Virinder Kumar Bansal, Mahesh C Misra, A Krishna, Gerhard F. Buess*
Department of Surgical Disciplines
All India Institute of Medical Sciences
New Delhi, India
* Section for Minimally Invasive Surgery,
Eberhard - Karls University Tuebingen,
Germany
Corresponding Author:
Dr Virinder Kumar Bansal
Email: drvkbansal@gmail.com
48uep6bbphidvals|248 48uep6bbphidcol2|ID 48uep6bbph|2000F98CTab_Articles|Fulltext Transanal excision of anorectal lesions is an attractive option for dealing with benign as well as malignant lesions of the anorectum. Benign lesions of the anorectum are best treated by local excision. Following transanal excision of rectal villous adenomas, recurrence rates range from 8% to 40% with most studies reporting a recurrence rate of around 20%[1,2,3]. Because of the ability to perform more precise dissections TEM confers a lower recurrence rate of less than 10%[4].
Radical resection with or without neoadjuvant or adjuvant therapy remains the most effective proven treatment for carcinoma rectum. With advances in surgical technique and the incorporation of a multi modality approach, sphincter preservation rates have improved but an abdominal operation is always associated with certain morbidity and mortality. In contrast local excision is associated with minimal morbidity and mortality and it preserves bowel continuity and avoids complications of radical excision like bowel, bladder and sexual dysfunction.
Local excision for rectal cancers was first described by Lisfranc in 1827[5]. It is appealing ecause of its technical ease and excellent functional results, but concern over inadequate pathologic staging and inferior treatment outcomes when compared with radical surgery remain a major hurdle for its widespread use. Local failure rates in recent series for local excision are 4%-18% for T1 rectal cancers and 22% to 67%for T2 cancers[6]. Cancer cure rates of 70-80% have been reported[6]. Highly stringent selection criteria in the form of tumour size less 3cm, well or moderately differentiated cancer with no lymphovascular invasion have been suggested. The development of better staging modalities in the form of endorectal ultrasound and magnetic resonance imaging has led to resurgence of interest in local treatment of early stage rectal cancers.The growing confidence in effective chemoradiation as adjuvant therapy has brought hope that more patients can be offered local excision.]
The aim of local excision is complete removal of the rectal tumour with a full thickness excision of rectal wall with clear margins. A 5 mm - 1 cm lateral margin of rectal wall and a clear deep margin are essential. The various techniques for local excision of anorectal lesions can be either surgical or endoscopic. The surgical techniques include Transanal Excision (TE), transcoccygeal excision, trans-sphincteric excision and Transanal Endoscopic Microsurgery (TEM). The endoscopic techniques include snare polypectomy, fulguration or Endoscopic Submucosal Resection (EMR) or Endoscopic Transanal Resection (ETAR).
Transanal excision for lower rectal adenomas, polyps and cancer was popularised by Parks[7]. It is one of the most frequently used techniques for rectal lesions situated up to 6- 8 cm from anal verge. This technique is especially good for excision of early rectal lesions with poor surgical risk or those who refuse permanent colostomy and radical surgery. Low complication rates has been reported in the literature with a bleeding rate of 10%, perforation in 6%, anal stenosis in 5% and a mortality rate of around 2%[8].
Pigot et al[1] reported a 36% recurrence rate, post operative complications in 8 patients and one death for benign rectal adenomas in 207 patients. Recurrence free survival probability was estimated to be 99.5% at 1 year, 96% at 5 years and 95% at 10 years. In a retrospective analysis, Bentrem et al[9] compared transanal excision with radical surgery in patients with T1 adeno-carcinoma of the rectum over a 17 years period. There was a 3 to 5 fold higher risk of tumour recurrence following trans-anal excision compared with patients treated by radical surgery. Bentrem et al[9] suggested that local excision should be reserved for low risk cancer in patients who will accept an increased risk of tumour recurrence, prolonged surveillance and possible need for salvage surgery.
