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Within linear response theory, the absorptive part of optical conductivities are analytically calculated for distinct tilts in two-dimensional (2D) tilted semi-Dirac bands (TSDBs). The transverse optical conductivities always vanish $\mathrm{Re}\sigma_{xy}(\omega)=\mathrm{Re}\sigma_{yx}(\omega)=0$. The interband longitudinal optical conductivities (LOCs) in 2D TSDBs differ qualitatively in the power-law scaling of $\omega$ as $\mathrm{Re}\sigma_{xx}^{\mathrm{IB}}(\omega)\propto\sigma_0\sqrt{\omega}$ and $\mathrm{Re}\sigma_{yy}^{\mathrm{IB}}(\omega)\propto\sigma_0/\sqrt{\omega}$. By contrast, the intraband LOCs in 2D TSDBs depend on $\mu$ in the power-law scaling $\mathrm{Re}\sigma_{xx}^{\mathrm{D}}(\omega)\propto\sigma_0\mu \sqrt{\mu}$ and $\mathrm{Re}\sigma_{yy}^{\mathrm{D}}(\omega)\propto\sigma_0\mu/\sqrt{\mu}$. The power-law scaling is similar to that in 2D untilted SDBs but distincts from a uniform behavior independent of $\omega$ (or $\mu$) as $\mathrm{Re}\sigma_{xx/yy}^{\mathrm{IB}}(\omega)\propto\sigma_0$ (or $\mathrm{Re}\sigma_{xx/yy}^{\mathrm{D}}(\omega)\propto\sigma_0\mu$) in 2D tilted Dirac bands (TDBs). The universal power-law scaling further dictates significant differences in the angular dependence of LOCs, which can be used to characterize 2D TSDBs from 2D TDBs in the optical measurements. The tilt-dependent behaviors of LOCs can qualitatively tell 2D TSDBs from 2D untilted SDBs, but show similarities in the impact of band tilting between 2D TSDBs and 2D TDBs., Comment: 16 pages, 3 figures

We report a unified theory based on linear response, for analyzing the longitudinal optical conductivity (LOC) of materials with tilted Dirac cones. Depending on the tilt parameter $t$, the Dirac electrons have four phases, untilted, type-I, type-II, and type-III; the Dirac dispersion can be isotropic or anisotropic; the spatial dimension of the material can be one-, two-, or three-dimensions. The interband LOCs and intraband LOCs in $d$ dimension (with $d\ge2$) are found to scale as to $\sigma_{0}\omega^{d-2}$ and $\sigma_{0}|\mu|^{d-1}\delta(\omega)$, respectively, where $\omega$ is the frequency and $\mu$ the chemical potential. The interband LOCs always vanish in one dimension due to lacking of extra spatial dimension. The angular dependence of LOCs is found to characterize the band tilting, and the constant asymptotic background values of LOC reflect features of the Dirac bands. The LOCs in the anisotropic tilted Dirac cone can be connected to its isotropic counterpart by a ratio that consists of Fermi velocities. The findings are valid for a great many Dirac materials in the spatial dimensions of physical interests., Comment: 11 pages, 3 figures

Purpose: To evaluate whether the European Neuroendocrine Tumor Society (ENETS) system or the 8th American Joint Committee on Cancer (AJCC) staging manual are suitable for gastric neuroendocrine carcinomas and/or mixed adenoneuroendocrine carcinomas (G-NECs/MANECs). Methods: Patients in a multicentric series with G-NEC/MANEC who underwent curative-intent surgical resection for a primary tumor were included. An optimal staging system was proposed base on analysis of the T and N status and validated by the SEER database. Results: Compared with the ENETS system, the survival curves of the T category and N category in the 8th AJCC system were better separated and distributed in a more balanced way, but the survival curves of T2 vs. T3, N0 vs. N1, and N3a vs. N3b overlapped. For the T category, the 8th AJCC T category was modified by combining T2 and T3, which was consistent with the T category in the 6th AJCC manual for GC. For the N category, the optimal cut-off values of metastatic lymph nodes using X-tile were also similar to those of the N category in the 6th AJCC system. The Kaplan-Meier plots of the 6th AJCC system showed statistically significant differences between individual substages. Compared with the other 2 classifications, the 6th AJCC system also showed superior prognostic stratification. Similar results were obtained in both multicentric and SEER validation sets. Conclusions: Compared to the 8th AJCC and ENETS systems, the 6th AJCC staging system for GC is more suitable for G-NEC/MANEC and can be adopted in clinical practice.

