Genotype-phenotype correlation of small-intestinal polyps on small-bowel capsule endoscopy in familial adenomatous polyposis

Clinical features and distribution of the APC variant in duodenal and ampullary polyps in patients with familial adenomatous polyposis: a multicenter retrospective cohort study in Japan

BACKGROUND

Management of duodenal or ampullary adenomas in patients with familial adenomatous polyposis (FAP) is a major challenge for clinicians. Insufficient data are available to evaluate the clinical manifestations and distribution of adenomatous polyposis coli (APC) variants in these patients.

METHODS

We enrolled 451 patients with data regarding duodenal or ampullary polyps from 632 patients with FAP retrospectively registered in a nationwide Japanese multicenter study. Clinicopathological features and distribution of APC variants were compared between patients with and without duodenal or ampullary polyps.

RESULTS

Duodenal and ampullary polyps were found in 59% and 18% of patients with FAP, respectively. The incidence of duodenal cancer was 4.7% in patients with duodenal polyps, and that of ampullary cancer was 18% in patients with ampullary polyps. Duodenal polyps were significantly associated with the presence of ampullary polyps and jejunal/ileal polyps. Duodenal polyps progressed in 35% of patients with a median follow-up of 776 days, mostly in those with early Spigelman stage lesions. Ampullary polyps progressed in 50% of patients with a follow-up of 1484 days. However, only one patient developed a malignancy. The proportion of patients with duodenal polyps was significantly higher among those with intermediate- or profuse-type APC variants than attenuated-type APC variants. The presence of duodenal polyps was significantly associated with ampullary and jejunal/ileal polyps in patients with intermediate- or profuse-type APC variants.

CONCLUSIONS

Periodic endoscopic surveillance of the papilla of Vater and small intestine should be planned for patients with FAP with duodenal polyps.

Update on Surgical Management of FAP

Familial adenomatous polyposis (FAP) is an autosomal dominant disease caused by pathogenic germline adenomatous polyposis coli mutation, and characterized with multiple adenomas in the colon and the rectum. Various genetic variants have been confirmed to be associated with corresponding FAP phenotypes, which play important roles in the diagnosis and surgical treatment of FAP. Generally, proctocolectomy is recommended for FAP patients at the age of 20s. Exceptionally, for patients with attenuated FAP, high-risk of desmoid, chemoprevention therapy, or other circumstances, surgery can be postponed. With the wide application of minimal invasive surgery in colorectal cancer, laparoscopic, robotic surgery, and natural orifice specimen extraction are proved to be feasible for FAP patients, but high-level evidences are needed to confirm their safety and advantages. In the times of precise medicine, the surgical management of FAP should vary with individuals based on genotype, phenotype, and clinical practice. Therefore, in addition to innovation in surgical procedures, investigation in links between genetic features and phenotypes will be helpful to optimize the surgical management of FAP in the future.

Familial intestinal polyposis and device assisted enteroscopy: where do we stand?

INTRODUCTION

Hereditary polyposis syndromes are a group of inherited disorders associated with a high risk of developing colorectal cancer. The best known ones are familial adenomatous polyposis (FAP), Peutz-Jeghers (PJS), juvenile polyposis and Cowden syndromes, as well as conditions predisposing to cancer, such as Lynch syndrome. Some of them are characterized by an increased risk of small bowel polyps occurrence.

AREAS COVERED

Literature search in PubMed was performed in November 2022 and a narrative review was carried out. Since performing small bowel polypectomy is important in such patients, device assisted enteroscopy (DAE) is the key for this procedure. A screening strategy for small bowel polyps is recommended only for PJS. Guidelines endorse either magnetic resonance imaging (MRI) or videocapsule endoscopy (VCE) every 1-3 years, according to the phenotype of the disease. Enteroscopy should be considered for therapeutic purpose in patients with a positive VCE or MRI. DAE has a central role in the resection of polyps larger than mm or causing symptoms of subocclusion or intussusception. Both single (SBE) and double balloon enteroscopy (DBE) are indicated and able to resect polyps up to 6-10 cm. American guidelines have restricted the indications to small bowel enteroscopy only to FAP patients with grade IV Spiegelman.

EXPERT OPINION

Only some groups of patients (PJS, FAP with demonstrated small bowel polyp burden) may benefit from DAE.