MicroRNAs act as tumor suppressors or oncogenes. The pathological roles of miRNAs in gastric tumorigenesis are largely unknown. Although miR-10b was identified as an miRNA deregulator expressed in gastric cancer (GC), there also exists some debate on whether miR-10b is acting as tumor suppressor or oncogene in GC.Quantitative RT-PCR was employed to investigate the level of miR-10b in GC tissues and matched adjacent normal tissues (n = 100). In vitro cell proliferation, apoptosis assays, cell migration, and invasion assays were performed to elucidate the biological effects of miR-10b. Because silencing of miRNA by promoter CpG island methylation may be an important mechanism in tumorigenesis, GC cells were treated with 5-aza-2′-deoxycytidine and trichostatin A, and expression changes of miR-10b were subsequently examined by quantitative RT-PCR. Furthermore, the methylation status of the CpG island upstream of miR-10b was analyzed by methylation-specific PCR in GC tissues (n = 29).We showed here that miR-10b was significantly downregulated in GC cell lines and tissues as demonstrated by quantitative real-time PCR. Overexpression of miR-10b in MGC-803 and HGC-27 dramatically suppressed cell proliferation, migration, invasion, and induced apoptosis. Moreover, we demonstrated that T-cell lymphoma invasion and metastasis (Tiam1) was a target of miR-10b. Furthermore, 5-aza-2′-deoxycytidine and trichostain A increased miR-10b expression, and the methylation level was high in the CpG islands upstream of miR-10b gene.Taken together, these findings suggest that miR-10b may function as a novel tumor suppressor and is partially silenced by DNA hypermethylation in GC.
The current AJCC staging system for gastric cancer (AJCC7) incorporated several major revisions to the previous edition. The T and N categories and the stage groups were newly defined, and adenocarcinoma of the esophagogastric junction (EGJ) was reclassified and staged according to the esophageal system. Studies to validate these changes showed inconsistent results. The International Gastric Cancer Association (IGCA) launched a project to support evidence-based revisions to the next edition of the AJCC staging system.Clinical and pathological data on patients who underwent curative gastrectomy at 59 institutions in 15 countries between 2000 and 2004 were retrospectively collected. Patients lost to follow-up within 5 years of surgery were excluded. Patients treated with neoadjuvant therapy were excluded. The data were analyzed in total, and separately by region of treatment.Of 25,411 eligible cases, 84.8 % were submitted from 24 institutions of Japan and Korea, 6.4 % from other Asian countries, and 8.8 % from 29 Western institutions. The T and N categories of AJCC7 clearly stratified the patient survival. Patients with pN3a and pN3b showed distinct prognosis in all regions, and by introducing pN3a and pN3b into a cluster analysis, we established a new stage grouping with better stratification than AJCC7, especially among stage III subgroups. Survival of Siewert type 2 and 3 EGJ tumors was better stratified by this IGCA stage grouping than by either esophageal or gastric scheme of AJCC7.For the next revision of AJCC classification, we propose a new stage grouping based on a large, worldwide data collection.
The Japanese Gastric Cancer Association (JGCA) started a new nationwide gastric cancer registration in 2008.From 208 participating hospitals, 53 items including surgical procedures, pathological diagnosis, and survival outcomes of 13,626 patients with primary gastric cancer treated in 2002 were collected retrospectively. Data were entered into the JGCA database according to the JGCA classification (13th edition) and UICC TNM classification (5th edition) using an electronic data collecting system. Finally, data of 13,002 patients who underwent laparotomy were analyzed.The 5-year follow-up rate was 83.3 %. The direct death rate was 0.48 %. UICC 5-year survival rates (5YEARSs)/JGCA 5YEARSs were 92.2 %/92.3 % for stage IA, 85.3 %/84.7 % for stage IB, 72.1 %/70.0 % for stage II, 52.8 %/46.8 % for stage IIIA, 31.0 %/28.8 % for stage IIIB, and 14.9 %/15.3 % for stage IV, respectively. The proportion of patients more than 80 years old was 7.8 %, and their 5YEARS was 51.6 %. Postoperative outcome of the patients with primary gastric carcinoma in Japan have apparently improved in advanced cases and among the aged population when compared with the archival data. Further efforts to improve the follow-up rate are needed.Postoperative outcome of the patients with primary gastric carcinoma in Japan have apparently improved in advanced cases and among the aged population when compared with the archival data. Further efforts to improve the follow-up rate are needed.
