The largest cohort analysis to date from the Colon Cancer family Registry examined 382 patients with colon cancer and mismatch repair gene mutations. Most patients (332/382 (87%)) underwent segmental resection. metachronous cancer occurred in 74 (22%) of 332 patients who had segmental colectomy versus 0 (0%) of 50 patients who had total colectomy. Both groups underwent appropriate endoscopic surveillance, with an average of 1 examination every 20 months in the segmental group and 1 examination every 16 months in the total colectomy group. the cumulative risk of metachronous colorectal cancer in patients in the segmental group was 16% at 10 years, 41% at 20 years, and 62% at 30 years. this rate is at least as high, or higher, than the anticipated risk of a patient with lynch syndrome developing colorectal cancer without ever having a segmental colectomy, suggesting that there is no risk reduction against metachronous cancer when patients undergo segmental resection. they noted that the risk of metachronous colorectal cancer was reduced by 31% for every 10 cm of bowel removed.

As noted in table 1, the US multi-society task force on Colorectal Cancer recommends total colectomy with ileorectal anastomosis for the treatment of colon cancer in the setting of lynch syndrome. The 2013 mallorca guidelines, composed of expert opinion from the mallorca group, recommend that “the option of subtotal colectomy including its pros and cons should be discussed with all lynch syndrome patients with CRC, especially younger patients. It should be noted that before available data regarding the benefit of metachronous cancer risk reduction was defined, segmental resection was widely preferred and performed (≈85%–87% of the time, as shown above). In part, this may be secondary to functional issues of a total versus segmental colectomy (see below), although oncologically segmental colectomy does not address the risk of metachronous cancer. this practice may be slow to change given the recent nature of the cited literature. However, based on currently available evidence, there is superior cancer risk reduction with total colectomy for the treatment of colon cancer in the setting of lynch syndrome, and total abdominal colectomy with ileorectal anastomosis is the preferred treatment for most patients.