Table 9. Practice Guidelines for Diagnosis and Colon Surveillance of Lynch Syndrome continued...
Similar results regarding a decrease in the number of metachronous CRCs after subtotal or total abdominal colectomy at the time of diagnosis of first CRC were reported by retrospective studies from Creighton University and the Cancer Family Registries.[346,346] No survival advantage was demonstrated when performing a more extensive procedure compared to a segmental resection in these studies.
When considering the surgical options, it is important to recognize that a subtotal colectomy will not eliminate the rectal cancer risk. The lifetime risk of developing cancer in the rectal remnant following a subtotal colectomy has been reported to be 12% at 12 years postcolectomy. In addition to the general complications of surgery, there are the potential risks of urinary and sexual dysfunction and diarrhea following a subtotal colectomy, with these risks being greater the more distal the anastomosis. Therefore, the choice of surgery must be made on an individual basis by the surgeon and the patient. In all LS patients who have undergone a partial surgical resection of the colon, endoscopic surveillance should be the mainstay of follow-up.
The data on a decrease in metachronous CRC, and thus, a decrease in the number of surgeries, support the notion of routine subtotal colectomy in patients with LS. However, it appears that this has not penetrated surgical practice where functional outcomes weigh heavily in decision making. While young patients will in theory live longer and therefore be at a higher risk of metachronous CRC and in general will adapt better functionally than older patients, the majority of young patients with LS and CRC undergo segmental resection.
Advances in Endoscopic Imaging in Hereditary CRC
Performance of endoscopic therapies for adenomas in FAP and LS, and decision-making regarding surgical referral and planning, require accurate estimates of the presence of adenomas. In both AFAP and LS the presence of very subtle adenomas poses special challenges—microadenomas in the case of AFAP and flat, though sometimes large, adenomas in LS.
The need for sensitive means to endoscopically detect subtle polyps has increased with the recognition of flat adenomas and sessile serrated polyps in otherwise average-risk subjects, very attenuated adenoma phenotypes in attenuated adenomatous polyposis (AFAP), and subtle flat adenomas in LS. Modern high-resolution endoscopes improve adenoma detection yield, but the use of various vital dyes, especially indigo carmine dye-spray, has further improved detection. Several studies have shown that the improved mucosal contrast achieved with the use of indigo carmine can improve the adenoma detection rate. Whether family history is significant or not, careful clinical evaluation consisting of dye-spray colonoscopy (indigo carmine or methylene blue),[327,354,355,356,357,358,359] with or without magnification, or possibly newer imaging techniques such as narrow-band imaging, may reveal the characteristic right-sided clustering of more numerous microadenomas. Upper gastrointestinal endoscopy may be informative if duodenal adenomas or fundic gland polyps with surface dysplasia are found. Such findings will increase the likelihood of mutation detection if APC or MYH testing is pursued.