF-NAC) for resectable locally advanced esophageal squamous cell carcinoma (ESCC)., Materials and Methods: To identify the optimal RDI, recurrence-free survival (RFS) and cumulative incidence function (CIF) for recurrence were calculated in low and high RDI groups with any cut-off points. The optimal RDI was defined as the highest RDI administered with a significant increase in either RFS or CIF. The clinicopathological characteristics of the two groups divided by optimal RDI were investigated. The preoperative prognostic factors associated with RFS were confirmed by multivariable Cox proportional hazards model., Results: Among the 150 eligible patients treated with DCF-NAC from 2010 to 2020, 3-year RFS and CIF were 56.3% and 37.8% in 90 patients in the less than 80% RDI group (<80% RDI) and 73.3% and 26.7% in 60 patients in the more than or equal to 80% RDI group (≥80% RDI), respectively. The optimal cut-off RDI was identified as 80%. The <80% RDI group included older individuals, a lower value of creatinine clearance, a higher Charlson Comorbidity Index, reduced RDI at first course, and grade 1-0 in the histopathological tumor response than the ≥80% RDI group. R0 resection and postoperative complication rates were equal in both groups. Cox proportional hazards model identified the response rate and RDI as predictors of RFS., Conclusion: An average RDI of more than or equal to 80% improved prognosis in patients receiving DCF-NAC for ESCC., (© 2023 The Author(s). Published by S. Karger AG, Basel.)

Background: Induction or adjuvant therapies are not always beneficial for thoracic esophageal squamous cell carcinoma (ESCC) patients, and it is thus important to identify patients at high risk for postoperative ESCC recurrence. We investigated the usefulness of the total metabolic tumor volume (TMTV) for predicting the postoperative recurrence of thoracic ESCC., Methods: We retrospectively analyzed the cases of 163 thoracic ESCC patients (135 men, 28 women; median age of 66 [range 34-82] years) treated at our hospital in 2007-2012. The TMTV was calculated from the fluorine-18 fluorodeoxyglucose ( 18 F-FDG) uptake in the primary lesion and lymph node metastases. The optimal cut-off values for relapse and non-relapse were obtained by the time-dependent receiver operating curve analyses. Relapse-free survival (RFS) was evaluated by the Kaplan-Meier method, and between-subgroup differences in survival were analyzed by log-rank test. The prognostic significance of metabolic parameters and clinicopathological variables was assessed by a Cox proportional hazard regression analysis. The difference in the failure patterns after surgical resection was evaluated using the χ 2 -test., Results: The optimal cut-off value of TMTV for discriminating relapse from non-relapse was 3.82. The patients with a TMTV ≥3.82 showed significantly worse prognoses than those with low values (p < 0.001). The TMTV was significantly related to RFS (model 1 for preoperative risk factors: TMTV: hazard ratio [HR] =2.574, p = 0.004; model 2 for preoperative and postoperative risk factors: HR = 1.989, p = 0.044). The combination of the TMTV and cN0-1 or pN0-1 stage significantly stratified the patients into low-and high-risk recurrence groups (TMTV cN0-1, p < 0.001; TMTV pN0-1, p = 0.004). The rates of hematogenous and regional lymph node metastasis were significantly higher in the patients with TMTV ≥3.82 than those with low values (hematogenous metastasis, p < 0.001, regional lymph node metastasis, p = 0.011)., Conclusions: The TMTV was a more significantly independent prognostic factor for RFS than any other PET parameter in patients with resectable thoracic ESCC. The TMTV may be useful for the identifying thoracic ESCC patients at high risk for postoperative recurrence and for deciding the patient management., (© 2022. The Author(s).)

