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A small differentiated gastric cancer with minute submucosal invasion after endoscopic resection is regarded as the curative resection criterion of an expanded indication. However, recent studies have shown a high incidence of lymph node metastasis in those meeting the expanded criteria. The aim of this study was to evaluate the validity of the 500 μm criterion and to determine an optimal cutoff value for the expanded indication. We reviewed the clinicopathological data of 1,322 patients who underwent curative resection for submucosal gastric cancer between 2001 and 2013. The full thickness of the submucosa and the incidence of lymph node metastasis according to the depth of the submucosal invasion were evaluated. The sensitivity, specificity, and positive and negative predictive values were calculated with receiver operating characteristic (ROC) curve analysis. The mean full thickness of the submucosa was 2,605 ± 1,760 μm, and the incidence of lymph node metastasis in 103 tumors meeting the expanded indication was 3.9 % (4/103). In the ROC analysis, the area under the curve was 0.664 (95 % confidence interval 0.538–0.791; p = 0.017), and the highest negative predictive value of 98 % was observed when the cutoff value was 300 μm. This study suggests that a range reduction in the depth of submucosal invasion is required to obtain a high negative predictive value. Further large-scale studies are required to validate the optimal cutoff value proposed in this study.

The possibility of lymph node metastasis is critical to the assessment of the indication for endoscopic submucosal dissection. The differentiation of tumors is an important predicting factor for lymph node metastasis. Even though gastric cancers frequently show intratumoral heterogeneity, most studies have not considered the effects of the minor histologic components. The purpose of this study was to investigate the relationship between the presence of undifferentiated type histology (UD-min) within differentiated type tumors and lymph node metastases in early gastric cancer confined to the mucosal layer.A retrospective study of 847 patients who underwent surgery for differentiated early gastric cancer, confined to mucosa, was conducted. We analyzed the proportion of the undifferentiated type components of the tumor and their relationship with lymph node metastasis.The overall rate of lymph node metastasis was 1.7 % (14/847 patients) and 215 differentiated tumors (25.4 %) have UD-min. UD-min was associated with female sex, younger age, larger tumor size, and the presence of ulcer. Lymph node metastasis rate with or without UD-min was 5.1 % (11/215) versus 0.5 % (3/632), respectively (p0.001). UD-min was found to be associated with lymph node metastasis in the multivariate analyses (odds ratio [OR] = 4.39, CI 1.08-17.89). When three risk factors (tumor size2 cm, ulcer, and UD-min) were present concurrently, the rate of lymph node metastasis was high (10 %).The presence of an UD-min component should be considered when assessing curative resection status of endoscopic submucosal dissection for differentiated type mucosal cancer.

While clinicians routinely follow up gastric cancer patients after curative resection to detect recurrence, the effectiveness of regular follow-up has not been proven, and no consensus has been reached regarding follow-up programs. Of the 1,767 patients who underwent curative resection for gastric cancer from 2001 to 2004, 310 (17.5%) developed recurrence during follow-up. The oncologic effectiveness of follow-up was evaluated using recurrence detection rates during follow-up and survivals. Clinicopathologic characteristics, the detection tools used, and times lapsed between recurrence and previous examinations were also investigated. Two hundred thirty-three (75.2%) of the 310 patients who developed recurrence were detected by regular follow-up (detected group). The frequencies of undifferentiated and diffuse-type recurrences were higher in patients with recurrence detected based on patient-initiated findings (undetected group) than in the detected group. Computed tomography and tumor markers were the first detection tools that yielded positive findings. Times between recurrence detection and previous examinations ranged from 2.8 to 5.3 months over the first 2 years. No difference in overall survival was found between the detected and undetected groups (log rank, P = 0.2). The oncologic effectiveness of regular follow-up after curative resection for gastric cancer was found to be unsatisfactory. A large-scale randomized controlled trial is required to identify the effectiveness of regular follow-up in terms of its oncologic, functional, psychological, and economical aspects.

