Genotype-Phenotype Associations of APC Mutations With Pouch Adenoma in Patients With Familial Adenomatous Polyposis

Surveillance and Management of Pouch Neoplasia in Familial Adenomatous Polyposis: A Systematic Review

BACKGROUND

Patients with familial adenomatous polyposis often require prophylactic colectomy with IPAA to treat or reduce the risk of colorectal neoplasia. However, after surgery, patients are still at some risk of developing pouch polyps and even cancer in both handsewn and stapled anastomoses. Management relies mainly on endoscopic or surgical interventions, whereas chemopreventive agents have a limited role in the management and prevention of pouch neoplasia. Novel endoscopic techniques are evolving and may gradually overtake surgical intervention in selected cases. Because familial adenomatous polyposis is relatively rare, there is a scarcity of data regarding the natural history of pouch polyps and cancer in this population.

OBJECTIVE

This systematic literature review aims to describe the evolution, characteristics, various treatment modalities and their outcomes, and recommended surveillance strategies of pouch neoplasia.

DATA SOURCES

PubMed and Cochrane databases and the International Ileal Pouch Consortium (for expert opinion).

STUDY SELECTION

Studies published between 1990 and 2023 in English were included. Studies reporting neoplastic outcomes of only patients with IBD-related pouch neoplasia were excluded.

MAIN OUTCOME MEASURES

Incidence of pouch neoplasia and its outcomes (successful resections, surgical complications, and mortality).

RESULTS

Thirty-five studies were included.

LIMITATIONS

Most studies focused on patients with IBD-related pouch neoplasia; there were scarce data regarding polyposis patients only. Most cohorts were small and retrospective. Data on interventions were mainly descriptive, and no randomized controlled trials were available.

CONCLUSIONS

Pouch adenomas are common and well managed by endoscopic resections because advanced endoscopic techniques are becoming more available. Additional data are required for defining updated recommendations for either endoscopic or surgical intervention. Pouch cancer is a very rare event and may arise despite surveillance. Continued endoscopic surveillance is key in cancer prevention and early detection. The outcome of cancer cases is poor, and management in a referral center should be advised with tumor board discussions. See video from symposium .

Endoscopic management of patients with familial adenomatous polyposis after prophylactic colectomy or restorative proctocolectomy - systematic review of the literature

BACKGROUND

Patients with familial adenomatous polyposis (FAP) develop early colorectal adenomas and if left untreated, progression to cancer is an inevitable event. Prophylactic surgery does not prevent further development of cancer in the rectal remnant, rectal cuff in patients with ileal pouch anal anastomosis (IPAA) and even on the ileal mucosa of the pouch body. The aim of this review is to assess long-term rates of cancer and adenoma development in patients with FAP after prophylactic surgery and to summarise current recommendations for endoscopic management and surveillance of these patients.

MATERIALS AND METHODS

A systematic literature search of studies from January 1946 through to June 2023 was conducted using the PRISMA checklist. The electronic database PubMed was searched.

RESULTS

Fifty-four papers involving 5010 patients were reviewed. Cancer rate in the rectal remnant was 8.8-16.7% in the western population and 37% in the eastern population. The cumulative risk of cancer 30 years after surgery was 24%. Mortality due to cancer in the rectal remnant is 1.1-11.1% with a 5-year survival rate of 55%. The adenoma rate after primary IPAA was 9.4-85% with a cumulative risk of 85% 20 years after surgery and a cumulative risk of 12% for advanced adenomas 10 years after surgery. Cumulative risk for adenomas after ileorectal anastomosis (IRA) was 85% after 5 and 100% after 10 years. Adenomas developed more frequently after stapled (33.9-57%) compared to hand-sewn (0-33%) anastomosis. We identified reports of 45 cancers in patients after IPAA of which 30 were in the pouch body and 15 in the rectal cuff or at the anastomosis.

CONCLUSIONS

There was a significant incidence of cancer and adenomas in the rectal remnant and ileal pouch of FAP patients during the long-term follow-up. Regular endoscopic surveillance is recommended, not only in IRA patients, but also in pouch patients after proctocolectomy.

