Major Genetic Syndromes
The surgical management of a patient with LS must be individualized. Management of these patients can be subdivided into patients with newly diagnosed CRC, those with CRC treated with segmental resection, and those who are at risk of developing CRC or who are mutation carriers. Because of the increased incidence of synchronous and metachronous colorectal neoplasms, many experts have advocated that the treatment of choice for a LS patient with newly diagnosed colon cancer is a subtotal colectomy with anastomosis of the ileum to either the sigmoid colon or the rectum. The risk of metachronous CRCs has been estimated to be as high as 40% at 10 years after less than a subtotal colectomy, and up to 72% at 40 years after the diagnosis of CRC.[217,313,314,315] There are no prospective data, however, to suggest a survival benefit from a subtotal colectomy over a segmental resection. In a decision analysis model, one study showed that performing a subtotal colectomy at a young age (27 and 47 years) led to an increased life expectancy of 1 to 2.3 years compared with a segmental resection. In this model, the potential benefit in life expectancy depended on the age of the patient and stage of the cancer at diagnosis. The older the patient and/or the more advanced cancer at diagnosis, the less theoretical benefit in terms of life expectancy from a subtotal colectomy as opposed to a segmental resection. This model did not take into account quality of life and was reported in absolute years. In a Markov decision analysis model taking into account both survival and quality of life based on assumptions obtained from published literature, the mean survival of a male aged 30 years with LS was 0.7 years better in an individual who underwent a total abdominal colectomy versus a segmental resection. When quality-adjusted life years (QALYs) were taken into account in this model, patients undergoing segmental resection had 21.5 QALYs, whereas patients undergoing an abdominal colectomy had 21.2 QALYs. Because the data underpinning these models are not likely to be validated and this topic is controversial, most surgeons choose to individualize the surgical decision based on patient-centered considerations.
Aside from the diagnosis of LS, other factors to consider in individualizing the surgical decision are age at diagnosis and the stage of the primary CRC. Most surgeons would consider loss of protein expression or MSI in the tumor in patients younger than age 50 years as evidence of LS even if germline mutational testing is uninformative or cannot be done before surgery.
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.[315,315] No survival advantage was demonstrated when performing a more extensive procedure compared to a segmental resection in these studies.