[The clinical influence of double or multiple primary cancers on the prognosis of patients with gastric cancer].

Background: An aging population and advances in diagnostic technology have led to an increase in the incidence of double or multiple primary cancers(DMPC) in patients with gastric cancer(GC). This study was designed to evaluate the clinical influence of DMPC on the prognosis of patients with GC.

Methods: Between 1997 and 2009, 1,086 patients underwent curative gastrectomy for GC in our hospital.

Results: 1) 1,086 patients were analyzed, and of these 166 patients (15%) had DMPC and the remaining 920 patients had no DMPC. GC patients with DMPC had a significantly higher age (p <0.0001) and higher incidence of differentiated cancer(p=0.0045) than those without DMPC. 2) Multivariate analysis showed the presence of DMPC was an independent prognostic factor for overall survival. It was particularly noteworthy that the prognosis of GC patients with hematological cancer, hepato-biliary pancreatic cancer and esophageal cancer was extremely poor. In contrast, those with colorectal cancer and urological cancer had a comparatively better prognosis. The number of DMPC had little influence on the prognosis of GC patients. 3) In a survival associated with GC, the presence of DMPC had no influence on the prognosis of GC patients.

Conclusions: The types of DMPC had more clinical influence on the prognosis of GC patients than the number of DMPC with respect to overall survival.