Dual primary gastric and colorectal cancer: is the prognosis better for synchronous or metachronous?

OBJECTIVES: The purpose of this study was to investigate the prognosis and clinicopathologic features of synchronous and metachronous dual primary gastric and colorectal cancer (DPGCC).

METHODS: We reviewed clinical data of 96 patients with DPGCC, comprising 63 men and 33 women, from among 4523 patients with gastric or colorectal cancer who underwent surgical treatment or chemotherapy, but no endoscopic resection, for colorectal cancer between 1990 and 2009. The selected patients were classified into 2 groups according to the time of gastric or colorectal cancer detection as follows: synchronous group (n= 42) and metachronous group (n = 54).

RESULTS: Among 4523 patients treated for gastric and colorectal cancer, DPGCC was diagnosed in 96 (2.1%). In terms of clinicopathologic features, the proportion of early-stage gastric and colorectal cancer was higher in the metachronous DPGCC group, with P values of 0.02 and 0.01, respectively. Overall survival in the metachronous DPGCC group was significantly longer than in the synchronous DPGCC group (P = 0.02). Metachronous DPGCC was identified as an independent predictor of survival by both univariate and multivariate analyses, with a P value of 0.02 and 0.006, respectively.

CONCLUSION: Metachronous DPGCC had a better prognosis than synchronous DPGCC due to the tendency for metachronous DPGCC to occur in patients with early-stage cancer.