In the AVAGAST study, fluoropyrimidine and cisplatin plus bevacizumab did not significantly improve overall survival (OS) versus fluoropyrimidine and cisplatin plus placebo in patients with advanced gastric cancer. Geographic differences in efficacy were observed in AVAGAST, but the study only included 12 Chinese patients. AVATAR, a study similar in design to AVAGAST, was a randomized, double-blind, phase III study conducted in Chinese patients with advanced gastric cancer.Patients more than 18 years of age with gastric adenocarcinoma were randomized 1:1 to capecitabine–cisplatin plus either bevacizumab or placebo. The primary endpoint was OS; secondary endpoints included progression-free survival (PFS) and safety.In total, 202 patients were included (placebo n = 102; bevacizumab n = 100). Baseline characteristics were well balanced. The primary analysis result did not show a difference in OS for the bevacizumab arm compared to the placebo arm [hazard ratio, 1.11 (95 % CI, 0.79–1.56); P = 0.5567]. Median PFS was also similar in both arms. Bevacizumab plus capecitabine–cisplatin was well tolerated. Grade 3–5 adverse events (AEs) occurred in 60 % of bevacizumab-treated and 68 % of placebo-treated patients, respectively. Grade 3–5 AEs of special interest with bevacizumab occurred in 8 % of bevacizumab-treated patients and 15 % of placebo-treated patients, mainly grade 3–5 hemorrhage (bevacizumab 4 %, placebo 12 %).Addition of bevacizumab to capecitabine–cisplatin in Chinese patients with advanced gastric cancer did not improve outcomes in AVATAR. There was no difference in OS between the two arms and PFS was similar in both arms. Safety findings were as previously experienced with bevacizumab, including AVAGAST; no new safety signals were reported.
In the Trastuzumab for GAstric cancer (ToGA) study, trastuzumab plus chemotherapy improved median overall survival by 2.7 months in patients with human epidermal growth factor receptor 2 (HER2)-positive [immunohistochemistry (IHC) 3+/fluorescence in situ hybridization-positive] gastric/gastroesophageal junction cancer compared with chemotherapy alone (hazard ratio 0.74). Post hoc exploratory analyses in patients expressing higher HER2 levels (IHC 2+/fluorescence in situ hybridization-positive or IHC 3+) demonstrated a 4.2-month improvement in median overall survival with trastuzumab (hazard ratio 0.65). The ToGA study provides the largest screening dataset available on HER2 overexpression/amplification in this indication. We further analyzed correlation(s) of HER2 overexpression/amplification with clinical and epidemiological factors.HER2-positivity was analyzed by histological subtype, tumor location, geographic region, and specimen type. Exploratory efficacy analyses were performed.The HER2-positivity rate was 22.1 % across analyzed tumor samples. Rates were similar between European and Asian patients (23.6 % vs. 23.9 %), but higher in intestinal- vs. diffuse-type (31.8 % vs. 6.1 %), and gastroesophageal junction cancer versus gastric tumors (32.2 % vs. 21.4 %). Across all IHC scores, variability in HER2 staining (≤30 % stained cells) was observed in almost 50 % of cases, with increasing rates in lower IHC categories, and did not affect treatment outcome. The polysomy rate was 4 %.HER2 expression varies by tumor location and type. All patients with advanced gastric or gastroesophageal junction cancer should be tested for HER2 status, preferably using IHC initially. Due to the unique characteristics of gastric cancer, specific testing/scoring guidelines should be adhered to.
