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Clinicopathological Features and Surgical Treatment of Gastric Cancer in South Korea: The Results of 2009 Nationwide Survey on Surgically Treated Gastric Cancer Patients

Purpose In an effort to examine the clinicopathological characteristics of GC and the status of its surgical treatment, the Korean Gastric Cancer Association (KGCA) conducted a nationwide survey targeting surgically-treated gastric cancer patients in 2009. Materials and Methods A standardized electrical case report was sent to every member institution of the KGCA via E-mail with detailed instructions regarding the survey data. Completed data forms were retrieved from each institution and analyzed by the KGCA information committee. Results Data on 14,658 patients was collected from 59 institutions. The mean patient age was 59.2±11.9 years with a male to female ratio of 2.05 : 1. Lower third cancer (56.0%) was the most common among all gastric cancers. The histological type revealed poorly differentiated adenocarcinoma (34.1%) to be the most common, and the Lauren classification revealed the intestinal type (50.0%) to be the most prevalent. Curative surgery was performed in 92.4% of patients with laparoscopic surgery in 25.8% of patients. A Billroth I reconstruction was performed most frequently after a distal gastrectomy (63.4% of distal gastrectomy). T1 cancers accounted for 57.6% of all cases, and 62.6% of patients showed no lymph node metastasis. Compared to previous reports, it was found that patients are becoming older, laparoscopic surgery is being performed increasingly, and the proportion of T1 cancer is increasing with time. Conclusions This survey presented the clinicopathological characteristics and current status of the surgical treatment of gastric cancer in Korea. This survey is expected aid research studies as well as planning and evaluation programs targeting cancer control.


Introduction
Despite the decreasing global incidence, gastric cancer (GC) remains one of the most common forms of malignancy around the world.(1) GC is now the fourth most common malignancy after lung, breast, and colorectal cancer, and the second leading cause of cancer death worldwide. Furthermore, age-standardized incidence rates are twice as high for men. (2) GC is the fourth most common male cancer after lung, prostate, and colorectal cancer, and the fifth most common female cancer after breast, uterine cervix, colorectum, and lung cancer. The geographical distribution of GC is characterized by wide international variations. More than 70% of cases occur in developing countries, and half of the world's case total occurs in Eastern Asia. (2) In South Korea, GC is now the most prevalent malignant neoplasm and annually affects over 25,000 patients. In addition, it is the second leading cause of cancer death after lung cancer, and is responsible for over 10

Data collection and processing
A standardized electrical case report form prepared using spread sheet program (Microsoft Excel Ⓡ ) was sent to every member institution of the KGCA via E-mail with detailed instructions regarding survey data. Completed data forms were retrieved from each institution and analyzed by the KGCA information committee. Retrieved data was reexamined for its correctness, for example, correct codes, and underwent a data validation process at the KGCA data center. During this process, if any question was raised about the data, an appropriate query was forwarded with the original data to the institution concerned. Data received on non-standard forms were converted into standardized format coded data. Missing values were either treated as 'unknowns' during the analysis of categorical data or were excluded from the analysis of continuous data. From

Statistical analysis
Continuous data are presented as means and standard deviations, and were analyzed using the student's t-test. The chi-square test was used to analyze categorical data. Statistical analyses were performed using SPSS for Windows ver. 12.0 (SPSS Inc., Chicago, IL, USA), and P-value of ＜0.05 were regarded statistically significant.

Institutions and patients
Fifty-nine institutions participated in the survey and data was collected on 14,658 patients, which represents a significant increase compared to the 29 institutions and 5,380 patients in the first survey   (5) The overall incidence of GC was as twice as high among men than women. However, when gender ratios were examined in age subgroups, the incidence of GC was found to be higher in women than in men in patient group aged ＜30 (male to female ratio of 1 :

Age and sex
1.5). The proportion of male patients gradually increased with age and peaked in the sixth decade (male to female ratio of 2.6 : 1 in the sixth decade) ( Table 1).      3.3% of patients after distal gastrectomy. The most common reconstruction procedure used after total gastrectomy was Roux-en-Y esophagojejunostomy, which was performed in 98.8% (3,308/3,348) of all total gastrectomy patients. Loop-esophagojejunostomy and jejunal interposition were performed in only in 18 (0.5%) and 10 (0.3%) patients, respectively, after total gastrectomy.
When tumor stages in the serial cohorts of GC patients were compared, the proportion of T1 cancers was found to have increased from 28.6% in 1995 to 57.7% in 2009. Similarly, the proportion of node negative cancers was also found to have increased   (18) Endoscopic resection is currently widely used to treat mucosal cancers without lymph node metastasis in Korea and Japan. (19) However, accurate preoperative diagnosis of tumor invasion extent and lymph node metastasis remain pivotal problems that must be adequately resolved to enable proper individualized treatments to be chosen for EGC patients.
In the present study, tumors located in the lower third were  The standard surgery for gastric carcinoma is radical gastrectomy with regional lymph node dissection, although the extent of lymph node dissection continues to be the subject of long standing debate. In Korea and Japan, D2 lymph node dissection is regarded as a standard surgery,(24) but the best form of reconstruction after distal gastrectomy has remained the subject of debate. Our survey showed that the most commonly performed reconstruction after distal gastrectomy is Billroth I reconstruction in Korea, which is probably because it is a simple and safe method to be performed using mechanical staplers. Gastrojejunostomy is often adopted when gastroduodenostomy is not technically feasible due concerns of anastomosis failure or the need for wide stomach resection. In Korea, Billroth II reconstruction is most widely used for gastrojejunostomy, and Roux-en Y reconstruction is seldom performed. The best reconstruction method after distal gastrectomy remains to be determined because most studies on reconstruction after gastrectomy have been small or non-randomized.