Key Points Question Are there any differences in prognoses or recurrence patterns associated with gastric neuroendocrine carcinoma, mixed adenoneuroendocrine carcinoma, or adenocarcinoma? Findings This cohort study included 3689 patients with resectable gastric adenocarcinoma, gastric neuroendocrine carcinoma, or gastric mixed adenoneuroendocrine carcinoma. Propensity score matching analysis found that, compared with gastric adenocarcinoma, gastric neuroendocrine carcinoma and gastric mixed adenoneuroendocrine carcinoma were independent risk factors associated with worse disease-free survival, postrecurrence survival, and distant recurrence outcomes. Meaning These findings suggest that different follow-up and treatment strategies should be developed to improve the long-term survival of patients with gastric neuroendocrine carcinoma or gastric mixed adenoneuroendocrine carcinoma, especially for patients with tumors penetrating into the subserosa or deeper layers and with lymph node metastasis., This cohort study examines differences in long-term survival and patterns of recurrence among patients with gastric neuroendocrine carcinoma, gastric mixed adenoneuroendocrine carcinoma, and gastric adenocarcinoma., Importance Gastric neuroendocrine carcinoma and mixed adenoneuroendocrine carcinoma are rare pathological types of gastric cancer, and there is a lack of multicenter studies comparing the prognosis and recurrence patterns of gastric neuroendocrine carcinoma, gastric mixed adenoneuroendocrine carcinoma, and gastric adenocarcinoma. Objective To compare the differences in long-term survival and patterns of recurrence among gastric neuroendocrine carcinoma, gastric mixed adenoneuroendocrine carcinoma, and gastric adenocarcinoma. Design, Setting, and Participants This cohort study included patients with resectable gastric neuroendocrine carcinoma and gastric mixed adenoneuroendocrine carcinoma at 23 hospitals in China from January 2006 to December 2016. In addition, patients with gastric adenocarcinoma were selected as controls. Propensity score–matched analysis was used to match pathological stage among the different pathological types, and disease-free survival (DFS), postrecurrence survival (PRS), and patterns of recurrence were examined. Data analysis was conducted from July 15, 2020, to October 21, 2020. Exposures Curative resection for gastric neuroendocrine carcinoma, gastric mixed adenoneuroendocrine carcinoma, and gastric adenocarcinoma. Main Outcomes and Measures The main outcomes were DFS and patterns of recurrence. Results A total of 3689 patients were analyzed (median [interquartile range] age, 62 [55-69] years; 2748 [74.5%] men), including 503 patients (13.6%) with gastric neuroendocrine carcinoma, 401 patients (10.9%) with gastric mixed adenoneuroendocrine carcinoma, and 2785 patients (75.5%) with gastric adenocarcinoma. After propensity score matching, 5-year DFS was 47.6% (95% CI, 42.7%-52.5%) for patients with gastric neuroendocrine carcinoma, compared with 57.6% (95% CI, 55.1%-60.1%) with gastric adenocarcinoma (P

