Defining the role of laparoscopic gastrectomy for gastric cancer.

Kim et al present one of the largest case-matched series comparing the long-term results of laparoscopic gastrectomy with the open approach for patients with surgically resectable gastric cancer. The authors are to be commended for this comprehensive, high-quality analysis that highlights all of the key elements of a valuable study. All 10 participating surgeons were from multiple high-volume centers performing at least 80 gastrectomies per year, removing institutional and referral-based bias and ensuring surgeon expertise. The cohort included nearly 3,000 patients with uniform approaches to staging and treatment that included approximately 1,500 laparoscopic and 1,500 open gastrectomies over a 7-year period. Five-year actual survival was analyzed, as was morbidity, mortality, and learning curve. Given that the population included all Korean patients, this was a homogeneous cohort of patients with relative standardization of work-up, treatment options, and ethnicity. All data were collected prospectively by an experienced data collection assistant and analyzed by a medical statistician who matched all cases for extent of resection, lymphadenectomy, body mass index, surgeons, and stage of tumor. This casecontrolled and case-matched analysis of a multi-institutional experience results in an analysis that provides reliable conclusions, to the extent possible by a retrospective study. The authors found that overall survival, disease-specific survival, and recurrence-free survival were no different except for the patients with stage IA disease, for whom there was a statistically better overall survival in the laparoscopic group. There was no significant difference in morbidity or mortality with a mean learning curve cutoff of 42 patients. These data are analyzed to provide background data for this group’s much larger randomized, prospective trial, the Korean Laparoscopic Gastrointestinal Surgical Society (KLASS) 01 study. They admit that in this retrospective analysis, follow-up and indications for adjuvant treatment were not standardized among involved hospitals. They also suggest that the differences seen in patients with stage IA disease could be attributed to selection bias, despite matching, given that the patients who were selected for open procedures tended to be older, with differing location of tumors. Interesting issues are raised by this work, including how to extrapolate these data to our Western population. There has long been debate that gastric cancer is different in the East and the West. Various studies report that cancer-related survival is better in Japan and South Korea, including outcome analyses from our own institution. This is coupled with differing philosophies and approaches to lymphadenectomy and neoadjuvant versus adjuvant therapy. Some studies suggest that genetic differences may account for observed differences. Statistics clearly demonstrate a varying epidemiology in gastric cancer rates, with a Japanese cancer rate of 78 cases per 100,000 compared with a US rate of 10 cases per 100,000, with a rising incidence of gastroesophageal adenocarcinomas in the Western part of the world. Hypotheses have included more accurate pathologic staging, extended nodal dissection, and meticulous histopathologic evaluation of surgical specimens. With recent advances in our understanding of gastric cancer, we can now better appreciate the heterogeneity of the disease and our perhaps previously oversimplified classification of the disease. Analyses such as gene expression profiling have uncovered distinct differences in various forms of gastric cancer that correlate with clinically relevant groups. Evidence is mounting that these genetic differences are reproducible and can be categorized into at least three distinct types of gastric cancer: proximal or gastroesophageal junction tumors that may be associated with obesity and reflux; distal, intestinal-type tumors that are linked to Helicobacter pylori infection and ulcer disease; and diffuse signet ring– type tumors that are often associated with genetic alterations such as the CDH1 mutation. Such understanding has further improved our ability to compare gastric cancer outcomes in the East and West; we realize that when we compare the same types of gastric cancer subtypes in the East and West, results are more similar than previously thought. The Korean series reported here includes predominantly distal-type gastric cancer, and previous comparisons have similarly demonstrated and confirmed the relative paucity of proximal/ gastroesophageal junction gastric cancers in Eastern compared with Western patients. If we carefully evaluate these data, then comparisons with the Western population with similar-type distal cancers is possible. The advantage of the Eastern series is unquestionably a quantity of similar cases that, when interpreted correctly, can provide valuable information and guidance for a subgroup of Western patients. Another important issue is the learning curve. In this series, 42 patients were required to improve lymphadenectomy skills, decrease complications, and improve outcomes. In the United States, for example, there are few high-volume centers that can achieve this learning curve; thus, the applicability of this approach for most surgical centers is unlikely. Only the larger volume cancer centers may be able to achieve these numbers; thus, the feasibility of the minimally invasive approach may be questioned. Only a few other groups have JOURNAL OF CLINICAL ONCOLOGY E D I T O R I A L VOLUME 32 NUMBER 7 MARCH 1 2014