This study was designed to identify the characteristics of patients with early gastric cancers that have skip metastases.The possibility of lymph node metastasis is the most important factor to consider when deciding on the resection procedure for patients with early gastric cancer.From February 2003 through July 2008, 739 patients with early gastric adenocarcinoma underwent gastric resection at the National Cancer Center, Korea, and were included in this study. Patients with skip metastases were analyzed and compared with those without skip metastases.Skip metastases were found in 2.8% of patients with early gastric cancer. Tumor size and the presence of lymphatic invasion were associated with skip metastases by both univariate and multivariate analysis. All skip metastases were metastases to the extraperigastric lymph nodes that skipped across the perigastric lymph nodes. Sixteen patients (66.7%) with these metastases had metastatic lymph nodes at No. 7, 8, and 9 stations.Tumor size should be considered during sentinel lymph node mapping to prevent false-negative results in patients with early gastric cancer. If sentinel nodes are not found in the perigastric lymph nodes, No. 7, 8, and 9 stations should be explored for prevention of false-negative sentinel node mapping results.

This study was conducted to evaluate the leaning curve of D2 lymph node dissection for patients with gastric cancer in a high-volume center. The authors prospectively reviewed the data of all patients who underwent total gastrectomy with D2 lymph node dissection during a 4-year period. Retrieved lymph node number was used as a surrogate marker of oncological outcome. The retrieved lymph node number cut-off value required for satisfactory D2 lymph node dissection was defined as >25. Cumulative sum analysis was used to examine the learning curves of individual surgeons at target accuracy rates of 85%, 90%, 92.5%, 95%, and 98%. Two junior staff surgeons performed 198 curative-intent total gastrectomies with D2 lymph node dissections during the study period; their success rates exceeded 90%. Operating time decreased with operative experience (Pearson correlation coefficient = −0.515, P < 0.001). The learning period for total gastrectomy with D2 lymph node dissection for these two junior members of staff was calculated as 23–35 cases, presuming a 92.5% success rate. The current study suggests that the surgical learning period for D2 lymph node dissection extends to at least 23 cases or 8 months. In clinical trials containing gastric cancer surgery, the learning curve for qualified surgery from the standpoint of oncological outcome should be considered to minimize bias due to surgeon-associated factors.

There is no consensus on the optimal method of primary tumor control, determined by preoperative clinical factors, during sentinel node (SN) navigation surgery for early gastric cancer (EGC). In this study, we investigated the accuracy of clinical diagnosis based on preoperative examination in patients with EGC and proposed surgical options for primary tumor control during SN navigation surgery.We analyzed 815 patients with clinical stage IA gastric cancer who underwent gastrectomy at the National Cancer Center in Korea between March 2001 and February 2011. The clinical stage was determined by endoscopy, endoscopic ultrasonography, and abdominal computed tomography.The preoperative assessment of tumor depth and tumor size was accurate in 57.5 and 70.8 % of patients, respectively. Tumor depth and size were underestimated in 8 and 25.3 % of patients. The overall accuracy of histologic diagnosis by endoscopic biopsy was 87.2 %. Of those tumors diagnosed preoperatively as differentiated, 20.5 % revealed mixed histology of undifferentiated type.The recommendation for SN biopsy may be limited to tumors sized 3 cm or smaller to avoid positive lateral margins and to minimize the risk of skip metastases. Endoscopic resection may safely be applied to small mucosal cancers, but other surgical options should be employed for undifferentiated large mucosal lesions, given their tendency for diffuse invasion. Full-thickness resection is preferable for submucosal cancers, to secure clear vertical margins.