In the Norway Rectal Cancer Study Group[10] patients with T1 cancer were treated with radical surgery (n=256) or transanal excision (n=35) over a 6 years period. Local recurrence was 12% with local excision compared to 6% with radical surgery.In an interesting review from the National Cancer Database, You et al11 found that over a 14 year period local excision increased significantly for both T1 lesions (26.6 to 43.7%) and T2 lesions (5.8- 16.8%) over the last 10 years.The 5 years local recurrence rate for local excision wassignificantly higher than standard resection for both T1 (12.5% to 6.9%)and T2 (22.1 to 15.1%) lesions. However, 5 years and 8 years overall survival was not significantly different between the two groups.
Chang et al[12] reviewed 10 nonrandomized studies out of which only one study was prospective, 5 were comparative, and 5 were case reports. Five-year overall survival rate varied from 69% to 83% in the local excision group versus 82% to 90% for the radical excision group. Local recurrence rates ranged from 9% to 20% for local excision and from 2% to 9% for radical surgery. Systemic recurrence rates ranged from 6% to 21% for local excision and from 2% to 9% for radical surgery. They concluded that radical surgery is the more definitive cancer treatment; however, it does not eliminate local excision as a reasonable choice for many patients, who will have lesser procedure-related morbidity and will accept an increased risk of tumor recurrence, a prolonged period of postoperative cancer surveillance, and a decreased success rate by salvage surgery.
The trans-sphincteric and transcoccygeal approaches have more or less been abandoned. These approaches were indicated for extensive lesions located in rectum upto a distance of 8-10 cm from anal verge.The posterior approach (represented by a combination of coccyx removal and partial sphincter division) was indicated for extensive lesions in the anterior rectum at a distance of 8-10 cm from the anal verge. Variable rates of complications in the form of fistulisation and wound infection and very high rates of recurrence have been reported.[13] In a review[13,14] of 360 cases treated for benign and malignant lesions, faecal fistula was the most frequent complication in 5%-70% of patients and faecal incontinence in 5%-25%. Adenoma recurrence rate was up to 33% and a stoma was necessary in 20%-70% of patients, as a temporary stoma to avoid faecal fistula or as a therapeutic stoma after its appearance.
Endoscopic transanal excision was first described in 1977 by Lindenschmidt et al[15] and has been used in the resection of rectal adenomas. The endoscopic approach has beenfound to be useful for polypoidal lesions and snare polypectomy can be done for such lesions. These give a very good local control with minimal morbidity and mortality and recurrences can be dealt with easily.Though these procedures can be done under sedation they have a significant disadvantage of inadequate margins.
The endoscopic submucocal resection (EMR) or endoscopic transanal resection (ETAR) have been found to be very useful technique for large villous adenomas. A review[16] of 304 cases (464 procedures) from seven studies, most of them in the United Kingdom, suggests that ETAR is valuable in the resection of rectal adenoma with low morbidity and mortality. This technique has shown low recurrence, however, it is impossible to know if the resection is complete and the margins are free of tumour after various procedures in the same patient from whom the adenoma is resected piecemeal.
TEM has been used successfully in the management of rectal adenoma and in selected cases of rectal carcinoma, since it was introduced by Professor Buess in 1984[17]. TEM enables local excision of selected low, middle and upper rectal tumours (both benign and malignant) up to 24 cm from the anal verge, and offers a minimally invasive alternative to TE and radical surgery[18]. Patients are able to avoid conventional open surgery with an abdominal incision, resume normal activities sooner and have improved survival.
The only disadvantage of TEM is that it requires special equipment and there is a long learning curve for this procedure.
It uses a transanal approach, with a set of endoscopic surgical instruments that can reach further into the rectum than other form of local excision, along with a form of enhanced or assisted vision (usually stereoscopic) (Figure 1 and 2). This magnified three dimensional image allows an optimal view of the tumour and this facilitates an extremely precise dissection. Insufflation of the rectum up to 40mm of Hg is used to improve the field of vision and access.
