Broadening risk profile in familial colorectal cancer type X; Increased risk for five cancer types in the national Danish cohort

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Background: Familial colorectal cancer type X (FCCTX) is a phenotypically defined subset of hereditary colorectal cancer with unknown and potentially heterogeneous genetic aetiology. FCCTX has been characterized as a colorectal cancer-specific syndrome, which we herein challenge by estimating the risk for extra-colorectal cancer in the Danish FCCTX cohort. Methods: Through the national hereditary non-polyposis colorectal cancer (HNPCC) register, 213 families fulfilling the Amsterdam I criteria and showing retained mismatch repair (MMR) function were identified. In here, sex and age-specific incidence rate ratios (IRR) were calculated for 30 extra-colorectal cancer types in comparison with the general Danish population. Results: In total, 494 extra-colorectal cancers developed with significantly increased risks for cancers of the urinary tract, breast, stomach, pancreas, and eye tumours. The age groups at increased risks were 30-49 years for gastric cancer, 30-69 years for female breast cancer, 50-69 years for ocular melanoma and above age 70 for pancreatic cancer and urothelial cancer. Conclusions: Danish FCCTX families show an increased risk of several extra-colorectal cancer types. This observation may indicate unidentified disease-predisposing genetic variants in this phenotypically defined subset of hereditary colorectal cancer and calls for awareness during genetic counselling and follow-up.


  • Christina Therkildsen
  • Maria Rasmussen
  • Lars Smith-Hansen
  • Thomas Kallemose
  • Lars Joachim Lindberg
  • Mef Nilbert
External organisations
  • Copenhagen University Hospital
  • University of Copenhagen
  • Danish Cancer Society Research Center
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Cancer and Oncology


  • Amsterdam I criteria, Cancer syndrome, Hereditary cancer, Mismatch repair proficient, Tumour spectrum
Original languageEnglish
Article number345
JournalBMC Cancer
Issue number1
Publication statusPublished - 2020 Apr 22
Publication categoryResearch