title: Comparison of clinical features between suspected familial colorectal cancer type X and Lynch syndrome in Japanese patients with colorectal cancer: a cross-sectional study conducted by the Japanese Society for Cancer of the Colon and Rectum.
abstract: OBJECTIVE
  The characteristics of familial colorectal cancer type X are poorly defined. Here we aimed to clarify the differences in clinical features between suspected familial colorectal cancer type X and Lynch syndrome in Japanese patients.
  
  
  METHODS
  We performed germline mutation analyses of mismatch repair genes in 125 patients. Patients who met the Amsterdam Criteria I but lacked mismatch repair gene mutations were diagnosed with suspected familial colorectal cancer type X.
  
  
  RESULTS
  We identified 69 patients with Lynch syndrome and 25 with suspected familial colorectal cancer type X. The frequencies of gastric and extracolonic Lynch syndrome-associated cancers were lower with suspected familial colorectal cancer type X than with Lynch syndrome. The number of organs with Lynch syndrome-associated cancer was significantly lower with suspected familial colorectal cancer type X than with Lynch syndrome. The cumulative incidence of extracolonic Lynch syndrome-associated cancer was significantly lower with suspected familial colorectal cancer type X than with Lynch syndrome. We estimated that the median cancer risk in 60-year-old patients with Lynch syndrome was 89, 36 and 24% for colorectal, endometrial and gastric cancers, respectively. Analyses of family members, including probands, revealed that the median age at diagnosis of extracolonic Lynch syndrome-associated cancer was significantly older with suspected familial colorectal cancer type X than with Lynch syndrome. The frequency of extracolonic Lynch syndrome-associated cancer was significantly lower with suspected familial colorectal cancer type X than with Lynch syndrome.
  
  
  CONCLUSIONS
  A significant difference in extracolonic Lynch syndrome-associated cancer was evident between suspected familial colorectal cancer type X and Lynch syndrome.
authors.affiliation: Department of Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo.
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Division of Clinical Genome Research, Advanced Clinical Research Center, Institute of Medical Science, The University of Tokyo, Tokyo.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Furukawa
authors.affiliation: Laboratory of Molecular Medicine, Human Genome Center, Institute of Medical Science, The University of Tokyo, Tokyo.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nakamura
authors.affiliation: Department of Surgery, Hyogo College of Medicine, Nishinomiya.
authors.forename: Nagahide
authors.initials: N
authors.lastname: Matsubara
authors.affiliation: Department of Molecular-Targeting Cancer Prevention, Kyoto Prefectural University of Medicine, Kyoto.
authors.forename: Hideki
authors.initials: H
authors.lastname: Ishikawa
authors.affiliation: Clinical Genetic Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, Tokyo.
authors.forename: Masami
authors.initials: M
authors.lastname: Arai
authors.affiliation: Department of Surgery, Hyogo College of Medicine, Nishinomiya.
authors.forename: Naohiro
authors.initials: N
authors.lastname: Tomita
authors.affiliation: Major in Science, Graduate School of Science and Engineering Research, Kinki University, Higashiosaka.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Tamura
authors.affiliation: Oncogene Research Unit/Cancer Prevention Unit, Tochigi Cancer Center Research Institute, Utsunomiya.
authors.forename: Kokichi
authors.initials: K
authors.lastname: Sugano
authors.affiliation: Department of Clinical Oncology, Institute of Development, Aging and Cancer, Tohoku University, Sendai.
authors.forename: Chikashi
authors.initials: C
authors.lastname: Ishioka
authors.affiliation: Genetics Division, National Cancer Center Research Institute, Tokyo.
authors.forename: Teruhiko
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: Department of Surgery, National Cancer Center Hospital, Tokyo.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Moriya
authors.affiliation: Department of Digestive Tract and General Surgery, Saitama Medical Center, Saitama Medical University, Kawagoe 05hishi@saitama-med.ac.jp.
authors.forename: Hideyuki
authors.initials: H
authors.lastname: Ishida
authors.affiliation: Department of Surgical Oncology, The University of Tokyo, Tokyo.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Surgical Oncology, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sugihara
mesh_terms: D000328:Adult; D000368:Aged; D044466:Asian People / Q000235:genetics* / Q000706:statistics & numerical data; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000175:diagnosis* / Q000453:epidemiology; D003430:Cross-Sectional Studies; D053843:DNA Mismatch Repair / Q000235:genetics*; D005260:Female; D018095:Germ-Line Mutation; D006801:Humans; D015994:Incidence; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged
keywords: Lynch syndrome; colorectal cancer; familial colorectal cancer type X