The Cumulative Incidence and Progression of Ileal Pouch Adenomas in Patients With Familial Adenomatous Polyposis

BACKGROUND

Patients with familial adenomatous polyposis who have undergone restorative proctocolectomy can develop adenomas in the pouch.

OBJECTIVE

To review experience with pouch surveillance and create a classification system for polyposis severity.

DESIGN

A retrospective review of patients undergoing IPAA and follow-up at 1 institution.

SETTING

A center for hereditary colorectal cancer within a quaternary referral center.

PATIENTS

All patients undergoing IPAA and followed endoscopically after surgery by the center.

INTERVENTIONS

Yearly pouchoscopy and treatment of polyps as required.

MAIN OUTCOME MEASURES

Primary outcome measure was incidence and severity of pouch neoplasia and its changes with time.

METHODS

A retrospective study of patients who had a restorative proctocolectomy for familial adenomatous polyposis at Cleveland Clinic. Severity of polyposis was classified on the basis of size, number, and histology.

RESULTS

One hundred sixty-five patients were analyzed. The median age at IPAA was 31 years and 52% were male. The median follow-up was 10.1 years; the median number of pouchoscopies per patient was 4. The median interval between pouchoscopies was 21.9 months. Overall, the incidence of pouch adenomas was found in 47 patients (28.5%). The median time from pouch to first pouch adenoma diagnosis was 10.3 years. The estimated cumulative incidence rates of pouch adenoma at 5, 10, 15, 20, and 30 years after IPAA were 5.9%, 21.7%, 40%, 54.8%, and 69.9%, respectively. At the first diagnosis of pouch adenoma, 25 patients had stage 1, 10 had stage 2, 8 had stage 3, and 4 had stage 4. Twenty of 47 patients progressed to a higher stage. No patient developed cancer.

LIMITATIONS

Genotype was not available for all patients.

CONCLUSIONS

There is an increasing incidence of pouch neoplasia after restorative proctocolectomy, reaching a plateau at 25 years. The polyposis is usually mild but sometimes increases in severity.

LA INCIDENCIA ACUMULADA Y LA PROGRESIN DE LOS ADENOMAS DE LA BOLSA ILEAL EN PACIENTES CON POLIPOSIS ADENOMATOSA FAMILIAR

ANTECEDENTES:Los pacientes con poliposis adenomatosa familiar que se han sometido a una proctocolectomía restauradora pueden desarrollar adenomas en la bolsa.OBJETIVO:Revisamos nuestra experiencia con la vigilancia de la bolsa y creamos un sistema de clasificación para la gravedad de la poliposis.DISEÑO:Una revisión retrospectiva de pacientes sometidos a anastomosis de bolsa ileoanal y seguimiento en una institución.ESCENARIO:Un centro para el cáncer colorrectal hereditario dentro de un centro de referencia cuaternarioPACIENTES:Todos los pacientes sometidos a anastomosis reservorio ileoanal y seguidos por vía endoscópica tras la cirugía por el centro.INTERVENCIONES:Bolsascopia anual y tratamiento de pólipos según sea necesarioPRINCIPALES MEDIDAS DE RESULTADO:Primaria: Incidencia y gravedad de la neoplasia del reservorio y sus cambios con el tiempo.MÉTODOS:Un estudio retrospectivo de pacientes que se sometieron a una proctocolectomía restauradora por poliposis adenomatosa familiar en la Clínica Cleveland. La gravedad de la poliposis se clasificó según el tamaño, el número y la histología.RESULTADOS:Se analizaron 165 pacientes. La mediana de edad del IPAA fue de 31 años y el 52% eran hombres. La mediana de seguimiento fue de 10,1 años; número medio de reservorioscopias por paciente = 4. El intervalo medio entre reservorioscopias fue de 21,9 meses. Incidencia global de adenomas de reservorio = 47/165 (28,5%). Tiempo mediano desde el reservorio hasta el primer diagnóstico de adenoma en reservorio = 10,3 años. La tasa de incidencia acumulada estimada de adenoma de bolsa a los 5, 10, 15, 20, y 30 años después de la IPAA es del 5,9%, 21,7%, 40%, 54,8%, y 69,9%, respectivamente. En el primer diagnóstico de adenoma de la bolsa, 25 pacientes tenían estadio 1, 10 estadio 2, 8 estadio 3 y 4 estadio 4. 20/47 pacientes progresaron a un estadio superior Ningún paciente desarrolló cáncer.LIMITACIONES:Genotipo no disponible para todos los pacientesCONCLUSIONES:Hay una incidencia creciente de neoplasia de la bolsa después de la proctocolectomía restauradora, alcanzando una meseta a los 25 años. La poliposis suele ser leve, pero a veces aumenta en severidad. (Traducción-Dr. Yesenia Rojas-Khalil ).

