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.
Modern high-resolution endoscopes improve adenoma detection yield, but use of various vital dyes, in particular indigo carmine dye-spray, have further improved the 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),[298,318,319,320,321,322,323] 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.
One study from Holland using indigo carmine dye-spray for detection of duodenal adenomas showed an increase in number and size of adenomas, including some large ones. Overall Spigelman score was not significantly affected.
An estimated 7% to 10% of people have a first-degree relative with CRC,[326,327] and approximately twice that many have either a first-degree or a second-degree relative with CRC.[327,328] A simple family history of CRC (defined as one or more close relatives with CRC in the absence of a known hereditary colon cancer) confers a twofold to sixfold increase in risk. The risk associated with family history varies greatly according to the age of onset of CRC in the family members, the number of affected relatives, the closeness of the genetic relationship (e.g., first-degree relatives), and whether cancers have occurred across generations.[326,329] A positive family history of CRC appears to increase the risk of CRC earlier in life such that at age 45 years, the annual incidence is more than three times higher than that in average-risk people; at age 70 years, the risk is similar to that in average-risk individuals. The incidence in a 35- to 40-year-old is about the same as that of an average-risk person at age 50 years. There is no evidence to suggest that CRC in people with one affected first-degree relative is more likely to be proximal or is more rapidly progressive.