PrécisWe present a valid and reproducible nomogram that combined the TNM stage as well as the Ki-67 index and carcinoembryonic antigen levels; the nomogram may be an indispensable tool to help predict individualized risks of death and help clinicians manage patients with gastric neuroendocrine carcinoma.BackgroundTo analyze the long-term outcomes of patients with grade 3 GNEC who underwent curative surgery and investigated whether the combination of carcinoembryonic antigen (CEA) levels and Ki-67 index can predict the prognosis of patients with gastric neuroendocrine carcinoma (GNEC) and constructed a nomogram to predict patient survival.MethodsIn the training cohort, data were collected from 405 patients with GNEC after radical surgery at seven Chinese centers. A nomogram was constructed to predict long-term prognosis. Data for the validation cohort were collected from 305 patients.ResultsThe 5-year overall survival (OS) was worse in the high CEA group than in the normal CEA group (40.5% vs. 55.2%, p = 0.013). The 5-year OS was significantly worse in the high Ki-67 index group than in the low Ki-67 index group (47.9% vs. 57.2%, p = 0.012). Accordingly, we divided the whole cohort into a KC(-) group (low Ki-67 index and normal CEA) and KC(+) group (high Ki-67 index and/or high CEA). The KC(+) group had a worse prognosis than the KC(-) group (64.6% vs. 46.8%, p < 0.001). KC(+) and the AJCC 8th stage were independent factors for OS. Then, we combined KC status and the AJCC 8th stage to establish a nomogram; the C-index and area under the curve (AUC) were higher for the nomogram than for the AJCC 8th stage (C-index: 0.660 vs. 0.635, p = 0.005; AUC: 0.700 vs. 0.675, p = 0.020). The calibration curve verified that the nomogram had a good predictive value, with similar findings in the validation groups.ConclusionsThe nomogram based on KC status and the AJCC 8th stage predicted the prognosis of patients with GNEC well.

To establish a novel nomogram to predict individual 1, 3, and 5 years disease-free survival (DFS) of patients with gastric neuroendocrine carcinoma/mixed adenoneuroendocrine carcinoma [(MA)NEC]. Among patients undergoing radical resection of gastric (MA)NEC, there is still a high tendency for relapse. A retrospective analysis of 777 patients with gastric (MA)NEC at 23 centers in China from 2004 to 2015 was performed. Based on the established nomogram, which included age, ASA, pT, pN and Ki67, the overall patients were divided into low-risk group (LRG) and high-risk group (HRG). The median follow-up time was 40 months (1–169 months). The C-index, AUC and time-ROC of the nomogram were significantly higher than that of the 8th edition AJCC and ENETS TNM staging systems. The 3-year DFS of patients in HRG generated by the nomogram was significantly lower than that in LRG (all patients: 35% vs 66.9%, p

For patients with locally advanced proximal gastric cancer (LAPGC), the individualized selection of patients with highly suspected splenic hilar (No. 10) lymph node (LN) metastasis to undergo splenic hilar lymphadenectomy, is a clinical dilemma. This study aimed to re-evaluate the feasibility and safety of laparoscopic spleen-preserving splenic hilar lymphadenectomy (LSPSHL) and to identify the population who would benefit from it. A total of 1068 patients (D2 group = 409; D2 + No. 10 group = 659) who underwent laparoscopic total gastrectomy from four prospective trials between January 2015 and July 2019 were analyzed. No significant difference in the incidence (16.9% vs. 16.4%; P = 0.837) of postoperative complications were found between the two groups. The metastasis rate of No. 10 LN among patients in the D2 + No. 10 group was 10.3% (68/659). Based on the decision tree, patients with LAPGC with tumor invading the greater curvature (Gre), patients with non-Gre-invading LAPGC with a tumor size > 5 cm and clinical positive locoregional LNs were defined as the high-priority No. 10 dissection group. The metastasis rate of No. 10 LNs in the high-priority group was 19.4% (41/211). In high-priority group, the 3-year overall survival of the D2 + No. 10 group was better than that of the D2 group (74.4% vs. 42.1%; P = 0.005), and the therapeutic index of No. 10 was higher than the indices of most suprapancreatic stations. LSPSHL for LAPGC is safe and feasible when performed by experienced surgeons. LSPSHL could be recommended for the high-priority group patients even without invasion of the Gre.

