title: Clinical characteristics of synchronous colorectal cancers in Japan.
abstract: BACKGROUND
  Incidence and clinical characteristics of synchronous colorectal cancer (sCRC) patients significantly vary among studies, likely due to differences in surveillance methodology. If remain undetected, sCRC can progress to more advanced stages seriously aggravating patient prognosis. We studied the incidence and clinicopathological characteristics of Japanese patients with sCRCs who underwent surgery for primary CRC and received exhaustive perioperative surveillance.
  
  
  METHODS
  We recruited 1005 patients with surgically resected CRCs between January 2007 and December 2011. The associations of clinical and pathological factors with sCRC development were assessed by univariate and multivariate logistic regression.
  
  
  RESULTS
  Eighty-four patients (8.4 %) developed sCRCs, 16 of them (19.0 %) harboring three or more cancers. Companion sCRCs were smaller and earlier stage than the index lesion (P < 0.0001). In multivariate analysis, advanced age (odds ratio (OR) 1.03 per year; P = 0.009) and left colon tumor location (OR 1.78; P = 0.013) are associated with higher risk of sCRCs, particularly in females. Overall survival did not differ between solitary CRC and sCRC (P = 0.62).
  
  
  CONCLUSIONS
  Our results highlight the importance of perioperative colonoscopy examination to ensure the absence of sCRCs that, being small and early staged, are more difficult to detect. The incidence of sCRC, and notably of triple or more sCRCs, was higher than previously recognized. Because they are also significantly higher than expected by merely stochastic accumulation of individual cancerous lesions, we suggest that the occurrence of many sCRC reflects a hitherto uncharacterized predisposition condition.
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan. tkato@jichi.ac.jp.|Institute of Predictive and Personalized Medicine of Cancer (IMPPC), Institut d'investigació en ciéncies de la salut Germans Trias I Pujol (IGTP), Campus Can Ruti, 08916, Barcelona, Spain. tkato@jichi.ac.jp.
authors: Takaharu
authors: http://orcid.org/0000-0002-7555-1654
authors: T
authors: Kato
authors: Institute of Predictive and Personalized Medicine of Cancer (IMPPC), Institut d'investigació en ciéncies de la salut Germans Trias I Pujol (IGTP), Campus Can Ruti, 08916, Barcelona, Spain.
authors: Sergio
authors: S
authors: Alonso
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan.
authors: Yuta
authors: Y
authors: Muto
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan.
authors: Hiroshi
authors: H
authors: Noda
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan.
authors: Yasuyuki
authors: Y
authors: Miyakura
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan.
authors: Koichi
authors: K
authors: Suzuki
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan.
authors: Shingo
authors: S
authors: Tsujinaka
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan.
authors: Masaaki
authors: M
authors: Saito
authors: Institute of Predictive and Personalized Medicine of Cancer (IMPPC), Institut d'investigació en ciéncies de la salut Germans Trias I Pujol (IGTP), Campus Can Ruti, 08916, Barcelona, Spain.|Sanford Burnham Prebys Medical Discovery Institute, 10901 N. Torrey Pines Rd., La Jolla, CA, 92037, USA.|Institució Catalana de Recerca i Estudis Avançats (ICREA), Catalan Institution for Research and Advanced Studies, Pg. Lluís Companys 23, 08010, Barcelona, Spain.
authors: Manuel
authors: M
authors: Perucho
authors: Department of Surgery, Saitama Medical Center, Jichi Medical University, 1-847 Amanuma-cho, Omiya-ku, Saitama, 330-8503, Japan.
authors: Toshiki
authors: T
authors: Rikiyama
mesh_terms: D000367:Age Factors; D000368:Aged; D003113:Colonoscopy; D015179:Colorectal Neoplasms / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D062665:Epidemiological Monitoring; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D009378:Neoplasms, Multiple Primary / Q000453:epidemiology* / Q000401:mortality / Q000473:pathology* / Q000601:surgery; D019990:Perioperative Care / Q000379:methods; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D012737:Sex Factors; D015996:Survival Rate
keywords: Colon stenosis; Colorectal cancer; Multiple colorectal cancers; Surgical resection; Synchronous colorectal cancer