Introduction

Transanal endoscopic microsurgery (TEMS) is a minimally invasive surgical technique, which is performed endoluminally (inside the lumen of the rectum).  It is primarily used for the removal of rectal tumours, both benign and malignant that cannot be removed by colonoscopy. The procedure may also be used on patients who are unfit or unwilling to undergo conventional open surgery. The relatively elderly local Dorset population forms a group perhaps most appropriate for the use of TEMS.

Background

Colorectal cancer is the second most common cancer in the UK, with an overall mortality rate of 40%. Up to half of these cancers are found in the rectum (Hermanek and Gall 1986). Polyps in the rectum are common and some of these will be removed at traditional endoscopic hot biopsy or snare. At the other end of the spectrum, some rectal cancers may be too advanced for local excision or even radical resection. Overall up to 5% of rectal cancers may be treated by TEMS.

 

 

TEM is used to locally excise tumours in the low, mid and upper rectum (both benign and malignant), enabling patients to avoid conventional open surgery with an abdominal incision.

This allows patients to resume normal activities sooner and have improved survival. Patients with small, early benign or malignant tumours of the rectum are candidates for this surgery. Early colorectal carcinoma is usually defined as an infiltrating carcinoma with submucosal spread but no involvement of the muscle equating to T1 stage (see Figure below).



Removal of precursor rectal lesions such as adenomas is thought to be crucial in preventing rectal cancers. A malignant polyp is an adenoma in which the carcinoma has invaded into the submucosa across the muscularis mucosa. Unless this layer has been invaded, the carcinoma usually has no metastatic properties because of the general absence of lymphatics (Welton et al 2001).

TEM may also be used with patients who are unable to undergo conventional open surgery, as well as patients who are unwilling to face a more radical procedure, such as an anterior resection or even an abdominoperineal excision.

Suitable Patient Groups for TEMS

The choice of surgical technique is influenced by the location of the tumour (determined using a sigmoidoscope) and its degree of mobility (mobile, tethered or fixed), which can be established by palpation (Dorudi et al 2002). Before considering TEM, liver imaging should be performed to establish the presence or absence of liver metastases. CT and MRI have been shown to be accurate (Dorudi et al 2002) and are routinely carried out for all rectal cancers at Poole preoperatively.

Locally available Endoluminal ultrasound can accurately show the main layers of the rectal wall (see Figure above) and the degree of tumour penetration. Visualisation of the submucosal layer is extremely important, since a breach of this layer defines an invasive cancer (Dorudi et al 2002). The accuracy of endoluminal ultrasound is reported to be between 67 per cent and 93 per cent.

If suitable rectal lesions cannot be offered TEMs then major invasive procedures with radical resection are indicated usually involving anterior resection or abdominoperineal resection (APR) with their accompanying morbidity and mortality rates.

Buess, the originator of the TEM procedure outlined cases best suited to the procedure (Buess and Mentges 1992):

• histologically confirmed adenomas in the rectum and lower sigmoid colon up to 25 cm (proximal limit) from anal verge
• well and moderately differentiated carcinoma of the preoperative stage uT1 (where ‘uT’ represents ultrasound staging of tumours)
• well and moderately differentiated carcinoma of the preoperative stage uT2 in patients over 70 years or younger patients with severe operative risks
• less common tumours and lesions, such as carcinoid or chronic rectal ulceration.

Alternative Treatments

Traditional Endoscopic Local Excision

Tumours in the lower part of the rectum (within 8 cm of the anal verge) can be excised by a direct transanal approach or with snare diathermy. TEM offers many advantages over conventional local excision methods including complete resection with a tumour-free margin because of improved visualization and the possibility of full rectal wall thickness resections with sutured repair. Alternatively endoscopic treatment using a resectoscope has been used, but since the tumour is removed in fragments, both histological analysis and complete excision may be difficult to achieve (Steele et al 1996).

Traditional Surgical Resection

Anterior resection or an abdominoperineal excision are the surgical alternatives but both have major morbidity and mortality of lengthy maximally invasive procedures including stomas, anastomotic leakage and urosexual dysfunction.

Results

Over night stay was suggested as bleeding is a possibility especially in the first 24 hours. The first dozen patients who underwent TEMS had no major morbidity, though in men urinary retention occurred three times. No significant bleeding occurred requiring transfusion. The margins were clear in all 12 cases and follow in required will usually be further endoscopy 6 – 12 months after the procedure. In these 12 patients there were three rectal cancers and the rest were adenomatous polyps. The rectal cancers patients have required no further treatment.