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive cancers and is primarily treated with platinum-based neoadjuvant chemotherapy (NAC). Some ESCCs respond well to NAC. However, biomarkers to predict NAC sensitivity and their response mechanism in ESCC remain unclear. We perform whole-genome sequencing and RNA sequencing analysis of 141 ESCC biopsy specimens before NAC treatment to generate a machine-learning-based diagnostic model to predict NAC reactivity in ESCC and analyzed the association between immunogenomic features and NAC response. Neutrophil infiltration may play an important role in ESCC response to NAC. We also demonstrate that specific copy-number alterations and copy-number signatures in the ESCC genome are significantly associated with NAC response. The interactions between the tumor genome and immune features of ESCC are likely to be a good indicator of therapeutic capability and a therapeutic target for ESCC, and machine learning prediction for NAC response is useful., Competing Interests: Declaration of interests All authors declare no conflicts of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: This study was performed to verify the superiority of a new "non-tensioning method" for avoiding stricture of the cervical esophagogastric anastomosis by circular stapling compared with the conventional method., Methods: In total, 395 consecutive patients who underwent McKeown esophagectomy with gastric conduit (GC) reconstruction were reviewed. A 4 cm-wide GC was created and pulled up at the cervical site through the retrosternal route. The esophagogastrostomy site of the GC was planned as far caudally as possible on the greater curvature side. In the conventional technique, the stapler was fired while pulling the GC to avoid tissue slack. In the non-tensioning technique, the stapler was fired through the natural thickness of the stomach wall. The length of the blind end was changed from 4 to 2 cm in the non-tensioning technique. Anastomotic leakage and stricture formation were compared between the two techniques, and adjustment was performed using propensity score matching., Results: The conventional group comprised 315 patients, and the non-tensioning group comprised 80 patients. Anastomotic leakage occurred in 22 (7%) and 2 (2.5%) patients, respectively (P = 0.134) [and in 9 (2.9%) and 2 (2.5%) patients, respectively, if leakage at the blind end was excluded]. Anastomotic stricture occurred in 92 (29.2%) and 3 (3.8%) patients, respectively (P < 0.001). The propensity score-matching analysis including 79 pairs of patients confirmed a lower stricture rate in the non-tensioning than conventional group (2.5% vs. 29.1%, P < 0.001)., Conclusions: The non-tensioning technique significantly reduced the incidence of anastomotic stricture compared with the conventional technique., (© 2022. The Society for Surgery of the Alimentary Tract.)

Objectives: To elucidate the efficacy of adjuvant vaccine monotherapy using 3 Human Leukocyte Antigen (HLA)-A∗24-restricted tumor-specific peptide antigens for ESCC, upregulated lung cancer 10, cell division cycle associated 1, and KH domain-containing protein overexpressed in cancer 1., Summary of Background Data: ESCC patients with pathologically positive nodes (pN(+)) have a high risk for postoperative recurrence, despite curative resection after preoperative therapy. Subclinical micrometastases are an appropriate target for cancer vaccine., Methods: This is a non-randomized prospective phase II clinical trial (UMIN000003557). ESCC patients curatively resected after preoperative therapy with pN(+) were allocated into the control and vaccine groups (CG and VG) according to the HLA-A status. One mg each of three epitope peptides was postoperatively injected 10 times weekly followed by 10 times biweekly to the VG. The primary and secondary endpoints were relapse-free survival (RFS) and esophageal cancer-specific survival (ECSS), respectively., Results: Thirty were in the CG and 33 in the VG. No significant difference was observed in RFS between the CG and VG (5-year RFS: 32.5% vs 45.3%), but the recurrence rate significantly decreased with the number of peptides which induced antigen-specific cytotoxic T lymphocytes. The VG showed a significantly higher 5-year ECSS than the CG (60.0% vs 32.4%, P = 0.045) and this difference was more prominent in patients with CD8+ and programmed death-ligand 1 double negative tumor (68.0% vs 17.7%, P = 0.010)., Conclusions: Our cancer peptide vaccine might improve the survival of ESCC patients, which is warranted to be verified in the phase III randomized controlled study., Competing Interests: The authors report no conflicts of interest., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Introduction: We compare planned salvage surgery after definitive chemoradiotherapy (SALV) versus neoadjuvant chemoradiotherapy plus surgery (NCRS) for borderline resectable T4 esophageal squamous cell carcinoma., Patients and Methods: A total of 37 patients underwent planned SALV, and 20 underwent NCRS from 2004 to 2017. The short-term outcome measures were the R0 resection rate, complications, and treatment-related mortality. The long-term outcome measures were the 5-year overall survival rate and causes of death., Results: R0 resection rate was similar between the SALV and NCRS groups (81% versus 85%). The incidence of postoperative pneumonia (35% versus 18%) and treatment-related mortality rate (9% versus 0%) tended to be higher in the SALV. ypT grade 2-3 (65% versus 30%, p = 0.012) and Clavien-Dindo grade ≥ IIIb complications (32% versus 0%, p = 0.008) were significantly more frequent in the SALV group. The groups had similar 5-year overall survival (26% versus 27%). The causes of death in the SALV and NCRS groups were primary esophageal cancer in 35% and 55% of patients, respectively, and pulmonary-related mortality in 24% and 5%, respectively. Multivariable Cox regression analysis revealed the following significant poor prognostic factors: stable disease as the clinical response, preoperative body mass index (BMI) of < 18.5 kg/m 2 , ypN stage 1-3, and R1-2 resection., Conclusions: SALV was associated with a higher incidence of late pulmonary-related mortality but had a stronger antitumor effect than NCRS. Consequently, the survival rate was similar between the groups. Surgery is recommended for patients with a partial response and preoperative BMI of ≥ 18.5 kg/m 2 ., (© 2021. Society of Surgical Oncology.)

