The Diagnostic Yield of Genetic Testing in Patients With Multiple Colorectal Adenomas: A Specialist Center Cohort Study.

INTRODUCTION: Adenoma multiplicity is associated with increased colorectal cancer (CRC) risk. The utility of genetic testing in patients with multiple colorectal adenomas (MCRA) remains uncertain. We evaluated the diagnostic yield of mutations in polyposis- and CRC-associated genes in patients with MCRA. METHODS: We performed a cross-sectional review of adult patients with 10-99 cumulative adenomas from the prospective database at the St Mark's Hospital Polyposis Registry and Family Cancer Clinic between 1999 and 2021. Genetic testing was performed for adenomatous polyposis-associated genes, hamartomatous polyposis-associated genes, and nonpolyposis colorectal cancer-associated genes. Clinicopathological outcomes were extracted for multiple logistic regression analysis. RESULTS: Two hundred fifty-nine patients with MCRA (median age 61 [interquartile range 53-69] years) were identified. Sixty-six patients (25.5%) had a pathogenic variant or likely pathogenic variant, with APC and biallelic MUTYH mutations constituting the majority of identified pathogenic variant/likely pathogenic variants. Diagnostic yields were greater than 10% at any adenoma burden. In univariate analysis, higher adenoma burden and younger age were associated with higher yield (both P < 0.0001). In patients with MCRA with 10-19 adenomas without a relevant personal or family history of CRC, the diagnostic yield was nil. In multiple logistic regression analysis, higher adenoma burden, younger age, personal history of CRC, and first-degree familial history of CRC were associated with higher diagnostic yield. DISCUSSION: Diagnostic yield of >10% at any adenoma burden supports current guidance for constitutional genetic testing in patients with MCRA, although the low yield in people older than 60 years with 10-19 adenomas suggests that a stratified approach might be appropriate.

Risk-stratified faecal immunochemical testing (FIT) for urgent colonoscopy in Lynch syndrome during the COVID-19 pandemic.

BACKGROUND: Lynch syndrome is a hereditary cancer disease resulting in an increased risk of colorectal cancer. Herein, findings are reported from an emergency clinical service implemented during the COVID-19 pandemic utilizing faecal immunochemical testing ('FIT') in Lynch syndrome patients to prioritize colonoscopy while endoscopy services were limited. METHODS: An emergency service protocol was designed to improve colonoscopic surveillance access throughout the COVID-19 pandemic in England for people with Lynch syndrome when services were extremely restricted (1 March 2020 to 31 March 2021) and promoted by the English National Health Service. Requests for faecal immunochemical testing from participating centres were sent to the National Health Service Bowel Cancer Screening South of England Hub and a faecal immunochemical testing kit, faecal immunochemical testing instructions, paper-based survey, and pre-paid return envelope were sent to patients. Reports with faecal haemoglobin results were returned electronically for clinical action. Risk stratification for colonoscopy was as follows: faecal haemoglobin less than 10 µg of haemoglobin/g of faeces (µg/g)-scheduled within 6-12 weeks; and faecal haemoglobin greater than or equal to 10 µg/g-triaged via an urgent suspected cancer clinical pathway. Primary outcomes of interest included the identification of highest-risk Lynch syndrome patients and determining the impact of faecal immunochemical testing in risk-stratified colonoscopic surveillance. RESULTS: Fifteen centres participated from June 2020 to March 2021. Uptake was 68.8 per cent amongst 558 patients invited. For 339 eligible participants analysed, 279 (82.3 per cent) had faecal haemoglobin less than 10 µg/g and 60 (17.7 per cent) had faecal haemoglobin greater than or equal to 10 µg/g. In the latter group, the diagnostic accuracy of faecal immunochemical testing was 65.9 per cent and escalation to colonoscopy was facilitated (median 49 versus 122 days, χ2 = 0.0003, P < 0.001). CONCLUSION: Faecal immunochemical testing demonstrated clinical value for Lynch syndrome patients requiring colorectal cancer surveillance during the pandemic in this descriptive report of an emergency COVID-19 response service. Further longitudinal investigation on faecal immunochemical testing efficacy in Lynch syndrome is warranted and will be examined under the 'FIT for Lynch' study (ISRCTN15740250).