There are few data on the clinical implications of immunosuppressive protein expression in tumors and immune cell infiltration within the tumor microenvironment in patients with gastric cancer (GC).In this study, 243 patients with curatively resected GC were included. The levels of immunosuppressive protein expression [programmed cell death 1 ligand 1 (PD-L1), cytotoxic T-lymphocyte antigen 4 (CTLA-4), and indoleamine 2,3-dioxygenase (IDO)] in tumors and the densities of immune cells [CD3(+), CD4(+), CD8(+), or PD-1(+) cells] within the tumor microenvironment were measured using immunohistochemical analysis.Positive PD-L1, CTLA-4, and IDO expression was observed in 43.6, 65.8, and 47.7 % of the patients, respectively. Expression of PD-L1, CTLA-4, and IDO was related to less advanced stage, intestinal type, and well/moderately differentiated adenocarcinoma (P < 0.05). PD-L1 expression was related to better disease-free survival (DFS) and overall survival (OS) in GC [PD-L1(+) vs. PD-L1(−) tumors: 5-year DFS rate, 82.6 vs. 66.9 %; 5-year OS rate, 83.0 vs. 69.1 % (P values <0.05)]. Survival outcomes were also better in patients with a higher density of CD3(+) cells within the tumor microenvironment than in those with a lower density of CD3(+) cells [5-year DFS rate, 80.9 vs. 67.0 %; 5-year OS rate, 82.5 vs. 68.0 % (P values <0.05)]. In multivariate analysis, these two immune markers had a prognostic impact on survival, independent of other clinical variables.GC patients with immunosuppressive protein expression (PD-L1, CTLA-4, or IDO) had distinct clinicopathological characteristics. PD-L1(+) expression and a high-CD3 tumor microenvironment are favorable prognostic markers in GC.
No confirmatory randomized controlled trials (RCTs) have evaluated the efficacy of laparoscopy-assisted distal gastrectomy (LADG) compared with open distal gastrectomy (ODG). We performed an RCT to confirm that LADG is not inferior to ODG in efficacy.We conducted a multi-institutional RCT. Eligibility criteria included histologically proven gastric adenocarcinoma in the middle or lower third of the stomach, clinical stage I tumor. Patients were preoperatively randomized to ODG or LADG. This study is now in the follow-up stage. The primary endpoint is relapse-free survival (RFS) and the primary analysis is planned in 2018. Here, we compared the surgical outcomes of the two groups. This trial was registered at the UMIN Clinical Trials Registry as UMIN000003319.Between March 2010 and November 2013, 921 patients (LADG 462, ODG 459) were enrolled from 33 institutions. Operative time was longer in LADG than in ODG (median 278 vs. 194 min, p < 0.001), while blood loss was smaller (median 38 vs. 115 ml, p < 0.001). There was no difference in the overall proportion with in-hospital grade 3–4 surgical complications (3.3 %: LADG, 3.7 %: ODG). The proportion of patients with elevated serum AST/ALT was higher in LADG than in ODG (16.4 vs. 5.3 %, p < 0.001). There was no operation-related death in either arm.This trial confirmed that LADG was as safe as ODG in terms of adverse events and short-term clinical outcomes. LADG may be an alternative procedure in clinical IA/IB gastric cancer if the noninferiority of LADG in terms of RFS is confirmed.
The aim of this review was to evaluate the clinical significance of serum tumor markers, particularly CEA, CA19-9, and CA72-4, in patients with gastric cancer. A systematic literature search was performed using PubMed/MEDLINE with the keywords “gastric cancer” and “tumor marker,” to select 4,925 relevant reports published before the end of November 2012. A total of 187 publications contained data for CEA and CA19-9, and 19 publications contained data related to all three tumor markers. The positive rates were 21.1 % for CEA, 27.8 % for CA19-9, and 30.0 % for CA72-4. These three markers were significantly associated with tumor stage and patient survival. Serum markers are not useful for early cancer, but they are useful for detecting recurrence and distant metastasis, predicting patient survival, and monitoring after surgery. Tumor marker monitoring may be useful for patients after surgery because the positive conversion of tumor markers usually occurs 2–3 months before imaging abnormalities. Among other tumor markers, alpha-fetoprotein (AFP) is useful for detecting and predicting liver metastases. Moreover, CA125 and sialyl Tn antigens (STN) are useful for detecting peritoneal metastases. Although no prospective trial has yet been completed to evaluate the clinical significance of these serum markers, this literature survey suggests that combinations of CEA, CA19-9, and CA72-4 are the most effective ways for staging before surgery or chemotherapy. In particular, monitoring tumor markers that were elevated before surgery or chemotherapy could be useful for detection of recurrence or evaluation of the response.
