Surgery plays a central role in the treatment of mid-stage gastric cancer (T2-T4a, N0-N3a). Chemo- or chemoradiotherapy before and/or after surgery may improve survival, but adequate and meticulous surgery is a prerequisite for cure of the disease. Optimal local tumor control is achieved with gastric resection having sufficient resection margins and adequate lymphadenectomy. In this section, the principles and techniques of standard gastrectomy with D2 lymphadenectomy for noncardiac distal gastric cancer are described.
PRINCIPLES OF GASTRECTOMY
Extent of Gastric Resection
Mid-stage distal gastric cancer is treated with either distal gastrectomy or total gastrectomy. In distal gastrectomy, two-thirds or more of the stomach is usually removed. Selection of gastrectomy depends on the tumor location and the mode of infiltration in the stomach wall, and proximal resection margin is the main determinant. A 5-cm margin has traditionally been recommended, and the ESMO guidelines1 advocate 8 cm for diffuse type cancer. According to the Japanese treatment guidelines,2 on the other hand, a 5-cm margin is recommended for tumors showing an infiltrative growth pattern with indistinct borders or diffuse-type histology, but 3 cm is usually sufficient for those showing an expansive growth pattern with grossly distinct borders for which the histology is most frequently of the intestinal type. Frozen section diagnosis is useful to confirm negative resection margins.
It was once argued that all gastric cancers should be treated by total gastrectomy. Theoretically, total gastrectomy ensures more certain negative margins and sufficient lymphadenectomy. However, it is associated with a higher operative morbidity and mortality, increased risk of long-term nutritional problems, and impaired quality of life as compared to distal gastrectomy. The policy of total gastrectomy "de principe" was abandoned after randomized trials comparing total and distal gastrectomy in distal gastric cancer failed to show a survival benefit.3
Lymph node metastasis is the most common mode of spread in gastric cancer. As the tumor invades deeper, the incidence of lymph node metastasis becomes higher: it is roughly estimated that 3%, 20%, 50%, and 80% of T1a, T1b, T2/3, and T4a/T4b tumors, respectively, have histological lymph node metastasis. The stomach is the organ that has the largest number of “regional lymph nodes” in human body, and its minimal number of examined nodes for adequate nodal staging defined in the TNM Classification is the largest. Unlike other distant metastases, lymph node metastasis from gastric cancer can be surgically removed for potential cure as long as it is confined to the regional area. However, intraoperative gross diagnosis of lymph node metastasis is quite unreliable, especially in gastric cancers of diffuse type histology, and thus systematic "prophylactic dissection" with optimal chance of removal of involved lymph nodes has been sought.4
Based on the analyses of large database of potentially curative resections, the Japanese Classification5 and the Treatment Guidelines2 defined D1, ...