___________________________________________________________________________ Colorectal Cancer
ASCRS GUIDELINES FOR SURGICAL MANAGEMENT OF RECTAL CANCER
Surgical Techniques and Operative Considerations, Local Excision Local excision is appropriate for carefully selected T1 rectal cancers without high-risk features. Surgical Techniques and Operative Considerations, Radical Excision A thorough surgical exploration should be performed and the findings documented in the operative report. Total mesorectal excision should be used for curative resection of tumors of the middle and lower thirds of the rectum, either as part of low anterior or abdominoperineal resection. For tumors of the upper third of the rectum, a tumor-specific mesorectal excision should be used with the mesorectum divided ideally no less than 5 cm below the lower margin of the tumor. A 2-cm distal mural margin is adequate for most rectal cancers when combined with a total mesorectal excision. For cancers located at or below the mesorectal margin, a 1-cm distal mural margin is acceptable. Proximal vascular ligation at the origin of the superior rectal artery with resection of all associated lymphatic drainage is appropriate for most rectal cancer resections. In the absence of clinical involvement, extended lateral lymph node dissection is not necessary in addition to total mesorectal excision. Patients with an apparent complete clinical response to neoadjuvant therapy should still be offered definitive resection. After low anterior resection and total mesorectal excision, the formation of a colonic reservoir may be considered. Intraoperative anastomotic leak testing should be performed to help identify an anastomosis at increased risk of a subsequent clinical leak. A diverting ostomy should be considered for patients undergoing a total mesorectal excision for rectal cancer. In patients undergoing a total mesorectal excision, an intraoperative rectal washout may be considered. In patients with T4 rectal cancers, resection of involved adjacent organs should be performed with an en bloc technique. Current evidence indicates that laparoscopic total mesorectal excision can be performed with equivalent oncologic outcomes in comparison with open total mesorectal excision when performed by experienced laparoscopic surgeons possessing the necessary technical expertise. Oophorectomy is advised for grossly abnormal ovaries or contiguous extension of a rectal cancer, but routine prophylactic oophorectomy is not necessary. Tumor-Related Emergencies In patients with large-bowel obstruction, an expanding stent is an acceptable treatment option in the palliative setting or as a bridge to definitive resection. Multimodality Neoadjuvant Therapy Neoadjuvant therapy should be used for locally advanced cancers of the mid or distal rectum. Multimodality Adjuvant Therapy Adjuvant chemoradiotherapy should be recommended for select patients with stage III or high-risk stage II rectal cancer who have not received neoadjuvant therapy. Adjuvant chemotherapy should be recommended for patients with high-risk stage II and all stage III disease previously treated with neoadjuvant therapy. Source: [189] Table 10
Endoscopic microsurgery cannot perform excision and staging of mesorectal lymph nodes, a limitation because T1 lesions have a 6% to 11% risk of harboring nodal metastasis [262]. Local recurrence rates range from 7% to 21% for T1 lesions and 26% to 47% for T2 lesions [262; 263; 264]. Total mesorectal excision with autonomic nerve preservation via low-anterior resection is preferred, followed by colorectal anastomosis in advanced mid- to upper-rectal tumor. Low ante- rior rectal resection is associated with bowel urgency, increased bowel frequency, clustering, and fecal incontinence from loss of rectum reservoir function. The colonic J-pouch is the superior approach for improving postoperative bowel function [58; 265].
In patients unsuitable for sphincter-preservation, total meso- rectal excision via abdominoperineal resection is preferred, although this leaves patients with a permanent colostomy [266; 267; 268]. Total mesorectal excision has demonstrated reproducible reductions in local recurrence and improvement in disease-free and overall survival [269]. The low incidence of local relapse after meticulous mesorectal excision has led some investigators to question the routine use of adjuvant radiation therapy. Because of an increased tendency for first failure in locoregional sites only, the impact of perioperative radiation therapy is greater in rectal cancer than in colon cancer [206].
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