Minimally Invasive Anorectal Surgery: From Parks Local Excision to Transanal Endoscopic Microsurgery to Transanal Minimally Invasive Surgery

Total mesorectal excision remains the preferred oncological treatment of tumors of the rectum, providing excellent cure rates and minimal local recurrence. Surgical advances have led to more sphincter-sparing procedures using coloanal anastomosis. However, abdominoperineal resection with permanent colostomy remains the most common procedure performed today for tumors of the distal rectum. In addition, even precise total mesorectal excision results in frequent incidence of sexual, urologic, and bowel dysfunction. Local excision has slowly gained popularity, but is still considered a substandard operation owing to higher recurrence rates. However, the innovation of potentially superior platforms (transanal endoscopic microsurgery/transanal minimally invasive surgery) designed to enable improved access and visualization to the rectum has allowed surgeons to excise lesions more proximally in the rectum and with improved precision, yielding diminished recurrence rates. More recent data demonstrate the use of transanal endoscopic microsurgery and transanal minimally invasive surgery in combination with multimodality therapy and careful patient selection results in outcomes approaching standard oncological treatment. The evolution of procedures, newer instrumentation, and increasing knowledge of the tumor biology is quickly closing the gap between classical resection and various modalities of local excision.