Cancer Risks in Attenuated and Classical Familial Adenomatous Polyposis: A Nationwide Cohort With Matched, Nonexposed
Søren Hammershøj Beck1, John Gásdal Karstensen1,2, Steffen Bülow1
1Danish Polyposis Register, Gastro Unit, Copenhagen University Hospital-Amager and Hvidovre, Hvidovre, Denmark.
Introduction:
Familial adenomatous polyposis (FAP) is caused by pathogenic variants in the APC gene. FAP is usually categorized according to phenotype: classical FAP (CFAP) and attenuated FAP (AFAP); the latter is considered to have a milder disease course. We aimed to assess the risk of overall and specific cancers in patients with CFAP and AFAP compared with matched, nonexposed individuals.
Methods:
All known Danish patients with FAP were classified as either CFAP or AFAP and assigned 4 matched, nonexposed individuals. The risk of overall and specific cancers, and mortality were analyzed.
Results:
The analysis included 311 patients with CFAP, 134 patients with AFAP, and 1,600 nonexposed individuals. The overall cancer risk was significantly higher for both patients with CFAP and AFAP than for nonexposed individuals, with hazard ratios (HRs) of 4.77 (95% confidence interval [CI], 3.61-6.32; P < 0.001) for CFAP and 3.22 (95% CI, 2.16-4.80; P < 0.001) for AFAP. No significant difference was observed when comparing CFAP and AFAP (HR = 1.48; 95% CI, 0.98-2.25; P = 0.0646). The HR of colonic cancer was 2.16 (95% CI, 0.99-7.72; P = 0.0522) and 2.72 (95% CI, 1.19-6.22; P = 0.0177 for CFAP and AFAP), respectively, compared with nonexposed and did not differ between patients with CFAP and AFAP (HR = 0.80; 95% CI, 0.32-2.00; P = 0.6278). Mortality was significantly higher in CFAP (HR = 2.96; 95% CI, 2.04-4.28; P < 0.001), but not in AFAP (HR = 1.40; 95% CI, 0.73-2.69; P = 0.311).
Discussion:
Nationwide data reveal differing risk profiles for specific cancers and mortality in AFAP and CFAP compared with nonexposed individuals. The cancer burden of AFAP necessitates consistent monitoring of these patients.
More Related Videos
Related Concept Videos
Cancer Prevention
Some...
Mismatch Repair
The Mutator Protein Family Plays a Key Role in DNA Mismatch Repair
The human genome has more than 3 billion base pairs of DNA per cell. Prior to cell division, that vast amount of genetic...
Cancers Originate from Somatic Mutations in a Single Cell
Cancer-Critical Genes II: Tumor Suppressor Genes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
Cancer-Critical Genes I: Proto-oncogenes
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
Loss of Tumor Suppressor Gene Functions
When the tumor suppressor genes develop mutations or are lost, cells start growing out of control, leading to cancer. However, a single functional copy of the tumor suppressor gene is enough for the cells to maintain their normal functions and cell...