Background and Objective: Few reports address the impact of surgery on the prognosis of rare and heterogeneous gastric neuroendocrine neoplasms (G-NENs). This study analyzed the influence of surgical treatments on prognosis to provide a personalized surgical treatment strategy for G-NEN patients. Methods: The clinicopathological data of 1126 G-NEN patients from 28 Chinese hospitals were analyzed. Cox regression analyses were used to analyze the prognostic factors affecting survival and recurrence, respectively. Results: Cox analysis revealed that in stage I-II but not stage III gastric neuroendocrine carcinoma/mixed adenoneuroendocrine carcinoma (NEC/MANEC) patients, Extended lymph node dissection (ELND) was an independent protective factor for OS and DFS (p 0.05). Furthermore, among patients with stage III disease, the incidence of complications after ELND was significantly greater than that after LLND (28.4% vs. 12.1%, p < 0.001), especially severe complications (Clavien-Dindo grade III-V). Conclusion: ELND may lead to enhanced long-term survival for stage I and II but not stage III NEC/MANEC patients. Our results in multicenter patients do not support the routine use of ELND in stage III NEC/MANEC patients. Funding Statement: This work was supported by National natural science foundation of China (No.81871899); Scientific and technological innovation joint capital projects of Fujian Province (2016Y9031, 2017Y9011); Construction Project of Fujian Province Minimally Invasive Medical Center (No. [2017]171); The second batch of special support funds for Fujian Province innovation and entrepreneurship talents (2016B013). China scholarship council (201908350095). National natural science foundation of China (No.81802312). Declaration of Interests: None of the authors have any competing interests in the manuscript. Ethics Approval Statement: The research proposal was reviewed by the Research Ethics Committee at the university, and all procedures were performed after obtaining written informed consent from the patients following an explanation of the surgical and oncological risks.

Background: Apatinib, a tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor 2 (VEGFR-2), is a novel treatment option for advanced gastric cancer (AGC) refractory to two or more lines of prior chemotherapy but has not yet been evaluated in patients with locally AGC. This trial investigated the efficacy and safety of apatinib combined with S-1 plus oxaliplatin (SOX) as a neoadjuvant treatment for locally AGC. Methods: Patients with M0 and either T2-T4 or N+ disease received apatinib (500 mg orally once daily on days 1-21 and discontinued in the last cycle) plus SOX (S-1, 40-60 mg orally twice daily on days 1-14; oxaliplatin, 130 mg/m2 intravenously on day 1) given every 3 weeks for 2-5 cycles. D2 gastrectomy was performed 2-4 weeks after the last cycle. To further compare the efficacy and safety between apatinib plus SOX (ASOX group) and SOX alone (SOX group), we reviewed historical control patients receiving SOX as neoadjuvant chemotherapy at the central center. The primary end point was the R0 resection rate. Findings: Between July 2017 and June 2019, 48 and 58 patients were enrolled in the ASOX and SOX groups, respectively. Forty patients in the ASOX group (83.3%) and 47 patients in the SOX group (81.0%) underwent surgery, with R0 resection rates of 75.0% and 67.2%, respectively (P=0.382). For patients proceeding surgery, the R0 resection rates were 90.0% (36/40) and 82.3% (39/47), respectively (P = 0.534). The proportion of patients with T downstaging in the ASOX group was significantly higher than that in the SOX group (36.4% vs 18.5%, P=0.036). For patients with target lesions, the radiological response rate was significantly higher in the ASOX group (75.0% vs 38.5%, P=0.015). Moreover, the ASOX group was associated with significantly higher proportions of patients achieving major pathological response (25.0% vs 10.3%, P=0.046). Grade 3 toxicities occurred in 33.3% of the ASOX patients, and no grade 4 toxicities or drug-related deaths were observed. Interpretation: Apatinib combined with SOX showed promising efficacy with an acceptable safety profile as the first-line neoadjuvant treatment for locally AGC. Trial Registration: The trial is registered with ClinicalTrials.gov, number NCT03192735. Funding Statement: This study was supported by Scientific and technological innovation joint capital projects of Fujian Province, China (No.2017Y9011, No.2017Y9004). Minimally invasive medical center of Fujian Province (No. [2017]171). National natural science foundation of China (No.81871899). The second batch of special support funds for Fujian Province innovation and entrepreneurship talents (No.2016B013). Declaration of Interests: There are no conflicts of interest or financial ties to disclose from any authors. Ethics Approval Statement: The informed consent form and study protocol were approved by the Institutional Review Boards of each participating institution. The study was conducted in accordance with the International Conference on Harmonization Good Clinical Practice guidelines, the Declaration of Helsinki, and Chinese law. All patients provided written informed consent before enrollment.

