BACKGROUND: During the 1970s, a special type of Gastric Cancer with excellent prognosis (early gastric cancer; EGC) was identified by the Japanese Research Society for Gastric Cancer. EGC has been defined as a tumor which invades the mucosa and/or submucosa, regardless of the lymph node status. Using this definition, we identified an initial phase of tumor development which could be treated both endoscopically and surgically.METHODS: We examined 412 EGC patients, recruited between 1976 and 1999, with an average follow-up of 9 years. All tumors were classified according to the macroscopic and microscopic criteria proposed by the Japanese Society of Gastroenterological Endoscopy (JSGE) and Lauren, respectively. The infiltrative growth pattern was evaluated according to Kodama's classification. Only tumor-related death was considered as an end-point of interest for the survival analysis.RESULTS: Submucosal tumors ( P = 0.008), Pen A (see definition below) type disease ( P = 0.0001), and lymph node-positive cancers ( P = 0.0002) were significant prognostic factors on univariate analysis. Moreover, bivariate analysis showed that the worst prognosis, in terms of survival, was for patients with nodal involvment, submucosal invasion, and node-positive and Pen-A type cancer. The abbreviation Pen, penetrating, indicates a lesion with a diameter of less than 4 cm, which invades the submucosa diffusely. Pen A type EGC represents a subgroup of tumors which infiltrates the submucosa extensively, with nodular masses, causing the complete destruction of the muscularis mucosae.CONCLUSION: In our series, Pen A type was an important prognostic factor (hazard ratio; HR, 8.32; 95% confidence interval [CI], 3.49-19.86. For this reason, we believe it is important to evaluate the infiltration into the wall in all patients with EGC, paying particular attention to the growth pattern of the neoplasm. Moreover, submucosal Pen A type tumors had a considerably worse prognosis and this finding was reinforced when lymph node metastases coexisted. We suggest, therefore, that surgical treatment with at least a D2 lymphadenectomy is performed in all these patients, as the lesions must be considered to be advanced, no longer being EGC.