The technical difficulty of lymph node dissection in laparoscopy-assisted distal gastrectomy (LADG) remains a barrier for extending the indication for this modality and limits its widespread clinical practice. The aim of this study was to evaluate our institutional guidelines for LADG, limiting the indications for this modality to only clinical stage T1N0 or T1N1 gastric cancer.From January 2002 to October 2006, a total of 294 cases of LADG and 664 cases of open distal gastrectomy (ODG) for clinical T1N0 or T1N1 gastric cancer were performed at the National Cancer Center, Korea. The two groups' clinicopathologic characteristics, surgical outcome, morbidity, and survival were compared.The mean operating time for the LADG group was significantly longer than that for the ODG group (265.8 +/- 56.3 vs. 171.4 +/- 43.1 minutes, P.001). The mean number of retrieved lymph nodes in the LADG group was higher than that of the ODG group (39.5 +/- 14.7 vs. 37.2 +/- 12.9, P = .017). The postoperative hospital stay was shorter in the LADG group (8.0 +/- 3.3 vs. 10.5 +/- 4.1 days, P.001). The complications rate was lower for the LADG group than that for the ODG group (6.8% vs. 11.3%, P = .032). The overall survival rate was not significantly different between the two groups (P = .880).Before considering expanding the indications for LADG, developing a carefully thought-out guideline and conducting an audit are mandatory.

Endoscopic resection (ER) is an effective treatment for early gastric cancer (EGC) without lymph node metastasis. However, after ER additional surgery may be needed to manage the risks presented by residual cancer or lymph node metastasis.ER was performed on 344 gastric adenocarcinomas between November 2001 and April 2006 at the Korean National Cancer Center under the strict pre-procedural indication. The authors performed operations in 43 patients due to: residual mucosal cancer, a mucosal cancer larger than 3 cm, or a submucosal cancer regardless of size or margin involvement. ER and surgical specimens were reviewed and analyzed for residual cancer and lymph node metastasis.Based on examinations of ER specimens, cancer was confined to the mucosal layer in 15 patients (34.9%) and invaded the submucosal layer in 28 patients (65.1%). Surgical specimens showed residual cancer in 17 patients (39.5%) and lymph node metastasis in four (9.3%). Neither residual cancer nor lymph node metastasis was found in patients with less than 500 microm submucosal invasion without margin involvement in ER specimens. In three of four patients with lymph node metastasis, the depth of submucosal invasion was 500 microm or more; the remaining patient had a 4-cm-sized differentiated mucosal cancer.When a pathologic evaluation of an ER specimen reveals more than 500 microm of submucosal invasion or a mucosal cancer of larger than 3 cm, surgery should be considered due to the risk of lymph node metastasis.

This study was conducted to determine whether laparoscopy-assisted distal gastrectomy (LADG) with complete D2 lymph node dissection for gastric cancer is a safe and effective surgical option.During an 8-month period, 64 patients, who were diagnosed preoperatively as having T1-2, N0-1 or M0 gastric cancer, were prospectively enrolled to undergo LADG with D2 lymph node dissection; two surgeons with experience of over 50 cases of laparoscopic gastrectomy performed the procedures. The compliance rate, defined as cases with no more than one missing lymph node station according to the Japanese Research Society of Gastric Cancer (JRSGC) lymph node grouping, for the open gastrectomy with D2 lymph node dissection was 66.0% in a pilot study and was used for calculations of sample size. Compliance rate and other surgical outcomes, including the number of retrieved lymph nodes from each lymph node station, morbidities, mortalities and conversion rate, were analyzed.The compliance rate was 67.2% and was similar to that of open distal gastrectomy reported in the pilot study. The mean number of retrieved lymph nodes was 50.1 (range 20-100). The most frequently missed lymph node station was no. 5 (31.2%) followed by no. 3 (25.0%). There were no missed lymph nodes at stations no. 6 and 9. The complication rate was 3.1% (2/66); there were two conversions (3.0%) and no mortalities.The current study suggests that LADG with D2 lymph node dissection is oncologically feasible, and phase-III clinical trials will be needed.