Image recognition using artificial intelligence with deep learning through convolutional neural networks (CNNs) has dramatically improved and been increasingly applied to medical fields for diagnostic imaging. We developed a CNN that can automatically detect gastric cancer in endoscopic images.A CNN-based diagnostic system was constructed based on Single Shot MultiBox Detector architecture and trained using 13,584 endoscopic images of gastric cancer. To evaluate the diagnostic accuracy, an independent test set of 2296 stomach images collected from 69 consecutive patients with 77 gastric cancer lesions was applied to the constructed CNN.The CNN required 47 s to analyze 2296 test images. The CNN correctly diagnosed 71 of 77 gastric cancer lesions with an overall sensitivity of 92.2%, and 161 non-cancerous lesions were detected as gastric cancer, resulting in a positive predictive value of 30.6%. Seventy of the 71 lesions (98.6%) with a diameter of 6 mm or more as well as all invasive cancers were correctly detected. All missed lesions were superficially depressed and differentiated-type intramucosal cancers that were difficult to distinguish from gastritis even for experienced endoscopists. Nearly half of the false-positive lesions were gastritis with changes in color tone or an irregular mucosal surface.The constructed CNN system for detecting gastric cancer could process numerous stored endoscopic images in a very short time with a clinically relevant diagnostic ability. It may be well applicable to daily clinical practice to reduce the burden of endoscopists.
Antibodies against programmed death 1 (PD-1) and its ligand programmed death ligand 1 (PD-L1) have recently demonstrated promising results in gastric cancer (GC). PD-L1 expression, the presence of tumor-infiltrating lymphocytes (TILs), and mismatch repair (MMR) deficiency have been proposed as predictive biomarkers for anti-PD-1/PD-L1 antibodies. The aim of this study was to investigate the clinical relevance of PD-L1 expression with TIL, MMR, and Epstein–Barr virus (EBV) status in GC.We performed a tissue microarray analysis in 487 advanced GC patients who underwent gastrectomy. PD-L1 expression on tumor cells (TCs) and tumor-infiltrating immune cells (TIICs), the densities of TILs, and MMR status were evaluated by immunohistochemistry. EBV was detected by in situ hybridization.PD-L1 expression on TCs and TIICs, MMR deficiency, and EBV positivity were identified in 22.8, 61.4, 5.1, and 5.1 % cases respectively. PD-L1 expression was more frequently observed in the elderly (TCs P = 0.002), in males (TCs P = 0.029; TIICs P = 0.043), in patients with poorly differentiated adenocarcinoma with solid-type histological features (TCs P < 0.001; TIICs P < 0.001), in patients with MMR deficiency (TCs P < 0.001; TIICs P < 0.001), and in patients with EBV positivity (TCs P = 0.001; TIICs P = 0.050). Strong association was observed between PD-L1 expression and high densities of CD3-positive, CD8-positive, or forkhead box P3 positive TILs (TCs P < 0.001; TIICs P < 0.001). Neither PD-L1 expression on TCs nor that on TIICs was an independent prognostic factor in multivariate analysis.In GC, PD-L1 expression was associated with distinct clinicopathological features, including high densities of TILs, MMR deficiency, and EBV positivity, but was not a prognostic factor.
The neutrophil-lymphocyte ratio (NLR) reflects inflammatory status. An elevated NLR has been reported to be a prognostic indicator in some malignant tumors. The aim of this study was to evaluate the clinical significance of the preoperative NLR in patients with primary gastric cancer.A total of 709 men and 319 women, with a mean age of 64.4 years, who underwent gastrectomy were included. The numbers of patients in each pathological stage were as follows: stage I, 584; stage II, 132; stage III, 153; and stage IV, 159. The mean NLR was 2.62 ± 1.68. A total of 127 patients (12.4%) with an NLR of 4.0 or more were classified as high NLR individuals in this study. The prognostic significance of a high NLR, together with various clinicopathological factors, was evaluated by multivariate analysis.The 5-year survival of patients with a high NLR was significantly worse than that of patients with a low NLR (57% vs 82%, P < 0.001). Univariate and multivariate analyses of clinicopathological factors affecting survival revealed that high NLR, depth of tumor, positive lymph nodes, distant metastasis, peritoneal metastasis, poorly differentiated type, and high platelet count were significant risk factors for reduced survival. On multivariate analysis, after adjusting for tumor stage, a high NLR was an independent risk factor for reduced survival (P = 0.003; adjusted hazard ratio, 1.845; 95% confidence interval, 1.236–2.747).A high preoperative NLR may be a convenient biomarker to identify patients with a poor prognosis after resection for primary gastric cancer.