Background: A challenge in esophageal reconstruction after esophagectomy is that the distance from the neck to the abdomen must be replaced with a long segment obtained from the gastrointestinal tract. The success or failure of the reconstruction depends on the blood flow to the reconstructed organ and the tension on the anastomotic site, both of which depend on the reconstruction distance. There are three possible esophageal reconstruction routes: posterior mediastinal, retrosternal, and subcutaneous. However, there is still no consensus as to which route is the shortest., Methods: The length of each reconstruction route was retrospectively compared using measurements obtained during surgery, where the strategy was to pull up the gastric conduit through the shortest route. The proximal reference point was defined as the left inferior border of the cricoid cartilage and the distal reference point was defined as the superior border of the duodenum arising from the head of the pancreas., Results: This study involved 112 Japanese patients with esophageal cancer (102 men, 10 women). The mean distances of the posterior mediastinal, retrosternal, and subcutaneous routes were 34.7 ± 2.37 cm, 32.4 ± 2.24 cm, and 36.3 ± 2.27 cm, respectively. The retrosternal route was significantly shorter than the other two routes (both p < 0.0001) and shorter by 2.31 cm on average than the posterior mediastinal route. The retrosternal route was longer than the posterior mediastinal route in only 5 patients, with a difference of less than 1 cm., Conclusion: The retrosternal route was the shortest for esophageal reconstruction in living Japanese patients.

Purpose: The purpose of this study is to determine the clinical significance of micrometastases after neoadjuvant chemotherapy (NAC) and the difference in controlling micrometastases using different NAC regimens in resectable advanced esophageal squamous cell carcinoma (ESCC)., Methods: We analyzed patients with ESCC who underwent esophagectomy with lymph node dissection after NAC with Adriamycin + cisplatin + 5-fluorouracil (ACF) or docetaxel + cisplatin + 5-fluorouracil (DCF). Micrometastasis was defined as a single isolated cancer cell or cluster of cancer cells on the cervical, recurrent nerve, or abdominal LNs as shown by immunohistochemical staining with anti-cytokeratin antibody (AE1/AE3). The associations between micrometastases, recurrence, prognosis, and regimen differences were investigated., Results: One hundred and one cases (ACF group: 51 cases; DCF group: 50 cases) were analyzed. Micrometastases occurred in 24 patients (23.8%): 17/51 (33.3%) in the ACF group and 7/50 (13.5%) in the DCF group (p = 0.0403). The 5-year recurrence-free survival (RFS) rates for patients without (n = 77) and with (n = 24) micrometastases were 62 and 32%, respectively, (hazard ratio, 2.158; 95% confidence interval, 1.170-3.980; stratified log-rank test, p = 0.0115). A multivariate analysis showed that stage pN1 or higher and micrometastases were significant risk factors affecting RFS., Conclusion: In resectable advanced ESCC, controlling micrometastases in the LNs after NAC varied by regimen and may be associated with preventing ESCC recurrence.