There is a prevailing belief that both obesity and abdominal shape influence abdominal accessibility, and thus affect short-term surgical outcomes of gastric cancer surgery.We measured the thickness of subcutaneous fat (SCF), abdominal anterior-posterior diameter (APD), transverse diameter (TD), and intra-abdominal fat volume (IFV) at the umbilicus level by using the abdominal CT scans of 291 gastric cancer patients who had undergone subtotal gastrectomy and D2 lymph node dissection. Clinicopathological factors including body mass index (BMI), APD, TD, IFV, and SCF and surgical outcomes, i.e., dissected lymph node number, morbidity, and mortality were analyzed.SCF thickness, APD, TD, IFV, and BMI mean values were 20.0 mm (range 2.0-64.0), 188.4 mm (range 128.0-332.0), 301.4 mm (range 160.0-651.0), 198.3 mm(2) (range 123.4-312.1), and 23.9 kg/m(2) (range 16.6-34.6), respectively. In male patients, APD was found to correlate with the number of retrieved lymph nodes (P = 0.045). Whereas in female patients, this was not the case (P = 0.093). Twenty-one patients experienced postoperative complications but no postoperative mortality occurred. Female patients who experienced postoperative complications had higher APD (32.9 +/- 10.0 mm versus 26.1 +/- 7.9 mm, P = 0.044) and BMI (27.3 +/- 4.1 kg/m(2) versus 24.3 +/- 3.5 kg/m(2), P = 0.049) values than those who did not.We conclude that obesity and abdominal shape of gastric cancer patients both influence the short-term surgical outcomes of subtotal gastrectomy with D2 lymph node dissection.

The results of sentinel node (SN) biopsy have been improved by the use of dye and isotope double tracers in melanoma and breast cancer. However, the usefulness of this double tracer technique has not been determined in gastric cancer. The aim of this study was to investigate the possibility of improving SN biopsy results by using double tracers in gastric cancer. Sixty-four gastric adenocarcinoma patients preoperatively diagnosed as cT1N0, were enrolled in the study. 99mTc tin colloid was injected by preoperative endoscopy, and lymphoscintigraphy was performed prior to operation. After laparotomy, isosulfan blue was intraoperatively injected using an endoscope. Blue-stained or radioactive nodes were identified and defined as SNs. Gastrectomy with D2 lymphadenectomy was performed in all patients. All dissected lymph nodes were evaluated for metastasis by hematoxylin and eosin staining and immunohistochemistry. SN detection rates using dye, isotope, or both tracers were 95.3%, 84.4%, and 96.9%, respectively, and their corresponding sensitivities were 52.9%, 52.9%, and 70.6%. In the pT1 subset, the sensitivity of the double tracer was 87.5%; and in a subset of tumors with diameter

The aim of this study was to determine how to select potential candidates for curative resection among advanced gastric patients with equivocal findings of para-aortic lymph node metastasis on computed tomography (CT). We analyzed the clinicopathologic results of 23 advanced gastric cancer patients who were diagnosed as having equivocal findings of para-aortic lymph node metastasis on a CT scan and who underwent gastrectomy with D2 and para-aortic lymph node dissection. Twenty-two patients were male, and one patient was female. The median age of all study subjects was 52 years (range, 31–75 years). Sixteen underwent total gastrectomy, and seven underwent subtotal gastrectomy. The median number of A2 (suprarenal) lymph nodes harvested was 2 (range, 1–5), and that of B1 (infrarenal) lymph nodes was 6 (range, 1–17). Ten (43.5%) of the 23 patients were proven pathologically to have metastasis to para-aortic lymph nodes. Two patients with cT2 cancer had no metastatic para-aortic lymph node, whereas three patients with cT4 disease had metastatic para-aortic lymph nodes (P = .021). Seven (70.0%) of 10 patients with pathologic para-aortic lymph node metastasis experienced recurrence, whereas only 2 (15.4%) of 13 patients without experienced recurrence (P = .008). The Lauren classification was found to be an independent predictor of para-aortic lymph node metastasis (relative risk; .13; 95% confidence interval, .02–.83; P = .03). More than half of gastric cancer patients with equivocal findings of para-aortic lymph node metastasis on CT are potential candidates for curative resection. The Lauren classification of gastric cancer in patients with equivocal CT findings of para-aortic lymph node metastasis would be helpful when deciding on clinical stage and treatment plans in these patients.