Familial Adenomatous Polyposis

In these patients, the disease begins at the age of 8-10 years with a small number of colonic polyps, increasing progressively until the colon becomes studded with adenomas. Endoscopy mainly plays a diagnostic role (Fig. 2) since colorectal cancer should be considered an inevitable consequence in the natural history of FAP, appearing approximately 15 years after the onset of the polyps. For this reason prophylactic proctocolectomy is the procedure of choice for this condition. After the proctocolectomy, the ileal pouch could develop polyps even if the risk of pouch cancer in FAP is unclear. Therefore, long-term endo-scopic surveillance (pouchoscopy) is recommended [1].

It is known that FAP patients frequently develop

Normal mucosa

Early adenoma

K-ras

Intermediate adenoma

DCC/18q genes

Late adenoma

Carcinoma

Fig. 1. Steps of colon carcinogenesis

Table 1. Features of adenomatous polyposis syndromes

Syndrome

Type of

Location of

Other manifestations

Germline gene

polyps

polyps

mutation

FAP (autosomal

Adenomas

Colon,

Benign: desmoid

APC

dominant)

(100s-1000s)

duodenum,

tumours, osteomas,

jejunum, ileum,

epidermoid cysts,

stomach, (fundic

CHRPE'

gland polyps)

Malignant:

medulloblastoma,

hepatoblastoma, thyroid

cancer, adrenal cancer

Attenuated FAP

Adenomas

Colon,

Osteomas

APC (5' and 3')

(autosomal

(5-100)

duodenum,

(mandible)

APC E1317Q

dominant)

stomach

MYH polyposis

Adenomas

Colon,

Osteomas, CHRPE"

MYHb

(autosomal

(5-100)

duodenum,

recessive)

stomach

'CHRPE, congenital hypertrophy of the retinal pigment epithelium; bMYH, is a gene that repairs DNA damage (if defecting, the resulting loss of APC function causes an increase in multiple adenomas)

'CHRPE, congenital hypertrophy of the retinal pigment epithelium; bMYH, is a gene that repairs DNA damage (if defecting, the resulting loss of APC function causes an increase in multiple adenomas)

tumours (either benign or malignant) in other organs besides the colon, mainly in the upper GI tract (stomach, small intestine). Gastric polyps occur in 30-100%, but adenomas are uncommon, occurring in approximately 5% of FAP patients usually in the gastric antrum (Fig. 3). The development of gastric carcinoma in FAP patients is only very high in Japan where the gastric cancer rate in the general population is higher. In other populations it occurs in less than 5% of the population. Proximal small-bowel cancer is one of the two leading causes of death in FAP patients with previous colectomy [2,3]. It develops

Small Bowel From Fap Patient
Fig. 2. Diffuse polyposis of the colon
Stomach Polyps
Fig. 3. Gastric polyps in FAP

from pre-existing adenomas which are present in approximately 100% of these patients in the duodenum (Fig. 4). Duodenal adenomas can be classified through macroscopic and histologic criteria in five stages (0-IV) following the Spigelman's classification (Table 2) [4, 5].

In all FAP patients submitted to proctocolectomy, screening and surveillance for duodenal and small-bowel polyps are mandatory. Duodenoscopy (side vision) should be performed, taking several biopsies from the duodenal papilla and from all the polyps,

Fig. 4. Duodenal adenoma in FAP

Table 2. Spigelman's score and classification (modified)

Score

No. of duodenal polyps

Size (mm)

Histology

2 points

3 points

1-4 5-20 > 20

Tubulous-villous

Villous

Low grade High grade

5-6 7-8 9-12

Duodenal Adenomatosis Fap

Fig. 4. Duodenal adenoma in FAP

Villous Adenoma Images
Fig. 5. Duodenal chromoendoscopy (methylene blue)

also by means of chromoendoscopy (Fig. 5). At the first duodenoscopy, the prevalence of duodenal adenomatosis is 58-74% in the major series, and only about 10% of adenomas are diagnosed histologically.

The risk of duodenal carcinoma is related to the Spigelman stage (about 7% in stage IV, 0.7% in stage 0—III) [6]. In Spigelman stage III-IV, endoscopic ultrasonography is recommended to ensure that invasive growth has not occurred. The regular endo-scopic surveillance of the duodenum should be offered to all FAP patients (Table 3) [7]. The first upper endoscopy should be carried out at the age of 30 years and include multiple random biopsies taken from the duodenal mucosa in patients without visible polyps. Endoscopic surveillance (included ultra-sonography) is recommended at intervals of 3 months in patients who are not suitable for or refuse surgery.

