Background: All patients with peritoneal-free cancer cells (CY1) do not always develop a peritoneal recurrence (P1). The goal of this study was to identify characteristic features of peritoneal-free cancer cells that could develop into peritoneal recurrence.
Methods: Of 1,474 patients, 91 were identified with CY1P0, and the remaining 1,383 with CY0P0. Immunohistochemical staining with anti-phosphorylated Smad 2 (p-Smad2) was performed on paraffin-embedded specimens from the 91 CY1P0 patients.
Results: CY1 was significantly correlated with Borrmann's type-4 cancer, clinical T stage, and lymph node metastasis. CY1P0 patients with Borrmann's type-4 cancer more frequently develop peritoneal recurrence than do those with other types of tumors. The 5-year survival rate of patients with Borrmann's type-4 tumors was significantly (p = 0.023) low (6.3%) compared with that of patients with other types of tumors (27.7%). The prognosis for p-Smad2-positive patients was significantly poorer than that of p-Smad2-negative patients. In CY1 and/or P1 patients with Borrmann's type-4 tumors, no significant difference in prognosis was identified between those who had surgery and those who did not.
Conclusions: Activated Smad signaling might be associated with a high potential for peritoneal recurrence in CY1P0 patients. Borrmann's macroscopic criteria and p-Smad2 expression are useful markers for surgeons selecting advanced gastric cancer patients with CY1P0 for gastrectomy.