Human epidermal growth factor receptor 2 (HER2) is involved in the pathogenesis and poor outcomes of several types of cancer, including advanced gastric and gastroesophageal junction cancer. Molecular-targeted drugs, such as trastuzumab, which prolong overall survival and progression-free survival in HER2-positive breast cancer, may also be beneficial in patients with HER2-positive gastric cancer. Several studies have examined this possibility, such as the Trastuzumab for Gastric Cancer trial. In this context, the first part of this review provides an update on our knowledge of HER2 in breast and gastric cancer, including the detection and prognostic relevance of HER2 in gastric cancer. The second part of the review discusses the results of pivotal clinical trials that examined the potential for using trastuzumab to treat this disease. This section also summarizes the trials that have been conducted or that are underway to determine the optimal uses of trastuzumab in gastric cancer, including its use as monotherapy and continuation beyond disease progression. The final section discusses the future prospects of other anti-HER2 drugs, including lapatinib, trastuzumab emtansine, and pertuzumab, for the treatment of HER2-positive gastric cancer. The introduction of trastuzumab led to the establishment of a new disease entity, “HER2-positive gastric cancer,” similar to HER2-positive breast cancer. It is expected that more anti-HER2 drugs will be developed and introduced into clinical practice to treat HER2-positive cancers, including gastric cancer.
Programmed cell death protein 1 (PD-1) and its ligand PD-L1 downregulate T cell activation and are related to immune tolerance. The aim of this study was to clarify the significance of PD-1 and PD-L1 expression and to analyze the relationships among PD-1, PD-L1, and Foxp3 expression in gastric cancer.A total of 105 patients who underwent curative gastrectomy for stage II/III gastric cancer were included in this study. PD-1, PD-L1, and Foxp3 expression were examined by immunohistochemistry and related to prognostic factors by univariate and multivariate analyses.PD-1 expression was correlated with both PD-L1 and Foxp3 expression. Disease-free survival (DFS) was significantly poorer in PD-1-positive patients than in PD-1-negative patients (3-year DFS, 36.1 % vs. 64.7 %, respectively; p < 0.05). Overall survival also tended to be poorer in PD-L1-positive patients than in PD-L1-negative patients. Univariate analysis identified sex, T factor, lymphatic invasion, and PD-1 positivity as significant predictors of poor DFS. Multivariate analysis confirmed male sex, lymphatic invasion, and positive PD-1 expression as independent prognostic indicators.PD-1 expression is associated with a poor prognosis and is correlated with PD-L1 and Foxp3 expression in patients with gastric cancer.
Endoscopic resection (ER) has been accepted as minimally invasive treatment in patients with early gastric cancer (EGC) who have a negligible risk of lymph node metastasis. It has already been determined which lesions in differentiated-type EGC present a negligible risk of lymph node metastasis, and ER is being performed for these lesions. In contrast, no consensus has been reached on which lesions in undifferentiated-type (UD-type) EGC present a negligible risk for lymph node metastasis, nor have indications for ER for UD-type EGC been established. We investigated 3843 patients who had undergone gastrectomy with lymph node dissection for solitary UD-type EGC at the Cancer Institute Hospital, Tokyo, and the National Cancer Center Hospital, Tokyo. Seven clinicopathological factors were assessed for their possible association with lymph node metastasis. Of the 3843 patients, 2163 (56.3%) had intramucosal cancers and 1680 (43.7%) had submucosal invasive cancers. Only 105 (4.9%) intramucosal cancers compared with 399 (23.8%) submucosal invasive cancers were associated with lymph node metastases. By multivariate analysis, tumor size 21 mm or more, lymphatic-vascular capillary involvement, and submucosal penetration were independent risk factors for lymph node metastasis (P < 0.001, respectively). None of the 310 intramucosal cancers 20 mm or less in size without lymphatic- vascular capillary involvement and ulcerative findings was associated with lymph node metastases (95% confidence interval, 0-0.96%). UD-type intramucosal EGC 20 mm or less in size without lymphatic-vascular capillary involvement and ulcerative findings presents a negligible risk of lymph node metastasis. We propose that in this circumstance ER could be considered.
