**3. Discussion**

Adjuvant chemotherapy is a standard treatment option for operable gastric cancer and improves patient outcomes, but the preferred treatment differs by geographical region [10]. The recommended adjuvant treatment is chemoradiotherapy in the United States and perioperative chemotherapy in the United Kingdom and some parts of Europe [1, 5, 12]. The Japanese ACT-GC trial was the first large-scale randomized trial of adjuvant chemotherapy after curative resection with D2 gastrectomy [4]. In the Republic of Korea, the CLASSIC trial was the second large-scale randomized trial after D2 gastrectomy [1]. The survival rate of two Asian large-scale randomized trials was substantially higher than in the US Intergroup-0116 and UK MAGIC trials (78% in the CLASSIC trial, 80% in ACT-GC vs. 30–40% in the Intergroup-0116 and MAGIC trials) [1, 4, 5, 12]. Most recurrences after surgery of gastric cancer occurred within 3 years of surgery [14]. The duration of adjuvant chemotherapy differed from previous studies. Kim et al. had adjuvant chemotherapy for 24 months [3]. The ACT-GC trial had adjuvant chemotherapy for 12 months [4]. CLASSIC trial had adjuvant chemotherapy 6 months [1]. The duration of adjuvant chemotherapy after surgery was different, although similar survival results were present in two clinical trials. Kim et al. reported that radical lymph node dissection, with more than 25 resected lymph nodes, improved survival in patients with stage II and IIIa disease [3]. Postoperative immunochemotherapy was most effective in patients with stage II and III disease [3]. The favorable outcomes of Asian studies were a result of the consistent adoption of D2 gastrectomy and the quality control of surgery using video techniques [1, 4]. But postoperative chemoradiotherapy in the United States and perioperative chemotherapy in Europe is not based on D2 gastrectomy. In the Intergroup-0116 study, quality assessment was done for radiotherapy before the initiation of this treatment [5]. However quality control of surgery was not done, because patients were usually identified postoperatively, and they could not require specific surgical procedures. Only 10% of the patients underwent a D2 dissection, while 36% had a D1 dissection, and 54% had a D0 lymphadenectomy (a resection in which not all of the N1 nodes were removed) [5]. The low long-term survival rate of stomach cancer patients in Western studies might result from excessive residual tumor left behind during surgery. The high survival rate in countries such as South Korea and Japan might be the reflection of the small amount of residual tumor due to radical gastrectomy and extensive lymph node dissection [10]. Songun et al. [15] reported that after a median follow-up of 15 years, D2 lymphadenectomy with strict quality control is associated with lower locoregional recurrence and gastric cancer-related death rates in patients with stage II and IIIa disease than D1 surgery; they recommended D2 resection as the standard surgical approach to resectable gastric cancer [15]. The CLASSIC and ACT-GC trials showed the effectiveness of postoperative adjuvant chemotherapy with S-1 and XELOX for stage II and III gastric cancer patients who underwent D2 gastrectomy [1, 4]. Biological aspects may cause the different gastric cancer results between East Asia and the Western world. However, no significant differences in prognostic factors were reported between these two regions of the world. In conclusion, for all patients with stage II and III gastric cancer worldwide, standard D2 gastrectomy and adjuvant chemotherapy are strongly recommended for a better rate of survival.