Long-term outcomes of pouch surveillance and risk of neoplasia in familial adenomatous polyposis

BACKGROUND

Long-term pouch surveillance outcomes for familial adenomatous polyposis (FAP) are unknown. We aimed to quantify surveillance outcomes and to determine which of selected possible predictive factors are associated with pouch dysplasia.

METHODS

Retrospective analysis of collected data on 249 patients was performed, analyzing potential risk factors for the development of adenomas or advanced lesions ( ≥ 10 mm/high grade dysplasia (HGD)/cancer) in the pouch body and cuff using Cox proportional hazards models. Kaplan-Meier analyses included landmark time-point analyses at 10 years after surgery to predict the future risk of advanced lesions.

RESULTS

Of 249 patients, 76 % developed at least one pouch body adenoma, with 16 % developing an advanced pouch body lesion; 18 % developed an advanced cuff lesion. Kaplan-Meier analysis showed a 10-year lag before most advanced lesions developed; cumulative incidence of 2.8 % and 6.4 % at 10 years in the pouch body and cuff, respectively. Landmark analysis suggested the presence of adenomas prior to the 10-year point was associated with subsequent development of advanced lesions in the pouch body (hazard ratio [HR] 4.8, 95 %CI 1.6-14.1; P = 0.004) and cuff (HR 6.8, 95 %CI 2.5-18.3; P < 0.001). There were two HGD and four cancer cases in the cuff and one pouch body cancer; all cases of cancer/HGD that had prior surveillance were preceded by ≥ 10-mm adenomas.

CONCLUSIONS

Pouch adenoma progression is slow and most advanced lesions occur after 10 years. HGD and cancer were rare events. Pouch phenotype in the first decade is associated with the future risk of developing advanced lesions and may guide personalized surveillance beyond 10 years.

An update of the variant spectrum of the APC gene in Iranian familial adenomatous polyposis patients

Familial adenomatous polyposis (FAP) is an autosomal dominant colorectal cancer syndrome that is characterized by the development of multiple adenomas in the colon and rectum with high penetrance rates. This disease has specific features like the occurrence of pathogenic variations in the APC gene and diverse FAP phenotypes due to the occurrence region. In this study we aimed to evaluate pathogenic variants in exons of the APC gene in Iranian patients with FAP. A total of 35 FAP individuals were referred to the gastroenterology ward of Taleghani Hospital. As the aim of the study was to study the germline variations in the participants, the peripheral blood was collected and after the DNA extraction, PCR, and Sanger sequencing processes for the APC gene, the results were evaluated by the ACMG classification guidelines to report their pathogenicity. Accordingly, out of eight specific detected variants, three of them were novel, and the rest were reported previously. These eight variants were all truncating protein and pathogenic, and they were limited to 849-1378 codons. Overall, detected variants revealed discrepancies and parallels with previous reported cases in terms of quantity, occurrence region, and association with demographic and clinicopathological characteristics of patients. The spectrum of detected variants and the patient's phenotype showed distinct characteristics, such as occurrence in specific regions and the absence of extracolonic symptoms like Congenital hypertrophy of the retinal pigment epithelium (CHRPE). These findings open the path to comprehending the typical symptoms, their rarity, and their occurrence in the Iranian population and also due to the facts, we found that the studying of the APC gene alone for diagnosing FAP disease is not sufficient, and considering other genes are completely rational in the case of sequencing and studying the variants.