Previous retrospective studies have shown that laparoscopic spleen-preserving D2 total gastrectomy (LSTG) for advanced upper third gastric cancer (AUTGC) is safe. However, all previous studies were underpowered. We therefore conducted a prospective, multicenter study to evaluate the technical safety and feasibility of LSTG for patients with AUTGC. Patients diagnosed with AUTGC (cT2-4a, N−/+, M0) underwent LSTG at 19 institutions between September 2016 and October 2017 were included. The number of No. 10 lymph node (LN) dissections, metastasis rates, intraoperative and postoperative complications were investigated. A total of 251 patients were enrolled in the study, and 242 patients were eligible for the per protocol analysis. The average numbers of No. 10 LN dissections and metastases were 2.4 and 0.1, respectively. Eighteen patients (7.4%) had No. 10 LN metastases, and among patients with advanced gastric cancer, the rate of No. 10 LN metastasis was 8.1% (18/223). pN3 status was an independent risk factor for No. 10 LN metastasis. Intraoperative complications occurred in 7 patients, but no patients required conversion to open surgery or splenectomy. The overall postoperative complication rate was 13.6% (33/242). The major complication and mortality rates were 3.3% (8/242) and 0.4% (1/242), respectively. The number of retrieved No. 10 LNs, No. 10 LN metastasis and TNM stage had no significant influence on postoperative complication rates. LSTG for AUTGC was safe and effective when performed by very experienced surgeons, this technique could be used in patients who needed splenic hilar lymph node dissection.

Importance Apatinib is a novel treatment option for chemotherapy-refractory advanced gastric cancer (GC), but it has not been evaluated in patients with locally advanced GC. Objective To investigate the effectiveness and safety of apatinib combined with S-1 plus oxaliplatin (SOX) as a neoadjuvant treatment for locally advanced GC. Design, setting, and participants This multicenter, prospective, single-group, open-label, phase 2 nonrandomized controlled trial was conducted in 10 centers in southern China. Patients with M0 and either clinical T2 to T4 or N+ disease were enrolled between July 1, 2017, and June 30, 2019. Statistical analysis was performed from December 1, 2019, to January 31, 2020. Interventions Eligible patients received apatinib (500 mg orally once daily on days 1 to 21 and discontinued in the last cycle) plus SOX (S-1: 40-60 mg orally twice daily on days 1 to 14; oxaliplatin: 130 mg/m2 intravenously on day 1) every 3 weeks for 2 to 5 cycles. A D2 gastrectomy was performed 2 to 4 weeks after the last cycle. Main outcomes and measures The primary end point was R0 resection rate. Secondary end points were the response rate, toxic effects, and surgical outcome. Results A total of 48 patients (mean [SD] age, 63.2 [8.2] years; 37 men [77.1%]) were enrolled in this study. Forty patients underwent surgery (38 had gastrectomy, and 2 had exploratory laparotomy), with an R0 resection rate of 75.0% (95% CI, 60.4%-86.4%). The radiologic response rate was 75.0%, and T downstaging was observed in 16 of 44 patients (36.4%). The pathological response rate was 54.2% (95% CI, 39.2%-68.6%); moreover, this rate was significantly higher in patients who achieved a radiologic response compared with those who did not (12 [80.0%] vs 1 [20.0%]; P = .03) and in those who had an Eastern Cooperative Oncology Group Performance Status score of 0 (20 [76.9%] vs 10 [45.5%]; P = .03) or had tumors located in the upper one-third of the stomach (16 [61.5%] vs 7 [31.8%]; P = .04). Patients who achieved a pathological response (vs those who did not) had significantly less blood loss (median [range]: 60 [10-200] mL vs 80 [20-300] mL; P = .04) and significantly more lymph nodes harvested (median [range]: 40 [24-67] vs 32 [19-51]; P = .04) during surgery. Postoperative complications were observed in 7 of 38 patients (18.4%). Grade 3 toxic effects occurred in 16 of 48 patients (33.3%), and no grade 4 toxic effects or preoperative deaths were observed. Conclusions and relevance This nonrandomized controlled trial found that apatinib combined with SOX was effective and had an acceptable safety profile as a neoadjuvant treatment for locally advanced GC. A large-scale randomized clinical trial may be needed to confirm the findings. Trial registration ClinicalTrials.gov Identifier: NCT03192735.