Re-evaluating the genotypes of patients with adenomatous polyposis of unknown etiology: a nationwide study.

In the Danish Polyposis Register, patients with over 100 cumulative colorectal adenomas of unknown genetic etiology, named in this study colorectal polyposis (CP), is registered and treated as familial adenomatous polyposis (FAP). In this study, we performed genetic analyses, including whole genome sequencing (WGS), of all Danish patients registered with CP and estimated the detection rate of pathogenic variants (PV). We identified 231 families in the Polyposis Register, 31 of which had CP. A polyposis-associated gene panel was performed and, if negative, patients were offered WGS and screening for mosaicism in blood and/or adenomas. Next-generation sequencing (NGS) was carried out for 27 of the families (four declined). PVs were detected in 11 families, and WGS revealed three additional structural variants in APC. Mosaicism of a PV in APC was detected in two families. As the variant detection rate of eligible families was 60%, 93% of families in the register now have a known genetic etiology.

Psychiatric and Educational Aspects of Familial Adenomatous Polyposis: A Nationwide Danish Cohort Study With Matched Nonexposed Individuals.

INTRODUCTION: Familial adenomatous polyposis (FAP) is an autosomal, dominantly inherited disorder that predisposes to colorectal cancer. An increased risk of cancer may affect mental health, but the magnitude of this effect remains unknown. We assessed the psychosocial functioning, including the educational level attained and risk of psychiatric comorbidity, of patients with FAP by comparing them with matched nonexposed individuals. METHODS: All Danish patients with FAP diagnosed before April 2021 were identified in the Danish Polyposis Register and paired with 4 matched nonexposed individuals. Educational history, psychiatric contacts or diagnoses ( International Classification of Disease, 10th Revision ), and treatment with antidepressants, anxiolytics, or antipsychotics were compared between patients with FAP and nonexposed individuals. RESULTS: The analysis included 445 patients with FAP and 1,538 nonexposed individuals. The highest educational level reached was significantly lower for patients with FAP ( P < 0.001). When comparing patients with FAP and nonexposed and adjusting for a cancer diagnosis, an increased risk was observed for a psychiatric contact (1.69, 95% confidence interval [CI] 1.25-2.29, P < 0.001), any psychiatric prescription (1.39, 95% CI 1.17-1.66, P < 0.001), a psychiatric diagnosis (1.64, 95% CI 1.19-2.26, P = 0.002), and experiencing any psychiatric event (hazard ratio 1.42, 95% CI 1.20-1.68, P < 0.001). An increased risk was specifically seen for mood (affective) disorders (1.76, 95% CI 1.09-2.83, P = 0.02) and behavioral and emotional disorders (2.01, 95% CI 1.10-3.69, P = 0.02) and the need for antidepressants (1.59, 95% CI 1.24-2.03, P < 0.001) and antipsychotics (1.85, 95% CI 1.26-2.70, P = 0.002). DISCUSSION: Compared with nonexposed individuals, patients with had significantly less education and an increased risk of developing mood and behavioral disorders, with an increased likelihood of needing antidepressants and antipsychotics.

Cancer in Patients With Familial Adenomatous Polyposis: A Nationwide Danish Cohort Study With Matched Controls.

BACKGROUND & AIMS: Familial adenomatous polyposis (FAP) is a hereditary disorder that predisposes patients to colorectal cancer (CRC). Prophylactic colectomy has greatly reduced the risk of CRC. However, new associations between FAP and the risk of other cancers have subsequently emerged. In this study, we assessed the risk of specific primary and secondary cancers among patients with FAP compared with matched controls. METHODS: All known patients with FAP up until April 2021 were identified in the nationwide Danish Polyposis Register and paired with 4 unique controls matched by birth year, sex, and postal code. The risk of overall cancers, specific cancer types, and risk of a second primary cancer was assessed and compared with controls. RESULTS: The analysis included 565 patients with FAP and 1890 controls. The overall risk of cancer was significantly higher for patients with FAP than for controls (hazard ratio [HR], 4.12; 95% confidence interval [CI], 3.28-5.17; P < .001). The increased risk was mainly due to CRC (HR, 4.61; 95% CI, 2.58-8.22; P < .001), pancreatic cancer (HR, 6.45; 95% CI, 2.02-20.64; P = .002), and duodenal/small-bowel cancer (HR, 14.49; 95% CI, 1.76-119.47; P = .013), whereas no significant difference was observed for gastric cancer (HR, 3.29; 95% CI, 0.53-20.23; P = .20). Furthermore, the risk of a second primary cancer was significantly higher for patients with FAP (HR, 1.89; 95% CI, 1.02-3.50; P = .042). Between 1980 and 2020, the risk of cancer among patients with FAP decreased by ∼50%. CONCLUSIONS: Despite an absolute reduction in the risk of developing cancer among patients with FAP, the risk remained significantly higher than for the background population due to colorectal, pancreatic, and duodenal/small-bowel cancers.

Colorectal Cancer in Individuals With Familial Adenomatous Polyposis, Based on Analysis of the Danish Polyposis Registry.

BACKGROUND & AIMS: Familial adenomatous polyposis (FAP) is an autosomal dominant disorder that increases risk for colorectal cancer (CRC). We assessed changes in the incidence and prevalence of CRC, and survival times, of patients with FAP participating in the Danish follow-up study. METHODS: We collected data from the Danish Polyposis Registry, a nationwide, complete registry of patients with FAP that includes clinical information, surgical procedures, follow-up findings, and pathology reports. We compared data between the periods of 1990-1999 and 2000-2017. In 2017, the registry contained 226 families with 721 individuals with FAP. Probands were defined as patients diagnosed based on bowel symptoms, without any knowledge of hereditary bowel disease. Call-up patients were defined as those found to have FAP during screening and due to a diagnosis of FAP in first-degree relatives. RESULTS: Although the mean incidence rate of FAP was stable from 1990-1999 (0.19/100,000/year) to 2000-2017 (0.32/100,000/year) (P = .91), the point prevalence increased from 4.86/100,000 in 1999 to 6.11/100,000 by the end of 2017 (P = .005). During 2000-2017, 25 of 72,218 CRC cases were associated with FAP (0.03%)-this was a significant decrease from 1990-1999 (26/30,005 cases; 0.09%) (P = .001). The risk of CRC was significantly higher for probands (n = 191; 61.6%) than call-up cases (n = 5; 1.9%) (P < .001). All CRCs in call-up patients were detected at the diagnosis of FAP (no cases were identified in the follow-up program). The median life expectancy for call-up patients was 72.0 years (95% CI, 63.3-80.7), compared to 55.0 years for probands (95% CI, 51.2-58.8) (P < .001). Therefore, the tracing and follow-up program increased life expectancy by 17.0 years for first-degree family members. CONCLUSION: The Danish Polyposis Registry enables close monitoring of patients with FAP, reducing risk of CRC and prolonging life.