Management of pouch neoplasia: consensus guidelines from the International Ileal Pouch Consortium

Surveillance pouchoscopy is recommended for patients with restorative proctocolectomy with ileal pouch-anal anastomosis in ulcerative colitis or familial adenomatous polyposis, with the surveillance interval depending on the risk of neoplasia. Neoplasia in patients with ileal pouches mainly have a glandular source and less often are of squamous cell origin. Various grades of neoplasia can occur in the prepouch ileum, pouch body, rectal cuff, anal transition zone, anus, or perianal skin. The main treatment modalities are endoscopic polypectomy, endoscopic ablation, endoscopic mucosal resection, endoscopic submucosal dissection, surgical local excision, surgical circumferential resection and re-anastomosis, and pouch excision. The choice of the treatment modality is determined by the grade, location, size, and features of neoplastic lesions, along with patients' risk of neoplasia and comorbidities, and local endoscopic and surgical expertise.

Cumulative incidence and risk factors for pouch adenomas associated with familial adenomatous polyposis following restorative proctocolectomy

BACKGROUND

The emergence of restorative total proctocolectomy has significantly reduced the lifetime colorectal cancer risk associated with familial adenomatous polyposis (FAP). However, adenomas may develop in the ileal pouch over time and may even progress to carcinoma. We evaluated the cumulative incidence, time to development, and risk factors associated with ileal pouch adenoma.

AIM

To evaluate the cumulative incidence, time to development, and risk factors associated with pouch adenoma.

METHODS

In this retrospective, observational study conducted at a tertiary center, 95 patients with FAP who underwent restorative proctocolectomy at our center between 1989 and 2018 were consecutively included. The mean follow-up period was 88 mo.

RESULTS

Pouch adenomas were found in 24 (25.3%) patients, with a median time of 52 mo to their first formation. Tubular adenomas were detected in most patients (95.9%). There were no high-grade dysplasia or malignancies. Of the 24 patients with pouch adenomas, 13 had all detected adenomas removed. Among the 13 patients who underwent complete adenoma removal, four (38.5%) developed recurrence. Among 11 (45.8%) patients with numerous polyps within the pouch, seven (63.6%) exhibited progression of pouch adenoma. The cumulative risks of pouch adenoma development at 5, 10, and 15 years after pouch surgery were 15.2%, 29.6%, and 44.1%, respectively. Severe colorectal polyposis (with more than 1000 polyps) was a significant risk factor for pouch adenoma development (hazard ratio, 2.49; 95% confidence interval: 1.04-5.96; P = 0.041).

CONCLUSION

Pouch adenomas occur at a fairly high rate in association with FAP after restorative proctocolectomy, and a high colorectal polyp count is associated with pouch adenoma development.

Incidence and Risk Factors of Cancer in the Anal Transitional Zone and Ileal Pouch following Surgery for Ulcerative Colitis and Familial Adenomatous Polyposis

Proctocolectomy with ileal pouch-anal anastomosis is the intervention of choice for ulcerative colitis and familial adenomatous polyposis requiring surgery. One of the long-term complications is pouch cancer, having a poor prognosis. The risk of high-grade dysplasia and cancer in the anal transitional zone and ileal pouch after 20 years is estimated to be 2 to 4.5% and 3 to 10% in ulcerative colitis and familial polyposis, respectively. The risk factors for ulcerative colitis are the presence of pre-operative dysplasia or cancer, disease duration > 10 years and severe villous atrophy. For familial polyposis, the risk factors are the number of pre-operative polyps > 1000, surgery with stapled anastomosis and the duration of follow-up. In the case of ulcerative colitis, a pouchoscopy should be performed annually if one of the following is present: dysplasia and cancer at surgery, primary sclerosing cholangitis, villous atrophy and active pouchitis (every 5 years without any of these factors). In the case of familial polyposis, endoscopy is recommended every year including chromoendoscopy. Even if anal transitional zone and ileal pouch cancers seldom occur following proctectomy for ulcerative colitis and familial adenomatous polyposis, the high mortality rate associated with this complication warrants endoscopic monitoring.