Purpose: We retrospectively investigated the risk factors for mediastinal lymph node (MLN) metastasis in esophagogastric junction (EGJ) cancer with an epicenter within 2 cm above and below the anatomical cardia, including both adenocarcinoma (AC) and squamous cell carcinoma (SCC)., Methods: Fifty patients who underwent initial surgery for EGJ cancer from January 2002 to December 2013 were included in this study. We defined metastatic lymph nodes as pathological metastases in resected specimens and recurrence within 2 years postoperatively., Results: Thirty-four patients had AC and 16 had SCC; 24 patients underwent transhiatal resection and 26 underwent transthoracic resection. MLN metastasis was observed in 13 patients (26%) regardless of the histological type, 9 of whom had metastasis in the upper and middle mediastinum. Metastasis occurred when the esophageal invasion length (EIL) exceeded 20 mm. In addition, 10/13 patients had stage pN2-3 cancer. Multivariable analysis identified EIL ≥ 20 mm and stage pN2-3 as significant risk factors for MLN metastasis. The 5-year overall survival was 38% and 65% in the MLN-positive and -negative groups, respectively (p = 0.12). Multivariable Cox regression analysis showed that only stage pN2-3, and not the presence of MLN metastasis, was a significantly poor prognostic factor., Conclusion: MLN metastasis in EGJ cancer may have a close association with the EIL of the tumor, but the presence of MLN metastasis itself was not a poor prognostic factor. The significance and indications for MLN dissection should be clarified in prospective clinical trials.

Background: In Japan, pre-operative 5-FU and cisplatin(CDDP)(FP)combination therapy has been the standard neoadjuvant chemotherapy(NAC)for advanced resectable esophageal cancer(EC); furthermore, the efficacy of the docetaxel (DTX)-containing triplet regimen, FP plus DTX, has been reported. However, patients with impaired renal function should not receive high-dose CDDP. We have been developing a non-CDDP-containing triplet regimen, comprising 5-FU, DTX, and nedaplatin(NED)(UDON), on a phase Ⅰ/Ⅱtrial basis. This retrospective study aimed to investigate the safety and efficacy of NAC with UDON in advanced EC patients with impaired renal function., Methods: Five patients with advanced resectable EC with impaired renal function were enrolled in this study. Patients received NAC(5-FU, 640mg/m / 2, days 1-5; DTX, 28 mg/m2, days 1 and 15; and NED, 72mg/m2, day 1, q28, 2 courses); following this, they underwent esophagectomy. The primary endpoint was response rate, and the secondary endpoint was adverse event(AE)., Results: The median age was 79 years (range: 58-80 years). The ECOG performance status was 1/2 : 3/2. The main tumor locations were Ce/Ut/Mt : 1/1/3 and the cStages were ⅡA/ⅢA/ⅢC : 1/2/2. The RR(CR/PR/SD/PD : 0/4/1/0)was 80%. The pathological response was grade 1a/1b : 2/3. Major grade 3 or 4 AEs included neutropenia(40%), febrile neutropenia(20%), diarrhea(20%), and hyponatremia( 40%). There was no treatment-related death or reoperation., Conclusions: NAC with UDON might be feasible and effective in patients with advanced resectable EC with impaired renal function, who are ineligible for high-dose CDDP administration. We are planning a phaseⅡclinical study based on the present results.