Screening or surveillance for small-bowel polyps is difficult with current technologies. By means of traditional push enteroscopy (PE), up to only 30% of the small-bowel length can be visualized. A new promising endoscopic method for allowing complete

Table 3. Programme for surveillance and treatment of duodenal adenomatosis

Spigelman's stage

Frequency of endoscopy

0

5 yearsa

I

5 years'

II

3 yearsb

III

1—2 yearsb

IV

Endoscopic ultrasonography

Consider pancreas sparing and

pylorus sparing duodenectomy

"Including multiple random biopsies from the mucosal fold in patients without visible polyps; bIncluding multiple biopsies from polyps

"Including multiple random biopsies from the mucosal fold in patients without visible polyps; bIncluding multiple biopsies from polyps

Fig. 6. Double balloon enteroscopy visualisation, biopsies and treatment in the small bowel is the double balloon enteroscopy (DBE; push and pull; Fig. 6), but the use of this technique in FAP patients is not yet routine [8].

Capsule endoscopy (CE) is another recent technology that allows a non-invasive endoscopic assessment of the entire small bowel (Fig. 7) [9]. Published clinical trials have shown that CE carries a high diagnostic yield in patients suffering from obscure gastrointestinal bleeding [10—13]. Beyond this role, the value of CE in other small bowel disorders has to be evaluated. CE may also be used to search for tumours or tumour-like lesions in patients that present with a known increased risk of small bowel carcinomas such as familial adenomatous polyposis, Peutz-Jeghers syndrome and familial juvenile poly-posis. The comparison between CE and DBE in detecting small bowel tumours is shown in Table 4 [12—16].

In FAP patients, preliminary results [17] suggest that capsule endoscopy can only be used additionally to identify patients with significant distal jejunal polyposis. However, this is suggested to be a rather infrequent situation. The correlation between the findings of capsule endoscopy and conventional endoscopy is reported in Table 5. Active control of the capsule endoscopy, the precise assessment of polyps size and the opportunity to obtain biopsies are important long-term future requirements for extending the indication to FAP patients.

In the first study that compares the value of CE and DBE in the diagnosis of small intestinal polypo-sis [18], the diagnostic yield of DBE was superior in comparison to CE in almost the same area explored. Even Yamamoto et al. [19] have shown that with this method, total enteroscopy can be achieved by combining antegrade and retrograde examinations, however, DBE in comparison with CE is an inconvenient and invasive procedure that requires specialized equipment, sedation of the patients, fluoroscopy and

Table 4. Comparison between capsule endoscopy (CE) and push enteroscopy (PE) in detecting small-bowel tumours

Author Year No. of patients No. of tumours (%)

Total PE CE

Capsule Endoscopy For Duodenal Polyps
Fig. 7. Ileal polyp at capsule endoscopy

a prolonged examination time.

At the end of this report, the role of endoscopic procedures in FAP patients can be summarized as follows (Table 6):

- Conventional colonoscopy should be performed with multiple biopsies and polypectomy, starting at the age of 8-10, considering prophylactic proc-

Table 6. Endoscopic procedures in FAP GI site

Stomach Duodenum Small bowel

Colon Ileal pouch

Table 5. Correlation of Spigelman's score (modified) measured by capsule endoscopy and conventional endoscopy

Capsule endoscopy Conventional endoscopy (score) (score)

Table 5. Correlation of Spigelman's score (modified) measured by capsule endoscopy and conventional endoscopy

Capsule endoscopy Conventional endoscopy (score) (score)

No. of patients

0

1-2

3-4 5-6

0

5

1

- -

1-2

1

-

1-

3-4

1

±

l-

5-6

-

-

1

tocolectomy when the number of polyps are increasing and the risk of carcinoma is very high (10-15 years from the onset of polyps).

- Pouchoscopy, after proctocolectomy, should be performed because the ileal pouch could develop polyps even if the real risk of pouch cancer is unclear.

- Gastric endoscopy to show fundic gland polyps (frequent) and adenomas (rare).

- Duodenoscopy with side view to remove all the polyps, particularly near the papilla, and to perform several random biopsies by using chromoen-doscopy with methylene blue.

- Endoscopic ultrasonography in patients with Spigelman stages III-IV.

Endoscope

Findings

Time and follow-up

Conventional Side vision

(±chromoendoscopy) Capsule endoscopy, double balloon enteroscopy Conventional Conventional

Fundic gland polyps

(adenoma)

Adenomas

Polyps

Adenomas (100s-1000s) Polyps

At first diagnosis

Spigelman stage (endoscope ultrasonography stages III-IV) At first diagnosis? Surveillance?

- Capsule endoscopy to better explore the small bowel.

- DBE to eventually remove the intestinal polyps found at CE examination.

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    What causes polyps in the stomach?
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