To determine the safety of laparoscopy-assisted distal gastrectomy (LADG) compared with open distal gastrectomy (ODG) in patients with clinical stage I gastric cancer in Korea. There is still a lack of large-scale, multicenter randomized trials regarding the safety of LADG. A large-scale, phase 3, multicenter, prospective randomized controlled trial was conducted. The primary end point was 5-year overall survival. Morbidity within 30 postoperative days and surgical mortality were compared to evaluate the safety of LADG as a secondary end point : A total of 1416 patients were randomly assigned to the LADG group (n = 705) or the ODG group (n = 711) between February 1, 2006, and August 31, 2010, and 1384 patients were analyzed for modified intention-to-treat analysis (ITT) and 1256 were eligible for per protocol (PP) analysis (644 and 612, respectively). In the PP analysis, 6 patients (0.9%) needed open conversion in the LADG group. The overall complication rate was significantly lower in the LADG group (LADG vs ODG; 13.0% vs 19.9%, P = 0.001). In detail, the wound complication rate of the LADG group was significantly lower than that of the ODG group (3.1% vs 7.7%, P < 0.001). The major intra-abdominal complication (7.6% vs 10.3%, P = 0.095) and mortality rates (0.6% vs 0.3%, P = 0.687) were similar between the 2 groups. Modified ITT analysis showed similar results with PP analysis. LADG for patients with clinical stage I gastric cancer is safe and has a benefit of lower occurrence of wound complication compared with conventional ODG.

To compare short-term surgical outcomes including financial cost of robotic and laparoscopic gastrectomy. Despite a lack of supporting evidence, robotic surgery has been increasingly adopted as a minimally invasive modality for the treatment of gastric cancer because of its assumed technical superiority over conventional laparoscopy. A prospective, multicenter comparative study was conducted. Patients were matched according to the surgeon, extent of gastric resection, and sex. The primary endpoint was morbidity and mortality. Outcomes were analyzed on an intention-to-treat and per-protocol basis. A total of 434 patients were enrolled for treatment with either robotic (n = 223) or laparoscopic (n = 211) gastrectomy for intention-to-treat analysis, and a total of 370 patients (n = 185 per treatment) were compared in per-protocol analysis. Results were similar between both analyses. In per-protocol analysis, both groups showed similar overall complication rates (robotic = 11.9% vs laparoscopic = 10.3%) and major complication rates (robotic = 1.1% vs laparoscopic = 1.1%) with no operative mortality in either group. Patients treated with robotic surgery showed significantly longer operative time (robotic = 221 minutes vs laparoscopic = 178 minutes; P < 0.001) and significantly higher total costs (robotic = US$13,432 vs laparoscopic = US$8090; P < 0.001), compared with those who underwent laparoscopic gastrectomy. No significant differences between groups were noted in estimated blood loss, rates of open conversion, diet build-up, or length of hospital stay. The use of robotic systems is assumed to provide a technically superior operative environment for minimally invasive surgery. However, our analysis of perioperative surgical outcomes indicated that robotic gastrectomy is not superior to laparoscopic gastrectomy. Clinical trials identification: NCT01309256.

Although the tumor stroma in solid tumors like gastric cancer (GC) plays a crucial role in chemo-resistance, specific targets to inhibit the interaction between the stromal and cancer cells have not yet been utilized in clinical practice. The present study aims to determine whether cancer-associated fibroblasts (CAFs), a major component of the tumor stroma, confer chemotherapeutic resistance to GC cells, and to discover potential targets to improve chemo-response in GC. To identify CAF-specific proteins and signal transduction pathways affecting chemo-resistance in GC cells, secretome and transcriptome analyses were performed. We evaluated the inhibiting effect of CAF-specific protein in in vivo and in vitro models and investigated the expression of CAF-specific protein in human GC tissues. Secretome and transcriptome data revealed that interleukin-6 (IL-6) is a CAF-specific secretory protein that protects GC cells via paracrine signaling. Furthermore, CAF-induced activation of the Janus kinase 1-signal transducer and activator of transcription 3 signal transduction pathway confers chemo-resistance in GC cells. CAF-mediated inhibition of chemotherapy-induced apoptosis was abrogated by the anti-IL-6 receptor monoclonal antibody tocilizumab in various experimental models. Clinical data revealed that IL-6 was prominently expressed in the stromal portion of GC tissues, and IL-6 upregulation in GC tissues was correlated with poor responsiveness to chemotherapy. Our data provide plausible evidence for crosstalk between GC cells and CAFs, wherein IL-6 is a key contributor to chemoresistance. These findings suggest the potential therapeutic application of IL-6 inhibitors to enhance the responsiveness to chemotherapy in GC.

Purpose: Histologic features of diffuse-type gastric cancer indicate that the tumor microenvironment (TME) may substantially impact tumor invasiveness. However, cellular components and molecular features associated with cancer invasiveness in the TME of diffuse-type gastric cancers are poorly understood.Experimental Design: We performed single-cell RNA-sequencing (scRNA-seq) using tissue samples from superficial and deep invasive layers of cancerous and paired normal tissues freshly harvested from five patients with diffuse-type gastric cancer. The scRNA-seq results were validated by immunohistochemistry (IHC) and duplex in situ hybridization (ISH) in formalin-fixed paraffin-embedded tissues.Results: Seven major cell types were identified. Fibroblasts, endothelial cells, and myeloid cells were categorized as being enriched in the deep layers. Cell type–specific clustering further revealed that the superficial-to-deep layer transition is associated with enrichment in inflammatory endothelial cells and fibroblasts with upregulated CCL2 transcripts. IHC and duplex ISH revealed the distribution of the major cell types and CCL2-expressing endothelial cells and fibroblasts, indicating tumor invasion. Elevation of CCL2 levels along the superficial-to-deep layer axis revealed the immunosuppressive immune cell subtypes that may contribute to tumor cell aggressiveness in the deep invasive layers of diffuse-type gastric cancer. The analyses of public datasets revealed the high-level coexpression of stromal cell–specific genes and that CCL2 correlated with poor survival outcomes in patients with gastric cancer.Conclusions: This study reveals the spatial reprogramming of the TME that may underlie invasive tumor potential in diffuse-type gastric cancer. This TME profiling across tumor layers suggests new targets, such as CCL2, that can modify the TME to inhibit tumor progression in diffuse-type gastric cancer.See related commentary by Huang and Brekken, p. 6284

The second multicenter randomized clinical trial (RCT) of the Korean Laparoscopic Gastrointestinal Surgery Study Group (KLASS-02) was launched in response to oncologic concerns about the technical appropriateness of laparoscopic D2 lymphadenectomy for locally advanced gastric cancer (AGC).¹ An independent quality control study (KLASS-02-QC) was performed to qualify the participating surgeons before the RCT.^2,3 The KLASS-02 RCT concluded that laparoscopic distal gastrectomy performed by qualified surgeons was noninferior in oncologic outcomes to open surgery for locally AGCs.⁴ Because its primary end point was 3-year relapse-free survival (RFS), the length of the trial may have been insufficient to determine the relative long-term outcomes of laparoscopic surgery, as some recurrences are diagnosed more than 3 years after surgery. In addition, the event rate in the KLASS-02 RCT was lower than expected as a high proportion of pathologic early GCs showed low relapse rates. Therefore, patients enrolled in this trial should be followed up for longer than 3 years to determine the clinical efficacy and safety of laparoscopic surgery for locally AGCs.