A 71-year-old man with a history of hypertension, diabetes mellitus, and cerebral infarction was admitted to our hospital with dysphagia. Gastroduodenoscopy, thoracoabdominal CT, and PET-CT findings showed type 2 advanced esophageal cancer( squamous cell carcinoma)with upper mediastinal and cervical lymph node(LN)metastasis: cT3N2M1(LYM #104L), cStage Ⅳ. Two courses of neoadjuvant UDONchemotherapy containing 5-FU(640mg/m / 2, days 1-5), docetaxel(28mg/m2, days 1 and 15), and nedaplatin(72mg/m2, day 1)were administered every 4 weeks. UDONtherapy caused grade(Gr)3 febrile neutropenia, Gr 2 diarrhea, and Gr 1 thrombopenia; the tumor and LNs partially responded to the therapy. After 2 courses of UDONtherapy, esophagectomy with right thoracotomy, 3-field LNdissection, and reconstruction of the gastric tube were performed. The postoperative course was almost uneventful besides recurrent nerve palsy, aspiration, pneumonia, and delirium, and the patient was discharged 60 days after surgery. The pathological diagnosis was ypT0N0M0, ypStage 0, and the histological response of the primary tumor and LNs were evaluated as Gr 3. Neoadjuvant UDON therapy is feasible for elderly patients with advanced esophageal cancer and renal failure or comorbidities, for whom CDDP could not be administered. We are planning a clinical trial to assess the effectiveness of neoadjuvant UDONtherapy.

According to the Guidelines for Diagnosis and Treatment of Carcinoma of the Esophagus in Japan, the standard treatment of esophageal cancer with cStage II / III is preoperative chemotherapy and radical resection. But when the tumor has deep ulcer, the perforation of it is sometimes occurred due of the anti-tumor effect and we are forced to change the standard treatment. In this time, we report a case of emergency resection of esophageal cancer which is on the brink of perforation after neoadjuvant chemotherapy. A 62-year-old woman had locally advanced esophageal cancer(cT4N2M0)and performed neoadjuvant chemotherapy(NAC). After 2 courses of NAC, the patient got into critical condition that the esophageal cancer was on the brink of perforation, thus we immediately performed emergency resection of the tumor. Unfortunately, the tumor was not completely resected because of invasion to the Botallo ligament, but we were able to avoid a critical state such as mediastinitis or penetration to the aorta. In multimodality therapy for locally advanced tumor, immediate response to oncologic emergency is significantly required, impacting on the prognosis and quality of life.

The patient was a 58-year-old man suffering from dysphagia. He was diagnosed with T3 cervicalesophagealcancer that invaded the posterior hypopharyngealwal lwith lymph node metastasis. The patient received neoadjuvant chemoradiotherapy (30 Gy with CDDP/5-FU), followed by larynx-preserving surgery(LPS)for cervicalesophagealcancer. Two techniques for successfulLPS consist of the dissections of cricopharyngealmuscl e and the inferior pharyngealsphincter, and the complete division of the bilateral infrahyoid muscles attached to the sternum(CDBIMS). The former technique of releasing the esophagus from the trachea at the cricoid cartilage level results in the extension of the oral surgical margin. The latter technique is expected to prevent postoperative aspiration pneumonia, as the lack of flexibility of scarred infrahyoid muscles is regarded as one of the major causes of dysfunction in swallowing. Free jejunum was transferred for cervical reconstruction. Pathological examination indicated degenerated squamous cell carcinoma(ypT2, INF b, ly0, v0, PM0, ypN0, ypStage II A). Although the patient had recurrent nerve palsy, he could eat meals without aspiration. He returned to normal life after discharge from the hospital. Five years after surgery, no recurrence had been observed.

Prognosis of locally advanced esophageal cancer is poor. The greatest prognostic factor of locally advanced esophageal cancer is a local control. We experienced a case of T4 locally advanced thoracic esophageal cancer who was successfully resected without any combined resection after multimodality therapy. A male in 75-year-old. was diagnosed with type 3 locally advanced upper thoracic esophageal cancer whose metastatic right recurrent laryngeal lymph node invaded into the trachea. Definitive chemoradiation therapy(CRT)was performed, leading to a significant shrinkage of the main tumor, but T4 lesion remained. Next, adding DCF therapy(docetaxel, CDDP and 5-FU), a relief of T4 was finally obtained. Then, salvage surgery with subtotalesophagectomy and retrosternalesophagealreconstruction with gastric tube was performed, resulting in R0 resection without any combined resection. The postoperative course was uneventful, and the patient has been alive without recurrence for 1 year after surgery. In locally advanced cancer, focusing on T4 downstaging, it is significantly important in terms of safety, curativity and organ preservation to perform surgery after a sure sign of T4 relief by multimodality therapy.