Diagnosis and classification of ileal pouch disorders: consensus guidelines from the International Ileal Pouch Consortium

Restorative proctocolectomy with ileal pouch-anal anastomosis is an option for most patients with ulcerative colitis or familial adenomatous polyposis who require colectomy. Although the construction of an ileal pouch substantially improves patients' health-related quality of life, the surgery is, directly or indirectly, associated with various structural, inflammatory, and functional adverse sequelae. Furthermore, the surgical procedure does not completely abolish the risk for neoplasia. Patients with ileal pouches often present with extraintestinal, systemic inflammatory conditions. The International Ileal Pouch Consortium was established to create this consensus document on the diagnosis and classification of ileal pouch disorders using available evidence and the panellists' expertise. In a given individual, the condition of the pouch can change over time. Therefore, close monitoring of the activity and progression of the disease is essential to make accurate modifications in the diagnosis and classification in a timely manner.

Heterozygous APC germline mutations impart predisposition to colorectal cancer

Familial adenomatous polyposis (FAP) is an inherited syndrome caused by a heterozygous adenomatous polyposis coli (APC) germline mutation, associated with a profound lifetime risk for colorectal cancer. While it is well accepted that tumorigenic transformation is initiated following acquisition of a second mutation and loss of function of the APC gene, the role of heterozygous APC mutation in this process is yet to be discovered. This work aimed to explore whether a heterozygous APC mutation induces molecular defects underlying tumorigenic transformation and how different APC germline mutations predict disease severity. Three FAP-human embryonic stem cell lines (FAP1/2/3-hESC lines) carrying germline mutations at different locations of the APC gene, and two control hESC lines free of the APC mutation, were differentiated into colon organoids and analyzed by immunohistochemistry and RNA sequencing. In addition, data regarding the genotype and clinical phenotype of the embryo donor parents were collected from medical records. FAP-hESCs carrying a complete loss-of-function of a single APC allele (FAP3) generated complex and molecularly mature colon organoids, which were similar to controls. In contrast, FAP-hESCs carrying APC truncation mutations (FAP1 and FAP2) generated only few cyst-like structures and cell aggregates of various shape, occasionally with luminal parts, which aligned with their failure to upregulate critical differentiation genes early in the process, as shown by RNA sequencing. Abnormal disease phenotype was shown also in non-pathological colon of FAP patients by the randomly distribution of proliferating cells throughout the crypts, compared to their focused localization in the lower part of the crypt in healthy/non-FAP patients. Genotype/phenotype analysis revealed correlations between the colon organoid maturation potential and FAP severity in the carrier parents. In conclusion, this study suggest that a single truncated APC allele is sufficient to initiate early molecular tumorigenic activity. In addition, the results hint that patient-specific hESC-derived colon organoids can probably predict disease severity among FAP patients.

Long-term outcomes of metachronous neoplasms in the ileal pouch and rectum after surgical treatment in patients with familial adenomatous polyposis

Background and study aims  Restorative proctocolectomy has become the most common surgical option for patients with familial adenomatous polyposis (FAP). However, adenomas and even carcinomas may develop in the ileal pouch over time. The aim of this study was to evaluate the long-term incidence and nature of ileal pouch or distal ileal adenomas and carcinomas in patients with FAP. Patients and methods  This was a retrospective study of 47 FAP patients with Kock's continent ileostomy (Kock) (n = 8), ileorectal anastomosis (IRA) (n = 13), and ileal pouch-anal anastomosis (IPAA) (n = 26). Patients were followed with a standardized protocol including chromoendoscopy and biopsies of visible polyps in the ileal pouch, distal ileum, and rectum every 6 to 12 months. Results  Median follow-up was 21.0 years. Overall risk of adenoma development was significantly higher in IRA patients, with incidence rates of 85 % and 100 % at 5 and 10 years' follow-up, respectively, compared to pouch patients (Kock + IPAA) ( P  < 0.001). However, there was also a high frequency of adenomas in the ileal pouch mucosa, with rates of 12 %, 33 %, and 68 %, at 5, 10, and 20 years of follow-up, respectively. Maximum size of ileal pouch adenomas was significantly related to time since surgery ( P  = 0.0214). Six cases of advanced adenomas including two cases of adenocarcinomas developed in the ileal pouch mucosa. Conclusions  There is a significant incidence of adenoma(s) in the ileal pouch of FAP patients on long-term follow-up. Regular endoscopic surveillance is recommended, not only in IRA patients, but also in pouch patients after proctocolectomy.