Regular endoscopic surveillance and polypectomy is effective in managing rectal adenoma progression following colectomy and ileorectal anastomosis in patients with familial adenomatous polyposis.

AIM: Total colectomy with ileorectal anastomosis (TC-IRA) is a surgical option for patients with familial adenomatous polyposis (FAP). Regular endoscopic surveillance of the rectum is recommended to prevent rectal cancer. We aimed to document polyp progression in the rectum following TC-IRA and evaluate the role of polypectomy during surveillance. METHOD: Patients with FAP who underwent TC-IRA between 1990 and 2017 were identified. Demographic, endoscopic and genetic data were retrieved. Cumulative rectal adenoma (polyp) counts were obtained, whilst accounting for any polypectomies during the study period. The rate of polyp progression and factors influencing secondary proctectomy were evaluated. RESULTS: One hundred and ninety-nine patients fulfilled our inclusion criteria, of which 44% were male. The median age at colectomy was 19 (range 11-70) years and median preoperative rectal polyp count was 7 (range 0-50). All patients had an APC pathogenic variant, of which 151 (79%) were 5' of the mutation cluster region (MCR), 19 (10%) in the MCR, six (3%) were 3' of the MCR and 15 (8%) had a gross deletion. After a median follow-up of 8.6 (range1-27) years and a median of 11 (range 2-37) flexible sigmoidoscopies per patient, the median rate of polyp progression was 5.5 polyps/year (range 0-70.2). There was no evidence of polyp regression. Eight (4%) patients underwent secondary proctectomy for neoplasia, of which one (0.5%) had rectal adenocarcinoma. A total of 13,527 polyps were removed, a median of 35 polyps/patient (range 0-829). The rate of polyp progression was not significantly associated with genotypic or phenotypic factors. CONCLUSION: Progression of rectal adenoma burden following TC-IRA appears to be slow and dependent on the length of follow-up. In the modern era of stringent endoscopic surveillance and therapeutic procedures such as cold snare polypectomy, the rate of secondary proctectomy and the risk of rectal cancer after TC-IRA are very low. These findings are important when counselling patients with regard to the choice of surgery for FAP and implementing endoscopic surveillance.

Polyp Progression in Paediatric Patients With Familial Adenomatous Polyposis: A Single-centre Experience.

OBJECTIVES: Prophylactic colectomy at a premalignant stage is the cornerstone of management of familial adenomatous polyposis (FAP). Before surgery, colonoscopy surveillance is recommended in children with FAP. This study aimed to examine the natural history of FAP in children by evaluating adenoma progression and factors influencing timing of colectomy. METHOD: Patients with FAP younger than 18 years at first surveillance colonoscopy and who had undergone more than 1 colonoscopy were identified. Demographic, endoscopic, genetic, and surgical data were retrieved. Cumulative adenoma (polyp) counts were obtained while accounting for any polypectomies during the study period. The rate of polyp progression and factors influencing the timing of colectomy were evaluated. RESULTS: Eighty-four patients (50% boys; mean age at first colonoscopy 13 years [standard deviation 1.97]) were identified, of which 83 had a family history of FAP. At first colonoscopy, 67 (79%) had <100 adenomas and 29 (35%) had colonic polyps identified despite rectal sparing. The median rate of polyp progression per patient was 12.5 polyps/year (range 0-145). Of the 45 (54%) patients who had undergone surgery, 41 (91%) underwent colectomy with ileorectal or ileodistal sigmoid anastomosis. Polyp progression did not alter the choice of surgical intervention in any patient. CONCLUSION: Our results suggest that adenoma number remains relatively stable in the majority of children under surveillance. Tailored surveillance intervals according to phenotype are a more appropriate strategy as recommended by recently published guidelines.