Patients with esophageal cancer are often treated with definitive chemoradiotherapy (dCRT). Regardless of arrival at dCRT, the risk of local/regional recurrence during follow-up is significant. Many patient are faced with limited options for therapy once dCRT has failed. Salvage surgery is the only way for complete cure of patients with local/regional recurrent esophageal cancer after dCRT. However, salvage surgery has a significant high risk of fatal complications. We examine our preventive measures to reduce the incidence of postoperative complications after salvage surgery for thoracic esophageal cancer. The points of our preventive measures are them; I. the ingenuity of surgery, II. the securement of blood supply for the respiratory tract, III. standard lymphadenectomy, IV. countermeasures of anastomotic failure, V. countermeasures of dead space, VI. countermeasures of respiratory complications, VII. perioperative managements. Salvage surgery is a reasonable option to treat patients with local/regional recurrence after failed dCRT. Our preventive mesures are effective, therefore, we have to make the further technological developments and the safety of salvage surgery.

Chromosomal band 11q13 seems to be one of the most frequently amplified lesions in human cancer, including esophageal squamous cell cancer (ESCC). The oral cancer overexpressed 1 (ORAOV1) gene has been identified within this region, but its detailed biological function in human ESCC remains largely unclear. In our clinical samples of stage III ESCC, ORAOV1 amplification was observed in 49 of 94 cases (53%). ORAOV1 amplification was significantly associated with a poorly differentiated histology and tumors located in the upper or middle esophagus. Patients with ORAOV1 amplification tended to have a shorter survival period, although the difference was not significant. To investigate the function of ORAOV1, we created ORAOV1--overexpressed ESCC cell lines that exhibited increased cellular proliferation and colony formation, compared with in vitro controls. In vivo, ORAOV1-overexpressed cells exhibited a significantly increased tumorigenicity and a significantly larger tumor volume and poorer differentiation than controls. The peptide mass fingerprinting technique demonstrated that ORAOV1 bound to pyrroline-5-carboxylate reductase (PYCR), which is associated with proline metabolism and reactive oxygen species (ROS) production. Then, ORAOV1-overexpressed cell lines were resistant to stress treatment, which was cancelled by PYCR-knockdown. In addition, the ORAOV1-overexpressed cell line had a higher intracellular proline concentration and a lower ROS level. Our findings indicate that the ORAOV1 gene is frequently amplified in ESCC, enhances tumorigenicity and tumor growth, and is associated with a poorly differentiated tumor histology via proline metabolism and ROS production. ORAOV1 could be a novel target for the treatment of ESCC.

Molecular targeted therapy is expected to be a promising therapeutic approach for the treatment of esophageal squamous cell carcinoma (ESCC); however, the gene amplification status of molecular targeted genes in ESCC remains largely unclear. The gene amplification of EGFR, HER2, FGFR2 and MET was examined using a real-time PCR-based copy number assay of 245 ESCC surgical specimens of formalin-fixed, paraffin-embedded samples. Fluorescence in situ hybridization (FISH) and comparative genomic hybridization analyses verified the results of the copy number assay. EGFR mutation was detected using the Scorpions-ARMS method. The EGFR status and drug sensitivity to an EGFR tyrosine kinase inhibitor was then evaluated in vitro. Gene amplification of EGFR and HER2 was observed in 7% (16/244) and 11% (27/245) of the ESCC specimens. A multivariate analysis revealed that HER2 amplification was a significant predictor of a poor prognosis in patients with stage III post-operative ESCC. The L861Q type of EGFR mutation with hypersensitivity to EGFR tyrosine kinase inhibitor was found in one of the eight ESCC cell lines and one del745 type of EGFR mutation was identified in 107 clinical samples. In addition, we demonstrated for the first time that FGFR2 amplification was observed in 4% (8/196) of the ESCC specimens. MET amplification was observed in 1% (2/196). In conclusion, the frequent gene amplification of EGFR, HER2 and FGFR2 and the presence of active EGFR mutations were observed in ESCC specimens. Our results strongly encourage the development of molecular targeted therapy for ESCC.