Differences in patients’ tumor characteristics and in surgical practices between eastern and western countries may limit the transferability of clinical trial results in early gastric cancer, according to Dr. Lockhart.
One major difference is tumor location. For example, in the Asian CLASSIC trial, distal tumors largely predominated, whereas in trials conducted in western populations, 20% to 30% of patients have had proximal tumors.
Extent of Surgery
A second major difference is the extent of surgery. All patients in the CLASSIC trial underwent a D2 resection (resection of the regional lymphatics, the perigastric lymph nodes, and the lymph nodes along the named vessels of the celiac axis), with a median of 42 to 43 lymph nodes examined. But just 10% and 30% of patients in the western Intergroup 0116 and MAGIC studies, respectively, had a D2 resection, and the median numbers of lymph nodes examined in western trials is more typically in the teens.
“Definitely, the type of surgery that’s being performed in Asia is substantially different than what we are doing in our current clinical trials,” he said. “And I think that’s impactful in that now there are new recommendations that D2 resections need to be standard or at least routinely attempted.” Those new recommendations also call for examination of more than 15 lymph nodes.1
Oncologists may worry about increased morbidity of a D2 vs D1 resection, Dr. Lockhart said. Reassuringly, a long-term follow-up comparison found that at least in terms of postoperative survival, patients given a D2 resection, in fact, fared better.2 “But I do think their recovery time is somewhat longer than in the patients who are undergoing the D1 resections,” he added. ■
1. NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines™). Gastric Cancer (including cancer in the proximal 5 cm of the stomach). Version 2.2011. Available at http://www.nccn.org/professionals/physician_gls/pdf/gastric.pdf. Accessed September 1, 2011.
2. Songun I, Putter H, Kranenbarg EM, et al: Surgical treatment of gastric cancer: 15-year follow-up results of the randomised nationwide Dutch D1D2 trial. Lancet Oncol 11:439-449, 2010.