Conversion therapy for gastric cancer (GC) has been the subject of much recent attention. It is defined as a surgical treatment aiming at an R0 resection after chemotherapy for tumors that were originally unresectable or marginally resectable for technical and/or oncological reasons. However, the indications for resection remain to be clarified. In the present review, we focus on the biology and heterogeneous characteristics of stage IV GC and propose new categories of classification. Stage IV GC patients can be divided based on the absence (categories 1 and 2) or presence (categories 3 and 4) of macroscopically detectable peritoneal dissemination, which has a different biological outcome compared to hematological metastasis. Category 1 is defined oncologically as stage IV but the metastasis is technically resectable. Category 2 includes a marginally resectable metastasis or patients for whom the operation would not necessarily be the best choice. Category 3 includes a potentially unresectable metastasis of peritoneal dissemination that is only macroscopically detectable. Category 4 includes noncurable metastasis with peritoneal and other organ metastasis. The indications for conversion therapy might include the patients from category 2, some patients from category 3 and a very small number of patients from category 4. The longer survival can be expected for patients corresponding to categories 1, 2 and, to a lesser extent, 3, while the treatment of other patients focuses on "care." The provision of conversion therapy for stage IV GC patients might be one of the main roles of surgical oncologists in the near future.
Some tyrosine kinase receptors (RTKs) play critical roles in gastric cancer progression. Not only trastuzumab, but also several other agents targeting RTKs are being investigated for gastric cancer therapy. However, the simultaneous expression of multiple RTKs, which may interfere with the effectiveness of therapeutic agents, has not been evaluated in a large cohort with gastric adenocarcinoma (GAC).We performed a tissue microarray analysis in 950 patients with GAC who underwent a gastrectomy without preoperative chemotherapy. The protein expressions of HER2, EGFR, MET and FGFR2 were evaluated using immunohistochemistry, and the gene amplifications of HER2, EGFR and MET were examined using dual-color in situ hybridization.The frequency of overexpression was 11.8 % for HER2, 23.5 % for EGFR, 24.9 % for MET and 31.1 % for FGFR2. Whereas strong staining for each of the RTKs was heterogeneous, tumors with homogeneously strong staining areas often exhibited gene amplification. Strong EGFR expression was significantly associated with a poor outcome, but no prognostic correlations were observed in other RTKs. The overexpression of single and multiple RTKs was observed in 40.4 and 22.7 % of the cases, respectively. HER2, EGFR, MET and FGFR2 predominance was observed in 10.1, 13.9, 16.1 and 22.9 % of the GACs, respectively.Approximately two-thirds of patients with GAC exhibited the expression of at least one RTK and would be candidates for targeted therapies. Moreover, one-third of at least one RTK overexspressing cases showed multiple RTKs expression. Our results may be useful for selecting the most suitable patients for each targeted therapy.
Malignancy is a secondary cause of sarcopenia, which is associated with impaired cancer treatment outcomes. The aim of this study was to investigate the prevalence of preoperative sarcopenia among elderly gastric cancer patients undergoing gastrectomy and the differences in preoperative dietary intake and postoperative complications between sarcopenic and non-sarcopenic patients.Ninety-nine patients over 65 years of age who underwent gastrectomy for gastric cancer were analyzed. All patients underwent gait and handgrip strength testing, and whole-body skeletal muscle mass was measured using a bioimpedance analysis technique based on the European Working Group on Sarcopenia in Older People (EWGSOP) algorithm for the evaluation of sarcopenia before surgery. Preoperative dietary intake was assessed using a food frequency questionnaire.Of these patients, 21 (21.2 %) were diagnosed with sarcopenia. Sarcopenic patients consumed fewer calories and less protein preoperatively (23.9 vs. 27.8 kcal/kg ideal weight/day and 0.86 vs. 1.04 g/kg ideal weight/day; P = 0.001 and 0.0005, respectively). Although the overall incidence of postoperative complications was similar in the two groups (57.1 % vs. 35.9 %; P = 0.08), the incidence of severe (Clavien–Dindo grade ≥ IIIa) complications was significantly higher in the sarcopenic group than in the non-sarcopenic group (28.6 % vs. 9.0 %; P = 0.029). In the multivariate analysis, sarcopenia alone was identified as a risk factor for severe postoperative complications (odds ratio, 4.76; 95 % confidence interval, 1.03–24.30; P = 0.046).Preoperative sarcopenia as defined by the EWGSOP algorithm is a risk factor for severe postoperative complications in elderly gastric cancer patients undergoing gastrectomy.