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Page 4 of 13 Ambe et al. Mini-invasive Surg 2018;2:37 I http://dx.doi.org/10.20517/2574-1225.2018.45

copy and malignancy represent the most common indications for surgery. LS, in contrast to familial pol-
yposis (FAP) is not associated with full penetrance, therefore prophylactic colorectal resection is not gener-
ally recommended. However, the indication for surgery can be extended in selected cases as personalized
decision-making based on gene and gender [16-18] . A personalized option might include a combination of
(sub)total colectomy in place of the indicated oncological segmental resection at the time of a first CRC in
combination with a purely prophylactic hysterectomy with or without adnectomy in a female with LS after
completion of family planning.

Surgical management of histologically confirmed LS-associated CRC as a minimal requirement should be
in accordance with current oncologic standards. Therefore colon cancer should be managed via colectomy
(right or left) without compromise in the oncological thoroughness, despite the observed better prognosis
[19]
of MMR-deficient tumors. Possibly, complete mesocolic excision (CME) as described by Hohenberger et al.
may as is suggested for sporadic cancer demonstrate superiority - this evidence is as of yet not demonstrat-
ed. In accordance, cancer of the proximal rectum or rectosigmoid junction should be managed with ante-
rior rectal resection and partial mesorectal excision, whilest mid and low rectal cancers are managed with
[20]
total mesorectal excision as described by Heald et al. . However, it is mandatory to discuss with patients
a prophylactically extended option of additional removal of the colorectum as an alternative to segmental
procedures and regular colonoscopies.

The benefits of the laparoscopic approach are well documented for oncological conditions which represent
[21]
the preferred means of access . For cancer of the mid and lower rectum the transanal total mesorectal
excision (taTME) is of increasing importance due to suggested advantages with regard to identification and
preservation of pelvic nerves [22,23] .

FAP
FAP is the second most common monogenetic hereditary syndrome with predisposition to CRC. FAP is
caused by germline mutations of the tumor suppressor APC-gene on chromosome 22q21-22 involving over
[24]
2800 codons . The prevalence of this syndrome has been estimated at 1 in 10,000 individuals with the
[25]
spectrum of clinical presentation depending largely on the mutated codons . Clinically, classical FAP
[26]
can be distinguished from an attenuated variant (aFAP) . Both conditions are caused by mutations in the
same gene, which are allocated to different coding regions.
Classically, FAP is characterized by the development of hundreds to thousands of colonic polyps (adenomas)
[27]
early in the adolescence . Unlike many other hereditary syndromes with predisposition to CRC, FAP
[28]
has a one hundred percent penetrance with regard to the development of CRC . Therefore, FAP patients
would inevitably develop CRC usually before the age of 40 years if left untreated. More so, close to 13%
of FAP patients develop CRC by the age of 25 and about 95% would have developed CRC by the age of 50
[29]
years .
The attenuated form of FAP (aFAP) is clinically characterized by a later onset on colonic polyposis after
[30]
ten years compared to cases with classical FAP . Besides, individuals with aFAP present with a significant
fewer amount of polyps, usually tens to a few hundreds, mostly in the proximal colon. Unlike FAP, aFAP is
not associated with a complete penetrance for CRC. The lifetime risk of CRC in aFAP is estimated at about
[31]
70% .
FAP (and aFAP) are not only limited to the colon. Extra-colonic manifestations are very common since the
[32]
germline mutations can affect virtually every organ . Current genetic studies, have identified formerly
defined syndromes like Gardner syndrome characterized by FAP, epidermoid cysts, osteomas, desmoid
[33]
tumors and dental anomalities as merely some aspects of presentation of FAP syndrome . Equally, pol-