How low is low? Evolving approaches to sphincter-sparing resection techniques

Although advances in rectal cancer staging may ultimately be accurate enough to reliably exclude disease outside the rectal wall (thereby allowing local approaches to be more widely and safely applied) and advances in the use of neoadjuvant chemo- and radiation therapy may ultimately produce more "complete responders" that can be accurately identified and spared surgery altogether, as it stands, radical resection forms the basis of curative treatment for rectal cancer. However, the concepts that guide the surgeon in choosing the optimal approach in radical resection are changing. In the past, the decision as to how to proceed surgically with radical resection was based primarily on the level of the tumor above the anal verge or anorectal ring. The issue was primarily "How low is the tumor?" and "Is the distal margin safe?" A more modern approach focuses attention on achieving a negative circumferential margin despite what historically may seem to be a very minimal distal margin, the current issue is not "How low is the tumor?" so much as it is "How deep does the tumor go?". This shift in focus has been a major impetus in the evolution of sphincter sparing resection techniques.