Colon and Rectal Surgeon
Surgical Specialists of Spokane
Considerable progress has been made in the management of rectal cancer since the advent of the Miles Procedure (Abdominoperineal Resection) at the turn of the last century. Now more so than ever patients with a newly diagnosed rectal cancer may be offered a curative treatment protocol while still maintaining gastrointestinal continuity and sphincter function. Patients owe this progress to improved pre-treatment staging, neoadjuvant treatment protocols and improved surgical technique.
Rectal Cancer Staging
Transrectal ultrasound (TRUS) has emerged as the most sensitive method for determining locoregional tumor stage and should be considered the standard of care in the pre-treatment evaluation of the patient with rectal cancer. This information is obtained in a well-tolerated outpatient endoscopic procedure. Combined with an assessment of the patient’s performance status it can be used to accurately predict prognosis and dictate the most appropriate treatment algorithm for each individual thereby maximizing cure rate and sphincter preservation while minimizing treatment related morbidity.
Surgical Technique
Following completion of neoadjuvant therapy discussed in detail by Drs. Chaudhy and Laing, surgical management consists of either local tumor excision or radical proctectomy. The best opportunity for cure rests with proctectomy/mesorectal excision with colorectal or coloanal anastomosis. When performed by a well trained surgeon with attention to complete mesorectal excision ensuring uninvolved tangential margins results in low local recurrence rates (2-3%), a devastating and often incurable problem. Low anastomoses (< 5 cm) are protected with fecal diversion in the form of a loop ileostomy. Continuity can be restored in 6-12 weeks with a well-tolerated second procedure. Long-term functional outcome can be improved with patients requiring a low anastomosis with the creation of a colonic J-pouch thereby improving the reservoir function of the neo-rectum. A new technique, the transverse coloplasty, may supplant the J-pouch due to ease of construction, anatomic advantages and similar functional outcome.
Abdominoperineal resection (APR) continues to have a role in selected cases. It is primarily required in patients in whom tumor location/characteristics and/or patient anatomy does not allow a curative resection while preserving sphincter function. It is almost required when salvage surgery for pelvic recurrence is being performed. En bloc pelvic organ resection and pelvic exenteration remain a radical option for the most advanced primary or recurrent tumors. This obviously requires a coordinated approach with multiple surgical specialists. While previously committing the patient to a permanent stoma, restoration of bowel continuity can now be offered to select patients requiring APR after an appropriate disease free interval with implantation of an artificial bowel sphincter.
A less radical approach aimed at minimizing morbidity and preserving sphincter function is termed local therapy. It takes the form of transanal excision (TAE) or transanal endoscopic microsurgery (TEM). TAE is accomplished via an operative proctoscope and is suitable for tumors within 5-7 cm of the anal verge. TEM is performed via a specially designed proctoscope employing laparoscopic instruments and techniques and allows access to higher tumors (10-12 cm from the anal verge). Local therapy for cure may be appropriate in selected early (uT1N0) tumors without high-risk features. High-risk features include poor differentiation and lymphovascular invasion. Patients with a lower performance status, a more advanced tumor (uT2N0) or one with high-risk features may also be appropriate for this modality. Local recurrence rates for this approach are related to the T stage of the tumor (T1 - 10%, T2 – 30%). T4 and node positive tumors uniformly recur. Recurrence can be salvaged in only 50% of cases with a resulting 5-year survival rate of only 50%.
Patients with locally advanced, obstructing tumors have been relegated in the past to fecal diversion often with little hope of restoration of intestinal continuity. A new technique, the endoscopic placement of a colonic wallstent allows colonic decompression and preparation and a one-stage resection of anastomosis. Additionally patients with unresectable, obstructing tumors can be effectively palliated and potentially avoid an operation and difficult recovery during a time of limited life expectancy with placement of a colonic stent.
Conclusions
Accurate pre-treatment staging allows individualization of treatment for patients with rectal cancer. Neoadjuvant therapy and improved surgical techniques have improved rates of sphincter preservation as well as long term functional outcome while also improving survival. New techniques for restoring sphincter function have allowed reversal of permanent stomas in select patients. Non-surgical palliative options have also lowered the incidence of fecal diversion.