Surgical Management by Preoperative Stage
Surgical management may include segmental resection techniques or local excision. Segmental resection techniques include anterior resection, low anterior resection, abdomino-perineal resection, and Hartmann resection. (See "Special Considerations – surgical techniques according to height from anal sphincter below). Wherever possible, total mesorectal excision (TME) should be performed. TME has been shown to reduce the local recurrence compared with non-TME resection in randomised trials and is considered the optimal surgical intervention. TME is a specialised resection technique that requires some training. Surgeons are encouraged to learn and adopt this technique as standard operative management for rectal cancers.
Clinical stage 1 (T1, T2, N0, M0)
These tumours are managed by segmental resection (with TME if possible). Preoperative radiation is not indicated. Local excision may be considered for favourable lesions. The usual criteria for favourable lesions are well or moderate differentiation, size <3 cm, and absence of lymphatic or vascular invasion. Postoperative radiation therapy is usually indicated after local excision has been carried out.
Clinical stage 2 (T3, T4, N0, M0)
For non-fixed rectal tumours where full thickness penetration of the rectal wall is suspected, preoperative short course radiotherapy is an option. This regimen consists of five daily fractions of 500 cGy with the surgery to follow within ten days. Local excision is contra-indicated. Some studies have demonstrated similar benefits in terms of reduction in local recurrence and overall survival with preoperative radiotherapy as compared to postoperative radiotherapy, with the added advantage of fewer side effects with the former.
If the tumour has characteristics which suggest fixation or invasion of surrounding structures, preoperative radical radiotherapy with or without chemotherapy may be indicated. This regimen is usually given over five weeks with surgery to follow six weeks after completion of therapy.
Stage 2 tumours recognized postoperatively should be referred for combined adjuvant treatment if none was given preoperatively. If short course radiotherapy was utilised preoperatively, chemotherapy should be considered postoperatively.
Clinical stage 3 (any T, N1, N2, N3, M0)
These lesions are managed as for those in stage 2.
Clinical stage 4 (any T, any N, M1)
In spite of the presence of metastases, excision of the primary tumour may still provide the best form of local palliation. In appropriate circumstances, operation may be facilitated by pre-operative chemotherapy and radiation. The occasional patient with an isolated liver or lung metastasis may benefit from resection of the metastatic lesion. A modest proportion of patients who undergo such therapy can be cured. In general, lesions must be confined to the liver and/or lung, located in one area or lobe, not involve major vasculature (or bile ducts), and the patient must be well enough to have major surgery such as partial hepatectomy or lung partial or complete lobectomy. This type of surgery should only be carried out in a tertiary referral centre by surgeons with specific expertise in this kind of procedure.
Special Considerations – Surgical Techniques According to Height from Anal Sphincter
Sphincter-sparing resection should be considered for rectal cancer more than 4 cm above the anal sphincter. Ability to perform sphincter-sparing resection and reconstruction using techniques for coloanal anastomosis for distal-third rectal cancers will depend on body habitus, cancer size, and comorbid medical status. Suggested surgical techniques for rectal cancer resection, according to the distance of the lower end of tumour from the anal sphincter, are described in the following sections.
Tumour more than 10 cm from the anal sphincter
The technique of anterior resection for upper-third rectal cancer should include the following points: distal resection margin 5 cm from distal edge of tumour, subtotal mesorectal excision with distal mesorectal margin at least 5 cm from the distal edge of the tumour, sparing the nervi erigentes where possible, en bloc resection of adjacent organs infiltrated by rectal tumour for curative resection, and a long-tie on the superior rectal or inferior mesenteric artery marking the apex of the mesenteric resection.
Tumour less than 10 cm from, but above the anal sphincter
The technique of lower anterior resection for mid- and distal-third rectal cancer should include the following points: resection of entire rectum with at least 1 cm negative macroscopic distal margin, resection of entire mesorectum to top of anal sphincter and pelvic floor, sparing the nervi erigentes where possible, en bloc resection of adjacent organs infiltrated by rectal tumour for curative resection, and a long-tie on the superior rectal or inferior mesenteric artery marking the apex of the mesenteric resection.
Although a 2 cm distal margin is preferable, a distal margin of 1 cm for mid- and distal-third rectal cancer is acceptable because longitudinal mural extension of tumour is rarely more than 1 cm (1,2). It is known that lymph nodes may be present in the mesorectum both proximal and distal to the tumour. A 5 dm distal margin for proximal lesions is recommended to assure that all lymph nodes in the area of the tumour will be removed when less than total mesorectal excision is performed. Mid- and distal-third rectal cancer resection should include the entire mesorectum to remove all perirectal lymph nodes.
Although long-course preoperative radiation can decrease the gross size of the cancer, residual tumour may be present in the submucosa distal to the shrunken mucosal margin of the tumour. Therefore, the distal resection margin for radiated cancers should be more than 1 cm and should be guided by the location of the distal tumour margin before radiation in order to assure a clear distal resection margin.
Tumour near or at the anal sphincter
The technique of abdominoperineal resection for rectal cancer near or at the anal sphincter should include the following points: resection of the entire rectum and anal sphincter with wide ischiorectal margins, resection of entire mesorectum to top of anal sphincter and pelvic floor, sparing the nervi erigentes where possible, en bloc resection of adjacent organs infiltrated by rectal tumour for curative resection, and a long-tie on the superior rectal or inferior mesenteric artery marking the apex of the mesenteric resection.
References:
- Br J Surg 1990; 77:510-512. Karanjia ND, Schach DJ, North WRS, Heald RJ. "Close shave in anterior resection".
- World J. Surg 1992; 16:848-857, Heald RJ, Karanjia ND. "Results of radical surgery for rectal cancer".