title: Dual primary gastric and colorectal cancer: is the prognosis better for synchronous or metachronous?
abstract: OBJECTIVE
  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.
  
  
  CONCLUSIONS
  Metachronous DPGCC had a better prognosis than synchronous DPGCC due to the tendency for metachronous DPGCC to occur in patients with early-stage cancer.
authors.affiliation: Department of Digestive Surgery, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: Megumu
authors.initials: M
authors.lastname: Watanabe
authors.forename: Mitsugu
authors.initials: M
authors.lastname: Kochi
authors.forename: Masashi
authors.initials: M
authors.lastname: Fujii
authors.forename: Teruo
authors.initials: T
authors.lastname: Kaiga
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Mihara
authors.forename: Tomoya
authors.initials: T
authors.lastname: Funada
authors.forename: Hidenori
authors.initials: H
authors.lastname: Tamegai
authors.forename: Hiroko
authors.initials: H
authors.lastname: Shimizu
authors.forename: Tadatoshi
authors.initials: T
authors.lastname: Takayama
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D016609:Neoplasms, Second Primary / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D011379:Prognosis; D013274:Stomach Neoplasms / Q000401:mortality* / Q000473:pathology / Q000628:therapy; D015996:Survival Rate