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Ambe et al. Mini-invasive Surg 2018;2:37 I http://dx.doi.org/10.20517/2574-1225.2018.45 Page 5 of 13

yposis of the upper GI is common in FAP patients. Duodenal polyps for example dependent of patient’s
age, occur in almost 90% of FAP patients and duodenal cancer is the second most common malignancy in
[34]
FAP patients .
The diagnosis of FAP (aFAP) is usually straight forward. Identifying multiple, up to hundreds of polyps on
colonoscopy in an individual with a family history of FAP is de facto the actionable phenotype. Alongside,
the presence of extra-colonic manifestations e.g. osteomas, congenital hypertrophy of the retinal pigment
epithelium, etc. are indicative of FAP. APC mutation analysis by genetic testing would confirm the suspect-
ed diagnosis. However, increasingly rarer heritable syndromes are clinically indistinguishable regarding
the colorectal phenotype. In order to adequately judge the risks, it is increasingly important to identify the
underlying gene, as demonstrated by gene panel testing with surprising results. This is leading to a shift in
paradigm regarding our clinical ability to identify hereditary predispositions to cancer.

Individuals with genetically confirmed FAP as well as individuals at risk should undergo endoscopic sur-
veillance every 1-2 years. The recommended surveillance frequency increases to once per year as soon as
adenomatous polyps appear. This interval stays until surgical management via proctocolectomy (colectomy
[35]
for aFAP) is performed and is further warranted for manifestations in other organs .
Generally accepted indications for surgical management include large adenomas > 1 cm, numerous ad-
enomas (> 20), unfavorable histology (high grade dysplasia or carcinoma), chronic anemia and failure to
thrive. Otherwise, surgical management is performed in a personalized manner, usually if possible post-
[36]
poned until after puberty .
Restorative proctocolectomy with an ileal pouch anal anastomosis (IPAA) is the recommended treatment
for classical FAP. The vulnerable colon and rectum are removed leaving a 2 cm sensitive rectal cuff (transi-
[37]
tion zone) above the anus for solid-liquid-gas discrimination . The rectal mucosal cuff, however, must be
[38]
seen as a risky island with a residual risk of mucosal dysplasia as high as 4.5% after 10 years follow-up .
Thus the need for a stringent endoscopic follow-up cannot be over emphasized. Some surgeons perform a
mucosectomy during IPAA with the goal of preventing future rectal cuff cancer although poor functional-
[39]
ity has been reported following mucosectomy . This has been attributed primarily to loss of the sensi-
tive transitional zone and secondary to injury of the sphincter apparatus during dissection. We perform
mucosectomy in selected cases when the transitional zone is involved in the disease process at the time
of primary surgery. Also, the recurrence rate of neoplasia following primary mucosectomy remains high
and may be repeated. For this reason at our institution we have also implemented the taTME approach
for benign disease. By performing a double purse-string anastomosis at the height of the dentate line the
rectal remnant and all mucosa is eliminated, it may be expected that this will further reduce the neoplastic
changes seen today in the ageing FAP population with a rectal remnant of (at least) 2 cm. Functional re-
sults in this small series, to date are excellent but require prospective documentation.

Preserving the rectum and it’s reservoir function via a colectomy with an ileorectal anastomosis is also
an established option in most aFAP individuals. This option is open to individuals with little or no rectal
polyposis. The advantages of the ileorectal anastomosis include a reduced number of bowel movements,
a better continence and potentially a better quality of life compared to IPAA, although this has not been
[40]
proven . However, such patients need to be closely monitored (annually initially, then in 4-6 monthly
intervals after the age of 50) via endoscopy of the disposed rectal remnant. Subtotal colectomy with ileosig-
moid anastomosis should be considered in individuals with aFAP with polyposis of the proximal colon.
These options should be considered in the attenuated FAP phenotype and especially in female patients of
reproductive age to avoid pelvic dissection and formation of adhesions.