In one of the largest studies19 of adenoma resection using TEM, the authors reported a 3.4% early postoperative complication rate and 1.2% and 7% recurrence rates after 1 and 5 years, respectively, in a series of 286 cases. In a review 16 of 1682 adenoma resection procedures from 18 studies, an average of 11% of the patients were found to have residual adenoma in the surgical margin, 6.3% had recurrence, and the complication rate was up to 11% during a follow-up period of 12 months in one series, and more than 24 months in the rest of the studies. Even for recurrent adenoma, TEM has now become an important alternative treatment. Five series[20,21,22,23,24] have reported the use of EM in the treatment ofrecurrent adenoma or residual disease without further recurrence.
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Moore et al[25] compared LE vs TEM in 171 patients with rectal masses; there was no difference in the complication rate between the groups (TEM 15% vs transanal excision 17%, P=0.69). TEM was more likely to yield clear margins (90 vs. 71 percent, P=0.001) and a non-fragmented specimen (94 vs. 65 percent, P<0.001) compared with transanal excision. Recurrence was less frequent after transanal endoscopic microsurgery than after traditional transanal excision (5 vs. 27 percent, P=0.004).
TEM has been used extensively recently for the treatment of early rectal cancers with good results. Although no randomized trials are available comparing TEM with transanal excision or radical surgery, but whatever prospective studies are available have shown good outcomes with TEM in selected patients. Buess and colleagues[26,27] reported a 4% local rate for T1 tumours while Floyd and Seclarids[28] reported 3% local recurrence rates. Winde and colleagues[29] conducted randomized trial to compare TEM with anterior resection and evaluated 24 patients of TEM and 26 patients with anterior resection with a mean follow up of 45 months. There were no differences in survival curves for both the groups.
Middletone et al[30] in 2005 reviewed three comparative studies (including one randomized, controlled trial) and 55 case series comparing TEM with traditional local resection and noted a 6% vs 22% local recurrence and complication rate of 10% vs 17%.
Zieren et al[31] reviewed 5 studies (two controlled randomized and three non-randomized) comparing outcome after TEM vs. radical surgery, either open or laparoscopic, in patients with rectal cancer. Hospital stay, complication rate and overall morbidity and mortality were lower in the TEM groups in all studies. With the exception of one study, recurrence was slightly (but non-significantly) increased in the TEM groups. No difference for T2 tumors with TEM vs. laparoscopic resection was seen though. Overall survival was not statistically different. Palma et al[32] compared TEM with radical surgery in patients with T1 rectal cancer. They found a recurrence rate of 5.8% vs 0% but complication and reoperation rate of 23.5% vs 2.9% in favour of TEM group and concluded that patients undergoing TEM showed no significant difference in terms of overall survival and disease free survival.
In a review of literature on TEM in rectal cancers, Suppiah et al[33] suggested that the strongest level of evidence (Level II) favored TEM over radical surgery and laparoscopic resection in term of mortality and morbidity. There was no difference in recurrence at follow-up of 41 and 56 months. The oncological outcomes in TEM were similar to radical surgery in highly selected cases but with far less mortality (near 0%), morbidity, blood loss, hospital stay and genitourinary/gastrointestinal dysfunction. TEM alone (+/- adjuvant therapy) appears sufficient for ‘favourable’ T1 tumors. ‘Unfavourable’ T1 or T2 tumors require adjuvant treatment. TEM should only be used for palliation in T3+ cancers.
Transanal excision is a feasible and attractive option for treatment of benign as well as malignant lesions of the anorectum because of its lower morbidity and good functional outcome. Stringent patient selection, tumor characteristics, staging of the tumour with adjuvant or neoadjuvant therapy can provide good results even in patients with rectal cancer. A careful follow up and discussion of all treatment options with the patient is mandatory. TEM offers better access with superior endoscopic magnification and allows complete resection with minimal morbidity. TEM seems to be the procedure of choice for local excision of anorectal lesions. However, there is a need for well designed randomized clinical trial comparing TEM, radical surgery and traditional transanal excision to come to any firm conclusions.
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