Background: Recently, endoscopic submucosal dissection has been carefully applied in early gastric cancer (EGC) with undifferentiated type. However, there are no individual guidelines for endoscopic treatment of EGCs with poorly differentiated tubular adenocarcinoma or signet ring cell carcinoma. The aim of this study was to investigate and compare the clinicopathologic features of these two types of EGC to guide the application of endoscopic treatment.
Methods: Patients to undergo radical gastrectomy for the treatment of EGC were selected for inclusion in this study. Histology was classified according to the Japanese Gastric Cancer Association. Between January 2005 and December 2008, 288 patients with poorly differentiated EGC and 419 patients with signet ring cell EGC were enrolled. Their medical records were reviewed retrospectively.
Results: Compared with signet ring cell EGC, poorly differentiated EGC had higher rates of male gender, old age (≥45 years), large tumor length (>20 mm), ulcer, submucosal invasion, lymphovascular invasion, and lymph node metastasis. In the multivariate analyses, poorly differentiated EGC was significantly associated with ulcer (odds ratio [OR]: 2.4, 95% confidence interval [CI]: 1.5-3.8), submucosal invasion (OR: 3.6, 95% CI: 2.6-5.1) and lymphovascular invasion (OR: 2.0, 95% CI: 1.1-3.6) with a reference of signet ring cell EGC. The independent risk factors for lymph node metastasis were large tumor length, submucosal invasion, and lymphovascular invasion in both types of EGC. Young age was an independent risk factor of lymph node metastasis only in poorly differentiated EGC.
Conclusions: Poorly differentiated EGC has clinicopathologic features that are less favorable to endoscopic treatment than are those of signet ring cell EGC. Therefore, these two types of EGC should be approached separately, not as a united type of undifferentiated histology, during the planning of endoscopic treatment.